BEPP NA Harvard edx Energy within Environmental Constratints

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Basic Questions Bookmark this page Multiple Choice 1/1 point (graded) This a multiple-choice problem. You will choose just one response, receiving credit for the right answer. Select a vowel fro... m the list below. A correct B C D E Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Dropdown 1/1 point (graded) This is a dropdown problem. It's basically identical to a multiple-choice problem, it just displays things in a different way. Dropdown problems only ever have one correct answer. Which of these numbers is a prime number? correct Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Checkboxes 1/1 point (graded) This a checkbox problem, also known as a "check all that apply" problem. You will choose ALL of the correct responses, receiving full credit only if you select all of them and none of the incorrect answers. 17 Schlumberger-Private This problem also allows for partial credit! It uses a scheme called "Every Decision Counts," which is the standard scheme in this course. Each choice is worth an equal amount of the total credit (20% in this case). Try answering the question different ways to see how partial credit works! Which of the following are vowels? Select all that apply. A B C D E Complex Questions Bookmark this page Numerical Input 1/1 point (graded) Some problems require a numerical input. Your answer will be marked correct if it is within a certain range of the right answer (usually about 5%, though it varies from problem to problem). If you need a calculator, you can find an icon in the bottom right-hand corner of your window that will show one for you. Click the (i) button to learn how to use it. You can also find many good calculators online, from Google's push-button calculator to Wolfram Alpha. Enter the approximate value of the mathematical constant π (pi): correct 3.14 Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Exponential Input 1/1 point (graded) Very large or very small numbers are best input with exponential notation. For instance, the number 8,000,000 (eight million) is equal to 8×106. In this course, you can enter 3.14 Schlumberger-Private that as either 8 * 10 ^ 6 or as 8e6 in these problems. Try out exponential notation in the question below. One gigajoule is equal to 947817 British thermal units. Enter this number below in exponential notation. The tolerance on this question is 5%. BTU correct 9.47×105 Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Formatting Numbers While there is a 5% tolerance for most of the problems in this course, you must also be sure to enter your numbers in the right format. If you type "9.48e5" in the answer box above, the computer knows how to interpret that. Similarly, it knows how to interpret "9.48*10^5" or"9.48 * 10 ^ 5" (with spaces). What it doesn't know how to do is handle "9.48 x 10 ^ 5" with an "x" instead of a star. That little change throws things off. You need to use exactlythe right formatting. This is one of the most common errors made by people who are new to edX. If you are working on a numerical problem, you should double-check your formatting before entering each answer. Also - did you look at the answer to the last problem? It contains extra information about partial credit in numerical problems! Go take a look if you didn't see it before. Matching 1.0/1 point (graded) This is a matching exercise. Drag the elements on the left into the ones on the right to create a match. Click on the [-] to remove the match. You can match items with more than one other item, but you should choose the best match if you can. Click on the individual items for a better view if you need it. This problem type gives partial credit! Each correct assignment is worth one point; each error takes a point away. Play around with different matches to see how it works. 9.47e5 Schlumberger-Private Syllabus Quiz, Part 1 Bookmark this page Now that you know how to answer edX questions, it's time for your first quiz. Below are some quick questions to make sure you understood the most important highlights from our syllabus. This should be very easy - all of the information can be found on the Syllabus, the Schedule page, and in the introductory videos in this section. A syllabus quiz might seem a little silly, but reading the syllabus carefully will improve your course experience. Also, our course staff often spend a substantial amount of time answering questions where the answer is in the syllabus. We're always happy to help, but hopefully this quiz will help you know the most important information before starting the course. Unlike the practice problems, this quiz is graded, so do your best! This quiz appears as Work01 on your Progress page. Annotate Collaboration Schlumberger-Private 1/1 point (graded) Select all that apply. Which of the following are acceptable ways to collaborate? Working jointly to develop an overall approach to an assignment Taking someone else’s formulas and plugging in your numbers to get the final answer Posting answers to a problem before the deadline Getting hints from peers or course staff if you’re stuck correct Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Graded Assignments 1/1 point (graded) Select all that apply. Which of the following types of graded assignments appear in this course? Quizzes Practice Exams Coursework Peer-graded Essays correct Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Course Content 1/1 point (graded) In this course you’ll learn... (Select all that apply.) Details of solar and nuclear power Details of wind power and biofuels Environmental impacts including climate change, air pollution, and land use The flow of energy through modern economies, including costs Details of end uses of energy (tranportation, industry, etc.) Schlumberger-Private Lots of theory, e.g. electrodynamics as a foundation for understanding solar panels Lots of details about real world devices, e.g. the performance and cost of modern commercial solar panels How to critically compare energy options, using good references and combining quantitative and qualitative analysis correct Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Deep Dives 1/1 point (graded) In this course, deep dives are... Underwater explorations Our recommended resources for learning more about a topic correct Required readings Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Navigating from Page to Page 1.0/1.0 point (graded) EdX courses have many parts to them. You can find page links at the top of the site, sections and subsections in the course overview, and the Contact Us button on the far left of your window. Some subsections (like this one) also have multiple pages. Where can you find the links that take you to these pages? Select all that apply. Via the buttons in the "ribbon" at the top of the page. Via the left-right arrows in the "ribbon" at the top of the page. Via the left-right arrows at the bottom of the page. Via links in the course that take you to a specific page. Schlumberger-Private Syllabus Quiz, Part 2 Bookmark this page Certificates 1/1 point (graded) If you pass this course and pay for a verified certificate, where will you get your certificate? This course does not give certificates In e-mail In your edX dashboard correct In the mail Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Grades 1/1 point (graded) Where can you find your grades? On the Progress page correct By e-mailing edX On the Discussion page This course is ungraded Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Deadlines 1/1 point (graded) When are the deadlines for your work in this course? There are no assignments in this course. Every Sunday night at 23:30 UTC. As long as we get it done before the last day it's ok. correct Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Where to Learn More 1/1 point (graded) Schlumberger-Private Where can you go for more information on this course and its topics? Select all that apply. I can visit the discussion boards. I can read the edX FAQ page. I can use the Energy Resources Page. I can search the web and beleive anything I read. I can search the web and carefully check what I find. I can read books on energy and the environment written in the last five years. I can read books on energy and the environment written fifty years ago. Background Questions Bookmark this page Background Questions These questions help you decide if you have appropriate background knowledge for this course. They cover the kinds of introductory physics and chemistry we assume students are comfortable with, as well as some small calculations. Please answer quickly with your best guess, and try to finish in less than 15 minutes. Annotate Unit Conversion Many of the problems on this page require you to convert from one unit to another - for instance, from miles to kilometers, or from gigajoules to kilowatt-hours. There are many different resources available online to help you with these conversions, and we encourage you to become familiar with one of them and use it throughout the course. Some options include:  Using a search engine, like Google or Bing, and typing in "20 miles in kilometers"  Using a site designed for unit conversions, like UnitJuggler.  Using a tool like Wolfram Alpha, which does unit conversions and also has curated data on energy costs and energy content. Schlumberger-Private Annotate Power or Energy? 0.5/1 point (graded) Some of these options are examples of energy, and some are examples of power. Put a check in the box for all the examples of power. Which of these are examples of power? This sandwich has 600 Calories That exercise burns 500 Calories/hour correct Our household used only 100 kWh of electricity last month My computer uses 60 watts of electricity correct partially correct Explanation Calories and kilowatt-hours are both measurements of energy. Watts and calories per time are both measurements of power. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Sandwich-Powered 0/1 point (graded) How many watts do I consume if I eat a 600-Calorie sandwich in 600 seconds? watts incorrect 4180 4180 Explanation Each calorie is 4.18 joules of energy. 600 food calories becomes 600,000 regular calories, which is 2,508,000 joules of energy. If we consume this over 600 seconds, the rate of consumption is 4,180 watts. Partial credit is awarded for an answer that missed the conversion between food calories and regular calories. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Coal Mine Growth 4180 Schlumberger-Private 0/1 point (graded) A local coal mine grows by 12 acres per year. How many square meters per day is this? square meters per day incorrect 133.047452055 133.047452055 Explanation We convert this unit as follows: 12 acres1 year⋅1 year365 days⋅4046.86 m21 acre=133.0 m2/day Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Power per Person 0/1 point (graded) Humanity used 160,000 Terawatt-hours of energy in 2015. If there are 7.4 billion people on earth and 8766 hours per year, how many Watts did each person use on average? Watts/person incorrect 2467 2467 Explanation We can do this problem by converting TWh to Watt-hours, then dividing by the number of hours in a year and the number of people on earth, as follows: 160000 TW⋅hours⋅1012 Watts1 TW⋅17.4×109 people⋅8766 hours=2500Watts/ person Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Atom Facts 1/2 points (graded) This is a two-part question. Answer both parts before hitting the "Check" button. Which particles have about the same mass? Check two boxes, or check the box marked "none" if they all have very different masses. Proton correct 133.047452055 2467 Schlumberger-Private Neutron correct Electron None correct Which particles appear in equal numbers in all uncharged atoms? Check two boxes, or check the box marked "none" if uncharged atoms tend to have different numbers of all of these things. Proton correct Neutron Electron correct None incorrect Explanation Protons and neutrons are very similar in mass; electrons are about 2000 times lighter than either of them. Uncharged atoms have equal numbers of protons and electrons. Heavier atoms generally have a greater number of neutrons than protons. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Chemical Equations 0.5/1 point (graded) Some of the chemical equations below might represent real-world reactions. Others are nonsense. Mark all of the equations that are valid, and leave the invalid ones unmarked. NaCl2+H2O→HCl+12NaOH 2Na+Cl2→2NaCl correct 6H2O+6CO2→C6H12O6+6O2 correct Pb+H2S→Au Course Content Questions Schlumberger-Private These questions cover content from within this course, including facts and calculations. Don't worry if you struggle with them - these are exactly the things that we're teaching! If you find them all easy you probably don't need to take the course. These questions serve several purposes: 1. They give you a taste of what you'll be able to do when you complete the course, 2. They serve as a benchmark of progress, for you and for us, and, 3. They help you see areas where you're strongest and weakest going into the course. Please answer quickly with your best guess, and try to finish in less than 40 minutes. Please spend no more than 10 minutes on each of the calculation problems near the end. There are detailed answers to each question that you can read after attempting it. We encourage you to read these, but not to spend too long figuring them out if you don't understand them right away. That's what the rest of the course is for. Annotate Electric Grid Efficiency 0.2/1 point (graded) What is the average efficiency of electric grids in developed countries? That is, what percentage of the electrical power generated at power plants actually makes it to end users in countries like Australia, the UK, and the US? % incorrect 94 1 Hint: Much too low. Explanation The World Bank keeps detailed data on electricity generation and losses in different countries. More than 90% of generated electricity is delivered to consumers in all developed countries, with an amazingly high average efficiency of 94%. The world average is 92%, but some countries are much lower, like India at 85%. Submit 94 Schlumberger-Private You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Coal Power Efficiency 0.2/1 point (graded) What is the efficiency of a typical coal-fired power plant? That is, what percentage of the thermal energy from burning the coal is successfully turned into electricity? % incorrect 35 1 Hint: Much too low. Explanation Coal plants vary, but are typically around 35% efficient. Some older plants are much lower, and some advanced plants are much higher (near 50%), but most in the world are in the mid 30's. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review First Climate Change Treaty 0/1 point (graded) In what year did the first global treaty regarding climate change enter into force? Please answer with a number, e.g. '2016' incorrect 1994 1 Explanation 35 1994 Schlumberger-Private The first international treaty regarding climate change was the UN Framework Convention on Climate Change, which was signed in 1992 and entered into force in 1994 (though it set no binding limits on greenhouse gas emissions). Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review SPENDING ON CLIMATE CHANGE In your opinion, about how much of total global GDP should be spent on managing climate change? This is an opinion question with no right or wrong answer RESULTS  3% 35%  10% 35%  1% 14%  30% Schlumberger-Private 13%  0.1% 4% Results gathered from 159 respondents. FEEDBACK There is no right answer here, but keep in mind how serious high responses (over 10%) are. The US' notoriously high military expenditure is only 3.5% of its GDP today. Even at the peak of World War II, when many common goods were rationed, people were conscripted into the military, and many civilian factories were converted to make equipment for war, the US only spent 1/3 of its GDP on the military. ECONOMIC IMPACT OF CLIMATE CHANGE What is your best estimate of the future economic impact of climate change by 2050 as a % of global GDP lost due to climate change damages? Assume a 'business-as-usual' scenario (greenhouse gas emissions continue to rise with little concerted effort to control them). This number is highly uncertain, but some answers are more plausible than others. RESULTS  6-10% 32%  11-20% Schlumberger-Private 32%  1-5% 19%  21-50% 12%  Over 50% 5%  Less than 1% 1% Results gathered from 161 respondents. FEEDBACK Most academic estimates place the damage around 1-5% by 2050. There is tremendous uncertainty, but it's hard to make a case for how damage would be more than 20%. Mortality Rates 3/3 points (graded) This problem has three parts. Answer all three before clicking the "Check" button. Schlumberger-Private How many premature deaths are caused by energy-related water pollution each year? Almost zero Thousands correct Millions Hundreds of millions How many premature deaths are caused by energy-related air pollution each year? Almost zero Thousands Millions correct Hundreds of millions How many premature deaths are currently caused by climate change each year? Almost zero Thousands correct Millions Hundreds of millions Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (3/3 points) Review Sulfur and Carbon 0/2 points (graded) This problem has two parts. Answer both before clicking the "Check" button. Every year humanity emits millions of tons of sulfur and billions of tons of CO2. Sulfur forms particulate air pollution that kills around 1 million people per year, and CO2 raises global average temperatures, 0.8°C above pre-industrial temperatures so far. Schlumberger-Private Suppose humanity continued to emit air pollutants and CO2 following “business-asusual”, and then suddenly in 2050 cut emissions of both to 0. Approximately how long would it take for sulfate-driven mortality from particulate matter to fall by 50%? a week correct a year hundreds of yearsincorrect thousands of years Approximately how long would it take for global temperatures to drop halfway from their peak to pre-industrial average? a week a year hundreds of yearsincorrect thousands of years correct Explanation It will only take a few days for most of the air pollution to fall out of the atmosphere and stop affecting peoples' lungs and cardiovascular systems. There is some residual mortality that would last longer. However, carbon dioxide lingers in the atmosphere for much longer, and the resulting temperature change will be with us for thousands of years. Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Relative Cost of Energy 1/4 points (graded) Please compare the prices of each of the below to crude oil on an energy basis. Select the closest answer. For example, if coal cost 8 times as much as crude oil for the same amount of energy, you would answer "Much more." If electricity cost 10% less than oil, you would select "Less." There is some regional variation in these prices, so try to imagine world average prices if you can. This is a multi-part question. Make sure you answer all the parts before clicking "Check". Natural Gas costs _________ than crude oil for the same amount of energy Much less (less than 1/3 the cost of oil) Schlumberger-Private incorrect Much less (less than 1/3 the cost of oil) Coal costs _________ than crude oil incorrect Much less (less than 1/3 the cost of oil) Electricity for a large industrial consumer costs _________ than oil incorrect More Electricity for a home consumer costs _________ than oil correct Much more (more than 2x the cost of oil) Explanation In July 2018 oil prices are around $72/barrel, and since there are ~6.1 GJ of energy in 1 barrel of oil, it costs $11.8/GJ. Natural gas costs $2.85/MMBTU, which translates to $2.85/GJ, about a quarter the price of oil. Coal costs only $2/GJ in the US, 1/5 the price of oil, though it has the largest regional variations. Electricity for large industrial customers is around $.07/kWh on average, which translates to $20/GJ, higher than oil, and it's much higher yet in some areas with high electricity prices. Electricity for home consumers is usually significantly higher than for industrial customers, around $.13/kWh on average, which is $36/GJ, dramatically more expensive than oil (but more useful - electricity for a lightbulb is much more convenient than burning oil for light). These relationships were qualitatively the same when oil and gas prices were much higher before the 2014 crash (~$100/barrel and ~$5/MMBTU), with the main exception being that electricity for industrial customers was comparable to the price of oil rather than being much higher. Submit You have used 3 of 3 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Much less (less than 1/3 the cost of oil) More Much more (more than 2x the cost of oil) Schlumberger-Private Answers are displayed within the problem Review Fraction of Energy From Fossil Fuels 0/1 point (graded) What fraction of humanity's energy supply is in the form of fossil fuels? % incorrect 80 1 Explanation About four fifths (80%) of total energy appropriated by humans is from fossil fuels. The next highest source is nuclear energy at 7%. Fossil's portion of human energy supply has fallen slightly in recent decades (down from 90% in the 1970's) thanks to the growth of renewables. But it is still dramatically higher than all of human history before 1850, when close to 100% human energy was from biomass. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review The History of Fossil Fuels 0/1 point (graded) England was the first country to industrialize. In what year did it first get more than half of its energy from fossil fuels? incorrect 1905 \(\) Explanation Fossil fuels first overtook biomass (mostly trees and crops) as England's primary energy source around the year 1900, which you may find surprisingly recent. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer 80 1905 Schlumberger-Private Answers are displayed within the problem Review Fraction of Energy From Fossil Fuels - In The Future 1/1 point (graded) What do you think the fraction of human energy from fossil fuels will be in 2050? This is an opinion question with no right answer. correct 50 \(\) Explanation The answer is marked as 50, but it accepts a range from 0 to 100. We just had to put in a number; we don't consider 50 to be the "correct" percentage. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Composition of Global Energy Supply 1/8 points (graded) Estimate the fraction of global primary energy supplied by the following sources. Use rough numbers and don’t worry about ensuring that they sum to exactly 100%. This is a multi-part question. Make sure you answer all the parts before clicking "Check". Biomass % incorrect 7.5 \(\) Coal % incorrect 25 \(\) 50 7.5 25 Schlumberger-Private Hydropower % correct 1.8 \(\) Natural Gas % incorrect 20 \(\) Nuclear Power % incorrect 3.5 \(\) Oil % incorrect 34 \(\) Solar % incorrect .05 \(\) Wind % incorrect .05 \(\) Explanation These values are taken from the IEA's Sankey Diagram. Wind and solar together make up less than .05% of the world's primary energy supply. These values are very different for individual countries - the IEA Sankey tool allows you to look at different countries and see, for example, how much higher the fraction of coal is in China and how much higher the fraction of solar and wind is in Germany. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review 1.8 20 3.5 34 .05 0.05 Schlumberger-Private Fraction of Energy as Electricity 0/1 point (graded) What percentage of global energy used by consumers is in the form of electricity? % incorrect 20 \(\) Explanation About one fifth (20%) of energy used by consumers globally is in the form of electricity. Despite the complexity of generating and distributing it, this number has increased steadily since the late 1800's because electricity is so incredibly convenient and useful. The International Energy Agency has good data for issues like these. Some of it can be accessed graphically at http://www.iea.org/sankey/ which shows energy supplies (primary energy) on the left and how energy flows to end uses on the right. We'll cover how to interpret these kinds of "sankey diagrams" in this course. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Energy for Computing 0/1 point (graded) What percentage of worldwide electricity consumption is used for computing devices? % incorrect 8 \(\) Explanation This is difficult to estimate, but is likely in the range of 5-10% as we'll discuss further in the "Energy Demand and Efficiency" Section of the course. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer 20 8 Schlumberger-Private Answers are displayed within the problem Review Calculating The Cost of Mitigating CO2 Emissions 0/1 point (graded) Suppose gasoline has an emissions factor of 91g of CO2/MJ and costs $1.52/liter, and biodiesel has an emissions factor of 54g of CO2/MJ and costs $1.92/liter. You may assume gasoline and biodiesel both have energy densities of 38 MJ/liter. What is the cost of mitigating CO2 by switching from gasoline to biodiesel, in dollars per kilogram of CO2 emissions prevented? We'll cover how to do calculations like this in the course, so don't worry if you struggle. Give it your best effort but please don't spend more than 10 minutes on it. dollars per kg CO2 incorrect 0.284495021337 \(\) Explanation The cost of mitigation is equal to the additional cost for biodiesel divided by the carbon savings that it provides. Since the masses above are given in grams, we will need to convert to kilograms. \[ \frac{$1.92/L - $1.52/L}{\left(91 \ g/MJ - 54 \ g/MJ \right)} \cdot \frac{1 \ L}{38 \ MJ} \cdot \frac{1000 g}{1 kg} = $0.284\] Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Calculating Levelized Cost of Electricity from Coal 0/1 point (graded) A proposed coal power plant has a capital cost of $3450 per kW of generating capacity. It is expected to run for 94% of the year. Its overall thermal efficiency is 39%. Fixed operations and maintenance (FOM) costs have been estimated at $48/kW-year, and variable O&M costs have been estimated at $0.0063/kWh. Coal costs $1.2/GJ. The capital charge factor (or capital charge rate) is 13%. 0.284495021337 Schlumberger-Private What is the levelized cost of electricity for this plant? We'll cover how to do calculations like this in the course, so don't worry if you struggle. Give it your best effort but please don't spend more than 10 minutes on it. dollars per kWh incorrect 0.077355224805 \(\) Explanation We need the final answer in dollars per kilowatt-hour, so we will convert all power units to kilowatts and all times to hours in this answer. Fixed Costs: Our fixed costs are the financing on the plant and the fixed O&M costs. The capital cost of $3450, at a charge factor of 13% becomes a yearly cost of $448.50 per kilowatt. If we are using the plant for 8230 hours per year, our fixed costs come out to: \[ \frac{$448.50}{8230 \ kWh} + \left( \frac{$48}{1 \ year} \cdot \frac{1 \ year}{365 \cdot 24 \ hours} \right) = $0.0600 \ per \ kWh \] Variable Costs: We have two variable costs: fuel, and the O&M costs. One gigajoule is 278 kilowatt-hours, so our cost for coal is: \[ \frac{$1.20}{1 \ GJ} \cdot \frac{1 \ GJ}{278 \ kWh} = $0.00432 \ per \ kWh. \] With our plant's 39% efficiency, the effective cost for our fuel is higher: \[ \frac{$0.00432 \ per \ kWh}{0.39} = $0.0111 \ per \ kWh \] Adding in variable O&M costs, we get a total of: \[ $0.0111 + $0.0063 \ per \ kWh = $0.0174\] Total Cost: \[ $0.0600 + $0.0174 = $0.0774 \ per \ kWh \] Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Outside References 1/1 point (graded) Did you use any outside references (like Wikipedia) when finding answers to these questions? It's ok if you did - this question is for our research purposes. No, I did this all on my own. I consulted outside resources for mathematical calculation only. 0.077355224805 Schlumberger-Private I consulted outside resources to look up scientific facts. I consulted outside resources for both calculations and scientific facts. correct Schlumberger-Private Simple Sankey 1/1 point (graded) Consider the Sankey diagram below, which represents the monthly flow of money for a couple, from income to shared bank account to expenses. Diagram created using SankeyMATIC Which of the following statements is definitely true? We cannot tell whose income was used to pay for what expenses The couple is going into debt The husband pays all of the bills 20% of the couple's combined income goes to taxes correct Answer Correct: Correct! Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Sankey Diagram Assignment Here's a Sankey diagram for the US, produced by Lawrence Livermore National Laboratory. We used this to make the simplified US Sankey diagram you saw in the video lecture. It's in units of Quadrillion BTU ("Quads"). 1 Quad is slightly more than 1 EJ. Click on the image for a larger version. Figure 1. This Sankey diagram of the US energy system in 2015 shows the flow of energy from intitial resources like petroleum and coal, through conversions like electricity generation, and to end users, which are divided into four major sectors. As mentioned in the video lecture, take the numbers for "rejected energy" with a grain of salt. Source: LLNL. We can use this to do some interesting calculations. For example, David mentioned that almost all coal in the US is used to generate electricity, but here we can see that a small amount is used for other purposes. What percentage is used for electricity? We can see that 14.3 Quads were used for electricity generation, out of 15.7 Quads used in total, or 90%. Another thing we can notice is the differences in electricity consumption between Schlumberger-Private sectors – the Residential sector consumed 4.78 Quads, or 38% of the total 12.6 Quads of electricity generation, while the Transportation sector consumed only .03 Quads, .2% of the total generation. Annotate Petroleum for Transportation 0/5 points (graded) What percentage of Transportation is powered by petroleum? % incorrect 92 \(\) Explanation Total transportation use was 27.7 Quads; petroleum provided 25.4 Quads of that, which is about 92%. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Electricity from Coal 0/5 points (graded) What percentage of primary energy flowing into electricity generation came from coal? % incorrect 38 \(\) Explanation Total electricity generation use was 38 Quads; coal provided 14.3 Quads of that, which is about 38%. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Low Carbon Sources 0/5 points (graded) 92 38 Schlumberger-Private What percentage of all US primary energy came from "low carbon" sources (biomass, geothermal, wind, hydro, nuclear, solar)? % incorrect 18 \(\) Explanation Total US primary energy was 97.5 Quads. Biomass provided 4.72, geothermal provided .224, wind provided 1.82, hydropower provided 2.39, nuclear provided 8.34, and solar provided .532. The total is about 18 Quads, which is also about 18% of the total. Remember that this chart uses the "accounting trick" David mentioned, where the primary energy from direct-to-electricity sources like hydro, wind, and solar is multiplied by 3 to represent the amount energy required from fossil fuels or nuclear power to generate the same amount of electricity. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Natural Gas Consumption 1/1 point (graded) Which sector of the economy had the most direct natural gas consumption? Residential Commercial Industrial correct Transportation Submit You have used 1 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. SaveSave Your Answer Show Answer Correct (1/1 point) Review Rooftop vs Utility Solar 0/1 point (graded) Some solar energy is shown flowing into the Residential sector, representing rooftop PV, and some into electricity generation, representing utility-scale solar installations. 18 Schlumberger-Private How do these flows compare in magnitude? They are about the same. correct There is notably more utility-scale solar power.incorrect There is notably more rooftop solar power. Explanation Rooftop solar power provided about as much electricity as was generated by electricity companies in 2015. Submit You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Sankey Diagram Assessment Part 2 Here's a Sankey diagram for the world in 2013, from an interactive tool freely available from the International Energy Agency. This is a great source for looking up the energy supplies and uses in different countries and regions since the 1970's. It has some important differences from the LLNL Sankey; for example, it shows imports and exports, shows the transformation of oil in refineries, and lumps residential and commercial energy use together as "Other." It uses units of "Million tons of oil equivalent" ("Mtoe") and petajoules. At the bottom you can see options to scroll through different years and look look at different graph types, like line graphs of some of the individual flows to easily visualize them over time. These diagrams do not use the "factor of 3" accounting that we discussed in the video and that is used in the LLNL diagram above, so the amount of energy flowing into electricity generation from renewables like wind and solar is equal to the actual amount of electricity they generate. Again, you can click on the image to view a larger version, or on the link above to get an interactive version. Figure 2. This Sankey diagram of the world's energy system in 2013 shows the flow of energy from initial resources like petroleum and coal, through conversions like electricity generation, and to end users, which are divided into three major sectors. Source: IEA. Please visit the interactive version and explore it a bit for interesting trends. Then answer these questions. Schlumberger-Private Annotate Coal for Electricity Around the World 0/1 point (graded) You can click on the "Power Station" box to see the composition of inputs to electricity generation. Did coal's fraction of energy supplied for world electricity generation increase or decrease from 1990 until 2013? Stayed about the same Decrease incorrect Increase correct Explanation The change was from 41% to 49%, which is about a one-fifth increase. Submit You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review World Electricity Growth 0/1 point (graded) Look at the actual generation coming out of the power plants on the diagram. How much did world electricity generation grow from 1990 to 2013? About doubled correct About 50% increase incorrect Stayed about the same About 50% decrease Dropped to near zero. Explanation The change was from 1017 Mtoe to 2006 Mtoe, so the amount roughly doubled. Submit You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Angola Fossil Exports Schlumberger-Private 0/5 points (graded) Some countries that produce fossil fuels use very little of them, and export heavily. Let's examine Angola. Set the country in the IEA tool to "Angola" to see the Sankey diagram for that country. What fraction of Angola's total Production and Imports (all energy types) were exported in 2013? % incorrect 83 \(\) Explanation Angola exported 85.26 Mtoe, out of the 102.82 Mtoe they produced in total. This is about 83%. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Japanese Coal Production 0/5 points (graded) Japan's coal mining industry has waned in recent decades after being unable to compete with cheap coal imports, to the point that the IEA's tool shows no local production in 2013 (though there is in fact a small amount). Scroll through the years 1973-2013 for Japan using the slider on the bottom of the page. You will see a steady decline in local coal production. What percentage of Japan's total coal supply came from local production in 1973? % incorrect 30 \(\) Explanation In 1973, Japan produced about 17.9 Mtoe, and imported 41.3 Mtoe. This made its production about 30% of its total supply. \[ \frac{17.9 \ Mtoe}{17.9 \ Mtoe + 41.3 \ Mtoe} \] Coal Use in the USA 1/1 point (graded) How is coal used in the United States? 83 30 Schlumberger-Private Mostly for industrial applications Almost entirely for electricity generation correct About equally split between electricity and transportation Mostly converted into liquid or gas fuels Coal Use in the China 1/1 point (graded) How is coal used in China? Split between electricity and industry correct Almost entirely for electricity generation Mostly for industrial applications Mostly converted into liquid or gas fuels Energy Growth 1/1 point (graded) Which region of the world is currently growing most quickly in terms of energy use? South America China correct Europe The United States Africa India Submit You have used 1 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. SaveSave Your Answer ResetReset Your Answer Show Answer Correct (1/1 point) Review US Oil Usage 1/1 point (graded) Where does most of the United States' oil energy get used? For electricity generation For lighting Schlumberger-Private For trade with other countries For transportation correct What's a commodity? 0/1 point (graded) When we say that a particular good is a commodity, what does that mean in this context? Commodity goods have preference- or taste-based attributes that change how specific people buy them.incorrect All versions of a commodity are treated as identical as long as they pass some basic quality standards correct A commodity good can be created anywhere in the world. Price Assignment Knowing where to find energy prices and being able to reference them quickly is a key skill for energy experts. In the video lecture you heard David mention that US electricity prices used to be heavily influenced by oil prices, but aren’t anymore since the US stopped generating significant amounts of electricity from oil. Let’s practice looking up historical energy prices by investigating this claim. Check out the Energy Resources page for suggested data sources for these questions. In general the US EIA has great historical data on energy use and prices in the US. Annotate Oil and Electricity 1.6666666666666667/10 points (graded) First let’s see if the spike in oil prices corresponded with a spike in electricity prices in the US from 1973 to 1974. This is a multi-part problem. Fill in all boxes before submitting your answer. Some questions ask for "change" in prices - if you find an increase use a positive number, and for a decrease, enter a negative number. What were the oil import prices in 1974 as a percentage of the 1973 prices? % incorrect 1 Schlumberger-Private 280 \(\) How much did US retail electricity prices change from 1973 to 1974? % incorrect 11 \(\) Oil made up what percentage of energy supply for electricity generation in the US in 1973? You can get this data from multiple sources; the IEA Sankey diagram might be the quickest. % incorrect 19 \(\) How much did US oil import prices change from 2009 to 2011? % incorrect 65 \(\) How much did US average residential electricity prices change from 2009 to 2011? % incorrect -3 \(\) Oil made up what percentage of energy supply for electricity generation in the US in 2009? % correct 1 \(\) Explanation Oil prices increased from $22/bbl to $61/bbl from 1973 to 1974. 1974's prices are 280% of 1973's prices. 1 1 1 1 1 Schlumberger-Private Electricity prices increased from $0.135 / kWh to $0.15 / kWh from 1973 to 1974, an 11% increase. The IEA sankey diagram says that oil accounts for 19% of electricity generation in the US in 1973. The EIA says closer to 17%. This problem accepts both answers. Both agree that the percentage in 2009 was about 1%. Oil prices in the US went up from $66/bbl in 2009 to $109/bbl in 2011. Average residential electricity prices were $0.128 / kWh in 2009, and went down to $0.124 / kWh in 2011, so the answer there would be -3%. