I'm not an expert here, but I believe that the maximum possible efficiency of all heat engines is governed by the temperature difference between the heat source

I'm not an expert here, but I believe that the maximum possible efficiency of all heat engines is governed by the temperature difference between the heat source and the heat sink [1,2]. Increasing the water T/P to supercritical both increases the T at which it can enter the system and, from what I gather by the link you posted and from [3], also results in some simplification of the plant mechanics, which likely increases efficiency as well. This should indicate that for a given amount of sunlight (or fossil fuels in a conventional power plant), a greater amount of electricity can be created. [1]: http://en.wikipedia.org/wiki/Carnot_cycle http://en.wikipedia.org/wiki/Carnot_cycle [2]: http://en.wikipedia.org/wiki/Rankine_cycle http://en.wikipedia.org/wiki/Rankine_cycle [3]: http://www.brighthubengineering.com/power-plants/32896-how-are-supercritical-boilers-different-from-subcritical-boilers/ http://www.brighthubengineering.com/power-plants/32896-how-a...