A dark horse concept in the race to develop clean and sustainable energy sources is getting its first major investment from the US government. The Advanced Research Projects Agency-Energy (ARPA-E), the high-risk, high-reward arm of the Department of Energy, announced it would fund $20 million in grants to advance technologies for extracting clean-burning hydrogen from deep rocks. At the moment, all of the world’s hydrogen is manufactured industrially. But some researchers have concluded that, contrary to conventional wisdom, Earth harbors vast deposits of the gas that could be tapped like oil—and that reserves could be stimulated by pumping water and catalysts into the crust.
The ARPA-E funding “will be the largest single investment in R&D of this nature worldwide,” says Yaoguo Li, a geophysicist at the Colorado School of Mines who plans to apply to the program. “It’s so new, a lot of other agencies and other countries are just waking up to this possibility.”
Hydrogen has drawbacks as an energy source: It is less energy rich than natural gas and occupies large amounts of space. But experts think it could replace fossil fuels in long-haul transport and heavy industries such as steelmaking—if it could be sourced in an environmentally friendly way. Most hydrogen today is manufactured by combining steam and methane in factories that emit carbon dioxide (CO2) and add to global warming. Governments are supporting efforts to make hydrogen cleanly, either by capturing the emitted CO2 and storing it underground (blue hydrogen) or by using renewable electricity to split water and harvesting the resulting hydrogen (green hydrogen). Later this year, DOE plans to select up to 10 blue and green hydrogen hubs as part of an $8 billion program.
But “geological” or “natural” hydrogen could be cheaper—and just as clean. The ARPA-E money is a good start in a field with many unknowns, said Geoff Ellis, a geochemist at the US Geological Survey (USGS) who leads a small, internally funded geological hydrogen program. “Right now, we’re starting from, essentially, nearly zero. So this is really important as a way to jumpstart research.”
For decades, few geologists believed Earth held significant hydrogen deposits because the gas is so readily eaten up by microbes or chemically altered into other forms. But prospectors are now fanning out across the globe, spurred by the discovery of a massive hydrogen field underneath a village in Mali, and records suggesting puzzling surges of nearly pure hydrogen in old boreholes. Whereas oil and gas companies tend to tap relatively youthful basins of sedimentary rock, hydrogen hunters are probing the crystalline, ancient hearts of continents for the iron-rich rocks thought to fuel hydrogen production.
The grant program will not support the hunt for existing deposits, because that is better left to USGS and industry, says ARPA-E Program Director Doug Wicks. Instead, it will focus on ways to artificially stimulate one of the main hydrogen producing reactions, called serpentinization, which occurs when water encounters iron-rich rocks at high temperatures and pressures. The reactions transform minerals such as olivine into serpentine, releasing hydrogen in the process. “How can we make the hydrogen come out faster?” Wicks asked.