Whatever happened to magnetohydrodyamics (MHD) for electric power generation? This was a big topic back in the mid '70s according to my "Standard Handbook for Electrical Engineers", with test setups being done by Avco in the United States and in Moscow...but I get the impression that MHD never really took off after those days.
I suppose with combined-cycle gas turbines hitting over 50% efficiency (the big new General Electric and Alsthom turbines being examples), that the motivation for MHD as a "topping" cycle has faded. Certainly the difficulties of getting a gas to conduct electricity didn't make MHD any easier to implement, and the issue of "seed" material recovery would also have added to the complexity.
Is there a commerical-scale MHD in operation out there, or, like fusion research, is the primary product of MHD research papers?