UAV is latest Air Force plane tested to run on alternative fuel

The Air Force has been running flight tests with the goal of certifying its US fleet to burn a 50-50 mix of fossil fuels and alternative fuels by 2016. On Monday it tested a Global Hawk UAV.

A drone that runs on alternative fuels?

That's the latest from the Air Force, which has been running tests to see how its aircraft perform burning something other than straight jet fuel. The initiative is aimed not only at shrinking its carbon footprint and spurring alternative fuels development, but also at strengthening national security.

Monday's alternative fuel test of the Global Hawk UAV was considered one of the most challenging yet for the Air Force.

The drone that flies at high altitudes and low temperatures was one of the last that the Air Force needed to test in its current spate of trial runs before its fleet is certified to run on a 50-50 blend of jet fuel and alternative fuels.

The ultimate gauge of success is that the aircraft flies without incident, and moreover, that “the pilots can’t tell any difference” in the performance of their respective planes, says Gary Strausburg, the Air Force’s chief of environmental public affairs.

The Air Force burns about the equivalent of a single midsize commercial airline each year, or about 2.5 billion gallons. For that reason, it can help encourage innovation in the development of alternative fuels.

But partnerships with industry are vital, too, because for many biofuels “the tricky part is the cost,” says Timothy Bridges, deputy assistant secretary of the Air Force for environment, safety and occupational health. The science, too, is a challenge, since the Air Force ultimately wants to be able to pump biofuels – including plant extracts and animal fats – into aircraft without changing out any parts.

There is also the issue of space. Growing crops that ultimately could become biofuel for the Air Force requires considerable land. It also takes time. Algae has proved particularly promising because it grows quickly – and can sometimes be harvested in just 24 hours, says Michael McGhee, who serves in the office of the deputy assistant secretary of the Air Force for energy.

Biofuels could ultimately give the military a more flexible and reliable source of energy, allowing it to abandon crops that may have been hit by a drought and buy up cheaper fuel made from crops that had a banner year and might be selling at a lower price.

This has a flip side, however: As the price of oil decreases, developing alternative fuels – and building the plants it takes to process them – can become less economically appealing, says Mr. McGhee, which can hold up production.

Greenhouse gas emission legislation is another variable. Industry, McGhee points out, is carefully watching the outcome of legislation making its way through Congress to see if new environmental standards become law, “before they invest too deeply in production.”

In the meantime, the hope is that the Air Force’s interest in alternative fuels will help drive industry, says Bridges – particularly since the Air Force has set a goal of certifying its fleet to use a blend of alternative and fossil fuels by 2011. Looking ahead, it aims to be able run a 50-50 blend incorporating biofuels in all of its planes that operate in the continental United States by 2016.

The Air Force has also taken other more immediate steps to increase its energy efficiency both in the US and abroad. It has found shorter flight routes, and has scoured the fleet to get rid of extra weight – including, for example, losing thick binders filled with information that can easily be put on a computer instead – to make the fuel go further.

The point “is not to be saddled with a dependence on foreign oil,” Bridges adds. “That’s a national security issue.”