Tasios Melis’s breakthrough came in 1998 when, as a UC Berkeley biochemist, he was tinkering with green algae, trying to coax the plants to convert water into hydrogen. Algae have long been known to produce minuscule amounts of the gas. Trouble is, the enzyme that propels the reaction (hydrogenase) stalls in the presence of oxygen, and – think back to high school bio – plants naturally produce oxygen during photosynthesis.

Melis found he could reprogram photosynthesis and stifle internal oxygen flow by depriving the plant cells of sulfur. Under these conditions, the algae pumped out hydrogen for days at a time – lots of it. Also see Melis Energy.