Renewable natural gas, also known as sustainable natural gas, is a biogas which has been upgraded to a quality similar to fossil natural gas.

Wave power is the transport of energy by ocean surface waves, and the capture of that energy to do useful work – for example, electricity generation, water desalination, or the pumping of water (into reservoirs).

Hydrogen fuel is a zero-emission fuel which uses electrochemical cells, or combustion in internal engines, to power vehicles and electric devices.

Hydro-power or water power is power derived from the energy of falling water and running water, which may be harnessed for useful purposes.

Geothermal energy is thermal energy generated and stored in the Earth.

Biomass is biological material derived from living, or recently living organisms.

A biofuel is a fuel that contains energy from geologically recent carbon fixation.

Oil sands, tar sands or, more technically, bituminous sands, are a type of unconventional petroleum deposit.

Oil shale, also known as kerogen shale, is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons called shale oil (not to be confused with tight oil—crude oil occurring naturally in shales) can be produced.

Petroleum (L. petroleum, from Greek: πέτρα (rock) + Latin: oleum (oil)) is a naturally occurring, yellow-to-black liquid found in geologic formations beneath the Earth's surface, which is commonly refined into various types of fuels.