primaryenergy

Primary energy is a term used in energy accounting to describe the energy content of resources found in nature or imported for use in an energy system, before any conversion or transformation. It includes fuels and energy carriers as they exist in the natural world or as they are extracted, such as crude oil, coal, natural gas, biomass, wind, solar radiation, hydro, geothermal energy, and nuclear energy. The concept is distinguished from final energy, which is the energy delivered to end users after transformations, transmission, and distribution losses.

In practice, primary energy reflects the input energy required to supply energy services. It accounts for energy used in extraction, processing, and conversion, and it is typically converted to common units such as tonnes of oil equivalent (toe) or exajoules (EJ) to enable comparison across fuels. Different energy systems apply different transformation losses, so primary energy can differ depending on the accounting framework.

The primary energy concept is widely used in policy, statistics, and research to assess total energy demand, energy intensity, and energy security. However, definitions vary by agency and region. Some approaches treat electricity as a final energy form and assign a separate primary energy value to the energy content of the original fuel, while others use the primary energy content of renewables directly.

Examples of primary energy sources include fossil fuels (coal, oil, natural gas), nuclear energy, biomass, hydro, wind, solar, and geothermal. The choice of accounting method affects how energy efficiency and environmental impacts are estimated in national and international energy balances.