solar matter is a renewable / inexhaustible discoveries
solar_power is clean_renewable_energy_source. earthling is solarian. renewable_resource is natural_resource. air is naturally_occurring_tangible_substance. renewable_resource is tangible_thing. geothermal_energy is tangible_thing. solar_energy is alternative_energy. natural_gas is organic_matter. natural_gas is renewable_resource. renewable_energy is energy.