Energy carrier

An energy carrier is a substance (energy form) or sometimes a phenomenon (energy system) that contains energy that can be later converted to other forms such as 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. An energy carrier does not produce energy; it simply contains energy imbued by another system.

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. It is any system or substance that contains energy for conversion as usable energy later or somewhere else. This could be converted for use in, for example, an appliance or vehicle. Such carriers include springs, electrical batteries, capacitors, pressurized air, dammed water, hydrogen, petroleum, coal, wood, and natural gas.

ISO 13600 series (ISO 13600, ISO 13601 and ISO 13602) are intended to be used as tools to define, describe, analyse and compare technical energy systems (TES) at micro and macro levels:

In the field of energetics, an energy carrier corresponds only to an energy form (not an energy system) of energy input required by the various sectors of society to perform their functions. Energy carriers (EC) are produced by the energy sector using primary energy sources (PES). The distinction between "Energy Carriers" and "Primary Energy Sources" is extremely important since these two labels refer to energy forms of different quality so that they cannot be aggregated: 1 megajoule (MJ) of EC is not the same as 1 MJ of PES. Sunlight is a main form of primary energy, which can be transformed into plants and then into coal, oil and gas. Solar power and wind power are other derivatives of sunlight. Note that although coal, oil and natural gas are derived from sunlight, 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).

...
Wikipedia