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2 Resource Base
Pages 45-66

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From page 45...
... Hence, renewable energy sources are by nature local or regional, and those that may be unable to contribute significantly to total U.S. electricity generation could still contribute to a substantial share of the renewable-based electricity generated in regions where that specific type of renewable energy flux is abundant and well suited for development.
From page 46...
... In energy units, 11 million GWh represents 40 EJ of energy, as compared to the 2007 domestic primary energy consumption of 100 EJ. The domestic large-scale wind electric energy resource estimate of 11 mil lion GWh is uncertain, however, and the actual wind resource could be higher or lower.
From page 47...
... onshore wind electricity value of 11 million GWh/yr, an upper value for the extractable wind electric potential would be about 2.2 million GWh/yr, equal to more than half of the electricity generated in 2007. This estimate assumes that large-scale wind farms are installed over all suitable Class 3 and higher wind speed areas in the continental United States, as mapped in Figure 2.1 (AWEA, 2007; DOE, 2008)
From page 48...
... R01203 Main Report 6-2 about 16 billion GWh of electric energy and, at a 10 percent average conversion efficiency, would therefore provide 1.6 billion GWh/yr of electricity. At a 10 per cent conversion efficiency, coverage of 0.25 percent of the land area of the conti nental United States would be required to generate the 4.2 million GWh of electric energy generated domestically in 2007.
From page 49...
... An analysis by the Energy Foundation and Navigant Consulting eliminated roofs on residences that were not generally facing southward and roofs that had too high a slope for routine installation of solar PV panels; considered the impacts of shading by trees, the presence of heating and air-conditioning units, and other obstacles on the remaining viable portion of the rooftops, but did not account for snow; and added suitable flat commercial building rooftop space to the total (Chaudhari et al., 2004)
From page 50...
... With an average annual capacity factor of 25–50 percent for CSP, depending on the thermal storage used for a plant, this land area could theoretically produce 15–30 million GWh of electric energy per year, again significantly more than the 4.2 million GWh total U.S. electricity supply in 2007.4 Only a fraction of this land area at present could be developed economically for CSP-based electricity genera tion due to factors such as generation and transmission costs discussed in later chapters.
From page 51...
... , thermal energy stored as hydrothermal resources ranges between 2,500 EJ (0.67 billion GWh) and 9,700 EJ (2.7 billion GWh)
From page 52...
... Since hydro thermal facilities typically operate at 90 percent capacity during much of their operational life, the 13 GW from identified hydrothermal resources could provide up to 0.1 million GWh/yr of baseload electric energy. These same western states consumed slightly more than 1 million GWh/yr of electricity from 2000 through 2003 (WGA, 2006a)
From page 53...
... electric generation capacity) would thus require a minimum land area footprint of 1 × 1013 m2.5 For comparison, the land area of the continental United States is 8 × 1012 m2, so the footprint needed to provide 20 percent of the 2005 average electric load from sustainably produced geothermal energy would exceed the total land area of the continental United States.
From page 54...
... Electricity from Renewable Resources  50°C 100°C 150°C 200°C 250°C 300°C 3.5 km 5.5 km 10 km FIGURE 2.5  Allocation of U.S. geothermal resources at 3.5 km (top panel) ,   5.5 km (middle panel)
From page 55...
... R 2.6 of the natural geothermal heat flux; such extraction rates are not sustainable in the long term, because they would deplete the heat more rapidly than it would be restored by the natural geothermal flux. Such heat mining would reduce the land area needed to be tapped by allowing heat extraction to exceed the 10 mW/m2 replacement rate.
From page 56...
... HYDROPOWER Conventional Hydroelectricity Conventional hydroelectricity generation in 2007 provided 0.25 million GWh. Hydroelectric generation capacity was 98 GW, representing about 9 percent of the total U.S.
From page 57...
... wave energy resource. Exhaustive use of the entire wave energy resource would therefore be required to produce less than 2 percent of the 4.2 million GWh of the electricity generated in the United States in 2007.
From page 58...
... -- enough to provide, if the stated resource were used in whole, 0.03 percent of the 2005 domestic generated electric energy. EPRI's study of the electric energy potential in river currents yielded a value of 0.11 million GWh/year (EPRI, 2005)
From page 59...
... Of this projected 1 billion dry tons that might be available in 35–40 years, 300–400 million tons would come from crop residues and 350 million tons would result from the substitution of high-yield perennial biomass crops for other land uses on at least 40 million acres of land. The geographical distribution of the biomass resource base shown in Figure 2.8 comes from Milbrandt (2005)
From page 60...
... According to the USDA/DOE study, providing 1.3 billion dry tons per year of biomass would require increasing the yields of corn, wheat, and other small grains by 50 percent; doubling residue-to-grain ratios for soybeans; developing more efficient residue-harvesting equipment; managing cropland with no-till cul tivation; growing perennial crops whose output is primarily dedicated to energy purposes on 55 million acres of cropland, idle cropland, and cropland pasture; using animal manure in excess of what can be applied on-farm for soil improve
From page 61...
... The AEF alternative liquid fuels panel did not extend its estimate to 2035, as did the 2005 USDA/DOE report. Electricity Generation from Biomass Based on 2005 biomass production levels, full use of the 190 million dry tons of sustainable biomass produced in the United States, at 17 GJ (1 GJ = 1 × 109 J)
From page 62...
... resource base for generation of renewable electricity. In summary, the United States has significant renewable energy resources, which, combined, have the potential, in principle, to provide more electric power than the total existing installed peak capacity and more electric energy annually than the total electricity consumed domestically in 2005.
From page 63...
... 2007. 20 Percent Wind Energy Penetration in the United States: A Technical Analysis of the Energy Resource.
From page 64...
... 1986. Wind Energy Resource Atlas of the United States.
From page 65...
... 2004. Can large wind farms affect local meteorol ogy?


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