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Oil and Electricity - Are they connected? 0/1 point (graded) What claim is supported by this data? The US has NOT significantly reduced its electricity generation from oil, and oil prices thus have MORE influence on US electricity prices. The US has NOT significantly reduced its electricity generation from oil, but oil prices have LESS influence on US electricity prices anyway. The US has significantly reduced its electricity generation from oil, and oil prices thus have MORE influence on US electricity prices.incorrect The US has significantly reduced its electricity generation from oil, and oil prices thus have LESS influence on US electricity prices. correct None of these claims are supported. Answer Incorrect: A 3% decrease is not only less impact than an 11% increase, it's even in the wrong direction. Explanation Though we cannot always take just two data points to examine a trend, these particular times have been selected as good representatives of the overall way things are happening. As we make less of our electricity from any one particular source, fluctuations in that source's cost will have less impact on the cost of electricity. Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Schlumberger-Private Coal in Japan and Europe 0/5 points (graded) How much more did Japan pay for coal in 2014 than typical prices in Europe, on a percentage basis? If Japan paid $10 while Europe paid $5, you would answer 100%. % incorrect 12 \(\) Explanation Japan paid about $84/ton, while Europe paid an average of $75/ton. Japan paid 12% more. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Gas Prices in the USA and Germany 0/10 points (graded) David mentioned that increased gas production in the US, coupled with the difficulty exporting it, have driven gas prices down in the US. Let’s see if BP’s data on gas prices supports this claim. This is a multi-part problem. Fill in all boxes before submitting your answer. What was the percentage difference between US gas prices and German gas prices in 1997? Answer with a negative sign if the US prices were lower. If the US price was $20 and the German price was $22, you would answer -9% (since 20/22 - 1 = -9%) % incorrect -4 \(\) How did US gas prices in 2014 compare with German prices? Answer with a negative sign if the US prices are lower. If the US price was $20 and the German price was $22, you would answer -9% (since 20/22 - 1 = -9%) % incorrect 1 1 1 Schlumberger-Private -52 \(\) Explanation All values are looked up from the BP link above. In 1997 the prices were $2.53/mmbtu for the US, and $2.64 for Germany. In 2014 the prices were $4.35/mmbtu in the US, and $9.11 in Germany. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Gas Price Trend 1/1 point (graded) Is the trend found above consistent when comparing the US against other countries in the report? That is, did the US gas price fall relative to all other countries from the late 1990's through 2011? Yes, the US price has fallen against all other countries in the report. correct No, the US price rises against some countries and falls against others. No, the US price has risen against all other countries in the report. The report does not contain this information. Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (1/1 point) Review Energy in Developed Economies 0/20 points (graded) David mentions a few times during the course that the energy inputs into developed economies is about 5% of GDP. Let’s try estimating this now, using data from the US. Fortunately, the EIA has detailed data on the total revenue from sales of electricity to consumers, which does a lot of the job for us. Looking at the LLNL sankey diagram, we can see that if we have data for the total cost of electricity, the main remaining inputs into the four sectors of the economy are natural gas and oil. (There’s also a small amount of coal and biomass and tiny amounts of geothermal and solar, which we’ll ignore.) We can find data for the price of oil and gas delivered to different sectors, and use that to get the total cost of those two resources. Combined with the total cost of Schlumberger-Private electricity, we’ll have a pretty good estimate of the total cost of energy inputs into the US economy. You’ll also get lots of practice using sankey diagrams, looking up energy prices, and converting units. This is a multi-part problem. Fill in all boxes before submitting your answer. According to the EIA, how much did all the customers in the US pay for electricity in 2015, in billions of USD? billions of $ incorrect 388 \(\) According to the LLNL 2015 Sankey Diagram, how much natural gas was used by the Residential Sector in 2015, in EJ? EJ incorrect 5.01 \(\) According to the EIA, how much did the Residential Sector pay on average for natural gas in 2015, in dollars per gigajoule? Use the real (inflation-adjusted price). $/GJ incorrect 9.2 \(\) Given the amount of natural gas used by the Residential Sector and the average price paid, what was the total amount that the Residential Sector paid (in billions of dolalrs) for natural gas in the US in 2015? billions of $ incorrect 46 \(\) Explanation Part 1: See Table 2 of the EIA for the first question. Part 2: Refer to LLNL and convert from Quads to EJ. 1 1 1 1 Schlumberger-Private Part 3: If you look at this table from the EIA (provided on the Energy Resources page) you’ll see an average price for the Residential Sector of $10.38/thousand cubic feet. To convert we can use the Conversion Sheet Page’s value of .04 GJ/m3 to convert this to $9.2/GJ. Part 4: Multiply your answer from part 2 (in gigajoules) by your answer from part 3. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Commercial Sector Gas 0/5 points (graded) Please repeat the same process above for the cost of natural gas to the Commercial Sector. How much did the US Commercial Sector pay for gas in 2015? Use the LLNL Sankey Diagram for gas consumption, and the EIA for commercial gas prices. billions of $ incorrect 24.5 \(\) Explanation There were 3.5 EJ consumed, at a price of $7.89 per thousand cubic feet or $7/GJ. \( 3.5 \ EJ \cdot $7/GJ = $24.5 \ billion \) Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Industrial Sector Gas 0/5 points (graded) Please repeat the same process above for the cost of natural gas to the Industrial Sector. (Notice how much lower the cost of gas is for industrial customers!) How much did the US Industrial Sector pay for gas in 2015? Use the LLNL Sankey Diagram for gas consumption, and the EIA for industrial gas prices. billions of $ incorrect 33.6 \(\) Explanation 1 1 Schlumberger-Private There were 9.88 EJ consumed, at a price of $3.84 per thousand cubic feet or $3.4/GJ. \( 9.88 \ EJ \cdot $3.4/GJ = $33.6 \ billion \) Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Petroleum in Transportation and Industry 0/15 points (graded) Let's look at the amount the Transportation and Industrial Sectors paid for petroleum in 2015. (The other sectors consume relatively small amounts, so we'll ignore them here. This is a multi-part problem. Fill in all boxes before submitting your answer. Assume that the Transportation Sector pays the same price for all of its petroleum consumption, and that it's equal to the average price of gasoline. How much is this in $/GJ? Use the EIA's "Regular Gasoline Retail Price." $/GJ incorrect 19 \(\) Given that price and the total consumption of petroleum by the Transportation Sector (from the LLNL Sankey Diagram), how much did the transportation sector pay for petroleum in total in 2015? billions of $ incorrect 509 \(\) Finally, how much did the Industrial Sector pay for petroleum in 2015? For simplicity, you can assume that this sector pays the average price of oil in the US. For the price of oil, you can use the EIA’s "average price of imported oil." For petroleum consumption, use the LLNL Sankey Diagram. billions of $ incorrect 66 1 1 1 Schlumberger-Private \(\) Explanation Part 1: According to the EIA, gasoline was $2.52/gallon in 2015. Using the energy density of gasoline (~35 GJ per cubic meter, as indicated on the Conversion Sheet), and converting from gallons to cubic meters, this is $19/GJ. Part 2: Since the transportation sector used 26.8 EJ of petroleum in 2015, the total cost was 26.8 EJ * $19/GJ = $509 billion Part 3: The industrial sector uses 8.65 EJ of oil. With a cost of $46.7/barrel and an energy density of 6.1 GJ/barrel, the total cost was $66 billion. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Total Energy Cost 0/10 points (graded) This is a two-part problem. Fill in both boxes before submitting your answer. Adding up all of your answers above, how much in total did US consumers pay for energy in 2015? billions of $ incorrect 1068 \(\) What percentage of 2015 US GDP is this? % incorrect 5.95 1 1 Schlumberger-Private Levelized Cost Definition 0/1 point (graded) Which of the following is the best definition of levelized cost? The average cost of something over time. correct A perfect, all-inclusive metric for how good an energy technology is.incorrect The price of electricity. Explanation Levelized cost is a broadly useful measurement that can apply not only to energy, but also to other commodities and goods. However, it only gives us an idea of what something will cost over time - it doesn't tell us anything about (for example) how much pollution is involved. Submit You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Fixed Costs 1/1 point (graded) Imagine you’re computing the levelized cost of a furnace, in $/month. Which of the following are relevant fixed costs? Choose all that apply. The price of the furnace The cost of fuel The cost of air filters The cost of a yearly maintenance contract The cost of maintenance done after every 1000 hours of operation Chest Freezer 0/10 points (graded) Schlumberger-Private Your teaching fellow, Daniel, was recently deciding whether to buy a chest freezer. This would allow him to buy more food in bulk, which would save him about $29/month, but he also would have to pay for the freezer and its electricity. What is the levelized cost of freezing Daniel's food in dollars per month given the following assumptions?  The freezer costs $198 to buy.  It uses 21 kWh/month.  Electricity costs 18 cents per kWh.  Because he’ll probably be moving to another city in a few years, assume he keeps it for 2 years. dollars per month incorrect 12.03 Calculating CCF 0/5 points (graded) What is the capital charge factor for a loan with an interst rate of 8% for 30 years? Make sure to answer to at least three significant figures. incorrect 0.0888274333873 \(\) Explanation The formula is as follows: \[ CCF = \frac{rate}{ \left( 1 - ( 1 + rate )^{-years} \right) } \] In our case, this comes out to: \[ CCF = \frac{0.08}{ \left( 1 - ( 1 + 0.08 )^{-30} \right) } = 8.883 \% \] Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review 1 1 Schlumberger-Private Loan Duration Difference 0/10 points (graded) Many power plants can last much longer than the 20-30 years assumed in most LCOE calculations, often 50 years or more. This affects the LCOE estimates for solar farms, where almost the entire LCOE is from capital costs that are multiplied by the CCF. How much lower is the CCF for an 8% loan over a 50 year period compared to the same loan over a 20 year period? For example, if the 50 year period has a CCF of .06 and the 20 year period has a CCF of .1, you’d answer 40%. % incorrect 19.7436569063 \(\) Explanation The formula is as follows: \[ CCF = \frac{rate}{ \left( 1 - ( 1 + rate )^{-years} \right) } \] In our case, for the longer time this comes out to: \[ CCF = \frac{0.08}{ \left( 1 - ( 1 + 0.08 )^{-50} \right) } = 8.174 \% \] And for the shorter case, we get: \[ CCF = \frac{0.08}{ \left( 1 - ( 1 + 0.08 )^{-$shortyears} \right) } = 10.185 \% \] The fractional change is: \[ \frac{10.185 - 8.174}{10.185} = 19.744 \% \] So the longer loan is 19.744% better when it comes to CCF, though it will cost more overall in the long run. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Levelized Cost for a Cheap Car 0/20 points (graded) In the video on levelized cost of driving, Daniel mentioned that given how little most people drive in a year, they generally can save money by buying a cheaper car than a Prius even if it has higher fuel consumption. Let’s investigate that claim now, assuming 1 Schlumberger-Private a car similar to a Ford Fiesta. The capital cost to buy it is substantially lower, as are the yearly taxes and insurance, but the fuel consumption is about 50% higher.  The car costs $14000 to buy.  The capital charge factor is 0.23, the same as the Prius.  The taxes, fees, and insurance each year total to $1000.  You drive the car 20000 km/year, the same as the Prius.  Variable operation and maintenance (VOM) costs add up to $0.019 per kilometer.  Fuel costs $1.90 per liter.  The car can travel 100 km on 7.2 L of fuel. Part 1: What is the total fixed cost in dollars per kilometer? dollars per km incorrect 0.2075 \(\) Part 2: What is the variable cost in dollars per kilometer? dollars per km incorrect 0.1558 \(\) Part 3: Is the total levelized cost higher or lower than the Prius (in the video above) given these assumptions? Enter the word "higher" or "lower". If the numbers are within 10% of each other, enter the word "same". incorrect lower Coal Plant LCOE 0/30 points (graded) 1 1 1 Schlumberger-Private Consider a coal plant with the following characteristics:  Capital cost of $2800 per kW  CCF of 0.13  FOM costs of $96 per kW-year  Fuel costs of $0.95 per GJ  Utilization of 78% (about 6837 hours per year)  VOM costs of $0.0054 per kWh  Efficiency of 31% Part 1: What are the fixed costs in dollars per kilowatt-hour? $/kWh incorrect 0.0672762479744 \(\) Part 2: What are the variable costs in dollars per kilowatt-hour? $/kWh incorrect 0.0164322580645 \(\) Part 3: What is the total LCOE in dollars per kilowatt-hour? $/kWh incorrect 0.0837085060389 \(\) Part 4: Is the LCOE more sensitive to the capital cost or to the fuel cost? For example, does doubling the capital cost affect the LCOE more or less than doubling the fuel cost? Enter the word "capital" or "fuel". If the numbers are within 10% of each other, enter the word "same". 1 1 1 Schlumberger-Private incorrect capital Part 5: Let’s look at the effect of a carbon tax. The simplest way to do this is to add a price for carbon emissions to the cost of the fuel (coal). We’ll assume a commonlydiscussed carbon tax of $20/tCO2. Looking at our Conversion Sheet, we can see that coal emits 90 kg of CO2/GJ; multiplying these emissions by $20/tCO2 gives us an additional $1.8 per GJ to add to the cost of the coal, almost tripling it! What’s the new LCOE with this carbon tax? $/kWh incorrect 0.104611731845 \(\) Part 6: Would the same carbon tax have more or less of an effect on a natural gas plant? Enter the word "more" or "less". If the numbers are within 10% of each other, enter the word "same". incorrect less Cost of Mitigation 1/1 point (graded) Which of the below is the right general expression for cost of mitigation? Cost of Clean Option+Cost of Dirty OptionPollution of Dirty Option+Pollution of Clean Option Cost of Clean Option−Cost of Dirty OptionPollution of Dirty Option−Pollution of Clean Option correct Cost of Dirty Option−Cost of Clean OptionPollution of Dirty Option−Pollution of Clean Option 1 1 1 Schlumberger-Private Solar Sidewalk 0/20 points (graded) In 2014 the Netherlands installed the world’s first solar bike path. Let’s compute the cost of mitigation relative to electricity from coal. Of course, the sidewalk probably wasn’t intended to be a cost-effective electricity option. It's designed for qualitative rather than quantitative value, to raise awareness. However, there are real proposals to scale up this kind of technology to large numbers of sidewalks and roadways, so cost analysis is relevant. The project cost $3.75 million for ~30kW of installed capacity (based on typical 150W/m2 solar panels). Assume a CCF of 9%, and a utilization of 8% (probably generous for solar panels flat on the ground in the Netherlands). You may ignore all other costs. Part 1. What is the levelized cost of electricity from the solar sidewalk? $/kWh incorrect 16.0420944559 \(\) Part 2. What is the cost of mitigation (in $/tCO2) relative to coal electricity at $0.09/kWh and 0.9 kg CO2/kWh. You may assume the solar sidewalk causes 0 kg CO2 emissions/kWh. $/tCO2 incorrect 17724.5493954 Pizza Mitigation 0/10 points (graded) A pepperoni pizza costs $10 and causes 0.8 tons of CO2 emissions. A super deluxe veggie pizza costs $13 and causes 0.4 tons of CO2 emissions. What’s the cost of mitigation for choosing the veggie pizza? $/tCO2 incorrect 7.5 1 1 1 Schlumberger-Private Pizza Mitigation Comparison 1/1 point (graded) Looking at the McKinsey Mitigation Cost Curve below, how cost-effective a mitigation strategy is the pizza approach? Fantastic Pretty good correct Awful Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. ResetReset Your Answer Show Answer Correct (1/1 point) Review Mitigation Cost for Biodiesel 0/10 points (graded) Part 1. Imagine you have a diesel-powered car, and you can buy either diesel or biodiesel fuel (which is possible in some parts of the US). The cost of biodiesel is $34/GJ, and the biodiesel causes 21 kg CO2 emissions per GJ over its lifetime. The diesel costs $26/GJ and causes 84 kg CO2emissions per GJ over its lifetime (4 times more!!). What is the cost of mitigation of choosing biodiesel? $/tCO2 incorrect 126.984126984 \(\) Part 2. What carbon tax would be required to make the biodiesel cost the same as the diesel? $/tCO2 incorrect 126.984126984 1 1 Schlumberger-Private Nitrogen Oxides 0/1 point (graded) Please read the third page of this report on NOx from the US EPA: https://web.archive.org/web/20150209034608/http://nchh.org/Portals/0/Contents/EPA_N itrogen_Oxides.pdf (PDF download, 700k) Which of the below are true of NOx? Select all that apply. Contributes to nitrogen pollution of water bodies, leading to eutrophication and lack of oxygen correct Reduces IQ of exposed individuals Forms irritants that can excacerbate respiratory and heart diseases correct Contributes to formation of ozone correct In the US, mostly emitted by factories and other industrial sources 7.47 Lifespan Decrease from PM2.5 Exposure Where You Live 0/5 points (graded) In the first box below, enter the PM2.5 level where you live again (in μg/m3 ). This should be the same value you entered above. Then, in the bottom box, enter the reduction of lifespan (in years) that would result from a lifetime at that pollution level relative to a pollution-free lifetime. Use the dose-response relationship mentioned in the video lecture (around 1:55). Be sure to fill both boxes before hitting "Check". PM2.5 micrograms per cubic meter incorrect Life Expectancy Decrease years incorrect Explanation As mentioned in the video lecture, an increase of PM2.5 exposure of 10 μg/m3 is associated with a decrease in lifespan of 3/4 of a year, which is .075 years per ug/m^3 (.75/10). To answer this question multiply your PM2.5 level by .075. 