Indirect fired gas turbines for cogeneration: open or closed cycle

Capable of using cheap, dirty fuels, the indirect-fired gas-turbine cycle is a candidate for cogeneration systems in either the open- or closed-cycle mode. Rockwell's evaluation of the two modes assessed the fuel consumption and economic viability of the cogeneration systems and compared them with steam-turbine plants. The trade-offs between the indirect open and closed cycles favor the closed system in most cases except those where the turbine exhaust can be used directly in the process or where cooling water is unavailable. The gas turbine would consume 13% less fuel than a coal-fired steam system.