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2 BACRGROIJND GENESIS OF THE 8TlJDY Global climate change emerged as a major issue in the United States during the 1980s. As a result of national concern, Congress adopted legislation in its 1989 Energy and Water Development Appropriation Bill for studies to clarify and define the extent of the problem and to recommend options for its management. The legislation was based on the premise that emissions of greenhouse gases (Gags) arising from energy production and use are significant precursors of global climate change. Accordingly, in Public Law 100-371, Congress directed the secretary of energy to ask the National Academy of Sciences and the National Academy of Engineering to: assess the current state of research and development (R&D) in the United States in alternative energy sources "including, but not limited to, nuclear power, solar power, renewable energy sources, improved methods of employing fossil fuels, energy conservation, and energy efficiency"; ~ suggest R&D strategies for stabs lizing the atmospheric concentrations of GHGs that contribute to global climate change; and ~ analyze what federal investments would encourage greater private investment in alternative sources of energy. This report presents the recommendations of the study committee (Committee on Alternative Energy Research and Development Strategies) appointed by the National Research Council in response to the directive. PROBLEM DESCRIPTION A number of atmospheric gases absorb infrared radiation emitted from the earth's surface and prevent its escape into space. This trapping of infrared radiation is commonly referred to as the greenhouse effect. The principal GHGs that are also constituents of the atmosphere are carbon dioxide (CO ), water vapor (H2O), and methane (CH43. Other important GHGs include ozone, nitrous oxide (N2O), and the chlorofluorocarbons (CFCs); of these the CFCs have no natural sources. Altogether, over 40 GHGs have been identified so far, most of which are radiatively active. ,-3 GHGs must be present in the earth's atmosphere for the earth's temperature to be suitable for life as we know it. However, human 15

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activities (primarily energy-related ones, as shown In Figure 2- 1) are increasing the atmospheric concentrations of many GHGs at a rate that is faster than the rate of absorption by natural sinks. The concern is that, if this rate of increase in the concentrations of GHGs continues, climatic changes may arise that would have maj4Or impacts on the natural environment and on human societies. Scientific uncertainty exists, however, regarding the timing and extent of potential glob,01,climate change from the accumulation of GHGs in the atmosphere. ~ Principal GHGs associated with energy production and use include CO2 emitted during the combustion of hydrocarbon fuels; CH4 emissions from coal mines and from the venting and leakage of natural gas during drilling, production, and transmission; and releases of CFCs from air conditioners, refrigeration equipment, and the production of insulating materials. N2O emissions come from the combustion of hydrocarbon fuels, including agricultural biomass, and from the use of nitrogenous ferti liners. The atmospheric concentration of CO2 is currently around 350 parts per million by volume (ppmv) , which is about 25 percent above the preindustrial level of 280 ~ 10 ppm estimated for 1860 (Figure 2-2) and exceeds atmospheric concentrations that can be inferred from geologic records. On average, CO2 emissions from fossil fuel combustion have increased by 4.3 percent per year since 1860 and are currently on the order of 20 billion metric tons of CO2 or 5.5 billion metric tons of carbon (OTC) per year out of a total of 6 to 8 GIC per year from all man-made sources. The contribution to CO2 emissions of hydrocarbons used for fuel depends on the carbon content of the fuel per unit of combustion energy. Among the fossil fuels, per quad (1035 Btu) of energy used, natural gas emits the least carbon (14.5 million metric tons carbon, MTC); coal the most (25.1 MTC); and petroleum an intermediate amount (20.3 MTC). Traditional biomass fuels, such as crop residues and dung, release CO' to the atmosphere in a balanced cycle of absorption and respirat' on. In contrast, other biomass fuels such as firewood may provide either a net annual source or sink for carbon, depending on whether the underlying biomass stock is being depleted or increased, respectively. Although the concentrations by volume and the annual rate of emissions of other GHGs such as CH4, the CFCs, and N2O are much less than those of CO2, they cannot be ignored (Table 2-1~. Carbon dioxide is nevertheless the single most signif icant anthropogenic GHG from energy production and use (Figure 2-3), and its control was the focus of this study. 16

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Energy tJse I and Production (57/0) CFCs (1 7'0) \ I Other ~ _ Industrial (3%) l ~ Detorestation (9/0) FIGURE 2-] Sources of GXGs. Energy production and use constitute the largest human source of greenhouse gases, but other activities are also significant.2 17

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350 330 310 .,' ~ _ ~ - , 290 270 FIGURE: 2 - 2 f / 1740 1790 ~ 840 Year Historical variation in concentration. '2 18 / ,4 - 1890 1940 1990 atmospheric carbon dioxide

