Rocks formed beneath the ocean floor by fast-spreading tectonic plates may be a large and previously overlooked source of free hydrogen gas (H2), a new Duke University study suggests.

The finding could have far-ranging implications since scientists believe H2 might be the fuel source responsible for triggering life on Earth. And, if it were found in large enough quantities, some experts speculate that it could be used as a clean-burning substitute for fossil fuels today because it gives off high amounts of energy when burned but emits only water, not carbon.

Recent discoveries of free hydrogen gas, which was once thought to be very rare, have been made near slow-spreading tectonic plates deep beneath Earth’s continents and under the sea.

“Our model, however, predicts that large quantities of H2 may also be forming within faster-spreading tectonic plates — regions that collectively underlie roughly half of the Mid-Ocean Ridge,” said Stacey L. Worman, a postdoctoral fellow at the University of Texas at Austin, who led the study while she was a doctoral student at Duke’s Nicholas School of the Environment.

Total H2 production occurring beneath the oceans is at least an order of magnitude larger than production occurring under continents, the model suggests.