Governments around the world are offering rich subsidies and incentives to producers of hydrogen energy, which many see as a holy grail. Companies are equally excited: Hundreds of projects worth at least $600 billion have been announced. Estimates suggest demand could increase up to tenfold by midcentury.
But whether and how much a hydrogen revolution helps the climate—and whether taxpayer and investor money is well spent—depends on how the gas is produced, managed and used. Avoiding unintended consequences may require hydrogen’s advocates to curb their enthusiasm as they follow the science.