Four open-cycle magnetohydrodynamic (mhd) processing schemes were selected for study. Each involved a different mode of coal combustion and level of gas cleanliness. The options considered were the following: (1) coal burned in a slagging combustor; (2) suspension gasification with slag removal prior to combustion; (3) parallel cyclone combustors, one operating fuel rich and the other operating with excess air; and (4) suspension gasification by the hot exhaust gases from the mhd duct with ash removed prior to combustion. Option 1 has the highest ash content in the combustion plasma and as a result would have the greatest operational difficulties associated with it. Options 2 and 4 have the cleanest mhd combustion plasma. For coal priced at $4/ton, the power generating cost of option 4, 11.78 Mills/kw-hr, is the highest, with option 1, at 9.04 Mills/kw-hr the lowest. These costs may be compared with a conventional power cost of 9.92 Mills/kw-hr for the late seventies. Capital costs of three of the four options were competitive with those of conventional thermal powerplants employing stack gas so2 cleanup systems. Option 2 has the most favorable combination of operating characteristics and power cost. It was concluded that a clean, high-temperature working fluid can probably be economically produced from coal.