Corncobs and woodchips the new jet fuel of the future
31 October 2017
University of Delaware researchers are working to develop an alternative jet fuel. Instead of petroleum, let’s power planes with corncobs and woodchips.
In UD’s Harker Interdisciplinary Science and Engineering Laboratory, researchers are transforming plant material, known scientifically as lignocellulosic biomass, into green products, including new fuels and chemicals.
The scientists are affiliated with the Catalysis Centre for Energy Innovation (CCEI), an Energy Frontier Research Centre supported by the U.S. Department of Energy. According to CCEI Associate Director Basudeb Saha, one of the biggest hurdles to making renewable jet fuel is increasing the speed and efficiency of two critical chemical processes - coupling and deoxygenation. Since the plant material the centre works with has a low carbon content once it’s broken down from a solid into a liquid, the carbon molecules must be chemically stitched together or “coupled” to create high-carbon molecules in the jet fuel range. Then the oxygen must be removed from these molecules to form branched hydrocarbons. This branching is essential to improving the flow of fuel at the freezing temperatures of commercial flight.
“International planes may fly at an altitude of 35,000 feet, where the outside temperature could be as low as -14°C,” says Saha, who is leading a renewable jet fuel project at the centre. “That’s the temperature at which a plane has to run, and the fuel can’t be frozen.”
Currently, several U.S. companies make renewable jet fuel from materials such as triglycerides extracted from used oil and grease, or from a combination of carbon monoxide and hydrogen called syngas. One company uses algae as its source material and even has an underground pipeline to the Los Angeles Airport (LAX), where a percentage gets mixed with conventional jet fuel, Saha says.
However, processing this non-conventional material requires high temperatures - 350°C - and high pressure as well.
Not so with those wood chips and corn cobs at UD, where Saha and his colleagues have developed new catalysts - so called “chemical goats” - that kick-start the chemical reactions that can transform this plant material into fuel. One of these catalysts, made from inexpensive graphene, looks like a honeycomb of carbon molecules. Its unique surface properties increase the speed of the coupling reaction. It also operates at low temperature (60°C). Another catalyst removes oxygen in an energy-efficient way and produces high yields of branched molecules, up to 99 percent, suitable for jet fuel. Both catalysts are recyclable, and the processes are scalable.
“The low temperature and high selectivity of our process can enable cost-competitive and sustainable production of bio-based aviation fuels from lignocellulosic biomass,” Saha says.
Material courtesy of University of Delaware