SCOTT AIR FORCE BASE, Ill. -- One of the key pillars of the Air Force Energy Strategy is to increase supply: "Increasing the amount of energy supplies available to enhance our nation's energy security." The strategy specifically references aviation and ground vehicle fuels.

This makes good sense. Fuel drives the Air Force. We are by far the largest consumers of this commodity in the federal government. Air Mobility Command alone uses roughly one quarter of all fuel purchased by the government to fulfill its global mission of airlift, aerial refueling, and aeromedical evacuation.

The vast majority of this fuel we use comes from petroleum, a dwindling, non-renewable resource which has the added disadvantage of price volatility. No doubt about it -- the supply needs supplementing.

Fortunately, the Air Force has a very effective fuels characterization and fleet certification process. We have a world-class fuel analysis team at the Air Force Research Laboratory where experts conduct comprehensive measurements of the properties of the fuel and its compatibility with materials it will encounter in tanks, pumps, and engines.

That feeds into a certification protocol, which was shaped and streamlined through a very methodical series of steps: testing the fuel in the laboratory; then gauging its performance in a baseline helicopter engine; followed by ground tests in actual platform engines; and, finally, flight tests. This process can now be applied to any proposed alternative fuel.

The Air Force has successfully certified its fleet on a Fischer-Tropsch/JP-8 synthetic blend (Fischer-Tropsch fuels are derived from coal or other carbon-based feedstocks). The current focus is on jet fuels derived from biological sources. In the end, we want "drop-in" alternative fuels that have the same characteristics and the same performance as the fuels we currently use.

The best testimony is when ground handlers and aircrews see no difference in operations. And to address the supply and cost issues, having a diversity of sources and feedstocks is the ultimate goal.

There are challenges. Because the Air Force is not in the business of fuel production, we must wait for affordable (and hopefully, sustainable) alternative fuels. There are environmental concerns--the Fischer-Tropsch process releases about twice the carbon dioxide (a greenhouse gas) as conventional refining of petroleum. In fact, Congress doesn't want the government to purchase any fuel that has a larger carbon footprint than standard refining. If the carbon dioxide can be captured during production, it could be stored, say deep in aquifers, or used to enhance growth in biomass for biofuels, for example.

For bio-fuels, a good rule of thumb is to avoid competition with food or feed-processing. Fuels, like ethanol from corn or soybeans, represent "first generation" biofuels. The sweet spot is in second-generation biofuels. Sources could include grasses or plants with non-edible fruits or seeds. Or consider parts of the plants that are not consumable, like cornstover. A lot of research is going into these biofuels, which could be available in large quantities over the next few years. Finally, if we look out a decade or more, we can consider third-generation biofuels such as those produced from algae -- a particularly oil-rich crop.

The Air Force may not be able to wean itself completely from petroleum. And if we want to increase supply, our aircraft and ground vehicles need ready and economical fuels derived from an assortment of sources. The Air Force is a significant part of our nation's strategy to establish greater energy security and become more energy efficient through conservation and use of alternative energy sources.