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.

"If hydrogen is meant to be the ultimate fuel that will enable a clean energy future with zero carbon emissions, then its production must also be zero carbon," said HyperSolar CEO, Tim Young in a press release on Monday. "Powering cars with fossil fuel based hydrogen is not sustainable, not renewable and not much cleaner than today's fuels."

Young has a point. Because hydrogen fuel has to be made, it is better to think of it as an energy store rather than an energy source - after all, energy had to go into making it. A car running on HyperSolar hydrogen gas would effectively be solar powered - the Sun being the ultimate energy source powering the car, with hydrogen gas merely the energy carrier. Alternatively, the hydrogen can alternatively be reacted with carbon dioxide to produce a sort of unnatural version of natural gas, which is not a completely clean fuel.

HyperSolar's approach adopts a breakthrough "solar-powered nanoparticle system" inspired by the natural process of photosynthesis. The photoelectrochemical nanoparticles float in wastewater in transparent vessels, creating hydrogen gas using solely the energy of sunlight. The company says the process is optimized for wastewater, which is simultaneously purified by the process. HyperSolar's solar concentrators that we discussed last February are not involved.

The process appears to be similar to that developed by Emory University which we reported in March 2010, and though it is not clear precisely what stage HyperSolar's technology has reached, this announcement indicates they at least have a working prototype system cable of producing hydrogen gas. The company stresses the commercially viability of the technology, since it effectively monetizes the process of wastewater treatment, as well as producing the marketable byproducts, hydrogen bromide and hydrogen chlorides. Additionally, HyperSolar claims the technology is eminently scalable - all you need is more water vessels with more nanoparticles, the company claims, though presumably there is also the consideration of the infrastructure required to remove the gas from the vessels.

In a similar vein, nanocrystals have been used at the research level to create hydrogen from water by harnessing the power of ambient noise.