Important features of these systems are summarized in Table 10-1. Information on state-of-the-art commercial pulverized coal systems is included in the table as a baseline. Current DOE funding levels for these various technologies were summarized in Chapters 2 and 7.
As shown in Table 10-1, DOE's efficiency goals for advanced power systems rise to 60 percent for the year 2010 (best current new plant levels are about 38 percent for the United States and 42 percent worldwide). In the DOE plan the highest efficiencies are expected to be achieved with IGFC technology (DOE, 1993a). A number of other systems are projected to achieve efficiencies of 45 to 55 percent using advanced combustion and gasification-based approaches and high-performance gas turbines. A major objective of the DOE plan is to achieve these higher efficiencies at an overall cost of electricity that is 10 to 20 percent lower than that of today's coal-fired power plants while also meeting more stringent environmental requirements (see Table 10-2).4
In the view of the committee, the DOE efficiency goals, especially for the later years, are quite optimistic. For example, the efficiency goals of 55 percent for systems using 1290 °C (2350 °F) gas turbine topping cycles exceed the performance capabilities of about 50 percent efficiency for current combined-cycle systems using natural gas. While turbine improvements are expected to raise the efficiency on natural gas to about 57 percent (see Chapter 7), coal gasification and gas cleanup energy losses will decrease efficiency by five to 10 efficiency points when using the gasification systems being demonstrated in the CCT program (see Chapter 6). Thus, substantial reduction of gasification-related losses is needed to achieve the DOE target system efficiency with IGCC. As noted in Chapter 7, the hybrid second-generation pressurized fluidized-bed combustion system, which gasifies only part of the coal, is estimated to have a potential for approximately four percentage points higher efficiency than IGCC systems where all the coal is gasified (Maude, 1993). Conceivably, this system could achieve the DOE efficiency goal; however, substantial technical hurdles remain to be overcome. Similar comments apply to the 60 percent efficiency goal for IGFC systems.
The goal of 10 to 20 percent reduction in the cost of power, concurrent with significant efficiency increases and emissions reductions, may be especially difficult to realize. For example, roughly 30 percent of the cost of electricity today for a new coal-fired plant represents the cost of fuel (EPRI, 1993). Thus, reducing fuel requirements by one-third by raising plant efficiency from about 40 to 60 percent would lower the overall electricity cost by about 10 percent, which is DOE's minimum cost reduction objective. A smaller efficiency gain would yield
Identical to Table 2-3.