Although today's fossil fuel reserves reside in Earth's crust, a new study suggests that hydrocarbon fuel might also nestle in the mantle, at depths of 100 kilometers or more. Determining whether fossil fuels can form in these extreme environments could not only point to new energy sources but also open a new avenue for origin-of-life researchers.
Commercial oil and gas reserves originate strictly from the breakdown of plants and animals, according to most scientists. Recently, however, geologists have shown that hydrocarbons such as methane—the main component of natural gas—can form in Earth's crust abiogenically, or in the absence of once-living matter. These sc