True. But the govt. report on this idea seems confident of 50% RTE, or 55% if they used a more-complex turbine system. For limited & short-term use, the plant

True. But the govt. report on this idea seems confident of 50% RTE, or 55% if they used a more-complex turbine system. For limited & short-term use, the plant with vastly-more-expensive storage masses might make sense. But as soon as you were faced with NIMBYs or environmentalists (hexane's MSDS is far closer to hydrogen fluoride's MSDS than it is to sand's), or if you are working in a less-prosperous part of the world...sand is great stuff.