Primary energy

Total primary energy supply (TPES) is the sum of production and imports, plus or minus stock changes, minus exports and international bunker storage.

[4] These expressions are often used to describe the total energy supply of a national territory.

It therefore generally grossly undercounts non-thermal renewable energy sources .

Electricity is particularly useful since it has low entropy (is highly ordered) and so can be converted into other forms of energy very efficiently.

In principle solar photovoltaic conversions could be very efficient, but current conversion can only be done well for narrow ranges of wavelength, whereas solar thermal is also subject to Carnot efficiency limits.

One full set of conversion factors is available as technical reference from Energy STAR.

There are very much less significant conversion losses when hydroelectricity, wind and solar power produce electricity, but today's UN conventions on energy statistics counts the electricity made from hydroelectricity, wind and solar as the primary energy itself for these sources.

[18] The false notion that all primary energy from thermal fossil fuel sources has to be replaced by an equivalent amount of non-thermal renewables (which is not necessary as conversion losses do not need to be replaced) has been termed the "primary energy fallacy".