Will it be cost-effective someday soon to produce jet fuel from algae - the same green, viscous substances that can choke aquatic life out of a pond?
The Defense Department posed that question to private industry recently and is pushing for an answer with funding.
It is motivated by an Air Force that spends around $6 billion annually on liquid aviation fuel. The Air Force has tested the B-52 bomber and the C-17 transport aircraft on a 50-50 synthetic-and-standard fuel mix.
But the Air Force hopes biofuel experiments will succeed because it could result in a more economical way to fly its aircraft, which burn around 2.4 billion liters of oil per year.
The idea of using algae to propel U.S. military aircraft is not new. The Energy Department explored the idea for 20 years. The military has looked at biofuels derived from soybeans, canola oil, the flowering cuphea plant and camelina, or wild flax seed as it is also known, but algae offer volume efficiencies.
The Colorado Oakhaven Permaculture Center reports that an acre (around .4 hectare) of corn annually produces 57 liters of oil; soybeans, 182 liters; safflower, 315 liters; sunflower, 391 liters; rapeseed, 483 liters; oil palm, 2,413 liters; and microalgae, 7,030 liters.
Drawing on algae as a fuel source instead of corn or soy also means more crops are available for human and animal consumption - an important consideration given high food costs.
The conversion process for turning microalgae to fuel works, but researchers concluded in the mid-1990s that it was too expensive to compete with diesel.
Now with soaring fuel prices (the cost of fuel in a combat zone is estimated at $400 per barrel), energy security officials are concerned about diesel supplies. They are also well aware of the environmental harm from fossil fuel consumption on the earth's climate.
The Defense Advanced Research Projects Agency (DARPA), the military's research arm, awarded two separate three-year contracts recently to General Atomics and Science Applications International Corporation in California. The agency is looking for an algae-based alternative to the petroleum-derived JP-8 fuel used by the Air Force, and if an inexpensive aircraft fuel alternative is possible, it will be considered for Army vehicles as well.
The challenge will be to reduce the production cost of extracting oil from algae from the current rate of around $30 per eight liters of fuel to less than $3.
General Atomics is building a 1.6-hectare demonstration plant. David Hazlebeck, the company's biofuels program manager, said the company's greatest challenge will be driving the cost down even lower.
DARPA spokeswoman Jan Walker told America.gov that algae offer the advantage of growing easily in a lot of different places. All it needs is light, carbon dioxide and any kind of water - it can thrive in saline, brackish or waste water - to reproduce rapidly.
Brine algae even reproduce in windy, dry desert conditions.
Algae could bring economic advantages through new jobs, in addition to its possible role in lowering fuel costs. General Atomics is creating a microalgae facility in Texas. The company already employs 40 algae researchers.
If growing and extracting algae oil is as promising as many hope, thousands of new jobs might be created, according to algae fuel proponents.
When the current contract ends, Hazlebeck said, the firm plans to build a commercial production facility that would supply fuel to military and commercial consumers.
Science Application International Corporation has assembled industrial and academic teams to work in Georgia, Hawaii, Florida and Texas on ways to reduce the military's reliance on foreign oil.
The algae-based fuel industry is growing. Sapphire Energy in La Jolla, California, is focused on producing "green crude" for fuel use. It says it has produced a 91-octane gasoline derived from algae. Aircraft manufacturer Boeing Corporation is looking at how algae-based fuel will best work with modified jet engine designs.
And the Energy Department's National Renewable Energy Laboratory is partnering with Chevron Corporation to see if algae really can be a ready supply of cheap jet fuel.
San Diego will host the Algae Biofuels World Summit on March 23. The event will attract broad elements of the algae biofuels community, including aquaculturalists, financiers and aircraft-engine manufacturers.