Dr. Sossina Haile and her colleagues at CalTech have created a solar-powered reactor that can produce clean hydrogen gas, methane, or syngas which is a precursor to hydrocarbon fuels. This reactor type is known as thermochemical, because it uses solar power to create heat, and the heating and cooling of a type of metal oxide inside called ceria is the basic process which creates fuel. Their prototype uses a large quartz window about two feet tall as a magnifying glass to concentrate sunlight into a cavity inside the reactor. Inside the reactor is a cylinder lined with ceria, which is a common material also found in self-cleaning ovens.
When cool, ceria absorbs oxygen, and sheds CO2 and H2O molecules which can be pumped into the reactor to make hydrogen gas for hydrogen fuel cells. It also sheds CO which can be combined with hydrogen gas to make liquid hydrocarbon fuel. Additionally, the process can be tweaked to make methane. These plants in turn generate more CO2, and H2O as byproducts which can be captured and re-used in the their reactor to create more fuel. When it is heated, ceria releases oxygen. This cycle of “inhaling” and “exhaling” oxygen by raising and lowering its temperature can be repeated over and over in order to make fuel.
Also, their thermochemical reactor might be employed at coal-burning power plants to capture their CO2, and use it to make fuel for vehicles. Such an application might be very helpful for the short-term considering the widespread use of coal for producing electricity, in terms of reducing climate change emissions. However, burning coal also produces air pollution detrimental to people and wildlife. A report from last year said over 13,000 premature deaths per year in the United States have been linked to air pollution from power plants. Acid rain is a direct result of burning fossil fuels in power plants.
So for the long-term for both public health and environmental reasons, it may be better to use the thermochemical reactor for creating hydrogen gas to run fuel cells, whether they are in buildings or someday even in vehicles. Another more environmentally-friendly application might be at solar power plants, where some of the heat generated by concentrated solar technology could be used by her reactor to create fuel, which could then be used to run electrical generators at night, when solar power is not available.
Image Credit: SolarNovus