extrapolate, making development of any system to commercial scale a costly operation (about $0.5 billion for each process). Thus, careful selection of R&D and demonstration programs to be pursued is extremely important. For maximum efficiency, the following general guidelines are offered: minimum gasification temperature to reduce temperature cycling and oxygen consumption and to maximize methane production. Production of fused ash to minimize solid waste removal/disposal problems also is an important goal. The use of catalysts to allow lower-temperature operations appears attractive to achieve significant improvements in efficiency and to minimize the production of tars. The cost of using catalysts would be a disadvantage.
DOE's participation in R&D and demonstration of gasification technologies falls into three categories: CCT programs,3 development programs, and advanced research programs related to gasification. The last two fall within the scope of the coal R&D program in DOE's Office of Fossil Energy.
The CCT programs summarized in Table 6-3 all involve gasification for power generation. The gasifiers, while constituting a fraction of the total program cost, are an essential feature of each demonstration. The gasification systems being demonstrated represent technologies of commercial interest to companies within the United States, including affiliates of overseas companies. Overall, the program should provide a basis for commercialization of IGCC power generation plants, as well as a framework for future advances in gasification efficiency and cost reductions for power generation.
Of the seven programs, five plan to use the currently experimental hot gas cleanup—one on a 10 percent slipstream. Use of cold gas cleanup reduces efficiency by approximately two percentage points (see Table 6-2). Four of the programs will use air as the oxidant with an efficiency advantage of approximately 1 percent over the use of oxygen. These advantages are specific to dedicated power generation systems and would not be applicable to the supply of hydrogen or syngas for coproduction of liquid fuels.
Recent DOE budgets for surface coal gasification are shown in Table 6-4. The major expense is for construction of facilities for development of an Advanced Hybrid Gasification System. This facility is designed for development of an air-blown moving fixed-bed system with hot gas cleanup. The proprietary CRS Sirrine Engineers, Inc., PyGasTM staged gasifier has been selected for development with 20 percent industry cost share (CRS Sirrine Engineers, Inc., 1994). Given the committee's concern regarding optimization of gasification systems and the central role of the PyGasTM staged gasifier in the DOE program, the proposed technology is discussed below in some detail.
The general nature of CCT programs is discussed in Chapter 8.