Energy refers to the general term for substances that can produce various kinds of energy (such as heat, electrical energy, light energy, mechanical energy, etc.) and various resources that can obtain useful energy directly or through processing and conversion, including coal, crude oil, natural gas, coal bed methane, hydro energy, nuclear energy, wind energy, solar energy, geothermal energy, biomass energy and other primary energy and electricity, secondary energy such as heat and refined oil, as well as other new and renewable energy.
