Magnetohydrodynamic Generator

A magnetohydrodynamic generator, or MHD generator, is a magnetohydrodynamic converter that transforms thermal energy and kinetic energy directly into electricity. Like a conventional generator, it works by moving a conductor through a magnetic field to produce current, but where a mechanical dynamo uses the motion of solid mechanical parts to do this, an MHD generator instead uses a hot, electrically conductive ionized gas, a plasma, as its moving conductor. Because it has no moving mechanical parts such as turbines, an MHD generator faces no upper limit on its operating temperature imposed by mechanical wear, and it has the highest known theoretical thermodynamic efficiency of any electrical generation method; the technology has been developed for use in combined cycle power plants, particularly those burning coal or natural gas, where the hot exhaust gas leaving an MHD generator can go on to heat the boiler of a steam power plant and raise the overall efficiency of the combined system. Practical MHD generators have been built for fossil fuel use, but less expensive combined-cycle designs, in which the exhaust of a gas turbine or a molten carbonate fuel cell heats steam to drive a separate steam turbine, have overtaken them in practice.