'Major discovery' from MIT primed to unleash solar revolution

Scientists mimic essence of plants' energy storage system

Anne Trafton, News Office
July 31, 2008

In a revolutionary leap that could transform solar power from a 
marginal, boutique alternative into a mainstream energy source, MIT 
researchers 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, because 
storing extra solar energy for later use is prohibitively expensive 
and grossly inefficient. With today's announcement, MIT researchers 
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.

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.
'Giant leap' for clean energy

Sunlight has the greatest potential of any power source to solve the 
world's energy problems, said Nocera. In one hour, enough sunlight 
strikes the Earth to provide the entire planet's energy needs for one 

James Barber, a leader in the study of photosynthesis who was not 
involved in this research, called the discovery by Nocera and Kanan a 
"giant leap" toward generating clean, carbon-free energy on a massive 

"This is a major discovery with enormous implications for the future 
prosperity of humankind," said Barber, the Ernst Chain Professor of 
Biochemistry at Imperial College London. "The importance of their 
discovery cannot be overstated since it opens up the door for 
developing new technologies for energy production thus reducing our 
dependence for fossil fuels and addressing the global climate change 

'Just the beginning'

Currently available electrolyzers, which split water with electricity 
and are often used industrially, are not suited for artificial 
photosynthesis because they are very expensive and require a highly 
basic (non-benign) environment that has little to do with the 
conditions under which photosynthesis operates.

More engineering work needs to be done to integrate the new 
scientific discovery into existing photovoltaic systems, 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 hopes that within 10 years, homeowners will be able to power 
their homes in daylight through photovoltaic cells, while using 
excess solar energy to produce hydrogen and oxygen to power their own 
household fuel cell. Electricity-by-wire from a central source could 
be a thing of the past.

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.