Biofuels for Military Aircraft

Commercial Jet fuel has stringent requirements. Alternatives are expected to perform exactly like kerosene so that aircraft do not have to be modified. They are expected to be environmentally sustainable and cost effective. First generation biofuels derived from crop did not meet these criteria for planes. Therefore the aviation industry is looking at second generation biofuels from non-crop sources.[1] Of these, algae are considered as the best. They can be grown in polluted or salt water, deserts and other inhospitable places. They can produce up to several hundred times more oil per hectare than first generation soybeans. According to Boeing, an area of land or water equivalent to the size of Belgium devoted to algae production could produce enough energy to fuel the entire global fleet of aircraft.

There have been several demonstration flights using second generation biofuels: In February 2008 a Virgin Atlantic Beoing 747-400 plane flew between London and Amsterdam, powering one engine with an 80:20 mix of Jet-A1 and a biofuel derived from babussi oil and coconut oil. In December 2008, Air New Zealand flew a similar plane with one engineer running on a 50:50 blend of Jet-A1 and synthetic fuel derived from jatropha oil. In January 2009, a Continental Airlines Boeing 737-800 aircraft undertook a test flight using a biofuel partly derived from algae. In the same month, a Japan Airlines Boeing 747-400 flew with one of the engines powered by a mix of 50:50 mix of Jet-A1 and biofuel including camelina. IATA targets biofuels to be commercially available by 2017.[2]

But the biodiesel produced through current commercial processes isn’t yet suitable for military tactical aircraft, which requires a fuel that meets exceptionally high standards – higher energy density and a wide operating temperature range.

DoD had initially focused in creating alternative fuels from agricultural and aquacultural oil. The aim was to use a variety of natural (vegetable) oils and animal fats (greases) as feedstocks, both edible and inedible. But later on, it shifted its focus to making synthetic fuel from algae — or other biological feedstocks that do not compete with food supplies — after earlier attempts to develop coal-based synthetic fuel ran into political hurdles.[3] However, efforts on synfuel derived from natural gas still continue. Note that USAF goal is to certify every aircraft synthetic fuel blends capable by 2011.

Defense Advanced Research Projects Agency (DARPA)[4] began its pursuit of biofuels back in 2006. DARPA is now undertaking new research to enable the efficient and economical production of military-grade jet fuel (JP-8) from a variety of agricultural and aquacultural products that are oil rich but are not competitive with the food supply.

DARPA’s new BioFuels Alternative Feedstocks program aims to develop affordable alternatives to JP-8 from algae and from cellulosic biomass. Wit affordable DARPA means at a cost that is competitive with petroleum-derived fuels. More specifically, DARPA seeks to produce a surrogate JP-8 that would cost less than $3 per gallon at a production rate of 50 million gallons per year.[5]

Cellulosic program aims at 50% conversion energy efficiency (the conversion of biomass to actual fuel), by energy content, of feedstock material into JP-8. Algae program aims at production of algae triglyceride at $1 per gallon. Also, Department of Energy’s National Renewable Energy Laboratory (in Golden, Co) currently is working with the Air Force office of scientific research on a project[6] to produce a $2 a gallon algae-based synthetic fuel that would be made locally.

All these are good news, at least the cost side. But the scale of required production still remains a problem. By the way, who will invest in biofuels production without having any purchase guarantee or government subsidies?

Notes:
[1] Algae, halophytes, babassu, switchgrass, jatropha, camelina.
[2] Paul Steele, Sustainable Transport – The Biofuel Aeroplane, The World Today, Vol 65, No.3, March 2009, pp 14-16.
[3] Under a 2007 law, the military is banned from buying alternative fuels that emit more greenhouse gases than petroleum-based fuels.
[4] DARPA was established in response to the Russian Sputnik launch, and celebrated its 50th anniversary in March 2009. Its work has built the foundations for the NASA space program, the World Wide Web, GPS, Stealth aircraft, advanced precision munitions, the Predator and Global Hawk unmanned aerial vehicles, and myriad other technologies.
[5] DARPA BioFuels – Alternative Feedstocks program website,
“Energy as a Tactical Asset,” speech delivered by Dr. Doug Kirkpatrick at DARPA’s 25th Systems and Technology Symposium (August 2007)
DARPA BioFuels program website
[6] This is part of a $100 million program funded by the DARPA.