Conceptual design and economics of coal and gas co-fired PFBC plants

Advanced 2nd-Generation pressurized fluidized bed (PFBC) cycles are viewed as having increased technological risk related to the pressurized carbonizer systems regardless of their favorable economics and performance. The 1.5-Generation PFBC cycle combines the performance advantages of the 2nd-Generation PFBC plant with the reduced risk of a natural-gas-fired gas turbine. This paper describes the technical and economic evaluation of 246-MW and 111-MW 1.5-Generation PFBC cycles for utility or industrial power generation. Economic evaluation includes sensitivity studies to determine the effects of operating variables and fuel prices on capital cost and COE. The thermal efficiency, capital cost, and cost of electricity of 1.5-Generation PFBC plants are better than pulverized coal plants, and in between 1st- and 2nd-Generation PFBC plants. Plant capacity turndown is expected to range from full-load (design flows of natural gas and coal) down to 38-percent load (zero natural gas and 50-percent coal flow). The plant can be reduced to 76-percent load by reducing natural gas flow without disturbing the coal feed to the rest of the plant, and other cost-effective variations are also possible. The 1.5-Generation PFBC plant is the logical repowering alternative to 1st-Generation PFBC, and provides a reasonable bridge to later conversion to a 2nd-Generation PFBC, thusmore » advancing the adoption of 2nd-Generation PFBCs in the future.« less