Navy Formulates New Biobased Fuels

To meet growing demand for renewable diesel and jet fuels to power heavy trucks, ships, and aircraft, Navy researchers have created clean-burning high-performance biofuels by blending sesquiterpanes and a paraffinic hydrocarbon (Energy Fuels 2015, DOI: 10.1021/ef5027746). Benjamin G. Harvey, Walter W. Merriman, and Thomas A. Koontz of the Naval Air Warfare Center Weapons Division, in China Lake, Calif., tested blends of several cyclic and long-chain hydrocarbons before settling on a mix of caryophyllane isomers and 5-methylundecane. Caryophyllanes are hydrogenated versions of tricyclic sesquiterpenes found in hemp, clove, and other plant oils and derived from the plants or prepared from sugar via fermentation. 5-Methyl­undecane is a C₁₂ hydrocarbon constituent of kerosene that can be prepared from bioethanol by a combination of fermentation and chemical synthesis. The researchers found that a blend of 65% sesquiterpanes and 35% 5-methylundecane exceeds diesel performance and safety standards. They further found that altering the blend to 40% sesquiterpanes and 60% 5-methylundecane maintains fuel performance while reducing the low-temperature viscosity so that the fuel is usable in jet engines.