Climate Solutions: Chapter 8

From The Encyclopedia of Earth
Jump to: navigation, search


Published: June 16, 2010, 5:50 pm
Updated: May 7, 2012, 11:55 am
Author: Leo Wiegman
Author: David Blockstein
Topic Editor: Peter Saundry
Topics:

Net Energy Value (NEV) and Energy Payback Time (EPBT)

In a world in which no biological ecosystem is free of human influence and no industrial ecosystem is free of biological influence, it is appropriate to abandon the artificial division between the two frameworks and develop a new synthesis—Earth system ecology—as the logical construct for all of Earth's ecosystems. [14]
—Thomas Graedel

Cradle to grave designs dominate modern manufacturing. P. 27
—architect Bill McDonough and chemist Michael Braungart

Energy analysis is the first step to determine and compare energy consumption and production of different options. This can involve complex life-cycle net energy analysis, but often the most useful energy analysis is done by calculating simple energy consumption or conversion efficiency on the back of an envelope. P. 166
—John Randolph and Gilbert Masters, 2008

The energy return on investment (EROI) value is a ratio and therefore has no specific dimension. When we use the EROI, we have to decide whether by-products (or coproducts) of the energy conversion process belong on the top or the bottom of the fraction. In the case of some energy systems, for example, ethanol production, the EROI result will be very different, depending on whether we consider the coproduced energy as a positive output—to be added to the numerator, on top, because it can be used “as is” without further conversion and it increases energy return—or a negative input—to be added in the denominator because it needs to be disposed of at some added energy cost and it shrinks energy return. In these cases, an alternative is to compute the net energy value in a system. For example, the production of ethanol creates not only liquid ethanol fuel but also usable animal feed and solid fuel that have energy value too. The total value of the net energy gain or loss in a system can be calculated as follows, which lets us avoid choosing whether a by-product is a gain or loss:

Equation 4: Net energy value (NEV) = Energy output - Energy input = (Energy in liquid ethanol + Feed by-product + Solid fuel by-product) - (Energy needed to product ethanol)

Net energy computes as an absolute value with a specific dimension, such as Btu per gallon (Btu/gal) in the case of ethanol or gasoline. One British thermal unit (Btu) is small unit of energy equal to 0.293 Watt-hours.

Notice the simple EROI expression did not have a time component. Very often we also want to examine the time value of energy conversions, that is, their break-even or payback period. For example, how much time will it take an energy system, such as a new geothermal system, a wind farm,a solar array, or even a new more-efficient oil burner, to recover its start-up costs? This is especially useful for systems that have one-time development costs and very low net operating costs, like wind or photovoltaic or solar thermal installations. For such systems, the energy payback time (EPBT) is the equivalent of the inverse of the energy return on investment value (1/EROI). All we need to do is add the time component—typically years—to the denominator on the bottom of the fraction:

Equation 5: Energy payback time (EPBT) = (Energy input of up-front one-time costs)/(Energy output) = Btu/(Btus per year)

where energy input is the up-front indirect energy cost of creating a system, which is divided by the energy output, which is usually written as the useful energy (or power) output per unit of time, for example, Btu/year.

For example, in the realm of photovoltaic technologies, the EPBT approach helps us compare the payback time for two different kinds of solar electric panels if we know the indirect up-front “embodied” energy costs of producing the system. The energy input for a crystalline silicon PV module is 5,600 kilowatt-hours per peak kilowatt-hour power output of the module, and for thin-film copper indium diselenide (CIS) modules the energy input is 3,100 (in the same units). So the new CIS module takes less energy to produce. Given that the Sun’s energy shining on two panels is going to be the same, 1,700 (in the same units), we can see that the thin-film module has a payback of 1.8 years versus 3.3 years for the silicon-based module. In reality, the actual net power performance of the panels is about 80% of the original because of system losses to the power after it leaves the module (line loss, inverter operations, etc.). So the energy payback times become 2.2 years for the thin-film and 4.1 years for the silicon modules.

