Thursday 31 July 2008
by: Anne Trafton, MIT News
MIT's Professor Daniel G. Nocera has discovered a way to do large-scale solar power generation. (Photo: Donna Coveney)
Scientists mimic essence of plants' energy storage system.
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
year.
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
scale.
"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
problem."
"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.
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