Powered By Solar Water

A new catalyst makes it feasible to split water with solar power. Suck on that NaCl batteries!

MIT chemists say the catalyst, used in conjunction with cheap photovoltaic solar panels, could lead to inexpensive, simple systems that use water to store the energy from sunlight. The catalyst enables the electrolysis system to function efficiently at room temperature and at ordinary pressure. Like a reverse fuel cell, it splits water into oxygen and hydrogen. By recombining the molecules with a standard fuel cell, the O2 and H2 could then be used to generate energy on demand.

Solar energy currently makes less than one percent of the world's electricity. The main drawback of the technology, preventing wider adoption, is that solar systems only make power while the sun is shining. At night or on cloudy days, those in need of power must look elsewhere. So storage of electrical energy has been a long-sought after technological advance. Batteries work but they're too big and expensive. Fuels, fossil or renewable, are different: They act as their own storage, allowing for easy transport and usage. That's one reason that coal and oil have such a dominant hold on the world's energy market. That, and nobody has bought the ocean...yet.

The key advancement is the development of an oxygen-producing catalyst made of cobalt and phosphate. Splitting water requires two half-reactions, one to create oxygen gas and the next to create hydrogen. For decades, scientists have been trying to reduce the cost of the oxygen part of the reaction, with little success...until now.

It's important to note that the breakthrough is in making it cheaper and simpler to split water by electrolysis. Expensive machines have long been able to do the same thing, but only by using iridium alloys or exotic nanoparticles. Because its made of common materials and can operate at room temperature and normal pressure, there is no need to heat and pressurize the water, and the energy needs and cost of running the process overall are much lower.

"It's never an issue in energy of whether you can do it or not," the scientists said. "It's whether you can do it cheaply."