Here is an interesting news article from the Society of Automotive Engineers website (SAE.org) on aviation fuels derived from plant matter. Here are some excerpts from the article.
Embraer is researching sugar cane fermentation as a fuel source for its 170 line and other jets.
Synthetic fuels made from a range of bio-feedstocks are advancing rapidly. ASTM International, a standards group that is shepherding the fuel standard, is expected to approve a document within the next year. Companies as diverse as Boeing, Continental Airlines, Air New Zealand, and Rolls-Royce have all successfully tested a 50:50 version of the synthetic fuel.
Much of the effort centers on synthetic paraffinic kerosene (SPK), a fuel that can be created from a variety of plants.
Studies are also underway at Pratt & Whitney and GE Avation.
It currently takes about an acre of soybeans to produce 100 gallons of jet fuel.
Much research focuses on algae, which may be able to produce as much as 1000 gallons per acre.