Now Jet fuel can be siphoned from the air.
Or at least in Móstoles, Spain, where researchers have demonstrated an outdoor kerosene system, used as jet fuel, using three simple ingredients: sunlight, carbon dioxide and water vapor. Solar kerosene could replace petroleum-jet fuel in private aviation and help stabilize greenhouse gas emissions, researchers report on July 20. Joule.
Burning solar-derived kerosene emits carbon dioxide, but only as much as it is used for, says Aldo Steinfeld, an engineer at ETH Zurich. “This makes the fuel carbon neutral, especially if we use the carbon dioxide captured directly from the air.”
Kerosene is the fuel of choice for airplanes, a sector responsible for about 5 percent of human-caused greenhouse gas emissions. Finding sustainable options has proven difficult, especially because of long-haul aviation, which relies on kerosene for so much energy, says chemical scientist Ellen Stechel of Arizona State University in Tempe, who was not involved in the study.
In 2015, Steinfeld and his colleagues summarized solar kerosene in the laboratory, but no one had produced the fuel at all in a single system in the field. Thus, Steinfeld and his team 169 observational mirrors track the sun to reflect and focus the equivalent of approximately 2,500 suns into a solar reactor on top of a 15 meter high tower. The reactor has a window to provide light in ports that provide carbon dioxide and water vapor as well as materials to catalyze chemical reactions called ceria pores.
When heated by solar radiation, ceria reacts with carbon dioxide and water vapor in a reactor to produce syngas — a mixture of hydrogen gas and carbon monoxide. The syngas is then pumped to the base of the tower where an engine converts it into kerosene and other hydrocarbons.
Over nine days of operation, the researchers found that the tower converted about 4 percent of the solar energy used into about 5,191 syngas, which were used for both kerosene and diesel synthesis. This proof-of-principle product is about a gallon of kerosene per day, Steinfeld says.
“Mileage is bigger,” Stechel says, though efficiency must be improved to make the technology useful for the industry. For context, a Boeing 747 jet passenger burns approximately 19,000 liters of fuel during takeoff and ascent to altitude. Recovering unused heat through the system and using better ceramic heat absorption could increase the efficiency of the tower to more than 20 percent, which is economically practical, the researchers say.
#jet #fuel #vaporized #sun #air #water