What is wrong with the term reusable energy resource?

Answer 1

Energy once used can hardly be used again, this would defy thermodynamics. Probably what is meant is renewable energy, which covers solar and wind power, tidal and hydro power, geothermal, and biomass. These are all (except geothermal) driven by the power we receive from the sun, and therefore won't fail to be renewed, though they may vary from year to year and century to century.