"The energy efficiency of a fuel cell is generally between 40-60%, or up to 85% efficient if waste heat is captured for use." A helicopter probably cannot put the heat to work. Idea: One thought regarding the subject of heat is that the hydrogen (or other) coming out of the (light carbon filament wound) tank will be expanding. The efficiency of motors increases when they running at low temperatures. Can the stator of the motor be located in the expansion zone of the gas?
