opportunity for a variety of coproducts produced by the primary coal gasification process. Steam and electricity would continue to be major products.
It seems reasonable to expect that the time for introduction of cogeneration systems based on coal would approximately correspond to the time when the projected cost and/or availability of natural gas would justify investment in new coal-based, power-generating facilities, perhaps during the mid-term period (2006-2020). This time might well arrive before manufacture of synthetic natural gas is required to meet domestic demand. The large world resources of petroleum and bitumen, combined with low prices, are expected to defer manufacture of liquid transportation fuels from coal until the price range is $25 to $30/bbl, although security considerations could call for an earlier date. The first major opportunity for coproducts would then arise from the predicted mid-term need for new high-performance coal-based, power generation systems. These high-performance systems will probably involve coal gasification offering the possibility of coproducts from the gasifier (syngas, fuel gas, and pyrolysis tar). The production of coproducts, in conjunction with SNG manufacture, was of major commercial and DOE7 interest until the 1980s, when low oil and gas prices and ample supplies eliminated the near-term economic incentive for synthetic fuels processes. The expected growth in coal-based power generation appears to offer a more robust opportunity for fuel and chemical coproducts than the traditional single product or dedicated plant approach.
The business environment and regulatory changes that have encouraged cogeneration could provide a framework for extension to the use of coal as a source of energy and a resulting greater variety of coproduct streams. Recent industrial concerns regarding efficient production of major products and conservation of capital are resulting in steam and power being supplied by external companies that build and operate facilities for supply of steam and electricity to both local manufacturing plants and utilities. In some cases these companies are subsidiaries of a utility. Such companies might supply fuel gas and syngas to chemical and petrochemical companies. Nonetheless, the complexity of the potential business relationships and the need for a flexible approach should not be underestimated.
With today's emphasis on increased generation efficiency and the availability of high-performance gas turbines and fuel cells, an incentive for development of high-efficiency gasification systems specifically designed to provide fuel for power generation has been established. As discussed earlier, these systems can differ from systems optimized to produce highly purified synthesis gas for conversion to chemicals and clean fuels in that dilution by methane and nitrogen is acceptable; a higher level of impurities can also be tolerated.