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14 Energy Supply and Use
Pages 349-376

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From page 349...
... Because America's Energy Future was the focus of a recent suite of National Research Council reports (NRC, 2009a,b,c,d) , and energy-related GHG emissions reductions are a major point of emphasis in the companion volume Limiting the Magnitude of Future Climate Change (NRC, 2010c)
From page 350...
... energy supply now comes from the combustion of fossil fuels -- coal, oil, and 1 In accounting for the energy or environmental implications of shifts in the mix of products produced and consumed in the economy, it is important to consider trade flows. For example, if a reduction in domestic production of steel is offset by an increase in steel imports, domestic GHG emissions may appear to decline but there may be no net global reduction in GHG emissions (and emissions may even increase, given the possibility of differences in production-related emissions and the energy expended in transporting the imported product)
From page 351...
... For example, the recent report Biomass 3% Other Renewables 1% Hydro 2% Nuclear 8% 70 60 Quadrillion Btu (Quads) 50 Fossil Fuels 86% 40 Total U.S.
From page 352...
... As discussed above and in Chapter 6, limiting the magnitude of future climate change will require significant reductions in climate forcing, and GHGs emitted by the energy sector are the single largest contributor. Hence, many strategies to limit climate change typically focus on reducing GHG emissions from the energy sector.
From page 353...
... The companion report Limiting the Magnitude of Future Climate Change (NRC, 2010c) also discusses energy efficiency at length.
From page 354...
... However, simply developing and making a new technology available is not sufficient to ensure its adoption; to be effective, research on all energy technologies, including efficiency technologies, needs to include analysis of the barriers to adoption of innovation and of public acceptance of new technology. ENERGY SOURCES THAT REDUCE EMISSIONS OF GREENHOUSE GASES Technologies that reduce the amount of GHGs emitted during the production of usable energy include renewable energy sources such as solar, wind, bioenergy, geothermal, hydropower, as well as nuclear power and carbon capture and storage (CCS)
From page 355...
... , which is more than 5,000 times the 15 TW of energy currently used by humans (of which roughly 12 TW now comes from fossil fuels) and more than 100 times larger than the energy potential of the next largest renewable source, wind energy (Hermann, 2006)
From page 356...
... While incremental improvements in CSP performance are anticipated, there is the potential for large improvements in PV electricity generation technologies. Over the past 30 years, the efficiency of PV technologies has steadily improved, though commercial modules achieve, on average, only about 10 to 15 percent efficiency (that is, only 10 to 15 percent of the solar energy incident on the cell is converted into electricity)
From page 357...
... Finally, the energy payback time, which is a measure of how much time it takes for an energy technology to generate enough useful energy to offset energy consumed during its lifetime, is fairly long for silicon-based PV. In addition to electricity generation, nonconcentrating solar thermal technologies can displace fossil fuels at the point of use, particularly in residential and commercial buildings.
From page 358...
... Though offshore wind power poses additional technical challenges, these challenges are being addressed by other countries. However, political, organizational, social, and economic obstacles may continue to inhibit investment in offshore wind power development in the United States, given the higher risk compared to onshore wind energy development (Williams and Zhang, 2008)
From page 359...
... Continued research on forecasting techniques, operational and system design, and optimal siting requirements would improve the integration of wind power into the electricity system. As with solar energy technologies, modifications to the electricity transmission and distribution system along with energy storage capacity would also improve the ability to exploit wind energy resources (see the section Energy Carriers, Transmission, and Distribution in this chapter)
From page 360...
... . If the land required to grow bioenergy crops comes from deforesting or converting natural lands, there could be a net increase in GHG emissions as well as losses of biodiversity and ecosystem services.
From page 361...
... The barriers to increased penetration of direct geothermal heating and cooling systems are not technical, but with the high initial investment costs and the challenges associated with developing appropriate sites. The resource for direct heating is richest in the western states, and geothermal heat pumps have extended the use of geothermal energy into traditionally nongeothermal areas of the United States, mainly the Midwestern and eastern states.
From page 362...
