Energy source
An energy source is a resource or process from which usable energy is obtained, including sunlight, fuels, moving water, and nuclear reactions.
Nuclear fission: A nuclear reaction in which a heavy atomic nucleus splits into lighter nuclei, releasing energy and neutrons. Fission releases heat that can generate electricity in nuclear power plants.
Primary energy: Energy in naturally occurring resources before conversion into a different energy carrier or form. It distinguishes original resources from electricity and other converted energy.
Electric power generation: The production of electricity by converting other forms of energy into electrical energy. Power plants connect primary sources to the electricity used by homes and industry.
Renewable energy: Energy obtained from sources replenished naturally on human timescales, such as sunlight, wind, and flowing water. Renewable sources are replenished, unlike finite fossil fuel deposits.
Greenhouse gas emissions: The release of gases that trap heat in the atmosphere, especially carbon dioxide and methane. Different energy sources produce sharply different emissions over their life cycles.
Nuclear fusion: A nuclear reaction in which light atomic nuclei combine, releasing energy when the products have greater binding energy. Fusion powers the Sun and is a potential source of terrestrial energy.
Energy carrier: A substance or system that stores or transports energy for use elsewhere. Electricity and hydrogen deliver energy but are not usually primary sources.
District heating: A system that distributes heat from centralized sources to multiple buildings through a network of pipes. It can use geothermal heat, waste heat, or combustion directly.
Fossil fuel: A fuel such as coal, oil, or natural gas formed from ancient organic matter. Fossil fuels are major energy sources but release greenhouse gases when burned.
Energy security: The reliable availability of energy at affordable prices, despite disruptions and external risks. Dependence on particular fuels or suppliers can expose energy systems to shocks.