Which describes the use of a renewable energy source?


burning natural gas to power city buses


using solar cells to heat water for use in homes


burning coal to operate the machinery in a factory


Which describes the use of a renewable energy source?


burning natural gas to power city buses


using solar cells to heat water for use in homes


burning coal to operate the machinery in a factory

Which energy item, the same stuff, can be reused after a previous use -- natural gas, the sun's rays, or coal?