Renewable energies are to be considered neither plentiful nor inexhaustible nor cheap. Indeed, using renewable energy sources requires – for the production of electricity, usable thermal energy and fuels – institutional regulations and activities, professionalism and work, technologies, facilities and investments and land and non-renewable resources for plants.   The exploitation of renewable sources for energy implies using limited, expensive and non-plentiful resources. For these reasons they must be used in moderation, efficiently, always prioritizing energy saving. To mitigate the current serious global climate crisis, the use of renewable energy sources must grow, thus replacing the use of fossil fuels. Such replacement stems not so much form scarcity of fossil ...