This could spell the end of the grid!

The problem with solar power has always been that it only works when the sun is shining, so the time it isn't generating power, cloudy days and sunset to sunrise means that for more than half the time it doesn't work.

I have been one of those wet blankets that has been saying for ages that we have gone about as far as we can with solar and wind until storage gets better because storing extra solar energy for later use is prohibitively expensive and grossly inefficient.

Well, it just got better! Researchers at MIT, using plant photosynthesis as their model, have hit upon a simple, inexpensive, highly efficient process for storing solar energy.

Requiring nothing but abundant, non-toxic natural materials, this discovery could unlock the most potent, carbon-free energy source of all: the sun. "This is the nirvana of what we've been talking about for years," said MIT's Daniel Nocera, the Henry Dreyfus Professor of Energy at MIT and senior author of a paper describing the work in the July 31 issue of Science. "Solar power has always been a limited, far-off solution. Now we can seriously think about solar power as unlimited and soon."

Inspired by the photosynthesis performed by plants, Nocera and Matthew Kanan, a postdoctoral fellow in Nocera's lab, have developed an unprecedented process that will allow the sun's energy to be used to split water into hydrogen and oxygen gases. Later, the oxygen and hydrogen may be recombined inside a fuel cell, creating carbon-free electricity to power your house or your electric car, day or night.

The key component in Nocera and Kanan's new process is a new catalyst that produces oxygen gas from water; another catalyst produces valuable hydrogen gas. The new catalyst consists of cobalt metal, phosphate and an electrode, placed in water. When electricity -- whether from a photovoltaic cell, a wind turbine or any other source -- runs through the electrode, the cobalt and phosphate form a thin film on the electrode, and oxygen gas is produced.

Combined with another catalyst, such as platinum, that can produce hydrogen gas from water, the system can duplicate the water splitting reaction that occurs during photosynthesis. If I understand correctly, this method requires about the same amount of platinum as is used in a catalytic converter.

The new catalyst works at room temperature, in neutral pH water, and it's easy to set up, Nocera said. "That's why I know this is going to work. It's so easy to implement," he said.

The sun is the most abundant energy source in the known universe. In just an hour, enough sunlight strikes the earth to provide all the energy needs for the entire planet for a year - if we could just manage to harness it.

Prior to this breakthrough, electrolyzers have been available for industrial applications, but at a prohibitive cost both financially and environmentally. Requiring a traditional source of electricity and a basic (non benign) chemical environment. Now that the workable idea has been proven, the engineering work to integrate the new scientific discovery into existing photovoltaic systems comes next, but Nocera said he is confident that such systems will become a reality. "This is just the beginning," said Nocera, principal investigator for the Solar Revolution Project funded by the Chesonis Family Foundation and co-director of the Eni-MIT Solar Frontiers Center. "The scientific community is really going to run with this."

Nocera believes that within a decade this development could allow individual homeowners to take their homes off the "grid." It is conceivable that during the daylight hours a home can be powered by photovoltaic cells, with excess power being stored in fuel cells. When the sun isn't shining, the fuel cells kick in.

The project is part of the MIT Energy Initiative, a program designed to help transform the global energy system to meet the needs of the future and to help build a bridge to that future by improving today's energy systems. MITEI Director Ernest Moniz, Cecil and Ida Green Professor of Physics and Engineering Systems, noted that "this discovery in the Nocera lab demonstrates that moving up the transformation of our energy supply system to one based on renewables will depend heavily on frontier basic science."

The success of the Nocera lab shows the impact of a mixture of funding sources - governments, philanthropy, and industry. This project was funded by the National Science Foundation and by the Chesonis Family Foundation, which gave MIT $10 million this spring to launch the Solar Revolution Project, with a goal to make the large scale deployment of solar energy within 10 years.

Since a picture is worth a thousand words, the graphic below illustrates how the system will work.



It's a good day to be a scientist!