7.47 0.56025 Schlumberger-Private Comparing Deaths from Air Pollution and Climate Change 0/1 point (graded) The present-day premature deaths from air pollution are how many times larger than the estimated premature deaths from climate change in 2050? .5x (climate change deaths higher) 1x (they're the same) incorrect 10x (air pollution deaths significantly higher) correct Submit You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Air Pollution Impact 0/1 point (graded) The air pollutant that has the most impact on human health globally is... NOx Lead Carbon Monoxide incorrect Particulate matter correct Natural vs. Human Emissions 1/1 point (graded) David just asked: how big is the human-caused movement of carbon from deep underground to the atmosphere relative to similar natural processes, like emissions from volcanic vents? What do you think? This a "guessing" problem. You will have unlimited attempts, and we'll reveal the answer in the next video. One percent as much - nature moves more carbon from geosphere to atmosphere every year Half as much About as much Schlumberger-Private Twice as much One hundred times as much - human activity moves far more CO2 than nature correct Using the References 0/10 points (graded) It's good for you to be able to look up historical and current CO2 emissions and concentrations. This problem gives you some practice. Please refer to the Energy Resources Page for recommended references to answer these questions: How many times higher was the concentration of CO2 in the atmosphere at the beginning of 2015 than it was upon the release of the first IPCC Assessment Report on climate change in 1990? A rough answer is fine. If the answer was four times as high, you would enter "4". incorrect 1.12 Explanation In January 2015 the level was about 397, and in 1990 it was about 355. 397/355 = 1.12%. Answers from 1.02 to 1.22 are accepted. In 2012, China emitted how many times as much CO2 as the next highest emitting country? If the answer was four times as high, you would enter "4". incorrect 2 Explanation In 2012 China emitted ~10,000 MtCO2, and the next-highest emitter (the US) emitted ~5000 MtCO2. Answers from 1.7 to 2.3 are accepted. Most countries' CO2 emissions have increased steadily over time, but they can decrease for multiple reasons, including reduced energy use. Russia is one such example. How much higher were Russia's CO2 emissions in 1990 than in 2012? If the answer was four times as high, you would enter "4". 1 1 Schlumberger-Private incorrect 1.5 CO2 from Land Use Change 0/5 points (graded) Let’s look at Figure 6.1 (pg 471 in the second reading) for a more quantitative understanding of where our emitted CO2 goes. First, note that this figure uses petagrams of carbon, not CO2. This is convenient when examining the full carbon cycle, because of all the different forms carbon atoms go through in such a cycle. It's predominantly in the form of CO2 in the atmosphere (and thus we mostly talk about CO2emissions and concentrations), but when it’s absorbed into the ocean or by plants the carbon atoms from CO2 end up in carbonic acid or in plant sugars. This figure only tracks the mass of the carbon atoms involved, to avoid these complexities. So then, the anthropogenic flux of 7.8 PgC from fossil fuels in the figure means that humanity released 7.8 petagrams of carbon atoms per year as a result of fossil fuel use. (Almost all of that carbon is in the form of CO2.) To figure out the total mass of the CO2 we released from fossil fuel use (not just the mass of carbon), we can use the molecular weights of CO2 (44 grams/mol) and carbon (12 grams/mol). In this case: \[ 7.8 \ PgC \cdot \frac{44 \ g/mol}{12 \ g/mol} = 28.6 \ Pg \ of \ CO_2. \] Using the same approach and the information on the figure, what mass of CO2 did we release did due to land use change? Pg incorrect 4.03 Updated Values 0/1 point (graded) Figure 6.1 uses average data for the period 2000 thru 2009, so it’s a bit dated. How does the mass of CO2 in the figure compare to humanity’s 2012 CO2 emissions? The values in the figure are... ...about 40% lower than the 2012 values. ...about 15% lower than the 2012 values. correct 1 1 Schlumberger-Private ...about 5% lower than the 2012 values. ...about the same. ...about 5% higher than the 2012 values. ...about 15% higher than the 2012 values. ...about 40% higher than the 2012 values. incorrect Explanation In 2012, humanity emitted about 15% more carbon dioxide than the yearly average from 2000 thru 2009. Submit You have used 3 of 3 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Anthropogenic Carbon Flux 0/5 points (graded) What is the total anthropogenic flux to the atmosphere, including both fossil fuels and land use, in PgC? We're looking for the flux to the atmosphere, not the net flux (don't subtract out red fluxes from atmosphere to land or ocean). incorrect 8.9 \(\) Explanation According to the figure, fossil fuels provide about 7.8 Pg, and land use provides about 1.1 Pg, so the total is about 8.9 Pg. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Carbon from Atmosphere to Ocean 0/5 points (graded) How much net carbon is going directly from the atmosphere into the ocean each year? Answer in PgC incorrect 1.6 \(\) Explanation 1 1 Schlumberger-Private According to the figure, 2.3 Pg goes into the ocean from the atmosphere, while 0.7 Pg comes out. This gives us a total of 1.6 Pg of Carbon. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Carbon from Atmosphere to Land 0/5 points (graded) How much net carbon is going directly from the atmosphere into the land on net each year? Answer in PgC incorrect 4.3 \(\) Explanation According to the figure, the land flux is 1.7 Pg (the historical value) plus 2.6 Pg (the anthropogenic values) for a total of 4.3 Pg of Carbon. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Carbon Absorption 0/5 points (graded) Clearly, the ocean and land are absorbing a significant chunk of our carbon emissions and helping to slow climate change as a result. What percentage of our emissions are they absorbing? % incorrect 66 \(\) Explanation To find this percentage, we make a fraction, with the ocean and land sinks on top and the carbon emissions on the bottom: \[ \frac{1.6 \ Pg + 4.3 \ Pg}{8.9 \ Pg} = 0.66 \] This is 66%. The Fate of Carbon 1 1 Schlumberger-Private Looking at the carbon cycle figure, it can be tempting to speculate how long it would take for the atmosphere to return to pre-industrial levels of carbon if we stopped our emissions. Unfortunately, the carbon cycle is a dynamic system, and we can’t make a simple estimate just by looking at that figure. Instead we can turn to careful research on the fate of emitted carbon detailed in Box 6.1 (in the second article). This box looks at the fate of a pulse of CO2, but because CO2 stays in the atmosphere for so long, all of our emissions over the last few centuries behave almost exactly the same as a pulse (see this paper on the lifetime of CO2 for more details, PDF download, 258 KB). Thus, we can think of this box as describing what would happen to our emitted CO2 after we stopped emitting. Said differently, if we stopped adding carbon to the atmosphere, how long would it take for all that we have added since the industrial revolution to come back out? Annotate CO2 Removal Mechanism Speed 0/1 point (graded) Which are the two fastest mechanisms by which CO2 is removed from the atmosphere? Select both answers. Ocean invasion correct Reaction with calcium carbonate Silicate weathering Land uptake correct incorrect Explanation Land uptake happens in 1-100 years. Ocean invasion happens in 10-1000 years. Calcium Carbonate reactions and silicate weathering are much slower, taking 1- 10 thousand years for Calcium Carbonate, and up to one million years for weathering. Submit You have used 3 of 3 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review CO2 Remaining 0/10 points (graded) Let’s look carefully at Figure 1 within Box 6.1. These figures show the amount of CO2 remaining after a pulse, over different timescales (100 years, 1000 years, and Schlumberger-Private 10000 years). The first two (a and b) only show the results from a 100 PgC pulse, equal to roughly 25 years worth of carbon accumulation at today’s rate. The last chart shows the results over 10000 years for pulses of different sizes, where it’s obvious that pulse size can affect the amount of CO2 remaining. Use this figure to answer the following questions: If a pulse of CO2 were released 50 years ago, what percentage of it would remain in our atmosphere right now? % incorrect 50 \(\) How what if the pulse were 100 years ago? % incorrect 40 \(\) 1000 years? % incorrect 25 \(\) Explanation The values can be read off the graph on page 473. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Long-Term CO2 Remaining 0/10 points (graded) If humanity follows a "business as usual" trajectory, with no significant attempts to slow emissions, and then suddenly stops emissions in 2100, we will have emitted about 2100 Pg of carbon since the beginning of the industrial revolution. 1 1 1 Schlumberger-Private Over long times, we can consider this as a single "pulse." How much of a 2100 PgC pulse would remain after 2000 years? Make your best guess. % incorrect 28 \(\) How much will remain 10000 years later? Again, make your best guess. % incorrect 18 Projected Temperature Increase (RCP8.5) 0/1 point (graded) Take a look at SPM2.6 (page 11). What is the central projection of temperature increase in 2100 under RCP8.5 (the dark red line)? 1° C incorrect 2° C 3° C 4° C correct Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Projected Sea Level Rise (RCP8.5) 1/1 point (graded) What is the central projection of mean sea level rise in 2100 under RCP8.5? No substantial rise 0.25 meters 0.5 meters 0.75 meters correct 1 1 Schlumberger-Private 1 meter or more Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (1/1 point) Review Projected Sea Level and Temperature Rise (RCP2.6) 0/5 points (graded) Which of the following accurately describes the temperature and mean sea level rise projections for RCP2.6? Temperature and sea level both increase steadily over the whole century Sea level rise stabilizes sooner than temperature doesincorrect Temperature stabilizes mid-century, but sea level rise still has not stabilized by 2100 correct Surface Temperature Change by Location 5/5 points (graded) Take a look at SPM.7 (page 12). Which of the following accurately describes the geographical distribution of increase in surface temperatures? It's spread evenly across the whole globe It's more extreme near the poles correct It's more extreme near the equator Climate Prospectus Now let's turn to the American Climate Prospectus 2014 (PDF download, 14.7 MB), a report produced by an interdisciplinary team of climate scientists, economists, and risk analysts to provide policy-relevant information about some economic impacts of climate change in the US. They do not attempt a comprehensive estimate of all impacts, instead focusing in detail on four major climate changes (temperature, precipitation & humidity, sea level, and extreme weather) and six major impacts (coastal damages, temperaturerelated mortality, labor productivity, agricultural productivity, crime, and energy demand). Like the IPCC, they use four RCP's as the basis for their projections. If you cannot access that version of the Prospectus, please try this locally hosted copy instead. Schlumberger-Private Please read "Using this Assessment" and "A Framework to Build On" (pages 7-10) to get an introduction to the report, its intent, and its limitations. Excluded Impacts 2.5/5 points (graded) Look carefully at Figure 1.2 on page 9 of the Climate Prospectus. Which of the following impacts are excluded from the report? Select all that apply. Changes in hurricane activity Impacts on grains, soy, and cotton Impacts on all crops other than grains, soy, and cotton correct Extreme-weather-related health effects] correct partially correct Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review More Sea Rise Projections 0/5 points (graded) In Chapters 6 thru 11 the report goes through each of its 6 major impacts in detail. For brevity, we’ll just look closely at one, damage to coastal communities, and then look at the summary of all 6 impacts at the end of the report. First, look at Figures 4.11 and 4.12 (page 32) for projected mean sea level rise. Figure 4.11 is very similar to Figure SPM.6 from the IPCC report. Which of the following accurately describe Figure 4.12? Select all that apply. Local sea level rise projections differ substantially around the coast of the US correct Sea level rise is generally higher on the western coast than the eastern coast Sea level rise is generally less at higher latitudes, and greater towards the equator correct incorrect Submit You have used 3 of 3 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Schlumberger-Private Answers are displayed within the problem Review Predicting Property Damage 0/5 points (graded) Next, please read all of pages 87, 88, and 89, and look at Figures 11.12-11.4 on page 92 and Figure 11.15 on page 93; these sections cover projected damages due only to sea level rise. Then read “Changes in Hurricane Frequency and Intensity” on pages 95 and 96 for additional projected damages due to an increase in hurricanes. How did the researchers translate projected local sea level rise and hurricane activity into dollar values of property damage? Check all that apply. They assumed all property below sea level would be destroyed in future coastal storms. They used a detailed model used by insurance companies and government officials to estimate coastal storm damage. correct They extrapolated from historical data on the costs of past hurricanes to predict future coastal storm damage. incorrect Submit You have used 3 of 3 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Property Loss 0/5 points (graded) Consider Figure 11.15. What is the median estimate of increased annual property losses due to SLR late this century under RCP8.5? billions of $ incorrect 21.5 \(\) Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review 1 Schlumberger-Private Heaviest Losses 1/1 point (graded) These losses clearly won’t be evenly distributed across the whole country. Look back at Figure 11.14. What fraction of that median estimate is expected to be incurred by the most severely affected state? Actually, the figure indicates that losses will be evenly distributed. About ten percent. About twenty percent. About half. correct About eighty percent. Almost all of the losses will be in the most severely affected state. Submit You have used 3 of 3 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (1/1 point) Review Hurricane Activity and Loss 0/1 point (graded) Look at Figures 11.17 and 11.18. How much do projected increases in hurricane activity raise the average annual losses? No change in loss from increased hurricane activity. 50% increase in loss from increased hurricane activity. 3x increase in loss from increased hurricane activity. correct 10x increase in loss from increased hurricane activity. incorrect Mid-to-late-century Impacts We encourage you to skim the other five chapters on impacts (5 thru 10) to see how the researchers estimated other impacts, like combining experimental studies on crops with historical data on crop productivity and weather to project productivity changes due to climate change, or combining laboratory and field studies of worker performance under different temperatures to project changes in labor productivity. Schlumberger-Private For now, we'll go straight to the concluding chapters. Please read "Summing Up" on pages 115 and 116, and look carefully at Figures 13.22 and 13.23 to see a summary of the six impacts' projected effects on the US economy in the middle of this century and late this century, under RCP8.5. Make sure to compare the relative severity of impacts as estimated here to your guesses at the beginning of this section. Also look at Figure 13.24 to see how all 6 impacts affect each US state. Note that the researchers used two methods to translate human lives lost (mortality) into dollar values. The first method is the "income method," which involves estimating the (discounted) income the deceased person would have earned over their lifetime (a pretty limited estimate of what human lives are worth!). The second method is to multiply all mortalities by the "value of a statistical life (VSL)," or around $7 million. This is the standard approach for most US governmental cost benefit analysis, and the precise dollar value is the result of "willingness to pay" studies where researchers either directly or indirectly solicit from people how much they would be willing to pay to reduce the risk of mortality. This is a deeply contentious topic (for example see Cass Sunstein's spirited discussion). The researchers argue that the income method is probably the minimum that anyone would say a life is worth, and the VSL method is probably near the maximum (especially since it counts the life of a teenager as equally valuable as a 95-year-old), so they use both to show a plausible range of impacts without suggesting either as the best method. Annotate Seeing the Bright Side? 1/1 point (graded) Examine Figure 13.24. Are there some states that might benefit on net from these 6 impacts, even under RCP8.5 late this century? No, every state will be harmed by the impacts of global warming. Yes, some states might benefit from the impacts of global warning. correct It is impossible to say, at this level of detail, what the impacts will be. Submit You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (1/1 point) Review Seeing the Dark Side? Schlumberger-Private 1/1 point (graded) Look back at Figure 13.24 again. Is there a region projected to incur only costs, and no benefits? No, every state will benefit to some extent from the impacts of global warming. It is impossible to say, at this level of detail, what the impacts will be. Yes, some states will only suffer from the impacts of global warning. correct Submit You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (1/1 point) Review Unequal Harm 2/5 points (graded) Which two of the following impacts are MOST unequally distributed between US states? Labor Agriculture correct Energy Coastal Damage correct Mortality based on measures other than VSL partially correct Explanation Agriculture and Coastal Damage have the most uneven impacts across the country, ranging from no impact in many states (due to a lack of agriculture or coastline), to several percent of that state’s economic output in others. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Comparing Mortality Estimates 0/1 point (graded) Examine Figure 13.23. Which of the following statements about mortality estimates is most accurate? Schlumberger-Private The income method makes mortality one of the smallest impacts, while the VSL method makes it by far the largest, roughly ten times as much as all the other impacts combined. incorrect The income method makes mortality one of the smallest impacts, while the VSL method makes it by far the largest, roughly as much as all the other impacts combined. correct The income and VSL methods produce nearly identical results. Submit You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Report Summary 1/1 point (graded) Lastly, look at Figure 14.1 on page 123. This summarizes most of the results of the report (and uses its more conservative estimates, excluding changes in hurricane activity and using the income method for mortality). The "Direct" estimates are similar to what we’ve seen throughout the rest of the report; the "RHG-MUSE" estimates include macroeconomic effects, for example the way that decreases in agricultural productivity in one region affect food prices across the country. What is the "likely range" estimate of the economic impacts of these climate impacts late this century, under RCP8.5? close to 0% 1-3% correct 5-10% Over 15% Two Percent 1/1 point (graded) Dr. Keith mentioned that producing 30 TW of power using solar energy would take up 2% of the Earths' land surface area. Approximately how large an area is this? The size of Russia The size of Canada partially correct The size of India correct The size of Peru Schlumberger-Private The size of Italy The size of Cuba Land Use Assignment In the previous lecture you heard David make some quick estimates of land use requirements. Now try doing some for yourself. Annotate Ethanol for Transport Part 1 0/5 points (graded) This set of problems asks you to answer a complex question: How much land would be required to power all of US transportation with corn ethanol?We'll break this down into parts. First, let's start with the raw energy requirement. How much energy did US transportation consume in 2017 (in EJ)? EJ incorrect 29.64 \(\) Explanation LLNL flowcharts are a quick way to look up US data. In this case, it shows 28.1 quad BTU or 29.64 EJ for transportation consumption. IEA sankey diagrams are also good, though usually not as up-to-date. