Cheap Catalyst Could Turn Sunlight, Water Into Fuel
By Alexis Madrigal <mailto:alexis.madrigal@...
> EmailJuly 31, 2008 |
2:33:37 PMCategories: Clean Tech
> , Energy
ocera2.jpg> Nocera2 A new catalyst makes it feasible to split water with
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.
In the process, the scientists may have cleared the major roadblock on the
long road to fossil fuel independence: Reducing the on-again, off-again
nature of many renewable power sources.
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.
"You've made your house into a fuel station," Daniel Nocera, a chemistry
professor at MIT said. "I've gotten rid of all the goddamn grids."
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.
The MIT discovery could help transform electricity generated through solar
energy into a fuel, making it more competitive with fossil fuels. That could
prove to be a major milestone in clean technology.
"I think it's a very interesting discovery," said Tom Mallouk, a chemistry
professor at Penn State. "It's one of those papers that really has the
potential to change the field."
The key advancement in Nocera's Science paper 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, Mallouk said, scientists have been trying to reduce
the cost of the oxygen part of the reaction, with little success.
"The hydrogen side of the cell is only two electrons per molecule. The
oxygen side is four electrons per molecule," Mallouk said. "There is a rule
in electrochemistry that the more electrons you have the more complicated
the process is."
It's important to note that Nocera's 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
The new catalyst is remarkable because its made of common materials and can
operate at room temperature and normal pressure. Without the need to heat
and pressurize the water, the energy needs and cost of running the process
overall are much lower. And that could make a standard solar array on a home
a viable source of electricity for creating all the hydrogen a household
The joke in clean tech circles about hydrogen is that "hydrogen is the fuel
of the future and always will be." But that's in large part because
producing hydrogen has been so expensive and energy-intensive to produce.
Most of the power in the world comes from fossil fuel, too, so making
hydrogen generated tons of greenhouse gases.
"It's never an issue in energy of whether you can do it or not," Nocera
said. "It's whether you can do it cheaply."
And whether or not the setup will prove cost-effective remains to be seen.
It still uses a platinum catalyst to produce hydrogen, for example.
> Erik Straser, a leading clean
technology investor with the venture capital firm, Mohr-Davidow, termed the
technology "promising," but said the new paper didn't shed light on its
"I think that having operation at room temp and standard pressure is a key
innovation," he wrote in an e-mail to Wired.com. "What is not there are any
of the metrics that would let you determine whether this made economic sense
(a huge issue in these energy technologies)."
Other scientists are, however, hard at work trying to find cheaper hydrogen
producing catalysts, including a group of scientists led by Bjorn
Winther-Jensen who published work on a carbon-based catalyst in the same
issue of Science this week.
Nocera himself admits that he hasn't "driven down the whole road" on what
the setup could cost. And, solar panels remain very expensive on a
per-kilowatt basis, even as innovation in the field continues to drive costs
down for consumers.
Still, despite the questions about the commercial viability of the
technology, Nocera said that the Bob Metcalfe-run venture capital firm,
> Polaris, had "swooped in" on the
technology and was filing for patent protections.
Though Nocera doesn't expect retail systems to be available for the better
part of a decade, the questions about the viability of his idea should begin
to be answered soon, as prototype designs attempt to deliver on his big
"Within two years, you'll start seeing module designs," Nocera said. "A lot
of my MIT colleagues are raring to go and work on this and they are all
engineers and they're pretty damn good."
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