énergies

Énergies is the French word for energy. In physics, energy is the quantity that enables work to be performed; it can be transformed from one form to another and is conserved in isolated systems. In policy and economics, 'énergies' is used to refer collectively to the energy sector and its choices, including production, distribution, and consumption of energy.

Forms of energy include kinetic, potential, thermal (related to temperature), chemical (stored in bonds), electrical, radiant (light), and nuclear. Energy can be stored and transported, and it often changes form as it is used—for example a light bulb converts electrical energy into light and thermal energy.

Measurement and units: the joule is the SI unit of energy; power is the rate of energy transfer, measured in watts. Larger quantities are commonly expressed in kilowatt-hours or terajoules. The law of conservation of energy states that energy cannot be created or destroyed in an isolated system, only transformed.

Primary energy versus final energy: primary energy refers to energy resources in nature (oil, coal, sunlight, wind), while final energy is what consumers actually use after transformations (electricity, heat). Energy carriers such as electricity and hydrogen enable delivery across sectors like electricity generation, transportation, and heating.

Policy and future directions: many economies aim to diversify towards renewable energy sources (solar, wind, hydro, geothermal) to reduce emissions. Efficiency improvements and storage technologies, such as batteries, are important to balancing supply and demand and ensuring energy security.