Climate activists use the term energy slave to provide a bodily referent to the vast quantities of mechanical labor that industrial societies derive from combusting fossil fuels. We speak, for instance, of North Americans relying on the labor of eighty-nine energy slaves to support their standard of living. This language of technological servitude is not sui generis but traces its origins back to the application of coal and steam to labor in the nineteenth century. And it has as its scientific context the emergence of a thermodynamic paradigm that redefined the meaning of work by erasing important distinctions between the labor performed by living bodies and that performed by so-called mechanical slaves (or inanimate prime movers) fueled primarily by coal and petroleum. This essay demonstrates that the tendency to equate fossil fuels to captive labor performs ideological work. It argues that the trope of energy as slave to humanity props up a faulty technological paradigm that underplays the persistence of sweated labor in the fossil economy; that distracts us from the class, race, gender, and international stratification of that economy; and that reproduces foundational errors about the ecological role (beyond fueling machines) that fossil fuels have played in precipitating today’s climate crisis.