Green Jet Fuel

By Michael Padilla

A Sandia team is investigating how to produce military Jet Propellant 8 (JP-8) fuel using renewable biomass oil feedstocks, including oil crops, unconventional sources like algae, and various forms of waste vegetable and animal oils.

The 18-month effort, backed by a $6.7 million DARPA project award, aims to develop, demonstrate, and commercialize a process by October to produce the JP-8 fuel used by U.S. and NATO militaries.

According to Sandia project leader Ron Pate, researchers are evaluating promising oil crops that will not directly compete with food and feed markets, can avoid the use of higher-quality agricultural land, and may also allow for reduced demand for energy, fresh water, and other inputs.

"National scale-up of oil crop-based aviation fuel production at the volumes, supply availability, reliability, and competitive costs desired is a complex and dynamic 'system of systems' challenge," says Pate. "We are leveraging our capabilities and expertise in systems dynamics modeling, simulation, and assessment to help provide insight and decision support to the project."

Several key problems for bio-oil projects include land use, water demand and availability, soil and climate conditions, energy, and other critical inputs.

The conversion processes under development are expected to yield high fractions of liquid biofuel product in the form of JP-8 and green diesel, along with other useful coproducts. Pate says oils derived from plants like soy, oil palm, sunflower, and numerous others provide an easy-to-handle material with high energy density and chemical structures that can more easily be converted into high-performance liquid fuels than other forms of biomass.

Production of conventional oil crops for biofuel will face limits due to competing markets for oil crop products and competing uses for the land and water required to grow the crops, Pate says.

Algae can be grown using land not otherwise suitable for agriculture, and can use lower-quality water sources such as inland brackish ground water, various waste waters, desalination concentrate, by-product water from oil, gas, and coal-bed-methane energy mineral extraction, and coastal sea water.

Despite the high productivity potential of algae, Sandia's preliminary techno-economic assessment reveals several major areas where innovation will be required before affordable algal biofuel production is possible.

Fuel produced using the new processes will have to meet stringent military specifications.The military needs high-energy efficiency in the conversion of renewable bio-oil feedstock to JP-8 fuel and other valuable coproducts that can include green diesel fuel and other industrial chemicals, Pate says.

Researchers expect the technology will also be viable for future use in the production of fuel for commercial jets.