* Fossil fuels: Oil, coal, and natural gas are all fossil fuels, formed from the remains of plants and animals that lived millions of years ago. These are non-renewable fuels, meaning that they will eventually run out and cannot be replaced naturally
* Biomass: Biomass is an organic material from living or recently living organisms can be used as a form of energy fuel. This includes wood, straw, and other plant matter, as well as manure and other animal waste, municipal solid waste and more.
* Hydropower: Hydropower is generated by the movement of water. Large amounts of flowing or falling water is passed through a turbine, spinning it, which in turn generates electricity.
* Nuclear power: Nuclear power is generated by the heat released from the splitting of atoms in a nuclear reactor, usually uranium atoms.
* Geothermal power: Geothermal power is generated by heat from the Earth's interior. Hot water or steam from underground reservoirs is passed through a turbine, spinning it, which in turn generates electricity.
* Solar power: Solar power is generated using solar panels, which convert sunlight directly into electricity.
* Wind power: Wind power is generated using wind turbines, which convert the kinetic energy of the wind into electricity.
