SUN ENERGY

http://web.mit.edu/newsoffice/2008/oxygen-0731.html"Major Discovery" From MIT Primed to Unleash Solar RevolutionThursday 31 July 2008by: Anne Trafton, MIT NewsScientists mimic essence of plants' energy storage system. In a revolutionary leap that could transform solar power from amarginal, boutique alternative into a mainstream energy source, MITresearchers have overcome a major barrier to large-scale solar power:storing energy for use when the sun doesn't shine. Until now, solar power has been a daytime-only energy source, becausestoring extra solar energy for later use is prohibitively expensive andgrossly inefficient. With today's announcement, MIT researchers have hitupon a simple, inexpensive, highly efficient process for storing solarenergy. Requiring nothing but abundant, non-toxic natural materials, thisdiscovery 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 andsenior author of a paper describing the work in the July 31 issue ofScience. "Solar power has always been a limited, far-off solution. Now wecan seriously think about solar power as unlimited and soon." Inspired by the photosynthesis performed by plants, Nocera and MatthewKanan, a postdoctoral fellow in Nocera's lab, have developed anunprecedented process that will allow the sun's energy to be used to splitwater into hydrogen and oxygen gases. Later, the oxygen and hydrogen may berecombined inside a fuel cell, creating carbon-free electricity to poweryour house or your electric car, day or night. The key component in Nocera and Kanan's new process is a new catalystthat produces oxygen gas from water; another catalyst produces valuablehydrogen gas. The new catalyst consists of cobalt metal, phosphate and anelectrode, placed in water. When electricity - whether from a photovoltaiccell, a wind turbine or any other source - runs through the electrode, thecobalt and phosphate form a thin film on the electrode, and oxygen gas isproduced. Combined with another catalyst, such as platinum, that can producehydrogen gas from water, the system can duplicate the water splittingreaction that occurs during photosynthesis. The new catalyst works at room temperature, in neutral pH water, andit'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. "Giant Leap" for Clean Energy Sunlight has the greatest potential of any power source to solve theworld's energy problems, said Nocera. In one hour, enough sunlight strikesthe Earth to provide the entire planet's energy needs for one year. James Barber, a leader in the study of photosynthesis who was notinvolved in this research, called the discovery by Nocera and Kanan a "giantleap" toward generating clean, carbon-free energy on a massive scale. "This is a major discovery with enormous implications for the futureprosperity of humankind," said Barber, the Ernst Chain Professor ofBiochemistry at Imperial College London. "The importance of their discoverycannot be overstated since it opens up the door for developing newtechnologies for energy production thus reducing our dependence for fossilfuels and addressing the global climate change problem." "Just the Beginning" Currently available electrolyzers, which split water with electricityand are often used industrially, are not suited for artificialphotosynthesis because they are very expensive and require a highly basic(non-benign) environment that has little to do with the conditions underwhich photosynthesis operates. More engineering work needs to be done to integrate the new scientificdiscovery into existing photovoltaic systems, but Nocera said he isconfident that such systems will become a reality. "This is just the beginning," said Nocera, principal investigator forthe Solar Revolution Project funded by the Chesonis Family Foundation andco-Director of the Eni-MIT Solar Frontiers Center. "The scientific communityis really going to run with this." Nocera hopes that within 10 years, homeowners will be able to powertheir homes in daylight through photovoltaic cells, while using excess solarenergy to produce hydrogen and oxygen to power their own household fuelcell. Electricity-by-wire from a central source could be a thing of thepast. The project is part of the MIT Energy Initiative, a program designed tohelp transform the global energy system to meet the needs of the future andto help build a bridge to that future by improving today's energy systems.MITEI Director Ernest Moniz, Cecil and Ida Green Professor of Physics andEngineering Systems, noted that "this discovery in the Nocera labdemonstrates that moving up the transformation of our energy supply systemto one based on renewables will depend heavily on frontier basic science." The success of the Nocera lab shows the impact of a mixture of fundingsources - governments, philanthropy, and industry. This project was fundedby the National Science Foundation and by the Chesonis Family Foundation,which gave MIT $10 million this spring to launch the Solar RevolutionProject, with a goal to make the large scale deployment of solar energywithin 10 years.