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Researchers Develop Cerium Reactor to Make Fuel from Sunlight

Scientists raise hopes for a large-scale renewable source of liquid fuel with a simple reactor that mimics plants

by Damian Carrington,

Dec 24, 2010

A simple reactor that mimics plants by turning sunlight into fuel has been demonstrated in the laboratory, boosting hopes for a large-scale renewable source of liquid fuel.

"We have a big energy problem and we have to think big," said , at the California Institute of Technology, who led the research.

Haile estimates that a rooftop reactor could produce about three gallons of fuel a day. She thinks transport fuels would be the first application of the reactor, if it goes on to commercial use. But she said an equally important use for the renewable fuels would be to store solar energy so it is available at times of peak demand, and overnight. She says the first improvements that will be made to the existing reactor will be to improve the insulation to help stop heat loss, a simple move that she expects to treble the current efficiency.

The key component is made from the metal , which is almost as abundant as copper, unlike other rare and expensive metals frequently used as catalysts, such as platinum. Therefore, said Haile, availability would not limit the use of the device. "There is nothing cost prohibitive in our set-up," she said. "And there is plenty of cerium for this technology to make a major contribution to global gasoline supplies."

The fossil fuels used by vehicles, ships and aeroplanes pose the biggest challenge in the search for low-carbon energy, as they are highly energy-dense and portable, unlike alternatives such as batteries or nuclear reactors. An efficient, large-scale way of converting solar energy into a renewable liquid fuel could play a major role in reducing greenhouse gas emissions and tackling climate change.

The device, reported in the journal , uses a standard parabolic mirror to focus the sun's rays into a reaction chamber where the cerium oxide catalyst breaks down water and carbon dioxide. It does this because heating cerium oxide drives oxygen atoms out of its crystal lattice. When cooled the lattice strips oxygen from surrounding chemicals, including water and CO2 in the reactor. That produces hydrogen and carbon monoxide, which can be converted to a liquid fuel.

In the experiments the reactor cycled up to 1,600C then down to 800C over 500 times, without damaging the catalyst. "The trick here is the cerium oxide – it's very refractory, it's a rock," said Haile. "But it still has this incredible ability to release oxygen. It can lose one in eight of its oxygen molecules." Caltech has filed patents on this use of cerium oxide.

The use of sunlight to make fuel is being explored by groups around the world, such as that lead by . His group's technology works at room temperature but is . At the Lawrence Berkeley National Laboratory last year researchers found , but only as nano-sized crystals. Imperial College in London is also .

Other groups are exploring the use of , while a related research effort is testing how can be .

Republished with permission.

Overconsumption, not overpopulation

Actually, SueAnn, the real problem here is the rate of overconsumption, not population. 

Focusing on controlling population before consumption puts the cart before the horse, IMO, and seems to be a distraction increasingly invoked by those who are uncomfortable with talk of tranisitioning away from fossil fuels. 

The rate at which the current existing population uses up resources -- in the US and other developed countries -- and creates greenhouse gases will continue to threaten human society in the coming decades.  Even if we reached zero population growth today, that would not change our emissions trajectory.

Population controls are meaningless to preserve our biosphere if you don't focus on making consumption sustainable first. 

BTW, solar energy is infinite, so there's no need to set aside some to have enough to grow food "to feed people".  Nice try, tho.




But what about ...

The efficiency reported, 0.7 to 0.8%, is pretty dismal, even if thermal insulation triples it. Meanwhile, a highly efficient DC-to-methane bioelectrochemical process has been vastly underreported. Using methanogenic archaea in a bioelectrochemical cell, application of 1 volt of DC results in production of large quantities of methane at 80% efficiency. Unlike water gas, methane can be used for immediate transport fuel without reformation, reprocessing, or special handling procedures.

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