HyperSolar claims it is developing a zero carbon method of producing hydrogen gas from wastewater by harnessing solar energy. Hydrogen gas is a clean source of fuel in that, theoretically at least, the only waste product is water. But hydrogen gas does not occur naturally on Earth, and requires energy to create. Typically that energy comes from traditional, carbon dioxide-emitting sources, rendering hydrogen fuel rather less environmentally friendly than it has the potential to be. HyperSolar’s work may mean truly clean, renewable hydrogen fuel could be a commercial reality sooner than we might have imagined.