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ER100/200 & PubPol 184/284 Energy and Society Lecture 2: Energy and Society Professor Kammen ’. How Energy Use Shapes Society & the Environment Units, forecasts, and ‘ back of the envelope. Last update: August 30, 2015. Rubin , EE , Rates of Technology Adoption , Pages 669 – 677.
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ER100/200 & PubPol 184/284Energy and SocietyLecture 2: Energy and Society Professor Kammen ’ • How Energy Use Shapes Society & the Environment • Units, forecasts, and ‘back of the envelope Last update: August 30, 2015
Rubin, EE, Rates of Technology Adoption, Pages 669 – 677. Lovins, Amory (1976) “Energy Strategy: The Road Not Taken”, Foreign Affairs, 55(1): 65–96. ER200 & Pub Pol 284: A nice commentary on the Lovins paper from The New York Times: http://www.nytimes.com/2008/10/07/science/07tier.html?_r=1&8dpc&oref=slogin Supplemental: Toolkit 1 (a review and refresher) – optional/reference for those who have done these sorts of problems before. A bit more than back of the envelope, applied to scaling-up technologies: http://www.gigatonthrowdown.org/ Readings Reminder …
1 barrel (bbl) of crude oil = 42 gallons = 6.12 x 109 joules, so …? • 1 MToe = million tons of oil, equivalent = 1013 joules, so …? • A useful unit calculator http://www.iea.org/statistics/resources/unitconverter/ • You will also find the unit conversions in the Reader Getting Comfortable with Energy Units We now will begin to use energy unit analysis to analyze, both the technical and policy aspects of energy conversion and use.
zettajoule (ZJ) Energy Units and Scales(Source: IPCC Energy Primer) Quick recap: exponentials to common basis are additive!103 x 106 = 10(3+6) = 109 or 1000 MJ = 1 GJ
Energy Stocks & Flows for the Earth(the whole story, but only an engineer could love it like this …
Energy Orders of Magnitude (EJ = 1018 J) 5,500,000 EJ Annual solar influx 1,000,000 EJ Fossil occurrences 50,000 EJ Fossil reserves 440 EJ World energy use 2000 (14 TW) 100 EJ USA primary energy supply 50 EJ OECD transport energy use 20 EJ Saudi Arabia oil production 4 EJ Italy oil reserves 1 EJ NY city or Singapore energy use Stocks; flows (yr-1)
Back of the envelope calculation: • How much gasoline is used in the U.S. for all light duty vehicles (passenger cars, SUVs and light trucks) in 1 year? • You may need to give the answer in gallons, barrels, and quadrillion Btus per year, etc …
Back of the envelope calculations: General approach • First make a model, balancing accuracy against the time needed to create the calculation • Back of the envelope, spreadsheet, or code • A simple model • Gas used per week (gallons) = • If a car gets 20 mpg in normal use, for a 1000 mile trip, the simple estimate is that the car will use 50 gallons.
BOE calculations: Unit analysis • You can always multiply some number by 1 without changing its value. • Example: Calculate the average load over 1 year (kW) for an electricity end-use that consumes 10,000 kWh per year In that equation, the hours and the years cancel, yielding kW.
Back of the envelope calculation: Answer: • The average rated fuel economy is 25 miles per gallon for light duty vehicles, but 21 mpg “on the road.” • A typical car is driven about 12,000 miles per year, and there are about 100 M households, each household owns just under 2 cars/light trucks, for a total of about 200 M vehicles. = 114 B gals/year = 2.7 B barrels/year = 7.4 M barrels/day = 14 quadrillion Btus
How about a more complex model? • If a 1000 mile trip does not have same highway/city split as normal use, we must rely on a more complicated model, Such as: • Gas/week (gals) = • assuming 15 mpg city, 25 mpg highway, and 95:5 split between highway and city driving, yields 41.3 gallons • Assumptions about how many miles driven are buried in the first model. • There are always buried assumptions … • How does regenerative braking, or an EV change things?
Use your simple model to test new cases… • Engine downsized ~15% • Idle-off and regenerative braking • Efficiency increased ~50% • Batter state of charge kept in narrow range • Engine downsized ~33% • Larger battery and grid charging • Energy for short trips is from grid • Deeper discharge of batteries Plug in hybrid with cellulosic ethanol in the tank: 100+ miles per gallon Breakthrough: stationary and mobile energy sources now linked
What about this vehicle …. August 15, 2003: 8:15 PM August 16, 2005—Speeding from the scene of the crime, a Chinese boy tows a floating plastic bag of stolen natural gas last week.
2002... 1942...
