Does measuring primary energy overstate the electricity needed to replace oil?
Core argument: The U.S. consumed 45 exajoules of useful final energy in 2024 compared with 95 exajoules of primary energy.
Energy is lost as waste heat in conversion of fuel energy to motion in internal combustion engines, and in conversion of heat to electricity. For example, if you use primary energy to estimate how much electric power is needed to replace oil in passenger cars, you would overestimate the power needed since electric motors are 80%-90% efficient at converting electricity to motion compared to 18% efficiency for gasoline cars. A better approach [is estimating] the energy net of waste heat that is actually consumed by end-users; this would help avoid overly high projections of fossil fuel demand in a more electrified world due to this “primary energy fallacy.” A few years ago I constructed a measure of useful final energy (UFE) that I use for my energy charts. With this approach, we can get closer to useful final energy actually consumed by end users. [For example the US consumed 45 exajoules (EJ) of useful final energy in 2024 compared to 95 EJ of primary energy.]






