Mercury and Steam

This article is a memoir of William Emmet, a General Electric engineer in the field of combined-cycle gas turbine power plants. Despite the odds against the idea, several combined mercury and steam plants were built and achieved the promised high efficiency. This improbable achievement can be credited to a General Electric engineer named William Emmet. While Emmet’s early experience had been with direct current, he recognized the benefits and challenges of alternating current. The fuel efficiency of Emmet’s mercury dual cycle was eventually made obsolete by increased steam plant efficiencies from higher pressures and reheating the steam. Emmet’s contributions today are mostly hidden improvements in rotating electric machinery and apparatus. In contrast, his success in developing the impulse turbine helped create a technology base of engineers and manufacturing. It positioned General Electric to take the lead in turbochargers for piston aircraft engines, and later global leadership in aircraft jet engines and land-based gas turbines for electricity and industry.