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Ethanol for Transport Part 2 0/5 points (graded) Ethanol has an energy density of .021 GJ/L. How many liters of ethanol are required to supply US transportation demand? Liters incorrect 1 1 Schlumberger-Private 1.4*10^12 \(\) Explanation Using the energy density for ethanol and the EJ/GJ converstion factor, we get: \[ \frac{29.64 \ EJ}{0.021 \ GJ/L} \cdot \frac{1000000000 \ GJ}{1 \ EJ} = 1.4 \times 10^{12} \ Liters \] Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Ethanol for Transport Part 3 0/5 points (graded) Optimistic estimates of corn ethanol productivity in the US are around \( 3.5 \times 10^5 \ liters/km^2 \) per year. How much land would be required to supply enough ethanol for all of US transportation demand? sq km incorrect 4*10^6 \(\) Explanation \[ \frac{1.4 \times 10^{12} \ Liters}{3.5 \times 10^5 \ Liters/km^2} = 4 \times 10^6 \ km^2 \] Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Ethanol for Transport Part 4 0/5 points (graded) How does this compare to the total US land area used for agriculture? Choose the closest answer. Make sure to use "total agricultural land" from whatever source you choose, including many things like permanent cropland, pasture land, etc. 95% less 50% less Almost the same correct 1 Schlumberger-Private 50% more incorrect 100% more Explanation Estimates of US agricultural land are around 50% of the total land area of the country. That's half of \(9 \times 10^6 km^2 \), so agricultural land is around \(4.5 \times 10^6 km^2\). The land needed to provide corn ethanol for all transportation demand is thus about the same as the total land the US currently uses for agriculture, and half the land area of the entire country! Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Solar Energy Supply Part 1 0/5 points (graded) Let's look at a closely related question: that of supplying the United States' energy needs with electricity generated by Solar PV. We'll look at just the existing electrical needs first. As before, we'll start with the demand question. How much electricity did the US generate on average in 2017, in TW? TW incorrect 0.42 \(\) Explanation Roughly 0.42 TW, using data from the LLNL sankey diagram. The US generated 12.5 Quad BTU of electricity, and 12.5 Quad BTU / year = .42 TW. There are other good sources with slightly different numbers, like the EIA. This problem accepts answers within 15% of the listed value. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Solar Energy Supply Part 2 0/5 points (graded) 1 Schlumberger-Private How much land would be required to meet this demand with solar installations in sunny locations in the southwest US that produce \( 15 \ W/m^2 \) on average? sq km incorrect 28000 \(\) Explanation Including the conversion factor from watts to terawatts, we get: \[ \frac{0.42 \ TW}{15 \ W/m^2} \cdot \frac{10^{12} \ W}{1 \ TW} = \ 28000 \ km^2 \] Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Solar Energy Supply Part 3 0/5 points (graded) How much land would be required if the solar installations were in the much-less-sunny northeast US, producing \( 7.5 W/m^2 \) on average? sq km incorrect 56000 \(\) Explanation With half as much incident energy, we need twice as much land: \[ \frac{0.42 \ TW}{7.5 \ W/m^2} \cdot \frac{10^{12} \ W}{1 \ TW} = \ 56000 \ km^2 \] Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Solar Energy Supply Part 4 0/5 points (graded) Now let's look at the land needed for solar to supply all the energy needs of the USA. Since the electricity can be used with nearly 100% efficiency at point-of-use, we can just look at the land needed to meet the amount of energy for "Energy Services" in the LLNL sankey diagram. How much energy was consumed as "energy services" in the US in 2017, in EJ? 1 1 Schlumberger-Private EJ incorrect 32.8 \(\) Explanation 31.1 Quad BTU = 32.8 EJ. We don’t need to supply as much energy as the current primary energy supply, since much of that is fossil energy with large efficiency penalties in electricity generation or in engines. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Solar Energy Supply Part 5 0/5 points (graded) If we scattered modern solar installations across the US, with higher concentrations in sunnier areas, we might be able to get \( 10 \ W/m^2 \) average performance for all of them. How much land area would this require to supply all US energy services? sq km incorrect 104000 \(\) Explanation Conceptually, all we need to do is divide the yearly energy requirement by the energy density of our solar cells in order to get the answer. However, we will also need to convert EJ to Joules, years into seconds, and square meters into square kilometers in order to get the result in units that we like. \[ \frac{32.8 \ EJ/year}{10 \ W/m^2} \cdot \frac{10^{18} \ J}{1 \ EJ} \cdot \frac{1 \ year} {365 \cdot 24 \cdot 3600 \ seconds} \cdot \frac{1 \ km^2}{1000000 \ m^2} = 1.04 \times 10^5 \ km^2 \] We don’t need to supply as much energy as the current primary energy supply, since much of that is fossil energy with large efficiency penalties in electricity generation or in engines. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review 1 1 Schlumberger-Private Solar Energy Supply Part 6 0/5 points (graded) Choose the closest answer. How does this compare to the total US land area used for agriculture? 95% less correct 50% less Almost the same 50% more incorrect 100% more Lifespans of Air Pollutants and CO2 0 point possible (ungraded) As mentioned in the video, the different lifespans of air pollutants and greenhouse gases have important implications for policy. Please answer two questions about these lifespans below. Make sure to answer both before hitting the "Check" button. Which of the following is closest to the half-life of air pollutants like SO2 and ozone in the troposphere? A week correct 100 years incorrect 1000 years 1 million years Which of the following is closest to the half-life of CO2 in the troposphere? A week 100 years 1000 years correct 1 million years Peer grade, self grade Schlumberger-Private Data Lookup Practice: Germany and Natural Gas 0.0/10.0 points (graded) Let’s practice looking up data from BP’s Statistical Review of World Energy, 2018 (PDF download, 6.5 MB). This is a free, yearly report with lots of great data about energy, and it’s especially good for data on fossil energy trade and prices. You can answer these questions just by looking at the PDF version of the report, but more detailed data is also available in Excel format. This is a multi-part problem. Fill in all boxes before submitting your answer. Let’s estimate how much Germany paid for imported natural gas in 2017. How much gas did Germany import on net in 2017? Subtract exports from imports, and answer in billions of cubic meters. bcm incorrect 87.7 1 What was Germany’s average import price? Answer in dollars per million BTU. $/MMBTU incorrect 5.62 1 How much did Germany pay for its gas imports in 2017? $ incorrect 18.6*10^9 1 Explanation The first two values are looked up using the link above. The amount imported can be found on page 35, and the average price on page 33. For part 3, the amount that Germany paid is: Volume times energy density times cost per energy, with a conversion factor, or... 87.7×109m3⋅0.04 GJ1 m3⋅5.62 $/MMBTU⋅0.947 MMBTU1 GJ=$18.6 billion 1 1 1 Schlumberger-Private Note: as a rule of thumb remember that 1 GJ = 1 Millon BTU - it's correct to within 5%. So the cost per MMBTU is nearly the same as cost per GJ. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Cost of Carbon Mitigation for Biofuels 0/15 points (graded) Biobutanol has long been proposed as an alternative to gasoline that could be better than ethanol. Estimate the cost of mitigation of switching from gasoline to biobutanol. At the moment gasoline costs $0.64/liter in the US, and optimistic estimates of biobutanol costs are around $1.14/liter. For greenhouse gas emissions, we’ll need to use lifecycle estimates that account for emissions at all stages of production and use, since biofuels lead to emissions from cars but involve negative emissions when plants used to make fuels absorb CO2. Lifecycle estimates of gasoline are 3.5 kg CO2e/liter; lifecycle estimates of biobutanol have substantial uncertainty, but 1.7 kg CO2e/liter is a good central estimate. As with most alcoholic biofuels, biobutanol is less energy-dense than gasoline, 30 MJ/liter as opposed to gasoline’s 35 MJ/liter. Give the cost of mitigation in $/tCO2e. dollars per ton CO2 incorrect 454.945054945 \(\) Explanation The cost of mitigation is the cost of reducing emissions over the amount of emissions reduced. To get to that, we'll need a common basis on which to compare these values. Let's use a single megajoule of fuel as our base. One MJ of biobutanol costs: \[ \frac{$1.14 / Liter}{30 \ MJ / Liter} = $0.0380 /MJ \] One MJ of gasoline costs: \[ \frac{$0.64 / Liter}{35 \ MJ / Liter} = $0.0183 /MJ \] One MJ of biobutanol produces: \[ \frac{1.7 \ kg/Liter}{30 \ MJ / Liter} = 0.0567 \ kg/MJ \] One MJ of gasoline produces: \[ \frac{3.5 \ kg/Liter}{35 \ MJ / Liter} = 0.1000 \ kg/MJ \] 1 Schlumberger-Private Now we can make a fraction where all the MJ units will cancel out, and we'll just have the cost per mass. The cost of mitigation for one kilogram is thus: \[ \frac{$0.0380 - $0.0183 }{0.1000 \ kg - 0.0567 \ kg } = $0.4549/kg \] Multiplying by 1000 to get the cost per ton, we have $455 per ton of CO2 via this method. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review CO2 from your Light Bulb 0/10 points (graded) A 60 W light bulb is used for 15 hours a day. The electricity for this bulb comes from a natural gas fired power plant that operates with 53% efficiency. How much CO2 is emitted per day to power this light bulb? Make a simple estimate of the CO2 emissions from the power plant, ignoring transmission losses. kg CO2/day incorrect 0.305660377358 \(\) We mentioned earlier in the course that energy technologies in developing countries often have much lower efficacies than those in developed countries. Let’s look at one example, lighting via kerosene lamps, which are common in developing countries but about 150x less effective than incandescent lightbulbs at turning energy into useful light. If a family wanted just one tenth of the light provided by the 60 W lightbulb, they’d need to consume 15x as much power, or 900 W. If a family ran 900 W worth of kerosene lamps for just 2 hours each day, how much CO2 would this emit? You may assume that kerosene produces the same emissions as gasoline. kg CO2/day incorrect 0.44064 \(\) Explanation 1 1 Schlumberger-Private Let's do the lightbulb first. Burning natural gas that contains one GJ of energy produces about 50 kg of CO2. Since our plant is 53% efficient, we need to adjust to get the true value: \[ \frac{50 \ kg \ per \ GJ}{0.53%} = 94.34 \ kg \ per \ GJ \] The total number of GJ we are using is: \[ 60 \ W \cdot 15 \ hours \cdot \frac{3600 \ sec}{1 \ hour} \cdot \frac{1 \ GJ} {1,000,000,000 J} = 0.00324 \ GJ \] Our emissions are therefore: \[ 94.34 \ kg/GJ \cdot 0.00324 \ GJ = 0.306 \ kg\] Now let's turn to the kerosene question. We'll go through a similar process, but we don't need to adjust for the efficiency of a power plant. The total number of GJ of kerosene we are using is: \[ 900 \ W \cdot 2 \ hours \cdot \frac{3600 \ sec}{1 \ hour} \cdot \frac{1 \ GJ} {1,000,000,000 J} = 0.00648 \ GJ \] The kerosene emissions are therefore: \[ 68 \ kg/GJ \cdot 0.00648 \ GJ = 0.441 \ kg\] And that's for just 2 hours, at one tenth of the light produced. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Levelized Cost Goes Bananas 0/20 points (graded) In the Costs section, Daniel mentioned that the fixed cost dominates the levelized cost of driving for most personal vehicles. However, this can change for different vehicles, like large trucks. Let’s try computing the levelized cost of driving in $/km for an 18 wheeler with the characteristics below. Then, we'll use this information to estimate how much shipping contributes to the cost of bananas.  The truck costs $150000 to buy.  It can haul 16000 kg of bananas.  The capital charge factor is 0.21.  The taxes, fees, and insurance each year total to $12000.  The truck is driven 210000 km/year.  Variable operation and maintenance (VOM) costs add up to $0.018 per kilometer. Schlumberger-Private  Fuel costs $1.05 per liter.  The truck can travel 100 km on 49 L of fuel. Part 1: What are the fixed costs in dollars per kilometer? dollars per km incorrect 0.207142857143 \(\) Part 2: What are the variable costs in dollars per kilometer? dollars per km incorrect 0.5325 \(\) Part 3: It’s also interesting to look at how much shipping contributes to the final price of goods. It often ends up being surprisingly low. Using the levelized cost of driving above, how much does driving contribute to the final price of bananas that are shipped by 18- wheeler from Los Angeles to Denver (1600 km)? Answer in $/kg of bananas. For reference, bananas sell for around $1.25/kg in the US. dollars per kg incorrect 0.0739642857143 \(\) Part 4: Finally, let’s look at the incredibly low fuel use of container shipping over the ocean. It usually takes 6-7x less fuel to ship a given payload a given distance than it would to drive it. If the bananas were shipped 6000 km over the ocean from Ecuador to Los Angeles, was more fuel used for ocean shipping or truck shipping from LA to Denver? Enter the word "ocean" or "truck". If the numbers are within 10% of each other, enter the word "same". incorrect truck Explanation Fixed Costs: Our fixed cost will be the financing for the truck plus the yearly taxes, fees, and insurance, divided by the total number of kilometers driven. 1 1 1 1 Schlumberger-Private \[ \left( $150000 \cdot 0.21 + 12000 \right) \cdot \frac{1}{210000} = $0.207 \ per \ km \] Variable Costs: The variable costs here are the fuel and the VOM costs. \[ \left( \frac{$1.05}{1 \ L} \cdot \frac{49 \ L}{100 \ km} \right) + $0.018 \ per \ km = $0.533 \ per \ km \] Now for the bananas. We'll divide the total cost of shipping by the mass of bananas that we can ship. \[ 1600 \ km \cdot ( $0.207/km + $0.533/km ) \div 16000 \ kg = $0.074/kg \] This is about ten percent of the price of bananas. It excludes the salary of the truck driver, but since the trip is only ~20 hours, their salary and benefits would probably be around $500, or just $.03/kg. The cost of fuel really dominates the cost of shipping. For Part 4, the comparison is easy: it costs more for truck shipping. Ocean shipping uses less fuel per distance by a factor of six to seven to one. The distance is higher in this case, but only 6000/1600 = 3.75x higher. Ocean shipping beats land shipping for this distance. Submit You have used 15 of 15 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Fossil Fuels in Daily Life 3.3333333333333335/20 points (graded) Let’s estimate the mass of fossil fuels required to power the daily life of an American. We can use the fossil fuel primary energy from the 2015 LLNL Sankey diagram and divide by a US population of about 322 million. Using primary energy like this will help us capture indirect energy use, like the energy required to make the devices people use, though it will, of course, still be just an estimate. Part 1: What amount of natural gas is used per person each day in the US? Divide total natural gas primary energy by population and days in a year, and answer in units of MJ. MJ incorrect 254 \(\) Part 2: What mass of natural gas is this? kg incorrect 4.9 \(\) 1 1 Schlumberger-Private Part 3: Do a similar calculation to estimate the mass of coal per person each day. kg incorrect 5.22 \(\) Part 4: Do a similar calculation to estimate the mass of petroleum per person each day. kg incorrect 6.76 \(\) Part 5: How does the total amount of fossil fuels we use compare to the mass of food consumed by a typical person each day? Most people eat between 1.5 and 2 kg of food per day. About 10 times more correct About 2 times more About the same About half as much About one tenth as much Part 6: Using the emissions factors on the conversion sheet, how much CO2 is released per person each day from the fossil fuel consumption you estimated above? kg CO2 incorrect 46 The Impact of Exercise 5/10 points (graded) If you haven’t already, take a moment to read the blog post Daniel and David wrote leading up to the course exploring the climate and land impacts of bike riding. Then let’s try estimating the impacts of hearty-healthy exercise. Part 1: What’s the impact of a previously-sedentary individual following American Heart Association guidelines for exercising? Assume that the person starts to jog 4 times per week, for 31 minutes each, at 9 km/hr, burning an additional 65 kcal/km. Assume their diet leads to 2.6 g CO2e/kcal, typical for an American. How much CO2 is released? 1 1 1 Schlumberger-Private kg CO2/year incorrect 163.4568 \(\) Part 2: What percentage of recent US per capita emissions is this? Since the estimate of dietary greenhouse gas intensity involves big contributions from gases other than CO2, make sure to use a per capita yearly emissions statistic that also includes other gases, like those from the CAIT data explorer. This problem has wide error tolerance since you could get different numbers from different sources. % correct 0.990647272727 \(\) Explanation Part 1: \[ \frac{4 \ times}{1 \ week} \cdot \frac{52 \ weeks}{1 \ year} \cdot \frac{ 31 \ minutes} { 60 \ min/hour} \cdot \frac{9 \ km}{ 1 \ hour} \cdot \frac{65 \ kcal}{1 \ km} \cdot \frac{2.6 \ gCO_2e}{1 \ kcal} = 163457 \ gCO_2e/year. \] 163457 grams is 163 kilograms. Part 2: The USA emits something like 16.5 tons of CO2e per person per year, which is 16500 kilograms. 163 kilograms / 16500 kilograms = 0.99%. The question accepts a wide range of answers, since there are many different estimates of US per-capita emissions. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Lightbulb vs Driving Emissions 0/15 points (graded) Imagine that you drove your car to work, only to realize that you accidentally left a lightbulb on. In terms of CO2 emissions, is it worth making a trip home from work to turn off the lightbulb? Make the following assumptions: 1 1 Schlumberger-Private  The lightbulb uses 100W, and would be on for an extra 8 hours if you don’t drive home to turn it off.  Electricity has an emissions intensity of .6 kg CO2e/kWh (close to the US average).  The drive would be very short, just 5 km round trip (the US average is closer to 45 km), in a Prius taking only 5 L/100km.  