1. coal preparation (conventional and advanced technology);

  2. solvent refined coal;

  3. low sulfur, low BTU gas from coal;

  4. fluidized bed combustion;

  1. shift fuel consumption from electricity to pipeline grade gas made from coal or to solar energy.

Other possible techniques are discussed in Chapters 11 and 12.

ASSESSMENT OF THE POTENTIALS FOR IMPROVED EFFICIENCY IN THE CONVERSION OF FUEL TO ELECTRICITY

Summary

Methods of generating electricity at increased efficiencies (in order to reduce the pollution load per unit of electricity generated) are not expected to come into widespread use until 1985 or later. As important as it is to continue R&D on these advanced power cycles, they offer no sollution for reducing sulfur oxide or particulate emissions in the period between 1975 and 1985.

The average heat rates (i.e. the number of heat units required to generate one net kw-hr. of electricity) for utility power plants in the U.S. declined steadily from 25,175 BTU/kw-hr. in 1925 to 10,479 BTU/kw-hr. in 1972. This increase in conversion efficiency was the result of a number of technologic improvements, the most important of which were those that permitted steam turbine plants to operate at higher temperatures and pressures. Through experience it has been found that the best current practical efficiency of operation is 38 to 39 percent. (Heat rate approximately 9000 BTU/kw-hr.).

The average heat rate was lowest in 1968 when it was 10,371 BTU/kw-hr., and it has increased steadily since that time for a number of reasons. The leveling off in the efficiency of new plants, the more widespread use of nuclear



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