BOE calculations: some advice • Once you’ve made a model, plug in the numbers you know, and make assumptions for those you don’t know. • Don’t get hung up on a particular number! Set up the calculation and get data later. • Don’t be afraid to approximate to speed things up (e.g., to divide 4000 by 35, divide 3500 by 35 instead to get 100). • Keep evolving your ‘model’ to check out interesting cases, like the fuel vs. EV slide…
BOE calculations … more to do • Bound the problem • Plug in high and low estimates for key parameters • Combine all high estimates in one scenario, and all low estimates in another • Test sensitivity of each variable to arbitrary changes in inputs • Create a data sheet, and get comfortable with the key units and conversions • Understand commonly used units (Quads, TWh, joules, Mbtus, MMBtus, kW vs kWh, tons) (don’t memorize, organize!)
50% CEC Data Business as Usual 40% AB 32 Scenario 30% 20% 10% 0% -10% 1990 1995 2000 2005 2010 2015 2020 AB 32 Emissions Reductions % Change from 1990 levels
The Cascade of Commitment: IPCC Science, CA and US targets 3.0 Business as usual (EIA) 2.5 Historic U. S. emissions Intensity Target: President Bush (2004) and China (current) 2.0 1.5 Kyoto protocol U.S. GHG Emissions (GT C eq.) 1.0 The Obama climate target The California target 0.5 0.0 1990 2000 2010 2020 2030 2040 2050 EU Copenhagen plan IPCC Assessment: Climate Stabilization Zone Kammen, “September 27, 2006 – A day to remember”, San Francisco Chronicle, September 27,
Check the Units, carbon emissions are often expressed at gC/MJ, and at present Global emissions are 16 gC/MJ, and global energy use is 420 EJ so:
Check the Units, carbon emissions are often expressed at gC/MJ, and at present Global emissions are 16 gC/MJ, and global energy use is 420 EJ so:
Major U.S. Public R&D programs red=defense, black=space, orange=health, blue=energy Nemet, G. F. (2007). Policy and innovation in low-carbon energy technologies. PhD Dissertation, University of California.
IPAT • Often useful to think of environmental impact as the product of three factors: • Population may increase (in poor countries) • Affluence should increase in poor countries • Can improved technology offset rising population and affluence?
The IPAT Identity: Why so handy? The controversial "Ehrlich" identity is often used to decompose growth in resource use, efficiency of resource use, and emissions.
The IPAT Identity In Use: Or, If all are exponential, then we have a very simple formulation: P = P1P2 …Pn P = (p1er1t) (p2er2t)... (pnernt) = (p1p2...pn)e(r1+r2 + …rn)t P = Pert
White’s Law “Culture advances as the quantity and quality of energy used increases. This relationship can be captured formally as an equation.” C = k x E x T Leslie White, 1973 C = culture E = energy T = technology k = scaling (efficiency) constant
The Chase Manhattan Bank stated, in its 1976 Energy Report, that “there is no documented evidence that indicates the long-lasting, consistent relationship between energy use and GDP will change in the future. There is no sound, proven basis for believing a billion dollars of GDP can be generated with less energy in the future. “
US energy use/$ GDP already cut 40%, to very nearly the 1976 “Soft Energy Pat1976h” Amory Lovins’Soft Energy Path: 1976
US energy use/$ GDP already cut 40%, to very nearly the 1976 “Soft Energy Pat1976h” Update: Amory Lovins’Soft Energy Path: 1976
Average Berkeleyite Energy Star Home Average Dane
U.S. Energy & Economy GNP Energy Carbon GDP Indexed (1950=100) Energy Carbon 37% improvement Source: EIA, BEA, PCAST
U.S. Efficiency Improvements Savings >$170 billion annually, since 1990 GDP Indexed (1950=100) Energy Carbon 37% improvement Source: EIA, BEA, PCAST
Two Views • Pessimists (“Mathusian” or “Cassandra”) • Developed economies unsustainable; developing cannot follow in their path; technology is not keeping pace with resource depletion, environmental impact • Optimists (“Cornucopian” or “Dr. Pangloss”) • No barriers to growth; substitutes will be developed for scarce resources; economic development and technology produce net improvement in environmental quality
The ER100 Bet: Simon offered to bet $1000 that the price of any five commodities would decrease from 1980 to 1990. Ehrlich et al. selected Cu, Cr, Ni, Sn, W. Simon won. Simon subsequently offered to bet that any set of environmental measures relating to human welfare would get improve. Ehrlich et al. selected CO2, N2O, O3, temperature, SO2 in Asia, tropical forest, per-capita grain and fish, species, AIDS, sperm counts, rich-poor gap. Simon declined.
Only 4 of 47 elements increased in price over the last century Price/Price in 2000
Caution and a Method: Know the Trend:Environmental Indicators vs. Income “Kuznets Curves”
The Paper of the Year, 2009 …. A recycled idea Rockstrom, et al, 2009