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Breakthrough solar reactor makes fuel from sunlight


December 26, 2010

The prototype solar reactor that directly converts the Sun's rays into fuel

The prototype solar reactor that directly converts the Sun's rays into fuel

Because conventional photovoltaic panels produce electricity directly from sunlight, the energy they generate must either be used as it is produced or stored – either in batteries or by using the electricity to produce a fuel that acts as a storage medium for the energy. Now U.S. and Swiss researchers have developed a prototype device that directly converts the Sun’s rays into fuels that can be stored, allowing the energy to be used at night or transported to locations where it is needed.

A BBC report citing a paper appearing in the journal Science describes how the prototype device uses a quartz window and cavity to focus sunlight into a cylinder lined with cerium oxide. Cerium oxide, also known as ceria, is hygroscopic (meaning that it attracts and holds water molecules from the surrounding environment) and will also absorb a small amount of carbon dioxide. As the sunlight heats the ceria, it thermochemically breaks down the water and carbon dioxide pumped into the cylinder to produce carbon monoxide and hydrogen that can be converted to a liquid fuel.

The resultant hydrogen could be used as fuel for hydrogen fuel cell vehicles such as those being developed by a number of automakers, including Hyundai and Honda, while a combination of hydrogen and carbon monoxide could be used to create syngas – a combustible gas that has less than half the energy density of natural gas but is often used as a fuel source or as an intermediate for the production of other chemicals. The researchers say the device can also be used to produce methane.

With cerium being the most abundant “rare-earth” metal, the developers of the device from the California Institute of Technology and the Swiss Federal Institute of Technology say it would be economically feasible to use the technology on a large scale.

Although currently, the prototype is not very efficient, with the fuel created harnessing between just 0.7 and 0.8 percent of the solar energy put into the device. This inefficiency is because most of the energy is lost through heat loss through the reactor’s wall or through the re-radiation of sunlight back through the device’s aperture. However, the researchers believe that a commercially viable device with efficiency rates of up to 19 percent is possible by using better insulation and smaller apertures.


About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

Good Innovation.

Dr.A.Jagadeesh Nellore(AP),India

Anumakonda Jagadeesh

I knew it. I knew someone would create fuel from sunlight and water. Holy s---!

bio-power jeff

Does efficiency really matter when the source is inexhaustable, how many cells are needed to produce enough fuel for average vehicle use and what is the estimated cost per cell. IF the cells are inexpensive to mass produce, IF feedstock is widely available and IF an affordable number would do the job then this would be a viable technology.

Michael Gene

Handy for Mars

Nathan Rogers

Hi Michael. Efficiency matters relative to the weight of the system to move the vehicle. If it takes more energy to move the weight of the system than the energy the system produces, it wouldn\'t be worth mass producing it until at least that threshold is significantly crossed, notwithstanding the other factors you mentioned which are important as well. The weight-to-energy produced is much less an issue with stationary energy production, such as for commercial or residential property, but for vehicles, it is to be considered.

Facebook User

You don\'t need the whole generator in your car - just re-fill your cars hydrogen fuel cells while it\'s parked in your garage ...

Arctic Giraffe

It seems your saying the unit would be on the vehicle and I dont think thats what bio power jeff was referring to . The unit produces hydrogen and that would be used to fill the fuel cell. The unit itself wouldnt be carted around with the vehicle and in that instance I agree with Jeff... Of course more efficiency is better but like Jeff said if its almost inexhaustible then it sitting there creating hydrogen should be started right away and the efficiency worked on.. Especially for vehicles...


Handy for Mars......plenty of sunlight no doubt......but how do we get the water there?


Great post! This solar reactor is truly a breakthrough in green technology. I think people nowadays should use tools and technology that have less toll on the atmosphere, or does not contribute to global warming and the greenhouse effect. For example, a simple greenhouse kit for gardeners and farmers can be a significant help for the lessening of global warming.

Facebook User

Ugh. Not another hydrogen \"solution.\" Hydrogen is a TERRIBLE fuel. It has a low energy density (about 3400 times less energy by volume than gasoline in gaseous form at STP) and only three times the specific energy of gas. Even worse the stuff leaks. Repeat after me, hydrogen sucks. If you want a viable fuel at least add a carbon atom and get something practical like methane.

I\'d also question what just what that 19% efficiency really means. Is that really total efficiency from sunlight to fuel or is that just a subset of the available wavelengths?

Plasma Junkie

to plasma : I understand that hydrogen (sort of) sucks, being so damn small it can leak from almost anything. Also, the hydrogen-rich molecules not (H2) in the air are about as bad as nitrous oxides.

I have to disagree about methane because it\'s 24X worse than CO2 as a greenhouse gas. As far as this reactor works, it\'s basically a nice looking device somone made in thier basement, that doesn\'t entirely understand the redundancy of the reaction. Think about it, you trade in CO2 and water for CO and hydrogen and oxygen?!?!

CO is worse than CO2 as a gas. plus, CO2 doesn\'t smell nearly as bad.

At least if the person has it on thier front lawn, they can show it to thier neighbours.


Just like all the other \"supposedly\" great ideas (that are not coal/oil/atomic) that are \"still\" only a \"small\" percent because they are all \"useless\" (but a \"lot\" of money being made). They all will \"take\" (or are taking) more energy/resources/money to implement and maintain than they will ever produce.

There is not \"just\" the cost of the units, it is \"always\" the environmental impact of \"all\" the resources/maintenance required for such systems and the environmental \"toxic\" side affects.

What a waste of time. Back to physics 101 for you. When even one of the \"great\" ideas pan out (this idea), then it\'ll be my turn to go back to physics 101.

Fred Meyers
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