Just a couple of weeks after Virgin Atlantic completed a test flight of one of its Boeing 747 jumbo jets using a biofuel blend, Continental Airlines (NYSE: CAL) on Thursday announced plans to conduct a similar demonstration.

Continental, which is partnering with Boeing (NYSE: BA) and General Electric’s aviation branch (NYSE: GE) on the demonstration, plans to use a Boeing Next-Generation 737 plane. The aircraft will be equipped with engines from CFM International, a joint venture between GE and Snecma, an engine company owned by the Safran Group.

The partners expect to conduct the demonstration in the first half of next year, and said  additional details -- including the flight plan – are coming.

While individual demonstration flights aren’t likely to make a major environmental impact, they are evidence that the next green frontier could be the sky.

Estimates vary, but the International Governmental Panel on Climate Change puts greenhouse-gas emissions from air travel at between 2 and 3 percent of world emissions. Planes made up between 4 and 12 percent of carbon-dioxide emissions in the United States, according to a range of studies, and 13 percent of the carbon-dioxide emissions in the U.K. in 2005, according to government statistics (via Two Steps Forward).

And biofuel isn’t the only green technology taking to the skies. A few greentech startups also have said they plan to target airplanes.

Emeryville, Calif.- based Amyris Biotechnologies, a company developing microorganisms to make biofuel from nonfood crops, in June said it was working to produce a bio jet fuel (see MIT Technology Review story). And Watertown, Mass.-based A123Systems, a startup developing batteries for electric cars, previously told Greentech Media it was starting a project on batteries for aircraft engines (see What’s Next for A123?).

Aerospace company Reaction Engines, based in Abingdon, U.K., also is working on a hydrogen-powered jet (see The Next Frontier: the Sky?).