Yes, doing something to either liquid or a gas.
(putting aside the alternative of changing their phase(s). It is another case, however, but it would be interesting if a wind mill drived directly a heat pump (that is, its compressor)).
I was thinking that wind or wave energy can be transformed directly to heat (where we need just the heat). Electricity generators utilising wind or wave energy are inevitably losing some of it on its transformations.
Only the power you would need to add to the system were for the controls and...
Friction is phenomenon we try to avoid but it may be useful.
Does anyone know about existing friction heat generators and what method they use ?
Seemingly, solid matter does not suit as it pulverizes as well as wears out the generator parts. Probably, remains gas compression. There cannot be a...