It's not as far off as you may think and the technology that could make it possible involves recycling scraps from sustainable forestry operations.
And the first cross-country flight of a commercial airliner using jet fuel made partially from forest residuals has already happened.
As with so many great things, the Northwest is leading the way as reported in The Seattle Times last fall:
"An Alaska Airlines flight from Seattle to Washington, D.C., on Monday morning was powered with a jet-fuel blend containing 20 percent renewable biofuel made from Pacific Northwest forest residuals — the limbs and branches that remain after the harvesting of managed forests.
"Billed as the first commercial flight running partly on wood, the alternative jet fuel was produced through the research efforts of the Northwest Advanced Renewables Alliance (NARA). Led by Washington State University, the group aims to build a sustainable supply chain for aviation biofuel using the leavings from logging operations.
"Alaska used 1,080 gallons of the biofuel on the flight. The airline said that replacing 20 percent of its entire fuel supply at Sea-Tac Airport with the same fuel would reduce greenhouse-gas emissions by about 142,000 metric tons of CO2 per year."
Source: Seattle Times, 11/14/16, "Biofuel from logging scraps powers Alaska Airlines on cross-country flight" [http://www.seattletimes.com/business/boeing-aerospace/biofuel-from-logging-scraps-powers-alaska-airlines-jet-on-cross-country-flight/]