Major Energy Companies Bet Big on Hydrogen;There are plenty of obstacles. But advocates see the fuel playing a vital role in slashing emissions

Hydrogen now supplies less than 5% of the world’s energy—most of it used for oil refining and chemical production—but research firm BloombergNEF says it could reach nearly a quarter of global energy consumption by 2050 with strong government policies promoting it. By then, the fuel could generate more than $2.5 trillion of direct revenue annually, according to the Hydrogen Council, a trade group that includes oil-and-gas majors.