Now, here is the interesting part. Both these technologies have an expected life of 30 years. So now we can compute the energy return on energy investment as follows, and learn that the newer thin-film module will have an EROI twice as high as the older silicon technology:

Equation 6:
EROIsilicon = 30 years/4.1 years = 7
EROIthin-film CIS = 30 years/2.2years = 14

Table 8.5 shows some current EROI values. Note the huge drop in energy return on US gas and oil production over the seven-decade time. Note also that the energy return on thin-film photovoltaic modules is only slightly lower that on nuclear power—without taking any of the actual economic costs of each into account.

Table 8.5 Some Energy Return on Energy Investment Values for Different Energy Sources
Energy source or system EROI* Research source
US gas and oil production (1930) 100 Cleveland (2005)
US gas and oil production (2000) 20 Cleveland (2005)
Electricity from hydro with reservoir 205 Gagnon et al. (2002)
Electricity from nuclear 16 Gagnon et al. (2002)
Electricity from coal (with SO2 scrubbers) 5 Gagnon et al. (2002)
PV modules (thin-film CIS) 14 Knapp and Jester (2001)
PV modules (crystalline silicon) 7 Knapp and Jester (2001)
US ethanol fuel from corn 0.78 Pimentel and Patzek (2005)
US ethanol fuel from switchgrass 0.79 Pimentel and Patzek (2005)
US ethanol fuel from soybeans 0.67 Pimentel and Patzek (2005)
*Other researchers arrive at very different EROI values for ethanol, depending on whether the coproducts are counted as positive or negative values.
Table Source: Adapted from Table 5.2 using data from 1 22, 33

