Revisiting MHD Generators with HTS Magnets

Abstract

Magneto-hydrodynamic (MHD) power generators can convert thermal and kinetic energy to electrical energy without any moving mechanical parts. They have the promise of competing against typical turbo-generators in a power plant. The advent of high temperature superconducting (HTS) magnets can give MHD generators the edge over other generators as the efficiency increases with the magnetic field strength. A robust mathematical model is derived to account for the plasma physics, fluid dynamics, and magneto-hydrodynamics involved with directing and harnessing the flow of an ionized gas. The resulting analytical model is computationally solved and then analyzed.

It is clear that HTS magnets greatly benefit MHD generators. For a coal-fired power plant, the enthalpy ratios between the input and output of the generator surpass 50%. In other words, over half of the thermal energy produced by the power plant is converted to electricity by the MHD generator. The remaining fraction of energy is directed to a bottoming cycle for additional energy conversion. In the end, modest estimates put the overall efficiency of this system over 65%, compared to the current most advanced coal power plants of less than 45% efficiency.