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4 Environmental Impacts of Renewable Electricity Generation
Pages 89-112

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From page 89...
... Overall, reducing environmental impacts is a major impetus for shifting from fossil fuels to renewable energy for electricity generation. Developing renewable energy technologies that exploit the sun, the wind, and geothermal energy is critical to addressing concerns about climate change and some environmental issues.
From page 90...
... FOSSIL FUEL VS. RENEWABLE ELECTRICITY GENERATION An LCA estimates resource requirements, energy use, and environmental impacts of products or services at all life stages.
From page 91...
... NERs are strongly influenced by a number of underlying assumptions, such as plant capacity and life expectancy. For electricity generation from wind and solar energy, the strength of the resource (which will affect the capacity factor of the installed technology)
From page 92...
... 0 Hydro Solar Wind Biopower Coal Gas Nuclear Energy Technology FIGURE 4-1 Net energy ratios for various renewable and non-renewable energy sources. Source: NAS/ NAE/NRC, 2010a.
From page 93...
... In addition, as shown in Figure 4-2, all forms of renewable electricity production are expected to have significantly lower life cycle GHG emissions (expressed as CO2 equivalents, CO2e) than electricity production from conventional coal and natural gas plants.
From page 94...
... . Local and Regional Air Pollution Electricity generation accounts for significant emissions of local air pollutants in the United States and China.
From page 95...
... . Most renewable energy technologies have much lower life cycle emissions of conventional air pollutants than conventional coal and natural gas plants.
From page 96...
... Energy Technology FIGURE 4-3 Estimates of life cycle NOx emissions from various technologies. Data compiled by NAS/NAE/NRC, 2010a.
From page 97...
... In China, the biomass materials likely to be used for electricity generation are mainly agri cultural residues (e.g., straw, bagasse, and rice husks) , forestry wastes (e.g., wood chips, sawdust, and bark)
From page 98...
... of water was withdrawn in 2000 for thermoelectric power generation in the United States, accounting for nearly half of total withdrawals (USGS, 2005)
From page 99...
... Gallons per Megawatt-hour Equivalent 0 500 1,000 1,500 2,000 2,500 3,000 Once-through low 25,000 Cooling tower low Cooling pond low Once-through high Nuclear 60,000 Cooling tower high Cooling pond high DOE, 2006a by NAS/NAE/NRC, 2010a. Once-through low 20,000 Cooling tower low Cooling pond low Coal Once-through high 50,000 Cooling tower high Cooling pond high Tower low IGCC Tower high Other Power Plant Use Power Plant Consumption Once-through low 7,500 Cooling tower low Power Plant Withdrawal-Consumption Once-through high NGCC 20,000 Cooling tower high Cooling tower Evaporation 4,500 Geo Hydro Mining/Processing Thermal low Thermal high Solar Power tower Mining Withdrawal-Consumption Dish engine S R 5.9 FIGURE 4-5 Estimates of water withdrawal and consumption for various electric generation technologies compiled from 
From page 100...
... Values shown in Figure 4-5 reflect operating experience with a 350 MW parabolic-trough system in the Mojave Desert, which uses evaporative cooling and consumes about 800 gal/MWh; a comparable estimate of water consumption for solar power tower technology; and a projection of negligible water consumption with an air-cooled parabolic dish system. Finally, if evaporative losses from hydroelectric reservoirs are ascribed fully to the generation of electricity, large-scale hydroelectric power can be considered to consume more water per MWh electricity output than any other electricity generation technology (Gleick, 1994)
From page 101...
... assumed the polycrystalline silicon is produced in part using the Siemens process and in part through a modified Siemens process, with an overall average electricity requirement of 110 kWh/kg Si and assuming 1.67 kg Si is used per square meter of PV panel. Whereas Alsema and de Wild-Scholten assumed electricity for polysilicon production was supplied from a mixture of hydroelectric and natural gas combined-cycle generation, the modified results shown here were calculated assuming electricity used at all stages in the process was produced from primary fuel with a net conversion efficiency of 31 percent.
From page 102...
... Assessments of Ecological, Aesthetic, and Cultural Impacts Cultural Impact Among renewable electricity technologies, large-scale hydroelectric projects have historically had especially stark consequences, especially if they involved flooding scenic valleys or town sites. For example, when the Dalles Dam on the Columbia River was completed in 1957, the associated reservoir flooded Celilo Falls and the village of Celilo, a tribal fishing area and cultural center that arche ologists estimated had been inhabited for millennia (Oregon Historical Quarterly, 2007)
From page 103...
... A case in Hawaii is another example of controversy surrounding the siting of renewable energy projects in locations of natural, cultural, or religious value. In 2007, Hawaiians celebrated the protection of a 26,000 acre tract of lowland rainforest on the island of Hawaii, after more than 20 years of efforts to restore public access and block the development of a geothermal power plant at the site (OHA, 2007)
From page 104...
... Aesthetic Impact Aesthetic concerns may not be specifically regulated but can be a significant issue for communities where new renewable energy projects will be located.
From page 105...
... Actions that fall under NEPA requirements range from the provision of loan guarantees for renewable energy projects to the granting of rights-of-way or the issuance of leases for con struction of projects or transmission lines on or across federal lands. The objective of NEPA is to ensure that agencies fully consider potential environmental impacts and allow all interested parties, including the public, to provide input into the process before decisions are made.
From page 106...
... In recent years, numerous environmental disputes have arisen over the construction of waste incineration power plants. For example, protests by nearby residents against the construction of the Liulitun waste incinera tion power plant in Beijing had a significant social impact at the time.
From page 107...
... The primary laws governing air and water pollution in the United States are the Clean Air Act and Clean Water Act, both of which include direct federal regulations as well as programs that are mandated and enforced by the federal government but administered by states or tribes. Compliance with air pollution regulations under the Clean Air Act is required for biomass combustion and geothermal facilities that release pollutants to the atmosphere during opera tion; other renewable projects that entail clearing land or construction of new roads may also have to address concerns about vehicle or construction equipment emissions and fugitive dust.
From page 108...
... . Since the adoption of the Renewable Energy Law, additional environmental regulations have appeared in China specifically to address environmental impacts of biomass power generation.
From page 109...
... With the exception of emissions of NOx and carbonaceous materials from biomass combustion, rates of life cycle emissions of conventional air pollutants from renewable electricity generation are also sharply lower than from coal and natural gas plants. Although renewable energy sources have major advantages over fossil fuels, they also raise some environmental concerns.
From page 110...
... The production of NOx from the nitrogen in biomass is not well understood, because the forms of nitrogen are different from those in coal. Therefore, research is needed to minimize pollutant emissions during biomass power generation processes.
From page 111...
... • For biomass power generation, the priority should be on reducing combustion emissions and using available waste resources (rather than dedicated energy crops) , including municipal solid waste and agricultural residues.


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