New Solar Reactor Makes Storable Fuels

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If power sources were in high school, coal would be the popular jock and solar the awkward little brother. Solar has so much potential, but scale, storage, and affordability still need development. A new prototype reactor could turn into a major boost for solar.

A team of scientists from Switzerland and the United States came up with a reactor that focuses sunlight through a quartz window, down into a chamber lined with the metal ceria, also called cerium oxide. From there, the cylinder uses the energy to split water, producing oxygen and hydrogen. I'm oversimplifying the process, which was recently published in Science (abstract).

The scientists, which include Caltech professor Sossina M. Haile and Swiss Institute of Energy Technology professor Aldo Steinfeld, wanted to figure out a way to harness the sun efficiently, without requiring incredibly precious materials like indium. Their reactor can also break carbon dioxide into carbon monoxide and oxygen, which Ars Technica's John Timmer points out are key ingredients for the fuel cell component methanol.

The advantage here is that the process is fairly simple, and cerium oxide heated by the concentrated lens will attract water molecules and break them down thermochemically. The resulting fuels are easier to store, and transport. While cerium oxide is a rare Earth element, it is one of the more common ones. Its abundance has been compared to copper.

To achieve true super-solar power however, the prototype needs to overcome several challenges. BBC News reported that the device is extremely inefficient: Only about 7 to 8 percent of the solar energy going into the reactor is converted to fuel. It gets lost through the reactor's walls and re-radiation through the lens.

The team told the BBC they think that with adjustments to the walls and quartz lens, they can improve the reactor's efficiency to 19 percent. With more tinkering, even the waste heat could be harnessed. The reactor components were created with a future industrial scale in mind, so after more successful prototyping I expect we'll be seeing a commercial version. And we all know how hot solar tech is right now.

Photo Credit: Bùi Linh Ngân. Image: A diagram showing how the solar machine prototype works. Credit: Science Magazine/BBC News.