Making a few stops along the way, BioJet 1 went 1,776 miles of a 2,486-mile journey from Reno, Nev., to Leesburg, Fla., exclusively on biodiesel. The fuel in question, made by Lake Erie Biofuels, was a blend of soy and animal fats turned to diesel.

The Aero L-29 jet kept the biodiesel from congealing at high altitude by continuously heating it—and landing every 300 miles or so to refuel. The flight is a proof of principle, according to Green Flight International CEO Doug Rodante, and is aimed at addressing the carbon dioxide (CO2) emissions from burning jet fuel -- roughly 3 percent of total worldwide greenhouse gas emissions, according to the U.N. Intergovernmental Panel on Climate Change (IPCC), but released in a very bad spot—high in the atmosphere.

"In aviation, there is a tremendous carbon output with jet airliners," Rodante told me. "Not enough is being done fast enough even though we are seeing ice sheets melting around us."

This past February, Virgin Atlantic flew a Boeing 747 from London to Amsterdam on a blend of 20 percent coconut and babassu biofuel and 80 percent kerosene and Air New Zealand plans to fly on a 50–50 blend on December 3. That biofuel will be made by UOP Honeywell from jatropha, a woody shrub from Africa that produces oily seeds.

But algae would be an even more sustainable source of the biofuel, because the tiny plants don't need to grow on land that could be used for food crops and can thrive on waste water. Green Flight International hopes to demonstrate such an algal jet fuel next. "Then," says CEO Doug Rodante, "we're going for the around the world."

Image courtesy of Rudi Wiedemann