Before revision: Active system These systems use the principle of harnessing the power generated from renewable and inexhaustible sources of energy, for example; solar, wind, thermal, biomass, geothermal, and hydropower energy.
After revision: Active systems These systems use the principle of harnessing the power generated from renewable and inexhaustible sources of energy, for example; solar, wind, thermal, biomass, geothermal, and hydropower energy.