New heating trick makes hydrogen and graphite from methane 10x more efficiently

Researchers at Stanford Engineering have developed a new, highly efficient method for producing hydrogen using methane pyrolysis. The approach addresses major environmental and economic challenges in hydrogen production. Hydrogen is essential both as a chemical building block for global industry and as a key energy carrier for deep decarbonization. Methane pyrolysis is a process that bakes methane gas to split it into hydrogen fuel and solid carbon. It has always promised a cleaner alternative to conventional hydrogen refining, but scaling up the process required heating massive industrial reactors to extreme temperatures. Heating these giant structures from the outside also proved slow, inefficient, and costly. “If you want to do pyrolysis at the scale required to fulfill hydrogen markets, then you have to create very large reactors,” said senior author Matteo Cargnello, an associate professor of chemical engineering at Stanford Engineering. “To heat up these reactors to very high temperatures, like 1,000 degrees Celsius, your heating methods have to be very efficient.” To break this challenge, the Stanford team tried something counterintuitive. And tried putting the burner inside the reactor. Direct internal heating Stanford researchers overcame this challenge by developing an internal heating method. Rather than heating massive reactors inefficiently from the outside or burning methane, the team placed a burner directly inside the reactor to combust a small portion of hydrogen. This internal process generates the necessary high heat and emits mostly water vapor, successfully driving the reaction forward without direct carbon emissions. This autothermal internal heating method yields a roughly tenfold increase in efficiency compared to conventional techniques. It optimizes heat transfer so effectively that one reactor matches the output of ten conventional, externally heated reactors using the exact same amount of energy. “It goes back to this idea of efficiency. You can reduce CO2 emissions by avoiding making them in the first place, but you can also reduce CO2 emissions by being more efficient about how you use your energy,” said Henry Moise, co-first author. “So there’s multiple ways to make a more sustainable process.” Surprise byproduct Then came the real surprise. An unexpected benefit of this process is that its solid carbon byproduct turned out to be graphite, a material used in batteries and electrodes that the US currently imports. Further research is needed to make the graphite pure enough for demanding battery applications. The team considers this surprisingly “high degree of graphitization” a major step forward for domestic supply. Earlier methods like Steam Methane Reforming (SMR) generate most of US hydrogen but release massive amounts of carbon. In this term, methane pyrolysis offers a clean alternative. Hydrogen remains a foundational building block of the global economy. It is essential for making methanol, stripping sulfur from gasoline, and producing the ammonia-based fertilizers that nourish nearly half the global population. At present, lithium-ion batteries excel at short-term electricity storage (hours), but hydrogen can be stored in large quantities in underground salt caverns for months, balancing seasonal swings in renewable energy production. This collaborative research aims to decarbonize a ubiquitous resource by enabling cleaner and cheaper hydrogen production. The team acknowledges that scaling the process for mainstream industrial use will require continued funding and cross-institutional effort.The findings were published in the journal Science on September 3. Get the latest in engineering, tech, space & science - delivered daily to your inbox.Mrigakshi is a science journalist who enjoys writing about space exploration, biology, and technological innovations. Her work has been featured in well-known publications including Nature India, Supercluster, The Weather Channel and Astronomy magazine. If you have pitches in mind, please do not hesitate to email her.