You can use a lifecycle emissions factor of 3.2 kg CO2e/liter of gasoline (a bit higher than what you find in the Conversion Sheet). How much CO2 will the electricity for the light bulb release? kg CO2e incorrect 0.48 \(\) How much CO2 will the car release? kg CO2e incorrect 0.8 \(\) What if Daniel walked home to do this? His round trip would be a 6.5 km walk, burning about 200 kcal in total. He estimates that his diet has an emissions intensity of 2 g CO2e/kcal, a bit below the American average. How much CO2 would Daniel release in this walk? kg CO2e incorrect 0.4 \(\) Explanation When driving, it's not worth it, even for this short trip in an efficient car. The lightbulb’s impact is: 0.1 kW * 8 hours * 0.6 kg CO2e per kWh = 0.48 kg CO2e The car’s impact is: 0.05 L/1km * 5 km * 3.2 kg CO2e/liter = 0.8 kg CO2e When walking, it’s worth the trip in terms of CO2, though probably not in terms of time spent. Walking impact: 200 kcal * 0.002 kg CO2e/kcal = 0.4 kg CO2e 1 1 1 Schlumberger-Private As a practical consideration, Daniel would need to walk quickly: he needs to get home before the electricity for the bulb is responsible for 0.08 kg of CO2! Otherwise, he might as well stay at work and be more cautious next time. There's also the question of whether Daniel can make up the time he lost at work! Making your decisions based only on CO2 is not necessarily a good idea in certain situations. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Energy in Food Waste 0/5 points (graded) You can find lots of examples of articles (like this one) proclaiming how wasteful developed countries are with food, and how we could address our environmental problems by capturing food waste to make natural gas or transportation fuels. How much energy could we really save if we captured all food waste? The USDA estimates that 1100 kcal/day go to waste each day per person in the US. How much is this as a percentage of 2015 US daily per capita energy consumption? % incorrect 0.53 \(\) Explanation The US yearly energy consumption in 2015 was 97.5 Quads/year, or about \( 1.03 \times 10^{11} \ GJ \). Per person, per day, that means we use: \[ \frac{ 1.03 \times 10^{11} \ GJ/year }{ 365 \ days/yr \cdot 322 \times 10^6 people} = 0.875 \ GJ/day \ per \ capita \] For countries with the highest energy-per-capita, about 1 GJ per day is a typical rating and a good rule of thumb, so we are pretty close to that. The food waste has a total energy of 1100 kcal, which is 4.6 MJ, or 0.0046 GJ. Our food waste is thus about (0.0046 / 0.875 = ) 0.53% of daily per capita consumption. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer 1 Schlumberger-Private Answers are displayed within the problem Review Mitigation Cost of Solar Cell Phone Charger 0/10 points (graded) In an upcoming section of the course we’ll look carefully at rooftop and industrial solar PV. For now, let’s look at the mitigation cost of using a small, portable solar charger, something commonly reviewed on tech websites. In general, energy system technologies become more cost-effective with scale, so we can guess these might be expensive mitigation options, but they do have some advantages over larger systems, like not requiring installation costs or staff to clean and maintain them. The cheapest chargers Daniel could find were $10 at the time of this writing. They would take around 5 hours to charge a typical 11 Watt-hour smartphone battery under bright sunlight. Part 1: What is the levelized cost of electricity from this system, if it’s used to charge an 11 Wh battery every day of the year? Use a modest individual capital charge factor of 0.15; you may neglect all costs other than the $10 purchase price. $/kWh incorrect 0.37 \(\) Part 2: What is the mitigation cost for Daniel to use this sytem instead of using grid electricity? Assume grid electricity costs $0.20/kWh, with 0.5 kg CO2e emitted per kWh. Answer in dollars per ton of CO2. $/tCO2 incorrect 340 \(\) Explanation Part 1: Levelized Cost \[ $10 \cdot \frac{0.15}{.011 \ kWh \cdot 365 \ days/year} = $0.37/kWh \] Part 2: Cost of Mitigation \[ \frac{$0.37 - $0.2}{0.5 \ kg \ CO_2e/kWh - 0 \ kg \ CO_2e/kWh} \cdot \frac{1000 \ kg}{1 \ ton}= $340/tCO_2 \] This is pretty high, but not bad for such a small device! If it were capable of charging two phones per day it would even start to save money in regions with expensive 1 1 Schlumberger-Private electricity. However, it probably couldn’t do that consistently over a full year, given the limited availability of sunlight and how long it takes to charge. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review How Green is an Electric Car? 0/15 points (graded) One possible worry about electric cars is that they're currently powered by dirty electricity. But proponents, as quoted in this story on the issue, claim that they're still cleaner than traditional cars even if their electricity comes from fossil fuels because of how efficient large-scale electricity production is and how efficient electric motors are. Let's investigate for ourselves. Let's look at the worst-case scenario, an electric car powered entirely by electricity from coal. Assume the car is a Nissan Leaf. How many kWh does it take to go 1 km, under "average" driving conditions? Try looking online to find the information that you need for this answer. We'll accept a range of answers for this. kWh incorrect 0.18 \(\) How many kg of CO2e emissions would this lead to? Use the median estimate from the figures at the US National Renewable Energy Laboratoryfor the emissions intensity of coal electricity. kg/km incorrect 0.18 \(\) What are the per-km emissions from a standard American car? Assume a fuel economy of 9.5L/100km, with gasoline that has a lifecycle impact of 3.2 kg CO2e/liter. 1 1 Schlumberger-Private kg/km incorrect .304 1 Schlumberger-Private Strengths of the Grid 0.6/1 point (graded) Thinking back on the ten facts that David presented, consider the strengths and weaknesses of our current system. Mark all of the boxes below that indicate a strength of our electric grid. The reliability of the grid correct The efficiency of transmission through the grid correct The age of the transmission poles and other equipment The flexibility of electricity as an energy source correct The ease with which the grid can be controlled Demand for Solar and Oil 1/1 point (graded) Why do renewable generators almost always get to feed their power into the grid, while oil-burning plants often only operate a small percentage of the time that they could operate? There are fewer oil-burning plants than solar plants, so solar plants are run more often. It costs nothing to operate a solar plant for an extra hour, while oil plants are expensive to run. correct Oil-burning plants are highly polluting, and solar plants create no pollution while operating. This actually isn't true: oil-burning plants are more often in operation than solar plants. Dominant Source of Electricity 5/5 points (graded) What is the dominant surce of electricity under the default conditions? That is, what has the most generation and most capacity built? Gas Coal correct Solar Battery Schlumberger-Private Submit You have used 1 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. SaveSave Your Answer ResetReset Your Answer Show Answer Correct (5/5 points) Review Solar Capacity 0/5 points (graded) What is the amount of solar capacity built? GW incorrect 0.3933 \(\) Explanation You can read this in the "Capacity" column. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Earliest Solar Power 5/5 points (graded) What is the earliest hour with solar generation? 6 AM 7 AM correct 8 AM 9 AM Answer Correct: 8 AM is also accepted, since it is difficult to see the power delivered at 7 AM. Submit You have used 1 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. SaveSave Your Answer ResetReset Your Answer Show Answer Correct (5/5 points) Review Coal at Noon 0/5 points (graded) 1 Schlumberger-Private How much coal power is being generated at noon? GW incorrect 1.6 \(\) Explanation You can read this value from the column for hour 12 on the graph. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Utilization 0/5 points (graded) Which generator has the highest utilization under the default conditions? Gas incorrect Coal correct Solar Battery Explanation You can read this in the "Utilization" column. Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Summer Load 0/5 points (graded) Now switch the input scenario and load curve to "Summer". How is the summer load curve different from the default? It has a lower evening minimum incorrect It has a stronger afternoon peak correct There is no overnight minimum Explanation The afternoon peak is higher for the summer, as air conditioning demands increase. Submit 1 Schlumberger-Private You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Increased Charge Factor 0/5 points (graded) Still using the summer settings, set the CCF to 0.2. What will happen? Take a guess and then run the simulation. What happened when the charge factor increased? High capital cost generators are penalized correct Solar and batteries become the dominant options The cost of electricity goes down No change incorrect Explanation You should see that gas became the dominant energy provider. Gas has the lowest capital cost out of the three generator types.) Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Why? 0/5 points (graded) Why did increasing the CCF have the effect that it did? Lower CCF’s reduce the levelized costs of electricity incorrect CCF’s are more relevant for fossil generators than renewables A high CCF increases the weight of capital costs in the levelized cost of electricity, so capital-intensive options like coal and renewables are penalized correct Explanation The higher the CCF, the more money one needs to pay for electricity when the cost of the plant is taken into account. Plants with higher capital costs are hit harder by this effect, and become less cost-effective. Submit You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Schlumberger-Private Review Untaxed Coal 0/10 points (graded) Using the default settings, try pressing the “Cost vs Intensity Curve” button. In the case of a $0/tCO2 carbon tax, how much coal capacity is built? GW incorrect 1.56 \(\) Explanation You can read this value from the column for "Capacity" on the table. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Pricing fossil fuels out of the system 0/5 points (graded) Mouse over each point to take a look at the carbon price and capacities built. How much higher does the carbon tax need to be to eliminate natural gas than to eliminate coal? $10/tCO2 higher Twice as high incorrect Ten times as high correct Explanation Natural gas emits substantially less carbon than coal. Carbon taxes will not quickly force natural gas out of the market. Submit You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Decarbonizing the Grid 0/5 points (graded) 1 Schlumberger-Private Let’s play with the 2010 and 2015 US scenarios. In 2015 US solar and battery prices were lower than in 2010, but natural gas prices were lower as well. How did these factors influence the carbon price needed to remove natural gas from the grid? Was the minimum carbon price to remove all natural gas lower in 2010 or 2015? In 2010 incorrect In 2015 correct Same value for both years Explanation You can use the Cost vs. Intensity curve to find this answer. Look at the top-left-most point, where the carbon intensity has dropped to zero. In 2015, setting the carbon price to $370 removed natural gas from the grid. In 2010, the price needed to be $850 per ton of CO2! So the drop in solar prices has had more of an effect in this regard, with gas now being less costly to drive out of the system. Submit You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Cost of Mitigation 0/10 points (graded) We can see that the response of the system is very sensitive to carbon price, with a substantial amount of coal generation being built with a carbon tax of $20/tCO2 and none being built at $30/tCO2. What is the cost of mitigation of a $20/tCO2 tax (relative to the default of $0/tCO2)? Keep in mind that the increased electricity cost with a carbon tax is partially due to the construction of more expensive generators, and partially due to tax payments on any emissions from the remaining fossil generators. From society’s perspective, those tax payments will be used somewhere else in the economy and shouldn’t count towards the cost of mitigation. You will need to calculate the cost of electricity for the $20/tCO2 and $30/tCO2 cases with the cost of the carbon taxes taken out. $/tCO2 incorrect 3.88 \(\) What is the cost of mitigation of a $30/tCO2 tax (relative to the default of $0/tCO2)? Don't forget the reminder from above. 1 Schlumberger-Private $/tCO2 incorrect 23.4 \(\) Explanation: For the $20/ton tax: The new electricity cost is $.088/kWh. To find the cost with direct contribution from carbon tax subtracted out, we can subtract the carbon price times the carbon intensity of the electricity (which is equal to the total carbon tax payments). \[ $.088/kWh - .73 \ kg \ CO_2/kWh \times $.02/kgCO_2 = $.0734/kWh \] The cost of mitigation is then: \[ \frac{$.0734/kWh - $.073/kWh}{.833 \ kgCO_2/kWh - .73 \ kgCO_2/kWh} \cdot \frac{1000 \ kg}{1 \ ton} = $3.88/tCO_2 \] For the $30/ton tax: The new cost of electricity is $0.094/kWh. Without the direct contribution of the carbon tax, that comes to: \[ $.094/kWh - .228 \ kg \ CO_2/kWh \times $.03/kgCO_2 = $.0872/kWh \] The cost of mitigation is then: \[ \frac{$.0872/kWh - $.073/kWh}{.833 \ kgCO_2/kWh - .228 \ kgCO_2/kWh} \cdot \frac{1000 \ kg}{1 \ ton} = $23.4/tCO_2 \] Note: this exercise is for pedagogical purposes only. The simulation isn’t nearly precise enough to estimate the actual cost of mitigation of these carbon prices in the real world, so don’t let this convince you that $30/tCO2 is much better than $20/tCO2, just that the results of a carbon price can be surprisingly sensitive to changes in the price Explanation for old version of problem: Cost of mitigation of a $20/tCO2 tax: \[ \frac{$.088 - $.073}{0.833 - 0.73} = $145 \ per \ ton \ CO_2 \] Cost of mitigation of a $30/tCO2 tax: \[ \frac{$.094 - $.073}{0.833 - 0.228} = $34.7 \ per \ ton \ CO_2 \] Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Peak Load Shifting 2.5/5 points (graded) Check out the "Peak Load Shifting" load curve, which makes the demand curve flatter by shifting some peak demand to the evening. Which of the following are true when you "Plan System" with the "Peak Load Shifting" load curve? CO2 emissions per kWh go down relative to the default load curve Electricity cost goes down, due partly to higher utilization rates that can be achieved with flatter demand correct 1 Schlumberger-Private Capital-cost-intensive options generally benefit correct More solar capacity is built when the minimum carbon price to eliminate coal is implemented partially correct Explanation In general, peak load shifting favors generators that are capital-intensive and need high utilization rates to keep their costs low. In this case, shifting peak loads to the evening to flatten the demand curve ends up favoring coal in particular which can run all day, and hurts solar a bit since more load is shifted to times when the sun isn’t out. When a carbon tax is used to drive coal out of the system, this peak load shifting still slightly penalizes solar relative to the default arrangement. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Peak Load Shifting Continued 2.5/5 points (graded) Which of the following might help encourage a lower-carbon grid under the default settings with peak load shifting? Note: The goal is to make the grid carbon-free; a switch from coal to gas is not enough. Raising the CCF Shifting more load to peak solar generation hours rather than night correct Including wind power (try looking up hourly generation of wind farms) correct Raising the price of coal by 15% partially correct Explanation Raising the price of coal could help, but with our parameters a 15% increase doesn’t affect solar capacity at all. Raising the capital charge factor is unlikely to help since solar is the most dominated by capital costs of any option. Load shifting to peak solar generation times instead of the night could definitely help, though we don’t implement it here; in the upcoming section on solar power David will mention some ways this could happen, for example using excess solar electricity midday to cool a reservoir that could be used to cool buildings in the evening when the sun is down. Including wind power could help encourage lower-carbon generation because it tends to generate most in the morning and evening, which would compliment solar’s midday peak. For a detailed analysis of combining all-low-carbon generators to manage variability and meet demand, check out Delucchi and Jacobson's 2011 Energy Policy paper. Submit Schlumberger-Private You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review How low do solar and batteries need to go? 5/5 points (graded) As we'll discuss in the upcoming section on solar power, the costs of solar electricity and batteries are declining quickly. Let's use this interactive to estimate how low they'll need to go for an all-solar-and-batteries system to be the cheapest. Try using the default settings but simultaneously decrease the capital cost of solar and batteries by integer factors (e.g. decrease both by a factor of 2, then factor of 3, etc). How far do they need to decrease to have an all-solar-and-batteries system? Keep in mind that the default settings represent an approximate average of North America and Europe in recent years; more detailed results for particular regions will vary. Factor of 2 Factor of 3 correct Factor of 4 Factor of 5 Submit You have used 1 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. SaveSave Your Answer Show Answer Correct (5/5 points) Review How low do solar and batteries need to go if gas is cheap? 0/5 points (graded) Low natural gas prices make it much harder for renewables to be the cheapest option. Repeat the previous problem but use the "US 2015 Average" scenario, which has a much lower natural gas price. Simultaneously decrease the capital cost of solar and batteries by integer factors (e.g. decrease both by a factor of 2, then factor of 3, etc). How far do they need to decrease to have an all-solar-and-batteries system? Factor of 2 Factor of 3 Factor of 4 incorrect Factor of 5 correct Schlumberger-Private Solar Resource Assignment Bookmark this page The Cost of Solar Tracking 0/15 points (graded) Is the extra capital cost of tracking and fixed-tilt systems worth it? Let’s investigate. For each question, Use a capacity factor derived from NREL. You can find this most quickly from the map, as is done on the Solar Resource page. You may ignore non-capital costs. This is a multi-part question. Make sure to enter all your values before hitting "Check". What is the LCOE of a horizontal plate installation in Arizona? Assume $1750/kW capital cost, and a CCF of 0.1. $/kWh incorrect 0.087 \(\) What’s the LCOE of a fixed-tilt installation in Arizona, pointed south at latitude? Assume $1800/kW capital cost (only a slight increase), and a CCF of 0.1. $/kWh incorrect 0.076 \(\) What’s the LCOE of a N-S axis tracking installation in Arizona, pointed south at latitude? Assume $1950/kW capital cost, and a CCF of 0.1. $/kWh incorrect 0.059 \(\) Explanation LCOE in this case counts only capital costs, making it a quick calculation: \[ LCOE = \frac{CapCost \cdot CCF}{8766 \ hours/year \cdot Capacity} \] This comes out to $.087/kWh for the horizontal plates, $.076/kWh for the plates pointed south at latitude, and $.059/kWh for the tracking installation pointed south. Comparing the tracking installation to the horizontal plates, it will take about 7,140 hours of operation to make up the difference. This may sound like a lot, but it's only two years worth of daylight operation in Arizona. 