In almost 30 countries, energy prospectors are hunting for a potential game changer in the quest to fight global warming. Their quarry is hydrogen gas trapped deep underground in hidden deposits. They hope to find big reservoirs of this geological hydrogen — substantial enough that the gas could become a green replacement for fossil fuels. How the hydrogen revolution can help save the planet — and how it can’t When hydrogen is burned to produce electricity, the only by-product is water vapour — no carbon dioxide is emitted. And the potential for geologic hydrogen has energy specialists buzzing. Since 2023, venture capitalists have invested nearly US$500 million in the search for deposits. A 2024 analysis suggests that Earth’s subsurface probably contains tens of trillions of tonnes of the gas1. If even a small fraction can be recovered at a profit, geologic hydrogen could meet projected clean energy needs for 200 years, potentially at, or even below, the cost of fossil fuels. “That’s why it has gathered momentum as quickly as it has,” says Owain Jackson, head of hydrogen-exploration company H2Au, headquartered in Epsom, UK, which started drilling in Kansas in August. Or all of this could be a pipe dream...

Power to Hydrogen (P2H2) and Repsol completed a 1,250-hour pilot of P2H2’s hybrid AEM electrolyzer technology, demonstrating operation at 40% to 100% load, pressures up to 30 bar and hydrogen purity o...