Hydrogen is flowing in pipes under the streets in Cappelle-la-Grande, helping to energize 100 homes in this northern France village. On a short side road adjacent to the town center, a new electrolyzer machine inside a small metal shed zaps water with electricity from wind and solar farms to create “renewable” hydrogen that is fed into the natural gas stream already flowing in the pipes. By displacing some of that fossil fuel, the hydrogen trims carbon emissions from the community’s furnaces, hot-water heaters and stove tops by up to 7 percent.
So begins my February 2020 feature article for Scientific American which explains why hydrogen energy — presumed dead after a round of hype and disillusion two decades ago — is roaring back. Renewable hydrogen is central to the European Commission’s vision for achieving net-zero carbon emissions by 2050, for example, and a growing focus for the continent’s industrial giants. As of next year, all new turbines for power plants made in the European Union are supposed to ship ready to burn a hydrogen–natural gas blend, and the E.U.’s manufacturers claim the turbines will be certified for 100 percent hydrogen by 2030.
This time around it is the push to decarbonize the electric grid and heavy industry—rather than hope for fuel cell vehicles—that is driving interest in hydrogen. “Everyone in the energy-modeling community is thinking very seriously about deep decarbonization,” says Tom Brown, who leads an energy-system modeling group at Germany’s Karlsruhe Institute of Technology. Cities, states and nations are charting paths to reach nearly net-zero carbon emissions by 2050 or sooner, in large part by adopting low-carbon wind and solar electricity. Integrated energy models show that they’ll have a hard time keeping the lights on during periods of low wind and sunlight without hydrogen, and that hydrogen will pay for itself long before it solves that problem.
By summer the 
Peter Fairley 