The Air Force doesn't exactly want its drones powered by purple bacteria. Instead, the air service would like to use a synthetic dye, based one the microorganisms, to juice up its robotic planes.

Let me explain: The U.S. armed services are on a slow crawl towards environmental friendliness, investing in everything from massive solar arrays to algae-based jet fuels to trash-powered generators. Military-funded researchers are also experimenting with downright novel methods to come up with green fuel and power. Like this bacteria-and-drones project.

The Air Force is sponsoring a University of Washington research effort to generate power using a bacterial pigment that can convert solar energy to electricity, Defense News reports. The pigment, found in purple microorganisms that thrive in shallow water, harnesses sunlight to convert carbon dioxide to carbohydrates, which the bacteria then uses for energy.

Dr. Minoru Taya's University of Washington lab has created a synthetic version of the pigment and embedded it into solar energy cells (the components of solar panels). When the dye-sensitized cells are hit by sunlight, the pigment launches an electron circuit, yielding electricity. That process can repeat over and over, so the cells rarely need replacing.

Right now, the cells are used commercially to recharge cell phones. It would take a lot more of them to charge an unmanned aerial vehicle (UAV), but the military thinks the project is feasible. Mostly because dye-sensitized cells are cheap and small compared to the silicon alternative. They’re a little less efficient, but cost a quarter as much to produce. And the cells are lightweight and thin, so they could spread across the wings of an UAV without taking up extra space.

And that’s exactly what the Air Force wants: panels of dye-sensitized cells that run along the wingspan of UAV’s, charging a battery that could power the plane’s propeller, surveillance systems, onboard computers and flight controls.

So far, the Air Force has spent $450,000 on the project, and expect to power an UAV with the mock bacterial dye within three to five years. But the cells could be used in other projects before that. The military is considering a bacteria-inspired solar "power shade" that would fit over Army tents to keep the electricity flowing inside.

[Photo: NASA]

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