CEE 107S/207S Summer 2021 Homework #4
UNDERSTANDING ENERGY
HOMEWORK SET 4
Electricity decarbonization || Energy Storage & Microgrids || Nuclear Energy, Fusion, SMRs
Due: 5 pm PST on Friday, July 30th, 2021
SUBMIT ONLINE IN CANVAS AS ONE PDF DOCUMENT!
Please refer to the Homework Policy posted on Canvas for details on the type of collaboration permitted between students on homework sets.
List any students with whom you discussed this HW: __________________________________
Show all calculations and conversions. State all assumptions. Explain your logic briefly and clearly. Cite sources if it is not the lecture slides or readings. Refer to Math Review Sheets (on Canvas) for example problems and help on unit conversions and other energy-related calculations.
Making a Dent in Carbon Emissions [7 points]
This question is meant to give a sense of the type of action required to stabilize carbon emissions. The US emitted 6.67 GtCO2e in 2018. 28.2% of that came from the transportation sector and 26.9% from the electricity sector.
Additionally, in 2018, the US generated about 4,000 billion kWh of electricity. There were approximately 327 million people in the US. Assuming that two, 43-watt light bulbs, which typically run for 9 hours per day year-round, are replaced with two, 5-watt LEDs for each person in the US, what are the resulting annual GHG emission savings in GtCO2e? [2 pts]
In 2018, there were 280 million light-duty vehicles (LDVs) on the road in the U.S. On average, each of those vehicles traveled roughly 13,400 miles per year. The fuel economy of the on-road fleet in 2018 was 25.1 per gallon (mpg). CO2 emissions averaged 353 grams per mile in 2018. The US government has set a target of 54.5 mpg for the fuel economy of LDVs by 2025. How many GTCO2e would have been reduced per year if 1/4 the US LDV fleet had met the 54.5 mpg target in 2018, and if CO2 per gallon and annual miles travelled remained constant? [2 pts]
What do you think are some of the greatest challenges to stabilizing global greenhouse gases and mitigating climate change? Name and describe at least two. [2 pts]
Using this EPA tool, report any one greenhouse gas equivalency of interest, for 1 MMTCO2 (1 million metric tons of CO2): https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator [1 pt]
The Nuclear Debate: Brand versus Jacobson. [10 pts]
This 23-minutes TED Talk from 2010 highlights two important perspectives on the role of nuclear energy and renewable energy resources in meeting a sustainable energy future. In this first-ever TED debate, Stewart Brand and Mark Z. Jacobson square off over the pros and cons of nuclear energy. It is “a discussion that’ll make you think — and might even change your mind.”
Link to TED talk: http://www.ted.com/talks/debate_does_the_world_need_nuclear_energy
From the talk, summarize the three most important points in favor of nuclear energy and the three most important points against. [6 pts]
Do you believe the US should build more nuclear power plants? Why or why not? What about other countries? Did the TED talk change your perspective? [4 points] There is no ‘right’ answer to this question – a variety of answers are accepted as long as the rationale is clear and thoughtful.
Biggest Battery in the World [3 pts]
Kemp mentioned how important battery technology and other forms of energy storage will be for the future of the grid. In the nearby town of Moss Landing, PG&E is working with Vistra Energy and Tesla Energy to replace 3 natural gas power plants with a massive installation of lithium-ion batteries. Explain two reasons why environmental advocates and renewable energy producers might be excited about battery technology (give one reason each) [2 pts]
Name one potential environmental concern from increased usage of batteries and how likely this concern is [1 pts]
Macro Thinking on Microgrids [7 pts]
What is the most common source of backup power generation for remote and island communities? [1 pt]
Explain, in 2-3 sentences, at least 3 disadvantages of using diesel generators for backup power in remote and island communities. [3 pts]
A microgrid is a small, self-contained energy network that serves a local area. It can operate in either grid-connected mode or island mode. Explain 1 service a microgrid can provide for each:
for an individual person (i.e. picogrid) [1 pt]
for a critical facility on an island [1 pt]
for the larger grid it’s connected to in a bigger city [1 pt]
Flex-tricity [8 points]
In order to get to 100% zero-carbon electricity for retail sales by 2045 (SB 100), California utilities and grid operators need more creative ways to address the ever-steepening duck curve, like the supply-side solutions discussed above. Let’s explore the demand-side role played by electricity consumption and rate design:
Name and describe 2 retail rate structures. Include one pro and one con with each of your picks. [4 pts]
Identify one rate structure that would be better aligned with flattening the “duck curve”. Why would grid operators support this rate design? [2 pts]
Does a tiered rate structure incentivize or disincentivize electrification and why? [2 pt]
IMPORTANT! —
● IF you are in CEE207A (Graduate credit) do Question 6.
● IF you are enrolled in CEE107A (Undergraduate credit), doing Question 6 is NOT REQUIRED, though you should feel free to try it – it may help you on the midterm and final! But please do NOT hand your answers in if you are not enrolled in 207A.
I Hear You Loud and Nuclear [11 points] You are at a very 90s music-centric concert and just happen to be pondering the intricacies of the nuclear industry.
Opening up is the band Cake, they start with “The Distance” (really great song), but you are still thinking about nuclear facts and figures. The term cake is commonly used at a nuclear power plant, but they aren’t talking about the band. What color is the cake they are talking about, what is its chemical name, and what is its chemical formula? [3 pts]
The band Lifehouse was also playing. While performing, they were curious about how long the nuclear fuel they were singing in front of would take to degrade – until it was “Halfway Gone.” The day they are performing was coincidentally the day that the nuclear plant workers are putting spent fuel in dry cask storage. If the half life of U-235 is 704 million years (no kidding), and the initial amount of spent fuel put in the dry cask is 15 tons, how much will be present in 1 billion years? [2 points]
Hint #1: use y(t) = a * ekt where “a” represents the value at the start, “k” is the rate of decay (negative value), and t is the time. Hint #2: first solve for ‘k’.
As of 2009, there were more than 13,000 tons of spent fuel stored in dry casks in just the United States. Based on your answer to part (b), what do you think should be done with nuclear waste? Describe at least three strategies implemented or considered across the world and explain which you think is best. [4 pts]
What political and economic roadblocks do you see to that best strategy you chose in part (c)? [2 pts]
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