Air Pollution as a Climate Forcing: A Workshop
Day 3 Presentations
Potential Emission Reductions from Advanced Power Generation
Office of Fossil Energy, U.S. Department of Energy, Washington, DC, U.S.A.
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Summary. The Department of Energy's Office of Fossil Energy funds research and development for new and improved energy technologies that reduce detrimental environmental effects of energy production and use. Electricity demand growth projections and regulatory drivers are presented to provide context, and past successes are briefly discussed. The discussion centers on fossil fuel technologies being developed to meet the Department of Energy's Vision 21 goals for powerplant efficiency improvements and emissions reduction.
Electricity Demand. Worldwide electricity consumption is projected (1) to grow at an average rate of 2.7% between now and 2020 (Figure 1). Developing Asia is expected to double its electricity consumption. China's electricity consumption alone is projected to triple. The expected growth rate for electricity is Central and South America is 3.9% per year — thus doubling by 2020. Electricity consumption in the modernized world is expected to grow at a more modest pace than in the developing world — 1.9% per year, but the sheer numbers are still large. By 2020, 355 gigawatts of new generating capacity are expected in the U.S. alone to meet growing demand and to replace retiring units.
-- FIGURE 1 --
Continued increase in the use of natural gas for electricity generation is expected worldwide. Coal is expected to retain the largest market share, but its dominance will be reduced by the rise in natural gas. The role of nuclear power is projected to lessen as reactors reach the end of their lifespans and few replacements are built. Electricity generation from hydropower and other renewables is expected to grow by more than 50% over the next 20 years, but their share of total production is expected to remain near the current level of 20%.
U.S. Regulations Affecting Power Production. President Bush has two initiatives aimed at reducing environmental pollutants. The President's Clear Skies Initiative is aimed at dramatically and steadily reducing power plant emissions of the three worst air pollutants. It would cap sulfur dioxide (SO2) emissions at 3 million tons by 2018, a 73% reduction. It would cap emissions of nitrogen oxides (NOx) at 1.7 million tons by 2018, a 67% reduction. And, it would cut mercury (Hg) emissions by 69% — the first ever national cap on mercury emissions, capped at 15 tons in 2018. In addition, the President's Climate Change Initiative calls for voluntary reductions in greenhouse gas intensity by 18 percent over the next 10 years.
Proven Technologies Currently Reducing Emissions. Commercial technologies developed in partnership with the U.S. Department of Energy (DOE) programs are contributing to substantial emission reductions (Figure 2). 75% of existing U.S. coal-fired units have been, or currently are being, retrofitted with low-NOx burners. An estimated 30% of U.S. coal-fired generating capacity will incorporate Selective Catalytic Reduction (SCR) technology by 2004. Over 60 million tons of NOx emissions have been avoided since 1970 based on average fleet emissions. Fluidized Bed Combustion (FBC) technologies offer inherently low NOx emissions, high combustion and SO2 capture efficiency, and extreme fuel flexibility. Six FBCs in Pennsylvania are using coal waste as fuel, eliminating an environmental problem, saving $1 billion in fuel costs, and avoiding 1.8 million tons of NOx emissions over their design life. For SO2 control technologies, an estimated 30% of U.S. coal-fired generating capacity will incorporate Flue Gas Desulfurization (FGD) technology by 2002. 127 million tons of SO2 emissions have been avoided since 1970 as a result of FGD installations. In summary, the U.S. uses 2 times the coal it did in 1970, yet pollutant emissions from power plants have decreased dramatically. In the future, increased coal use will bring pressure to reduce emissions even further.
-- FIGURE 2 --
Developing Technologies Hold Promise for the Future. The U.S. Department of Energy is developing advanced technologies such as gasification-based systems for power production. A gasification-based process converts solid and liquid feedstocks to synthesis gas that can be easily cleaned of pollutants. It also can convert potential pollutants to salable by-products such as sulfur, construction materials, and abrasives. Gasification enables production of electricity, steam, clean transportation fuels, chemicals, hydrogen, and natural gas substitutes. In addition, gasification systems will be amenable to future CO2 separation and capture technologies.
Fuel cells are being developed for distributed generation applications. The Solid State Energy Conversion Alliance (SECA) is working specifically toward mass customization of 3-10kW fuel cell modules with aggressive cost reduction goals ($400/kW by 2010). Research is also being performed on integration of a fuel cell and turbine into a hybrid system that will lower system costs and improve overall system efficiency.
Research and development funding for carbon sequestration is increasing greatly. In the near term, DOE is focusing on reducing cost and showing feasibility of capture and separation of CO2 from power plants, with sequestration in geological structures including enhanced oil recovery and coal bed methane extraction, while reducing net cost from $200/ton carbon to $30-$70 /ton carbon. In the long term, greater emphasis is being placed on advanced reuse and conversion concepts with target costs of $10/ton carbon, or a 0.2 cent/kwh impact on electricity costs. Still longer term, the plan is to integrate carbon sequestration with advanced power facility designs for use with both gasification and combustion systems.
-- TABLE 1 --
Research and Development Strategy and Goals. The Department of Energy's fossil energy based power R&D goals culminate in its Vision 21 program, with long-term (2015) goals for advanced future energy plexes. Performance targets are listed in Table 1. In general, the short term goal is to develop affordable environmental technologies for existing coal-fired power plants (controls for mercury, NOx, SO2, particulates.) The mid-term goal is to develop much cleaner, more efficient options for new coal and gas plants in the 2005-2015 timeframe emphasizing Integrated Gasification Combined Cycle (IGCC) advanced combustion technologies. The long-term goal is near-zero emission, high efficiency coal and gas power plants — with low-cost carbon sequestration — by 2015 (Vision 21 systems, including fuel cells).
- Energy Information Administration, International Energy Outlook (IEO) 2002. Energy Information Administration, Annual Energy Outlook (AEO) 2002. (http://www.eia.doe.gov.