Before revision: Conversion factor conventions Where primary energy is used to describe fossil fuels, the embodied energy of the fuel is available as thermal energy and around 70%DIF < is typically lost in conversion to electrical or mechanical energy.
After revision: Sankey diagram for the United States 2016 shows that 66.4%DIF > of primary energy ends up as waste heatConversion factor conventions Where primary energy is used to describe fossil fuels, the embodied energy of the fuel is available as thermal energy and around 70%DIF < is typically lost in conversion to electrical or mechanical energy.