Bibliography

  1. BedZED (2008) Beddington Zero Energy Development. BioRegional. South London, UK (read December 13, 2008). http://www.bioregional.com/programme_projects/ecohous_prog/bedzed/bedzed_hpg.htm
  2. Berst J, Bane P, Burkhalter M, Zheng A (2008) The Electricity Economy: New Opportunities from the Transformation of the Electric Power Sector. http://www.globalenvironmentfund.com; http://www.globalsmart energy.com
  3. Cleveland CJ (2005) Net energy from the extraction of oil and gas in the United States. Energy 30(5):769?– 782. http://linkinghub.elsevier.com/retrieve/pii/S0360544204002890
  4. Cleveland CJ (2008) “Energy Return on Invest--ment,” (topic ed) Constanza R, in Encyclopedia of Earth, (ed) Cleveland CJ. (Environmental Information Coalition, National Council for Science and the Environment, Washington, DC). [[1]]
  5. Epstein P (2007) “Climate Change: Healthy Solutions.” Guest Editorial. Environmental Health Perspectives, April 115(4):A 180. http://chge.med.harvard.edu/programs/ccf/
  6. Epstein P (2008) Healthy Solutions for the Low Carbon Economy: Guidelines for Investors, Insurers and Policy Makers. The Center for Health and the Global Environment. Harvard Medical School. http://chge.med.harvard.edu/programs/ccf/
  7. Ewing R, Kreutzer R (2006) Understanding the Relationship between Public Health and the Built Environment. US Green Building Council. New York. http://www.usgbc.org
  8. Fava J, Hall J (2004) Why Take a Life Cycle Approach? UNEP Life Cycle Initiative. United Nations Environment Programme Division of Technology, Industry and Economics, Paris. http://www.unep.fr/scp/lcinitiative/publications
  9. Fisk WJ (2000) Health and productivity gains from better indoor environments and their relationship with building energy efficiency. Annual Review of Energy and the Environment 25:537?– 566. http://arjournals.annualreviews.org/loi/energy
  10. Friedman T (2008) Hot, Flat and Crowded: Why We Need a New Green Revolution and How It Can Renew America, 410. (Farrar, Straus, and Giroux, New York). http://www.thomaslfriedman.com
  11. Frumkin H, Frank L, Jackson RJ (2004) Urban Sprawl and Public Health: Designing, Planning, and Building for Healthy Communities. (Island Press, Washington, DC). http://islandpress.org
  12. Gabbard A (2008) Coal Combustion: Nuclear Resource or Danger. Oak Ridge National Laboratory. Oak Ridge, TN (read December 22, 2008). http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html
  13. Gagnon L, Bélanger C, Uchiyama Y (2002) Life-cycle assessment of electricity generation options: the status of research in year 2001. Energy Policy 30(14):1267?– 1278. http://linkinghub.elsevier.com/retrieve/pii/S0301421502000885
  14. Graedel TE (1996) On the concept of industrial ecology. Annual Review of Energy and the Environment 21:69?– 98. http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.energy.21.1.69
  15. Hall C, Balog S, Murphy DJR (2009) What Is the Minimum EROI That a Sustainable Society Must Have? Energies 2:25?– 47. http://web.mac.com/biophysicalecon/iWeb/Site/Downloads.html
  16. IAEA (2008) Nuclear´s Great Expectation: Projections Continue to Rise for Nuclear Power, but Relative Generation Share Declines. International Atomic Energy Agency. September 11, 2008 (read October 20, 2008). http://www.iaea.org/NewsCenter/News/2008/np2008.html
  17. Jones V (2008) The Green Collar Economy. (HarperCollins Publishers, New York). http://www.greenforall.org
  18. Kammen D (2007) The Low-Carbon Imperative and Economic Opportunity. US House of Representatives Committee on Oversight and Government Reform Testimony for the November 8, 2007, Hearing on: Opportunities for Greenhouse Gas Emissions Reductions. http://socrates.berkeley.edu/~kammen/;
  19. Kammen D, Farrell AE, Plevin RJ, Jones AD, Delucchi MA, Nemet GF (2007) Energy and Greenhouse Impacts of Biofuels: A Framework for Analysis, in OECD Research Round Table: Biofuels: Linking Support to Performance, (ed) Perkins S. (Organization for Economic Cooperation and Development, Paris). http://www.internationaltransportforum.org/jtrc/RoundTables/BiofuelsOutline.pdf
  20. Kats G (2006) Greening America’s Schools: Costs and Benefits. http://dsforgau.ozstaging.com/downloads/greening_americas_schools.pdf
  21. Kellert SR, Heerwagen J, Mador M (2008) Biophilic Design: The Theory, Science and Practice of Bringing Buildings to Life. http://www.wiley.com/WileyCDA/WileyTitle/productCd-0470163348.html
