Fossil hydrocarbons, according to Nate Hagens, refer to the ancient decomposed organic matter - predominantly from plants and microorganisms - that has been subjected to intense heat and pressure over geological time scales, resulting in the formation of energy-dense fuels. These fuels, including coal, oil, and natural gas, represent stored solar energy from millions of years ago, harnessing the captured carbon and hydrogen molecules within them. Hagens emphasizes that these resources have been central to the industrial and economic development of modern society, providing an unprecedented energy surplus essential for complex systems. He often highlights the finite nature of these hydrocarbons, cautioning that their depletion poses significant challenges for future energy sustainability.

See also: fossil fuel, fossil carbon, nuclear power, nuclear fuel, energy surplus