Energy carrier

Such carriers include springs, electrical batteries, capacitors, pressurized air, dammed water, hydrogen, petroleum, coal, wood, and natural gas.

According to ISO 13600, an energy carrier is either a substance or a phenomenon that can be used to produce mechanical work or heat or to operate chemical or physical processes.

Such carriers include springs, electrical batteries, capacitors, pressurized air, dammed water, hydrogen, petroleum, coal, wood, and natural gas.

Note that although coal, oil and natural gas are derived from sunlight,[5] they are considered primary energy sources which are extracted from the earth (fossil fuels).

Natural uranium is also a primary energy source extracted from the earth but does not come from the decomposition of organisms (mineral fuel).