  22. Knapp K, Jester T (2001) Empirical investigation of the energy payback time for photovoltaic modules. Solar Energy 71(3):165?– 172. http://linkinghub.elsevier.com/retrieve/pii/S0038092X01000330
  23. Koeppel S, Ürge-Vorsatz D (2007) Assessment of Policy Instruments for Reducing Greenhouse Gas Emissions from Buildings. (United Nations Environment Programme, Central European University, Budapest). http://www.unepsbci.org
  24. Krauss C (2008) “An Export in Solid Supply.” New York Times, March 19, 2008. http://www.nytimes.com
  25. Kurz W (2008) Making the paper: mountain pine beetles contribute to carbon release and climate change. Nature 452:987?– 990. http://www.nature.com/nature/
  26. Lovins A, Sheikh I (2008) The nuclear illusion. Ambio, in November 2008 preprint. http://www.rmi.org/sitepages/pid257.php#E08-01
  27. Mastny L (2003) Purchasing Power: Harnessing Institutional Procurement for People and the Planet. Worldwatch Paper #166. http://www.worldwatch.org
  28. McDonough W, Braungart M (2002) Cradle to Cradle: Remaking the Way We Make Things. (North Point Press/FSG, New York). http://www.mbdc.com
  29. (a) MIT (2003) The Future of Nuclear Power. http://web.mit.edu/nuclearpower(b) MIT (2007) MIT Study on the Future of Coal: Options for a Carbon-Constrained World. http://web.mit.edu/coal/
  30. NIOSH (2008) Faces of Black Lung. National Institute for Occupational Safety and Health (NIOSH). Centers for Disease Control and Prevention. August 18, 2008 (read September 4, 2008). http://www.cdc.gov/niosh/blog/
  31. NIRS (2007) Report on Earthquake Damage to Japan’s Kashiwazaki-Kariwa Nuclear Power Facility. Nuclear Information and Resource Service (read September 12, 2008). http://www.nirs.org
  32. Patzek TW (2006) The Earth, Energy, and Agriculture. Paper presented at Climate Change and the Future of the American West: Exploring the Legal and Policy Dimensions. http://petroleum.berkeley.edu/papers/Biofuels/BiofuelsTop.htm
  33. Pimentel D, Patzek TW (2005) Ethanol production using corn, switchgrass and wood; biodiesel production using soybean and sunflower. Natural Resources Research 14:65?– 76. http://www.springerlink.com
  34. Randolph J, Masters GM (2008) Energy for Sustainability: Technology, Planning, and Policy. (Island Press, Washington, DC). http://www.energyforsustainability.org
  35. Remmen A, Jensen AA, Frydendal J (2007) Life Cycle Management: A Business Guide to Sustainability. (Life Cycle Initiative, United Nations Environment Programme). http://www.unep.fr/scp/lcinitiative/publications/
  36. REN21 (2008) Renewables 2007 Global Status Report. (Deutsche Gesellschaft für Technische Zusammenarbeit, Worldwatch Institute, Paris: REN21 Secretariat and Washington, DC:Worldwatch Institute). http://www.ren21.net
  37. Renner M (2008) Working for People and the Environment. Worldwatch Report #177. http://www.worldwatch.org
  38. US EIA (2008) Annual Energy Review 2007. DOE/EIA-0384(2007). http://www.eia.doe.gov/emeu/aer/
  39. USGS (1997) Radioactive Elements in Coal and Fly Ash: Abundance, Forms, and Environmental Significance. Fact Sheet FS-163-97. US Geological Survey. Denver, CO. http://pubs.usgs.gov/fs/1997/fs163-97/FS-163-97.html
  40. Wald ML (2008) “As Nuclear Waste Languishes, Expense to US Rises.” New York Times, February 19, 2008. http://www.nytimes.com
  41. Weber CL, Matthews HS (2008) Food-miles and the relative climate impacts of food choices in the United States. Environmental Science and Technology. http://pubs.acs.org/cgi-bin/abstract.cgi/esthag/asap/abs/es702969f.html
  42. WHO (2003) National Healthy Cities Networks: A Powerful Force for Health and Sustainable Development in Europe. http://www.euro.who.int

Online resources

Action items

  • Action 1: Green Buildings and Building Design
  • Action 7: Biofuel Industry and CO2 Emissions?— Implications for Policy
  • Action 9: How to Ensure Wind Energy Is Green Energy
  • Action 10: Nuclear Energy?— Using Science to Make Hard Choices

Instructor resources

(password required)


This is a chapter from Climate Solutions Consensus.
Previous: Chapter 7: No Silver Bullet, Many Silver Wedges (Climate Solutions: Chapter 8)|Table of Contents (Climate Solutions: Chapter 8)|Next: Chapter 9: Multiple Intensity Disorder (Climate Solutions: Chapter 8)

Citation

Wiegman, L., & Blockstein, D. (2012). Climate Solutions: Chapter 8. Retrieved from http://editors.eol.org/eoearth/wiki/Climate_Solutions:_Chapter_8
Retrieved from "https://editors.eol.org/eoearth/index.php?title=Climate_Solutions:_Chapter_8&oldid=139527"