... Enhanced geothermal systems represent the much larger resource base -- the theoretical potential EGS resource below the continental United States is over 130,000 times the total 2005 U.S. energy consumption (MIT, 2006)
From page 363...
... New technologies to generate electricity from ocean water power include those that can harness energy from currents, ocean waves, and salinity and thermal gradients. There are many pilot-scale projects demonstrating technologies tapping these sources, but only a few commercial-scale power operations worldwide at particularly favorable locations.
From page 364...
... However, these technologies currently only exist as conceptual designs, laboratory experimentation, and field trials. In general, even though waves, currents, and gradients contain substantive amounts of energy resources, there are significant technological and cost issues to address before such sources can contribute significantly to electricity generation.
From page 365...
... These technological innovations include improvements or modification of existing plants, alternative new plant designs (e.g., thermal neutron reactor and fast neutron reactor designs) , and the use of alternative (closed)
From page 366...
... While there have been pilot projects and small commercial-scale projects to demonstrate the feasibility of some of these approaches, for the most part they remain in the research stage, and many involve important legal, practical, and governance concerns, as well as further technical research. Additional details about these approaches can be found in the companion report Limiting the Magnitude of Future Climate Change (NRC, 2010c)
From page 367...
... . Further details and discussion about direct air capture approaches can be found in the companion report Limiting the Magnitude of Future Climate Change (NRC, 2010c)
From page 368...
... . Improving energy storage technology and finding new ways to store energy is critical for addressing the intermittency of many renewable energy sources.
From page 369...
... energy sector itself is expected to be affected by climate change and will need to adapt to the accompanying changes. Research on the possible impacts on energy system operations is still in its infancy; therefore, the examples noted below are merely illustrative of the ways climate change could affect energy systems (see the companion report Adapting to the Impacts of Climate Change [NRC, 2010a]
From page 370...
... Double counting occurs because a single deployment activity may impact multiple technology strategies. The count does not include activities that are authorized but not implemented.
From page 371...
... 3 2 8 1 7 7 4 4 19 11 28 22 24 10 15 Coalitions & partnerships 165 7 5 7 6 6 9 8 7 6 19 14 12 13 15 15 International cooperation 149 Market conditioning, including 2 3 5 4 4 2 1 1 1 5 2 2 18 20 16 86 government procurement 2 4 6 6 6 5 3 0 0 1 2 3 4 11 12 65 Technology demonstration 0 7 3 2 1 2 6 2 0 0 0 1 0 14 10 48 Codes and standards 1 0 7 0 3 1 5 7 5 0 0 2 0 1 0 32 Legislative act of regulation 2 2 1 1 1 2 3 1 1 1 2 1 1 1 1 21 Risk mitigation  Energy Supply and Use
From page 372...
... TABLE 14.2 Summary of Major Barriers to Deployment of New Energy Technologies  External Benefits and Costs High Costs Technical Risks Market Risks Incomplete and Imperfect Information Lack of Specialized Knowledge Infrastructure Limitations Industry Structure Policy Uncertainty Competing Fiscal Priorities CCTP Goal Area ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ Energy End-Use and Infrastructure ✓ ✓ ✓ ✓ ✓ ✓ ✓ Energy Supply ✓ ✓ ✓ ✓ ✓ ✓ ✓ Carbon Capture and Sequestration ✓ ✓ ✓ ✓ ✓ ✓ Non-CO2 Greenhouse Gases NOTE: Checks indicate that a barrier is judged to be a critical or important obstacle to the deployment of two or more technology strategies within a particular CCTP goal area.
From page 373...
... For example, increased cloudi ness could reduce solar energy production, and wind energy production could be reduced if wind speeds increase above or fall below the acceptable operat ing range of the technology. Not all of the possible impacts on intermittent renewable energy sources are well understood.
From page 374...
... . RESEARCH NEEDS The remainder of this chapter focuses on what we still need to know -- what we need research to tell us -- in order to optimize strategies to both reduce emissions and adapt to climate changes in energy supply and use.
From page 375...
... . For example, along with the benefits of reducing GHG emissions and climate change, use of almost every energy efficiency or loweremissions energy alternative will yield co-benefits in terms of reduced air pollution and associated health impacts.


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