Now BP is scaling back those plans, saying it’ll develop between five and ten projects. The company is keeping quiet about which ones will receive the green light.

Hydrogen has the potential to reduce carbon pollution significantly in a range of industries, including petrochemical refining, steelmaking, and long-haul shipping. But infrastructure for hydrogen, especially green hydrogen, which is produced using renewable electricity, remains underbuilt. That’s in part because green hydrogen is the most expensive form of the gas to produce, and because transporting hydrogen is costly relative to fossil fuels.