Proton Exchange Membrane electrolysis produces hydrogen at up to ninety-nine point nine nine nine percent purity, making it the leading technology for clean hydrogen production. The process splits water using a solid polymer membrane and achieves real-world efficiency of seventy-five to eighty percent. Over thirty major companies, including Siemens Energy, Nel Hydrogen, ITM Power, and Plug Power, are scaling up this technology globally. Replacing fossil-derived hydrogen with green hydrogen could eliminate around eight hundred and thirty million metric tons of carbon dioxide emissions every year.