The standard recipe for oil and natural gas is simple: Take animal or plant remains, bury them under layers of Earth's crust, turn up the pressure and temperature, and set a very, very long timer.
But a new study suggests that Earth could be cooking up the same finished products using a few substitutions.
By mimicking the extreme conditions found deep inside Earth, scientists have created the chains of carbon and hydrogen that make up so-called fossil fuels—without the fossils.
The feat may be a boost to an unorthodox theory that Earth could hold significant amounts of abiotic, or life-free, fuels far below conventional oil reserves.
Experts caution, however, that even if such reserves exist, exploiting them commercially could pose a challenge.
Diamonds and Lasers
Most of today's oil comes from deposits found a mere three to five miles (five to eight kilometers) below Earth's surface.
But Vladimir Kutcherov and colleagues wanted to know if fossil fuels could form where no organic matter exists: the upper mantle, 40 to 95 miles (65 to 150 kilometers) underground.
For their raw material, the team started with methane—a component of natural gas—that had been previously produced in the lab from only water and minerals.
(Related: "Methane Bubbling Up From Undersea Permafrost?")
The scientists crushed the "artificial" methane between two diamonds and heated it with a laser to re-create conditions thought to exist in Earth's mantle—although with a much shorter "cooking time" than what would be needed in nature.
The lab technique created pressures more than 20,000 times those found at sea level and temperatures topping 2,240 degrees F (1,227 degrees C).
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