Producing hydrogen is essential for some of the world’s biggest industrial and agricultural needs, but it also comes with a steep environmental cost: most hydrogen made today is generated through processes that release large amounts of CO2. This is due to a combination of high-heat requirements and direct emissions resulting from the process. Now, researchers have developed a new, highly efficient way to make hydrogen that drastically reduces CO2 emissions and comes with an unexpected and potentially valuable byproduct.

The method, described in a new study published in Science, uses a process called methane pyrolysis, which breaks methane down into hydrogen gas and solid carbon rather than the gaseous CO2 released by conventional hydrogen production.

“Today we take natural gas and produce hydrogen from it, but you’re also producing CO2,” said co-first author Henry Moise, a researcher in Stanford’s Department of Chemical Engineering in the School of Engineering. “Pyrolysis is a similar process, but instead of producing CO2, you produce solid carbon.”

Read more about the paper, co-authored by chemical engineering professor Eric McFarland and former UCSB postdoc Shailesh Pathak, at Stanford Report.