1 1 1 Schlumberger-Private Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Outsourcing European PV 0/15 points (graded) Instead of building PV systems in Europe, European countries could partner with north African countries to build PV there and import the electricity along HVDC lines. Use SolarGIS maps to estimate the levelized cost of electricity of solar installations in southern Germany and Libya. Assume $1800/kW capital cost and a CCF of .1. You may neglect all other costs. This is a multi-part question. Make sure to enter all your values before hitting "Check". What's the capacity factor for a flat panel, horizontal to the ground in south Germany? The conversion is similar to the one for Boston on the Solar Resource page, but slightly different because SolarGIS uses kWh/m2 -yr rather than kWh/m2 -day. % incorrect 13.1 \(\) Assume that the installation in Germany is a fixed-tilt system, which has a 20% higher capacity factor than you estimated above. What's the LCOE, using the above assumptions? $/kWh incorrect 0.131 \(\) Assume that the installation in Libya is also a fixed-tilt system, with a 20% higher capacity factor than the GHI from SolarGIS's map (and use the irradiance value from roughly the center of the country). What's the LCOE, using the above assumptions? $/kWh incorrect 0.067 \(\) 1 1 1 Schlumberger-Private Explanation Part 1: \[ Capacity = \frac{1150 kWh/(m^2 yr)}{8766 \ hours/year \cdot 1 kW} = 13.1\% \] Part 2: LCOE in this case counts only capital costs, making it a quick calculation: \[ LCOE = \frac{CapCost \cdot CCF}{8766 \ hours/year \cdot Capacity} \] This comes out to $.131/kWh for Germany, $.067/kWh for Libya. Note: we did this the standard way for this course, using the capacity factor, but you could have just plugged the kWh/m2 -yr number directly into the LCOE formula. Cost of Solar Electricity 0/5 points (graded) Estimate the cost of electricity in a highly favorable site like the US southwest. Assume capital costs have continued to fall and are now at $1000/kW. This would be a big government project with a very low CCF of 0.06. Fixed operations and maintenace cost (FOM) is $5/kW-yr, and the installation will be a tracking system with capacity factor of 0.37. $/kWh incorrect 0.02 \(\) Explanation You may wish to review the Costs section if you are having difficulty calculating LCOE. The LCOE for this plant is: \[ \frac{$1000 \cdot 0.06 + $5}{ 0.37 \cdot 8766 \ hours/year } = $0.02/kWh \] This is an unbelievably low cost for electricity! But the source is intermittent - it generates only when the sun is shining. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Cost of Hydrogen 10/10 points (graded) Now let’s estimate the cost of hydrogen produced with this electricity. 1 Schlumberger-Private This 2014 report by the US DOE estimates that hydrogen produced at large scales via electrolysis would cost $4.3/kg, with $3.5/kg of that cost coming from electricity. However, that electricity is produced at a rate of $.065/kWh, not at our cheaper rate. How much would the electricity part of the cost be with our cheaper solar power? Give your answer in $/kg of H2. $/kg H2 correct 1.08 \(\) Explanation Multiply the original electricity cost by a fraction made out of the electricity costs: \[ $3.50/kg \cdot \frac{$0.02}{$0.065} = $1.08 \ per \ kg \ H_2 \] Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review FOM Cost Increase 0/5 points (graded) Unfortunately, the intermittent nature of solar power will mean that the hydrogen plant's hardware will be left idle more often. This means that fixed costs will contribute more to the cost of hydrogen. The original estimate had fixed costs at $0.8/kg when the plant had 90% utilization. Now that it only has 37% utilization, what are the fixed costs in $/kg? $/kg H2 incorrect 1.95 \(\) Explanation Multiply the old fixed costs by a fraction composed of the utilization factors: \[ $0.80/kg \cdot \frac{90\%}{37\%} = $1.95/kg \] This is a big increase! We could run the plant on grid electricity when the sun isn’t available to improve utilization, but in this case it has little effect on the cost of H2, so we’ll neglect that option. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem 1 1 Schlumberger-Private Review Energy Cost of Hydrogen 0/5 points (graded) Using the new fixed and variable costs that you determined above, what is the total cost of hydrogen produced by solar power? Answer in dollars per gigajoule. $/GJ incorrect 21.6 \(\) Explanation Adding the previous values together, we get $3.03 per kilogram. Hydrogen's energy density is 0.14 GJ/kg, and we can divide to get our total cost of $21.6 per gigaloule. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Pump Price 3.75/5 points (graded) Which nations had gasoline pump prices substantially (more than 15%) higher than this in 2014? Select all that apply. Norway correct USA India correct Germany correct partially correct Explanation As an example: Germany had a cost of $1.8 USD per liter at the pump for gasoline. Gasoline's energy density is 35 GJ/m3 , which is 0.035 GJ/liter. Dividing, we find a total cost of $51.40 per GJ. Submit You have used 4 of 4 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review 1 Schlumberger-Private Is this as good as it looks? 3.75/5 points (graded) Why doesn’t this actually represent a huge cost savings opportunity for some of those nations above? You may want to read this article on gasoline prices before answering. Choose all of the answers that apply (and there may be more reasons we don't list below). We only calculated cost to produce hydrogen, not to store or transport it. correct Infrastructure hurdles raise the price of a hydrogen economy correct Hydrogen vehicles have lower fuel economy Many nations' gasoline prices are only higher than the US's because of taxes. correct Community Electricity Demand 0.0/5.0 points (graded) First let’s estimate the village's electric demand. Assume the system needs to power the following devices for a village of 50 households:  Mini fridges: one per household, .15 kWh/day each  Lights: 25 W of LED’s per household averaging 4 hrs/day  Phones: 4 cell phones per household with 5 Wh batteries charged every other day  Computers, TV’s, etc: .1 kWh/day per household  Air Conditioning: one for small schoolhouse, 1.5 kW used for 4 hrs/day What’s the total demand per day? kWh incorrect 24 1 Explanation Per-person expenses: 0.15+(0.025×4)+(4×0.005÷2)+0.1=0.36 kWh Community-wide costs: Just the school's AC. 1.5 kW×4 hours=6 kWh Total for 50 people: 0.36×50+6=24 kWh Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. 1 Schlumberger-Private Show Answer Answers are displayed within the problem Review Capital Cost 0.0/5.0 points (graded) Next let's estimate the capital cost of the solar system in dollars per kilowatt. Use Figure 7 from the US National Renewable Energy Laboratory’s 2015 US Photovoltaic Prices and Costs Breakdown report. Since this will be a small system, use values for residential systems. For simplicity, include only the hardware costs and installation labor (sometimes called "direct labor") costs, and assume that the installation labor only costs half as much as in the US. You may ignore all other costs (permitting, profit, supply chain costs, etc). $/kW incorrect 1475 1 Explanation The costs are: $0.70 for the module, $0.29 for the inverter, $0.12 for the rack, and $0.20 for the balance-of-system materials. Installation labor, at half the US rate, would be $0.165. The total for all of that is $1.475 per watt, which is $1475 per kW. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem Review Critical Factors 0.0/5.0 points (graded) What other figures are critical for estimating the levelized cost of electricity for this system? Operations and maintenance Capital charge factor correct 1 Schlumberger-Private Capacity factor correct incorrect Note: Make sure you select all of the correct options—there may be more than one! Explanation Operations and maintenance costs are significant but small. Given the low cost of labor in the region we can neglect this cost. For capital-cost-dominated renewables, the two other critical figures are the capital charge factor and capacity factor. Submit You have used 3 of 3 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Capacity Factor 0.0/10.0 points (graded) What's the capacity factor? SolarGIS has nice maps for Global Horizontal Irradiation. Adjust the GHI for northwestern Mali upward by 20% (multiply by 1.2) to very roughly account for the gain from tilting the panels at latitude. % incorrect 29.4 1 Explanation The map shows about 2150 kWh per square meter per year. To find the percentage of the maximum power, we set up a fraction, and adjust upward by 20%: 2150 kWh/m2/yr1 kW/m2⋅8766 hrs/yr⋅120%=29.4% Because of the different values in the map, this problem accepts answers between 27% and 32%. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Hint Show Answer Answers are displayed within the problem 1 Schlumberger-Private Review LCOE 0.0/10.0 points (graded) What is the LCOE for this system? Assume a capital charge factor of 0.1 $/kWh incorrect 0.057 1 Explanation The total cost takes into account both the CCF and the capacity factor: $1475/kW⋅10%/yr29.4%⋅8766 hrs/yr=$0.057/kWh Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review LCOB 0.0/10.0 points (graded) Assume that the village would like a modest 2 kWh battery backup system, costing $500/kWh. Unfortunately, the batteries have a much shorter lifespan than the solar panels, only around 8 years at the village's usage rate, leading to a higher CCF of .15. What’s the additional LCOE that the batteries will add to the system? Ignore any costs of operating the battery, or electric losses. $/kWh incorrect 0.017 1 Explanation The batteries will cost $1000 in total. Using our standard LCOE approach, we find: $1000⋅15%/yr24 kWh/day⋅365 days/yr=$0.017/kWh Submit 1 1 Schlumberger-Private You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Peer grade, self grade Schlumberger-Private Energy density 1/1 point (graded) As David mentioned, nuclear power is basically one hell of a way to boil water, and the steam it generates turns a turbine and generates electricity much like in a natural gas or coal plant. But as he described, the method of extracting thermal energy from the fuel is very different – rather than combusting the fuel, we rely on nuclear chain reactions. The total amount of energy extracted from a given unit of fuel is called the “burnup,” and is usually around 50 GW-days of thermal energy per ton of uranium in modern plants (this “burnup” is analogous to the heat of combustion for fossil fuels). In terms of mass, how much more energy dense is nuclear fuel at a burnup of 50 GWdays/ton than gasoline (use gasoline's higher heating value)? Note that this question is about real nuclear power plants and is different from the comparison David made in the first video involving the energy released from an individual fission or fusion (so you'll actually need to do a calculation). 100 times more energy dense 100,000 times more energy dense correct 10,000,000 times more energy dense Submit You have used 1 of 1 attemptSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (1/1 point) Review Cost of fuel 1/1 point (graded) What’s the cost of fuel, in $/GJ, for a nuclear plant that extracts 50 GW-days/ton of fuel, with fuel costing $2500/kg? $.6/GJ (much less than any fossil fuel) correct $2/GJ (about the same as inexpensive coal) $8.5/GJ (a typical natural gas price in Euorpe in recent years) Nuclear LCOE 0/15 points (graded) Compute the cost of electricity (in units of $/kWh) from a nuclear power plant under the following assumptions. Schlumberger-Private  Fixed O&M is 75 $/kW-year.  Variable O&M is $.0075/kWh  Capital cost is $5500/kW  capital charge factor is 10%  Utilization is 85%  Plant thermal efficiency is 35%  Each ton of uranium oxide fuel provides 50 GW-days of thermal energy  Fuel cost is $2,500,000 per ton $/kWh incorrect 0.097 \(\) What percentage of the total LCOE is due to fuel costs? % incorrect 5.87 \(\) Explanation 50 GW-days comes out to \( 1.2 \times 10^9 \ kWh \) of thermal energy. Fuel costs \( $2.5 \times 10^6 \div 1.2 \times 10^9 \ kWh_{th} = $.00208/kWh_{th} \) where the "th" subscript denotes thermal energy. We still need to factor in efficiency to get the fuel’s cost per kilowatt-hour. The terms in the equation below are the fixed costs, the variable O&M, and the fuel cost. \[ LCOE = \frac{$5500 \cdot 0.1 + 75}{0.85 \cdot 8766} + $0.0075 + \frac{$0.002}{0.35} = $0.097/kWh \] The cost for just the fuel is: \[ \frac{$0.002}{0.35} = $0.0057/kWh \] ...which comes out to 5.87% of the total LCOE. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Fuel per Year 1 1 Schlumberger-Private 0/5 points (graded) How much fuel would a 1 GW plant with an 85% capacity factor and 50 GW-days/ton burnup consume in a year, in metric tons? tons incorrect 17.75 \(\) Explanation 1 GWe plant at 85% capacity produces \[ 1 \ GW \cdot 0.85 \cdot 8766 = 7.45 \times 10^9 \ kWhe \] in one year. This requires \[ \frac{7.5 \times 10^9}{0.35} = 2.13 \times 10^{10} \ kWh \] of thermal energy per year. To find the mass, we use the per-ton energy density: 50 GW-days comes out to \( 1.2 \times 10^9 \ kWh \) of thermal energy. \[ \frac{2.13 \times 10^{10} \ kWh}{1.2 \times 10^9 \ kWh/ton} = 17.75 \ tons \] Each plant requires about 18 tons of uranium oxide per year. Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review The Equivalent Coal Plant 0/5 points (graded) What mass of coal would an equivalent coal plant consume in a year, in metric tons? Assume the same 1 GW power, 85% capacity factor, and 35% thermal efficiency. tons incorrect 2.85*10^6 \(\) Explanation As before, we need to supply \( 2.13 \times 10^{10} \ kWh \) of thermal energy. To find the mass, we use the energy density of coal: \[ \frac{2.13 \times 10^{10} \ kWh}{0.027 \ GJ/kg} = 2.85 \times 10^6 \ tons \] 2.87 million tons of coal, compared to 17.75 tons of uranium oxide. Submit 1 1 Schlumberger-Private You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review US Nuclear Waste 2014 0/5 points (graded) Without reprocessing, all of this nuclear fuel will become "spent fuel" waste. When stored in a container, the waste usually has a density around .25 tons/m3 . The EIA estimates that in 2014 the US generated about \( 8 \times 10^{11} \) kWh from nuclear power. Given this information, estimate the volume of waste from nuclear power in the US in 2014. cubic meters incorrect 7600 \(\) Explanation For 1 GW plants we established 17.75 tons of spent fuel per \( 7.45 \times 10^9 kWh \). This comes out to \( 2.38 \times 10^{-9} \ tons/kWh \). According to the IEA, the USA produced \( 7.97 \times 10^{11} \) kWh of electricity via nuclear power in 2014. The total amount of waste in 2014 was therefore... \[ 7.97 \times 10^{11} \ kWh \cdot 2.38 \times 10^{-9} \ tons/kWh = 1900 \ tons \] If the density is 0.25 tons/m3 , the volume will be: \[ \frac{1900 \ tons}{0.25 \ tons/m^3} = 7600 m^3 \] For reference, consider that an Olympic swimming pool is about 2500 m3 . Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Doubling US Nuclear Capacity 5/20 points (graded) 1 Schlumberger-Private Now imagine that the US, in response to climate change, decides to double its yearly output of nuclear electricity. What volume of spent fuel would be generated in 50 years at this level of production with current technology? cubic meters incorrect 760000 \(\) How does that compare to the \( \approx 3 \times 10^5 m^3 \) of commercial spent fuel waste in the US currently? 10 times all our spent waste so far. 2 or 3 times all our spent waste so far. correct About the same as all our spent waste so far. About 1/3 of all our spent waste so far. A tenth of all our spent waste so far. What mass of waste would be generated? tons incorrect 190000 \(\) How does this compare to the mass of waste that could be stored in the US's Yucca Mountain facility, which stores approximately 70,000 metric tons? Select the closest answer. 10 times what Yucca Mountain can handle. 2 or 3 times what Yucca Mountain can handle. correct About what Yucca Mountain can handle. incorrect About 1/3 of what Yucca Mountain can handle. A tenth or less of what Yucca Mountain can handle. Explanation Parts 1 and 2: 1 1 Schlumberger-Private \( 7600 \ m^3/yr \cdot 2 \cdot 50 \ years = 7.6 \times 10^5 \ m^3 \), about 2.5x current levels of nuclear waste. Parts 3 and 4: \( 1900 \ tons \cdot 2 \cdot 50 years = 2 \times 10^5 \ tons \), about 2.7x what could be stored in Yucca mountain Submit You have used 10 of 10 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Yucca Mountain Costs 0/5 points (graded) Finally, let's make a crude estimate of the cost of storing waste in Yucca Mountain. If Yucca Mountain cost $100 billion total over its lifetime (to build, transport and store the waste, etc) and stored 70,000 metric tons of waste, how much does it add to the cost of electricity for the plants that store their waste there? Assume the plants extract 50 GWdays of thermal energy for each ton of waste, and have 35% efficiency. $/kWh incorrect 0.00333 he importance of capital cost 0/1 point (graded) As David mentioned, capital costs are very important for nuclear power but are highly uncertain in many regions. Let's compare the LCOE of nuclear electricity to wholesale electricity using two different capital costs for nuclear, $4000 and $8000/kW. How much higher is the LCOE of nuclear electricity using the following assumptions than wholesale electricity at $.065/kWh? If the LCOE for nuclear was $.195/kWh, you would answer "200% higher." For now you may ignore the contribution of nuclear waste storage (a later problem will include it). Nuclear plant capital costs of $4000/kW and $8000/kW, CCF of .11 Fixed operations and maintenance $100/kW-yr, utilization 85% VOM $.002/kWh, Fuel $.6/GJ, efficiency 35% 1 Schlumberger-Private 25% higher than wholesale for $4000/kW and 100% higher for $8000/kW correct 10% lower than wholesale for $4000/kW and 50% higher for $8000/kW 100% higher than wholesale for $4000/kW and 200% higher for $8000/kW incorrect 50% lower than wholesale for $4000/kW and equal for $8000/kW Estimating the effects of exposure 0.5/1 point (graded) David described how cancer risks from radiation exposure are commonly calculated, with a 1 person-Sievert (person-Sv) dose corresponding to an additional 5% cancer mortality risk. The risk is conservatively assumed to be linear in dose, so a 2 person-Sv dose corresponds to an additional 10% cancer mortality risk, and a .01 person-Sv dose corresponds to an additional 0.05% cancer mortality risk. The 1979 Three Mile Island accident in the US lead to an average exposure for civilians around the plant of 14 microSv. What is such a person's additional cancer mortality risk? .00007% correct 1% .05% incorrect The accident exposed 2 million people to such a dose. What is the expected number of cancer mortalities due to this exposure? none 1.4 correct 2.9 16 Nuclear power's cost of mitigation 1/2 points (graded) Before you move on to some readings offering different views on nuclear power, let's try a cost-of-mitigation-style question. Instead of making some assumptions and working out the cost of mitigation, let's work backwards to see what capital cost would be necessary for nuclear power to have a low cost of mitigation of $25/tCO2. If we want a cost of mitigation of $25/tCO2, and wholesale electricity currently costs $.065/kWh and causes .5 kg CO2/kWh of emissions, what LCOE will the nuclear power need to have? This is a two-part problem. Answer both parts before hitting "Check." Schlumberger-Private $.067/kWh $.091/kWh incorrect $.078/kWh correct What capital cost would be required for a nuclear plant with the following assumptions to have that LCOE? You're welcome to use a tool like wolfram alpha to solve for the capital cost, or to do it by hand. Once you calculate it, take some time to compare this capital cost to recent capital costs in different countries as discussed in The Economist's View. This will be a useful thing to know when evaluating the divergent arguments about the costs of nuclear power, and should be helpful when you write your essay in the next section. Assumptions: CCF of .11, with 90% utilization; FOM of $100/kW-yr; VOM of $.002/kWhr, Fuel cost of $.6/GJ, and thermal efficiency of 36%; waste storage cost of $.005/kWh $3150/kW $3750/kW correct $5300/kW $8000/kW Peer grade, self grade Schlumberger-Private Cost of Mitigation for a Gas Furnace 0/1 point (graded) What's the cost of mitigation of installing an efficient natural gas furnace, using the following assumptions? (These are based on Daniel's actual home heating usage and furnace purchasing options).  