Hydrogen from Rocks

You may have heard that hydrogen could be a fuel of the future, with lower carbon emissions than any we’re using today. When it’s burned, it produces only water vapor and a lot of useful energy as heat. That sounds pretty good. And hydrogen is the most abundant element in the universe. That sounds good too. But nearly all hydrogen on Earth is bound up in other compounds, like water. Or natural gas—methane—which is one carbon atom and four hydrogens. Today, we get most of our hydrogen by splitting that carbon atom off methane, leaving the hydrogen behind. But that means making it also makes carbon emissions. This has researchers looking for alternative methods. The most common is electrolysis. An electric current is run through water, which splits the atoms, releasing oxygen and hydrogen. But it costs a lot of money because it consumes a lot of energy—more than is carried by the hydrogen itself. There’s another, naturally occurring process that makes hydrogen deep within Earth. When water contacts iron-rich rocks, like olivine and pyroxene, it oxidizes and releases hydrogen gas, and heat. Scientists at the Bureau of Economic Geology are experimenting with catalysts that could speed up this natural process, but near the surface. This has the potential to release large amounts of hydrogen—without consuming much energy or releasing CO2. If successful, this process could make hydrogen a fuel of the very near future.