It wasn’t long ago that the great promise of biodiesel lay in getting a ’72 VW Bus to sputter a few miles down the road for its weekly trip from the organic rutabaga commune to the farmer’s market. In just a few short years, biodiesel has emerged as an increasingly promising energy alternative, embraced by environmental activists and politicians alike for its potential in reducing both harmful greenhouse emissions as well as our reliance on imported fossil fuels. Now, biodiesel has taken flight—literally.

Last October, entrepreneur Douglas Rodante piloted a biodiesel powered Aero L-29 Delfin on a half-hour flight above the Nevada flats. Rodante has plans to take the same plane on an 8-stop trip across the United States. The number of stops isn’t an indication of any inherent limitations to biodiesel fuels, but of a design feature of the Soviet-era training jet, which was specifically engineered with a short range to discourage attempts at defection. What the L-29 lacks in range, it makes up for with its remarkably robust engines, which comfortably burn biofuel without any modification.

Rodante and his partners at Green Flight International are currently awaiting FAA approval for the cross country endeavor, but are already planning an even more impressive feat for biodiesel powered aviation: a round-the-world flight. That trip will be attempted using a modified Bombardier Learjet 25. While the Learjet’s increased range over the L-29 makes the trip possible, its higher cruising altitude does pose a technical challenge for biodiesel flight. In the frigid air 40,000 feet above sea level, biodiesel congeals into an incombustible slurry. In order to keep the biodiesel viscous and usable at such altitudes, Green Flight will have to mix in chemical additives or combine the biodiesel with traditional jet fuel. Luckily, even if the fuel is only partially composed of biodiesel, it will represent a significant reduction in greenhouse emissions when compared with the status quo.

British mogul Richard Branson’s recent $3 billion climate pledge could see these sorts of pioneering efforts carried through into fundamental changes for the aviation industry and beyond. Already, Branson’s newly established Virgin Fuels has allotted $400 million worth of investments to biofuels over the next four years. With jets being one of the chief culprits for greenhouse gas emissions, the development of viable biofuel technologies for commercial and private aviation looks to be an imperative investment for the years ahead.