34. Magnetohydrodynamic (MHD) Power Generation Systems

A magnetohydrodynamic (MHD) power generation system is an electrical power generating system which generates the electricity utilizing the MHD principle. MHD power generation technique generates the electric power directly from a moving stream of ionized fluid flowing through a magnetic field. Therefore, the MHD power generation systems are found as the non-conventional electric power generation modality which is considered as the green energy harvesting procedures. The MHD generators utilizes the electromagnetic interaction of an ionized fluid flow and a magnetic field. The ionized fluids in MHD generators work as the moving electrical conductor and hence the electromotive force (e.m.f.) could be generated across the ionized conductor due to the Faraday’s electromagnetic principle. An MHD system, therefore, can act as a fluid dynamo or MHD power converter. In MHD, as the flow (motion) of the conducting fluid (conductor) under a magnetic field causes an induced voltage across the fluid, the e.m.f. would be found at the perpendicular direction to both the magnetic field and the fluid flow according to Fleming's right-hand rule. The concept of MHD power generation technique was first introduced by Michael Faraday in 1832 during his lecture at the Royal Society, UK. Since then, the MHD systems have been developed and studied by several research groups. Different types of MHD generator geometries have been proposed with different channel geometries, different electrode configurations, different magnetic coil structures, and different working fluids or plasmas. Though a typical coal-fired MHD generator converts about 20% of the thermal input power to the output electricity but, using the combined MHD/steam cycle systems, an energy conversion efficiency up to 60% of the coal’s energy can be converted into the electrical energy. In recent time, the green energy harvesting processes are found extremely important to reduce the pollution and to save the fossil fuel in the world for its sustainable development. In this direction, the MHD power generation technique could be utilized for green energy generation without any environmental pollution. In this chapter, The MHD technology has been discussed in detail followed by a discussion on its components, system design issues, and crucial design aspects. A detail review on the historical developments and the associated research works conducted on the MHD power generation process has been presented highlighting the major developments. Along with the limitations and challenges of the MHD power generation method, the present scenario and the future trends are also discussed.