Geothermal Energy Turns Planets Into Power Sources
Geothermal heat is today a marginal source of renewable energy. Technological breakthroughs could make it an effectively limitless source of cheap electricity and heating, possibly anywhere on Earth.
Geothermal energy comes from heat generated by natural subterranean geological processes. Hot underground rocks and water that are accessible to human drilling can be used to produce steam and thus both heating and electricity for human use. The deep inner workings of the Earth are not well understood by scientists, but most geothermal heat is believed to come from radioactive decay of elements in the Earth’s mantle and crust or from primordial heat left over from the planet’s formation 4.5 billion years ago, which emanates out from the Earth’s extremely hot core.1 Worldwide, geothermal energy is currently a negligible source of electricity or heating, but has the raw physical potential to dwarf all other energy sources combined, with the notable exception of solar power. By one estimate, there is nearly three thousand times more thermal energy in the Earth’s crust than there is chemical energy in the combined reserves of all hydrocarbons, uranium, lithium, and thorium.2