My home is my power station

In general, 'renewable energy' is about electricity. The reason is simple: Practically everything mankind has invented over the last century runs on electric power, even most of a modern car's systems, combustion engine or not. Since mankind has still not really mastered harnessing naturally occurring electricity like lightning, transforming mechanical, chemical or quantum-physical forms of energy into electricity is still the challenge – with the laws of thermodynamics as limiting factors. However, there's more to 'renewable' than wind or sun.