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TABLE 2-1 Key Atmospheric Trace Gases Whose Concentrations Are Increas ing,4 - Concentrattona ~n 1985 Annual Rate of Increase As of 1985 CO2 345 ppmv 1. 4 ppmv ~ 0 . 4% ~ CH4 1. 65 ppmv 18 . O ppbv (1.1%) N2O 305 ppbv CEC-11 220 pp~cv CFC- 12 380 ppev 0.6 ppbv (0.296) 11.0 pptv (5. o%)b 1 9 . O pp tV ~ 5 . 0% ~ b a Concentrations are global averages in 1985. Values shown for the rate of increase are representative as of 1985. b These chlorofluorocarbons will be phased out under the terms of the Montreal Protocol that is now in force. 19

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1 880-1 980 1 980s Other (8~) . LC'C 11 ~ -12 (8%)- ~ [ 1 N2O (3/O) ~ CH~(lS.Mo) - ~ CO2 (66~) 1 Her (13/O) . ~~ CFC-11 &-12 jet 1 N2O (6%) CO2 (49%) . 51 J 1 CH4(18%~ FIGURE 2-3 GIlGs responsible for increases in the greenhouse effect worldwide .2 20

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Notwithstanding the uncertainties regarding climate change and its consequences, the central task of this study was to determine the priorities and federal strategies for energy R&D efforts and the deployment of alternative energy technologies to significantly reduce GHG emissions. The strategies are to include actions in both the public and private sectors and consideration of how they might mesh and complement one another. THE GLOBAL CONTEXT On the premise that increasing accumulation of GHGs increases the probability that significant global waffling will occur, a major goal would be to reduce atmospheric emissions of such gases, especially CO2. Global fossil fuel energy resources are large and include petroleum, coal, natural gas, tar sands, oil shale, and deposits of bitumen.35 Approximately 80 percent of the world's coal resources are in the United States, the U.S.S.R., and the People's Republic of China, and coal is expected to be the dominant fuel that will be used around the world over the next several decades. Continued use of increasing amounts of fossil fuels, unconstrained by considerations of the potential impacts of GHG emissions, could lead to atmospheric accumulation of CO2 approaching concentrations likely to initiate irreversible changes in the earth's climate. Controls may therefore be required on the use of such fuels and could be targeted to hold CO2 concentrations and the rate of increase from exceeding some generally acceptable limits. The U.S. Environmental Protection Agency's study, Policy Options for Stabilizing Global Climate, 2 concluded that very large reductions (on the order of 50 to 80 percent of current levels) in worldwide CO2 emissions are required, starting now, to achieve stabilization of atmospheric GHG concentrations at their current levels. Despite considerable uncertainties in this estimate, it raises at least two fundamental questions: (1) How much reduction in the emissions of GHGs (from a specified baselines is achievable with various energy production and end-use technologies? (2) What would it take to implement those technologies (whether currently available Or yet to be developed) and effectively replace their less energy-inefficient or more polluting counterparts? As a first step, this study addresses these questions for the electric power, transportation, buildings, and industry sectors in the United States. Aside from the CFCs (phaseout of which is now governed by the Montreal Protocol) , increases In worldwide emissions of CO2 and other GHGs are expected to continue over the next century unless strong public policies are adopted for their control . It is further expected that the bulk of the emissions will result from increasing exploitation of hydrocarbon fuels, primarily coal, necessitated by energy demands from industrial iced countries such as the United States and the U.S.S.R., from countries with 21

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expanding industrial development such as China and India, and from growing populations. Concerted action by all countries is essential if successful responses to regional and global environmental problems such as acid rain and the greenhouse effect are to be developed and implemented in a timely and effective manner. What is still an open issue is how such action is to be taken worldwide and what the roles and responsibilities of various countries would be to assure its successful execution. For developing countries, all of which will need more energy to fuel their economic growth, even the prospect of restrictions on the use of relatively cheap, easily accessible fossil fuels raises questions of equity and fairness. Their vied is that the bulk of the burden of reducing the use of fossil fuels ought to rest on the industrialized countries, because annual consumption of energy resources in those countries has thus far accounted for about 80 percent of the worlds consumption and attendant emissions of GHGs. _ _ . . . . . The United States is currently the primary contributor to the greenhouse effect. According to a recent study, ]6 U. S. emissions of CO have increased over the past 2 years, and the U.S. share of global CO2 emissions in 1988 was estimated to be around one- quarter. In this milieu there is growing opinion in the United States that a number of innovative and cost-effective U.S. actions are possible, which could significantly reduce GHG emissions from the nation's current levels, establish a leadership position for the United States with which to support other countries in similar efforts, and create a setting in which actions needed world,7i'9de can be planned and executed in a timely and concerted manner. . . The committee appreciates the value in such a role being taken by the United States even as it recognizes that unilateral action taken solely bv one country will be much less ef festive than ,^ ,, _, ~ concerted actions. In the committee's view, developing a strategic vision for the United States in terms of energy R&D and adoption of alternative energy technologies that are low or even nonemitters of GHGs is an important first step. The vision should then serve and be used as a point of departure toward a broader program of global cooperation and joint efforts for safeguarding the environment. This study was approached with such a viewpoint and expectation. 22