A low-efficiency furnace costs $1000, and is 79% efficient.  A high-efficiency furnace costs $1800, and is 93% efficient.  Either furnace will be used to supply 100 GJ of heat per year (not including losses due to inefficiency).  Gas costs $9.90/GJ and has lifecycle emissions of 65 kg CO2e/GJ. (Note that this is higher than the combustion-only emissions on the Conversion Sheet.)  Installation cost $2050, the same for both furnaces.  Use a CCF of 0.16.  Calculate levelized cost of heating for each using only purchase price, installation, and yearly heat supply (including fuel cost and efficiency). Then calculate the emissions of each, and use the levelized cost and emissions to calculate the cost of mitigation. $/tCO2 incorrect Energy Cost of Crude Oil 0/5 points (graded) What’s the cost of crude oil, in $/GJ? Use a major spot price (Brent, WTI, etc) and use an average for 2017. Keep in mind that spot prices have occasionally been twice as high as the 2017 average since that year. $/GJ? incorrect 8.8 Energy Cost of Gasoline 0/5 points (graded) 1 1 Schlumberger-Private What’s the cost of gasoline in the US, in $/GJ? Use World Bank or EIA data for US retail or pump price for the year 2017. Keep in mind that prices can easily be 2x as high in other countries. $/GJ? incorrect 19 \(\) Explanation Gasoline costs about $2.528/gallon, and provides 35 GJ/m3 . The resulting price is $19/GJ Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Energy Cost of Vegetable Oil 0/5 points (graded) What’s the cost of store-bought vegetable oil, in $/GJ? An average retail price for the US for this isn’t easy to find, so you can use the lowest price Daniel could find, $1.6/liter. You can find lots of resources online for the energy density of vegetable oil (notice how similar it is to gasoline). $/GJ? incorrect 46 \(\) Explanation Many online sources are around 8.4 kcal/mL, or .035GJ/liter, the same as gasoline. $1.6/liter / .035 GJ/liter = $46/GJ Note that vegetable oil can be much cheaper on the bulk market. If you're willing to purchase it by the ton, with a minimum order of 100 tons, you can get it for around $200 per ton, which is about $0.184 per liter. We're not sure where you'd want to store 108,600 liters of sunflower oil. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Energy Cost of Bananas 1 1 Schlumberger-Private 0/5 points (graded) What’s the cost of bananas in $/GJ? Use a US average retail price of bananas (you can find this from many sources, including the Bureau of Labor and Statistics, and the UN FAO, or if you’ve shopped in the US you could probably take a good guess since this problem has wide tolerance). You can find lots of resources for the energy density of bananas; use an estimate for medium-sized bananas that includes the skin of the banana (which is part of the purchase price; medium-sized with skin is around 160-200 grams). $/GJ? incorrect 520 \(\) Explanation Most sites seem to indicate ~2400 kJ/kg for medium sized bananas with skin. The US BLS’s “Average Retail Food and Energy Prices” and FAO’s “Banana Market Review” give prices around $1.25/kg. $1.25/kg / 2400 kJ/kg = $520/GJ after conversion. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Energy Cost of Electricity 0/5 points (graded) What’s the cost of residential electricity in the US, in $/GJ? Use the US-average residential price for 2017 from the EIA. $/GJ? incorrect 35.8 \(\) Explanation The US average cost is $0.129/kWh, which is $35.8/GJ after conversion. Submit You have used 5 of 5 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Energy Cost of Batteries 1 1 Schlumberger-Private 0/5 points (graded) How many times higher is the cost of AA batteries than residential electricity? Use a price of $.25/battery (reflecting a bulk order online; retail prices in stores are usually much higher). They have a voltage of 1.5V and around 1200 mAh when used in low discharge applications, for around 1.8Wh of energy total. about the same 10x higher 100x higher incorrect 1000x higher correct stimating Carbon Reduction These problems will help you estimate the carbon savings (in CO2e) of different measures you might take to reduce your impact. Notice how the results compare to many popular "ways to shrink your carbon footprint" lists, which often include things like unplugging electronics and printing double-sided, and detailed breakdowns of current carbon footprints, which usually emphasize the dominance of transportation, diet, and home heating and cooling for most people. The answers are all multiple-choice-style for expediency and to help you compare orders of magnitude, but please avoid guessing. We recommend that you carry out all of the calculations fully to get a numerical value before choosing an answer. We purposefully avoid some important things you could do because estimating them accurately is beyond the scope of this class. Examples include changes to building envelope or insulation, or setting an automatic thermostat. We included a mix of things, from simple behavioral changes to moderate technology upgrades to showerheads or furnaces to major changes like moving into or building a smaller house. We also give fairly specific scenarios for the problems below. These are usually close to US averages, but please feel free to try this exercise on your own with data from your life. That will help you see what major opportunities you have for impact reduction. Commuting 0/5 points (graded) How much CO2 can be saved every year by reducing a car commute by half (roughly equivalent to carpooling with one other person)? Assume the average US commute is 30 km round trip, with 250 commutes per year, in 8 L/100km vehicles, with 3.2 kg CO2e/L of fuel (lifecycle intensity of fuel). ~1-3 kg CO2e/yr Schlumberger-Private ~10-30 kg CO2e/yr ~100-300 kg CO2e/yr incorrect ~1000-3000 kg CO2e/yr correct Explanation This problem is primarily one of unit conversion: \[(30-15) \ km/day \cdot 250 \ days/year \cdot 8L/100km \cdot 3.2 \ kgCO_2e/L = 960 \ kgCO_2yr \] Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Shower energy use 1.6666666666666667/5 points (graded) This is a multi-part problem. You have only two submissions. Enter all responses before hitting "Check". How much CO2 can be saved every year by installing a low-flow showerhead? Assume the shower is used for 8 minutes of warm showering per day with an 11 L/min showerhead, using 2.8 kWh of electricity (mostly for water heating), and the new showerhead will use only 5.5 L/min for 1.4 kWh of electricity use per day. ~1-3 kg CO2e/yrincorrect ~10-30 kg CO2e/yr ~100-300 kg CO2e/yr correct ~1000-3000 kg CO2e/yr How much CO2 can be saved every year by reducing shower length from 8 minutes to 5 minutes? Assume the shower has an 11 L/min showerhead, using 2.8 kWh of electricity for 8 minute showers. ~1-3 kg CO2e/yrincorrect ~10-30 kg CO2e/yr ~100-300 kg CO2e/yr correct ~1000-3000 kg CO2e/yr Schlumberger-Private Note that these two measures (shorter showers and low flow showerheads) interact - if you do one, doing the other will have less of an impact than it would have on its own. If you already installed the low flow showerhead, how would the savings from reducing shower length be reduced from the number you calculated for the problem above? The shower-length-reduction savings would be 1/4 as much if the low flow showerhead had already been installed The shower-length-reduction savings would be 1/2 as much if the low flow showerhead had already been installed correct The shower-length-reduction savings would be the same Explanation For the low-flow showerhead: \[ 1.4 \ kWh \cdot 365 \ days/yr \cdot 0.5 \ kgCO_2e/kWh = 256 \ kgCO_2e/yr \] For shorter showers: \[ \frac{3}{8} \cdot 2.8 \ kWh/day \cdot 365 \ days/yr \cdot 0.5 \ kgCO_2e/kWh = 208 \ kgCO_2e/kWh \] Combining the two means that the shower-length-reduction savings would be 1/2 as much. Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Diet 0/5 points (graded) This is a multi-part problem. You have only two submissions. Enter all responses before hitting "Check". How much CO2 can be saved every year by reducing an individual's meat consumption? Assume the average diet yields 10 kg CO2e/day, a vegetarian diet yields 7 kg CO2e/day, and a vegan diet yields 5 kg CO2e/day. (Estimates of the carbon footprint of diets are quite uncertain; see Appendix A of the "Biking vs Driving" blog post Daniel and David wrote for a discussion of some references and methodological difficulties). What's the yearly CO2 savings for an individual switching from an average diet to a vegetarian diet? ~1-3 kg CO2e/yr ~10-30 kg CO2e/yr incorrect ~100-300 kg CO2e/yr Schlumberger-Private ~1000-3000 kg CO2e/yr correct What's the yearly CO2 savings for an individual switching from an average diet to a vegan diet? ~1-3 kg CO2e/yr incorrect ~10-30 kg CO2e/yr ~100-300 kg CO2e/yr ~1000-3000 kg CO2e/yr correct Explanation Switching from omnivore to vegetarian is a 3-kg improvement per day: \[ 3 kgCO_2e/day \cdot 365 \ days/year = 1100 \ kgCO_2e/yr \] Switching from omnivore to vegan is a 5-kg improvement per day: \[ 5 kgCO_2e/day \cdot 365 \ days/year = 1800 \ kgCO_2e/yr \] By far biggest meat impact is from beef. One can get a good chunk of the average omnivore-to-vegetarian benefit simply by avoiding beef and lamb. Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Lighting 0/5 points (graded) How much CO2 can an average household save, per person each year, by upgrading all of their lighting to LEDs? Assume that the average household has 3 people and currently uses 1700 kWh for lighting per year, with 2/3 of their bulbs being incandescents (15 lumens/W) and 1/3 of their bulbs being some mix of CFL's and LED's (140 lumens/W). Assume that they consume the same amount of light (in lumens) before and after the uprade. ~1-3 kg CO2e/yr incorrect ~10-30 kg CO2e/yr ~100-300 kg CO2e/yr correct ~1000-3000 kg CO2e/yr Explanation The starting average value in lumens per watt is \( \frac{2}{3} 15 + \frac{1}{3} 140 = 57 \ lm/W\). The average after replacement will be 140 lumens/watt. This will result in a savings of: Schlumberger-Private \[ \frac{83}{140} \cdot 1700 \ kWh/yr \cdot 0.5 \ kgCO_2e/kWh \div 3 \ people = 168 kgCO_2/yr \] Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Printing 0/5 points (graded) How much can an individual save by printing double sided? Assume that their paper weighs 4.5 grams per page, takes 10 kWh/kg to make and deliver to them with a carbon intensity of ~.4 kg CO2e/kWh (to account for the mix of electricity and fossil fuels used), and that they would otherwise print 3000 single sided pages. Assume that the only benefit of double sided printing is a reduction in paper use. ~1-3 kg CO2e/yr incorrect ~10-30 kg CO2e/yr correct ~100-300 kg CO2e/yr ~1000-3000 kg CO2e/yr Explanation This problem is primarily one of unit conversion: \[ 4.5 \ g/page \cdot 1500 \ pages/yr \cdot 10 \ kWh/kg \cdot 0.4 \ kg CO_2e/kg = 27 \ kg CO_2e/yr \] Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Cell Phone Charger 5/5 points (graded) How much CO2 can an individual save each year by unplugging their cellphone charger when it's not in use? Assume that it consumes at most 1W when plugged in but not in use, and that it's only used for 4 hours each day. ~1-3 kg CO2e/yr correct ~10-30 kg CO2e/yr ~100-300 kg CO2e/yr Schlumberger-Private ~1000-3000 kg CO2e/yr Explanation This problem is primarily one of unit conversion. Typical wall electricity causes about 0.5 kg of CO2 emissions per kWh. \[ 1 W \cdot 20 \ hrs/day \cdot 365 \ days/yr \cdot 0.5 \ kg CO_2e/kWh = 3.6 \ kg CO_2e/yr \] You can read more about the low impact of idle chargers in David MacKay's excellent Sustainable Energy here, and about the more considerable impact of other idle electronics in a different part of his book here. Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Air travel 0/5 points (graded) How much CO2 can an individual save each year by flying 10000 km less? (This is roughly the round trip distance of a flight across the US, or from the eastern US to western Europe.) Assume the flight takes 4.5L/100-passenger-kilometers and that jet fuel provides 35 MJ/liter and causes 90 kg CO2e of emissions per GJ. ~1-3 kg CO2e/yr incorrect ~10-30 kg CO2e/yr ~100-300 kg CO2e/yr ~1000-3000 kg CO2e/yr correct Explanation This problem is primarily one of unit conversion: \[ 1 \ flight \cdot 4.5 L/100 km \cdot 0.035 \ GJ/liter \cdot 90 \ kgCO_2e/GJ = 1400 \ kg CO_2e/yr \] Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Furnace 0/5 points (graded) How much CO2 can a household save, per person each year, by upgrading from an 80% efficient gas furnace to a 95% efficient gas furnace? Assume that the household has 3 Schlumberger-Private people and consumes 70 GJ of heating each year (not including the losses due to inefficiency). ~1-3 kg CO2e/yr incorrect ~10-30 kg CO2e/yr ~100-300 kg CO2e/yr correct ~1000-3000 kg CO2e/yr Explanation We need to look at the difference between the enegry consumed in each furnace, and find the emissions saved from that difference: \[ \left( \frac{70 \ GJ}{0.8} - \frac{70 \ GJ}{0.95} \right) \cdot 65 \ kg CO_2e/GJ \div 3 \ people = 300 \ kg CO_2e/yr \] Submit You have used 2 of 2 attemptsSome problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Answers are displayed within the problem Review Home size 0/5 points (graded) How much CO2 can a household of 3 save, per person each year, by reducing the size of their home by 50% (roughly the difference between US homes in the 1950's and today)? Assume that they currently use 50 GJ of electricity and 50 GJ of natural gas per year, and that energy use is linear in home size with a slope of approximately 1/2 (so a 20% reduction in home size leads to 10% reduction in energy use, etc; for more on this relationship see US Green Building Council). Only count the savings from electricity and natural gas (though note that the embodied energy in homes can be substantial, making the savings larger than you'll calculate here for construction of new homes of different sizes). ~1-3 kg CO2e/yr incorrect ~10-30 kg CO2e/yr ~100-300 kg CO2e/yr ~1000-3000 kg CO2e/yr correct Schlumberger-Private Peer grade, self grade lectric Grid Efficiency 1/1 point (graded) What is the average efficiency of electric grids in developed countries? That is, what percentage of the electrical power generated at power plants actually makes it to end users in countries like Australia, the UK, and the US? % correct 90 Exact answer: 94% Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (1/1 point) Review Coal Power Efficiency 1/1 point (graded) What is the efficiency of a typical coal-fired power plant? That is, what percentage of the thermal energy from burning the coal is successfully turned into electricity? % correct 50 Around 35% Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (1/1 point) 90 50 Schlumberger-Private Review SPENDING ON CLIMATE CHANGE In your opinion, about how much of total global GDP should be spent on managing climate change? This is an opinion question with no right or wrong answer RESULTS  1% 100%  0.1% 0%  3% 0%  10% 0%  30% Schlumberger-Private 0% Results gathered from 2 respondents. FEEDBACK There is no right answer here, but keep in mind how serious high responses (over 10%) are. The US' notoriously high military expenditure is only 3.5% of its GDP today. Even at the peak of World War II, when many common goods were rationed, people were conscripted into the military, and many civilian factories were converted to make equipment for war, the US only spent 1/3 of its GDP on the military. Mortality Rates 3/3 points (graded) This problem has three parts. Answer all three before clicking the "Check" button. How many premature deaths are caused by energy-related water pollution each year? Almost zero correct Thousands Millions Hundreds of millions How many premature deaths are caused by energy-related air pollution each year? Almost zero Thousands Millions correct Hundreds of millions How many premature deaths are currently caused by climate change each year? Almost zero correct Thousands Millions Schlumberger-Private Hundreds of millions Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (3/3 points) Review Composition of Global Energy Supply 8/8 points (graded) Estimate the fraction of global primary energy supplied by the following sources. Use rough numbers and don’t worry about ensuring that they sum to exactly 100%. This is a multi-part question. Make sure you answer all the parts before clicking "Check". Biomass % correct 10 Coal % correct 20 Hydropower % correct 2 Natural Gas % correct 20 Nuclear Power % correct 4 Oil % correct 10 20 2 20 4 40 Schlumberger-Private 40 Solar % correct 0.05 Wind % correct 0.05 Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (8/8 points) Review Energy Prices 4/4 points (graded) Please compare the prices of each of the below to crude oil on an energy basis. Select the closest answer. For example, if coal cost 8 times as much as crude oil for the same amount of energy, you would answer "Much more." If electricity cost 10% less than oil, you would select "Less." There is some regional variation in these prices, so try to imagine world average prices if you can. This is a multi-part question. Make sure you answer all the parts before clicking "Check". Natural Gas costs _________ than crude oil for the same amount of energy correct Coal costs _________ than crude oil correct 0.05 0.05 Much less (less than 1/3 the cost of oil) Much less (less than 1/3 the cost of oil) Schlumberger-Private Electricity for a large industrial consumer costs _________ than oil correct Electricity for a home consumer costs _________ than oil correct Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (4/4 points) Review Sulfur and Carbon 2/2 points (graded) This problem has two parts. Answer both before clicking the "Check" button. Suppose humanity continued to emit air pollutants and CO2 following “business-asusual”, and then suddenly in 2050 cut emissions of both to 0. Approximately how long would it take for sulfate-driven mortality from particulate matter to fall by 50%? a week correct a year hundreds of years thousands of years Approximately how long would it take for global temperatures to drop halfway from their peak to pre-industrial average? a week More Much more (more than 2x the cost of oil) Schlumberger-Private a year hundreds of years thousands of years correct Submit Some problems have options such as save, reset, hints, or show answer. These options follow the Submit button. Show Answer Correct (2/2 points) Review Fossil Fuel Remaining 1/1 point (graded) Compare humanity's current annual primary energy supply to estimates of the total remaining fossil fuel resource (the "ultimately recoverable resource"). How much larger is the total fossil fuel resource? Around 10 times larger than annual primary energy supply Around 500 times larger than annual primary energy supply Around 1,000 times larger than the annual primary energy supply correct Around 1,000,000 times larger than the annual primary energy supply Schlumberger-Private [Show More]

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