Primary Energy

The term Primary Energy refers to the energy contained in a source before conversion into some other energy carrier that we use: for example the energy content of a tonne of coal before it enters a power station to be converted to electricity. Since any energy conversion is less than 100% efficient, the energy out of a system (such as the output of a power station or the energy consumed by end-users) will always be less than the energy put into it (the primary energy). Primary energy is usually used in analyses of country-scale or world-scale energy usage.

In practice, primary energy statistics usually focus on the energy content of fuels used for thermal conversion; like coal, natural gas, oil, biomass and so on.

You could also regard the primary energy of renewable power production such as hydro, solar or wind as the total natural energy available to go into the fleet of hydro turbines, solar farms or wind farms (for example). However when large-scale energy statistics are reported it’s usually not the case that primary energy numbers reported for non-fuel renewables attempt to quantify this total natural resource. Instead these numbers usually give either the electricity generated from these sources or else this electricity adjusted by a factor which estimates the amount of primary energy usage from fossil fuels that has been avoided.