Sun Catalytix has raised $3 million in venture capital to its coffer as the company sets out to make cheap hydrogen energy storage.

The one-year-old startup in Cambridge, Mass., seeks to use solar electricity to split water molecules to harvest hydrogen, which would sit in a tank before being fed to a fuel cell to generate electricity at night or otherwise employed as a transportation fuel. Electricity storage would be the company's primary focus, said Bob Metcalfe, a partner at Polaris and a member of the startup's board of directors.

Conventional means of extracting hydrogen requires clean water, and water purification equipment can be costly, Metcalfe said. The startup's catalyst, on the other hand, would use cheap, an inorganic compound that doesn't require clean water.

"This new catalyst will take dirty water, salt water," he said. "We've made hydrogen from the Boston Harbor."

It also would have a longer lifespan by mimicking photosynthesis, where proteins in organisms convert sunlight to produce sugars. The company wants to develop a catalyst that could last five to 10 years. 

"The catalyst is self-repairing," Metcalfe said. "It'll self deposit on the electrodes."

Sun Catalytix is developing its technology based on patents developed by noted professor, Daniel Nocera, at the Massachusetts Institute of Technology. Nocera has published research papers describing the use of cobalt and phosphate to create the catalyst.

Electrolysis is but one of many ways to produce hydrogen, but it's the zero-emission process compared with the less expensive but more polluting method of steam reforming, said the National Renewable Energy Laboratory. Some companies, such as Avalence in Milford, Conn., and Proton Energy Systems in Wallingford, Conn., already are selling electrolysis equipment for producing hydrogen.

Avalence has even sketched out a setup that includes solar panels as the source of energy, storage tank for hydrogen storage and fuel cell for electricity generation. Some of these systems generally are intended for industrial applications and lab research, not residential use. Proton does discuss the potential of making hydrogen production possible in homes. 

About 95 percent of the hydrogen in the United States is produced using steam reforming, which grabs hydrogen atoms from methane. NREL has a handy webpage describing various hydrogen-harvesting technologies.

Nocera envisions building hydrogen storage for solar-powered homes, a way to live off the grid. He's particularly interested in making this kind of storage available to third-world countries, Metcalfe said.

Commercializing lab research will not be easy. The company hasn't settled on whether it would eventually license its catalyst technology or sell the material, or if it would build the entire storage device.

Although Sun Catalytix has done the math to determine the economics of developing and manufacturing the catalyst, it's not willing to share its numbers.

The company is set to receive about $4.1 million from the Advanced Research Projects Agency-Energy, a newly funded program that supports early-stage research on technologies that promise to deliver affordable alternative energy and cut greenhouse emissions (see New Form of Solar Energy: Direct Solar Fuel).