"Hydrogen can be produced by several means. Most hydrogen produced today is gray hydrogen, made from natural gas through steam methane reforming (SMR). This process accounted for 1.8% of global greenhouse gas emissions in 2021. Low-carbon hydrogen, which is made using SMR with carbon capture and storage (blue hydrogen), or through electrolysis of water using renewable power (green hydrogen), accounted for less than 1% of production.
"Virtually all of the 100 million tonnes[5] of hydrogen produced each year is used in oil refining (43% in 2021) and industry (57%)"