Total Final Energy Consumption
Final energy refers to energy in its useable form. This contrasts to primary energy, which refers to energy as found “raw” in nature. For example, barrels of crude oil are primary energy; we can then refine this into gasoline, which is used to power cars. Using final energy thus captures many of the inefficiency losses that occur when converting primary energy. For example, refining barrels of crude oil into gasoline costs energy itself. In calculating how much energy an economy needs, the concept of final energy is therefore very helpful, as demand can be met either by increasing primary energy or increasing its efficiency.
However, final energy also contrasts to useful energy — which is the ultimate fraction of energy that then actually gets used for its intended purposes. Final energy thus does not capture all efficiency losses. For example, not all petroleum will be converted into kinetic energy; some will be lost as heat or noise.
PTEC fixes the useful-to-primary conversion efficiencies at the current technology-sector specific value. This methodology is laid out in Way et al. (2020). The PTEC Scenarios fix useful energy growth at 2% per annum and then works out accordingly how final energy consumption is needed to satisfy this. A more conversion efficient technology means that less final energy is demanded. Thus, shifting from less inefficient fossil fuels to more efficient renewables lowers TFC, whilst maintaining the level of useful energy.