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NOTES AND REFERE ACES 1. See, for example, A Primer on Greenhouse Gases: CO2, Report No . TR040, DOE/NBB 0083, U. S . Department of Energy, Of f ice of Energy Research, Of f ice of Basic Energy Sciences, Carbon Dioxide Research Division, Washington, D.C., March 1988. 2. U.S. Environmental Protection Auencv. Office of Policv. Planning and Evaluation, Presentation to the Committee on Alternative _ , ~ ~ Energy Research and Development strategies, National Research Council, Washington, D.C., June 12, 1989. 3. V. Ramanathan, R. J. Cicerone, H. B. Singh, and J. T. Kiehl, ''Trace Gas Trends and Their Potential Role in C1 imate Change," Geophys. Res., 90: 5547-5566, 198S. 4. V. Ramanathan et al, "Climate and the Earth's Radiation Buaget,'t Pnyslcs Today, p. 22, May 1989, S. National Academy of Engineering, Energy: Production, Consumption and Consequences, National Academy Press, Washington, D.C., 1990. 6. National Academy of Engineering, Technology and the Environment, National Academy Press. Washinaton, D.C., 1989. 7. National Research , ~ _, _ _ ~ _ _ , _ _ , Council. Global Chance and Our Common Future, Forum Papers, National Academy Press, Washington, D. C . 1989 . 8. Greenhouse Warming: Abatement and Adantation. Workshop Proceedings, Resources tor One Future, Washington, D.C., June 14-15, 1988. 9. Energy Policies to Address Global Climate Change, Workshop Proceedings (unpublished), University of California, Davis, September 6-8, 1989. 10. Discussions regarding uncertainties are contained in a number of published reports, including those cited above. For a viewpoint that does not anticipate significant adverse impacts of GHG emissions on climate, see Scientific Perspectives on the Greenhouse Problem, George C. Marshall Institute, Washington, D.C., 1989. 11. J. F. Mitchell, "The Greenhouse Effect and Climate Change," Rev. Geophys. 27:115, February 1989. 23

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12. Data from 1958 to the present are from Keeling's observations at Mauna Loa, Hawaii C. D. Keeling, D. J. Moss, and T. P. Wholf, Measurements of Concentrations of Atmospheric Carbon Dioxide at Mauna Loa Observatory Hawaii, 1958- 1986, Final Report for the Carbon Dioxide Information and Analysis Center, Martin Marietta Energy Systems, Inc., Oak Ridge, Tenn. April 1987, and updated by National Oceanic and Atmospheric Administration/Scripps Institution of Oceanography, Boulder, Colo. May 1988~. Data for the period 1740 to 1956 are taken from measurements of air trapped in glacial ice sheets (A. Neftel, E. Moor, H. Oeschger, and B. Stauffer, "Evidence from Polar Ice Cores for the Increase in Atmospheric CO2 in Past Two Centuries", Nature, 315:45-47, 1985. Stephen H. Schneider, "The Changing Climate," Sci. Am September 1989. Atmospheric Ozone 1985, World Meteorological Organization, Geneva, 1985; see Chapter 3, pp. 56-116. 15. J. P. Riva, Jr., "Fossil Fuels" in Encyclopedia Britannica, vol. 19, 588-612, 1987; "Oil Distribution and Production Potential," Oil Gas J. 86~3~:58, 1988~; Domestic National Gas Production, CRS Issue Brief, Congressional Research Service, Library of Congress, Washington, D.C., May 2, 1989. 16. World Resources Institute study as referred to by M. Weisekopf in "U.S. Contribution to Greenhouse Effect Rises," The Washington Post, September 16, 1989. 17. Cool Energy: The Renewable Solution to Global Warming, Union of Concerned Scientists, Cambridge, Mass., 1990. 18. "Global Change and Public Policy: A Special Issue," Earth Ouest, 3~1), Spring 1989. 19. C. Schneider, "Preventing Climate Change," Issues Sci.` and Tech., 5:~4), p. 55, Summer 1989. 24