It looked like a pretty ordinary day on the water at the United States naval base in Norfolk, Virginia: a few short bursts of speed, a nice tail wind, some test manoeuvres.
But the 14m-long gunboat had algae-based fuel in the tank in a test hailed by the navy as a milestone in its creation of a new, energy-saving strike force.
The experimental boat operated on a 50-50 mix of algae-based fuel and diesel.
"It ran just fine," said Rear Admiral Philip Cullom, who directs the navy's sustainability division.
The tests were part of a broader drive within the navy to run 50% of its fleet on a mix of renewable fuels and nuclear power by 2020.
The navy plans to roll out its first group of about 10 ships, submarines and planes running on a mix of biofuels and nuclear power in 2012.
Fuels made from algae oil burn more cleanly than fossil fuel, but preventing climate change is not a major factor in the Pentagon's calculations.
"Our programme is about combat capability, first and foremost," Cullom said. "We no longer want to be held hostage by one form of energy."
http://www.mg.co.za/article/2010-10-29-algaefuelled-gunship-runs-just-fine