The carbon footprint of air travel is currently being scrutinized in the news. Here's a renewable energy angle that probably won't be covered in the mainstream media:
According to the Inventory of U.S. Greenhouse Gas Emissions and Sinks (1990-2016), the transportation sector is one of the largest contributors to U.S anthropogenic greenhouse gas emissions, at 28%. Of the 28%, aircraft transportation contributes 9% of emissions. Luckily, biobased technology companies have found ways to convert post-harvest forest residuals, or left over woody biomass, into renewable jet fuel. In fact, researchers in Maine are working on technology to make renewable diesel and jet fuel from woody biomass. Nationally, companies have perfected and proven their technology at commercial scale, and their fuel has been deployed on commercial flights.
Researchers at the University of Maine’s Forest Bioproducts Research Institute (FBRI) are turning woody biomass, including fallen tree limbs and other wood harvest residuals, into “green” chemical intermediates. From there, the University uses their patented conversion technology to produce small amounts of hydrocarbon fuel oil. In 2017, the University demonstrated the technology in 100 hours of continuous operation.
Leaders in the manufacture of renewable jet fuels from wood include Gevo and Velocys. Gevo is a low carbon chemicals and fuels company which uses the greenhouse gas emissions stored in plants in the form of carbohydrates, to produce renewable jet fuel, gasoline, and other products traditionally made using petroleum and natural gas. To make Gevo’s renewable jet fuel, carbohydrates (which store CO2) from woody biomass are separated from protein and fermented using specially designed yeast to make ethanol, isobutanol, and higher alcohols. The isobutanol is then converted using catalytic processes to produce hydrocarbons, and ultimately the Gevo bio-jet fuel.
In Lakeview, Oregon, Velocys is licensing technology for the Red Rocks Biofuels (LLC) biorefinery, which will produce 15 million gallons per year of renewable fuels. The RRB biorefinery is currently under construction. When operational, Velocys reports that RRB will produce enough jet fuel to power 1,800 round trips per year from Portland, Oregon to San Francisco. Crucial to the success of this project are RRB’s big-brand commercial off-take agreements. Biofuels Digest reported that FedEx and Southwest Airlines joined in an offtake agreement to purchase the total volume of Red Rock’s jet fuel from its first commercial plant.
Velocys uses gasification and Fischer-Tropsch technology to create renewable fuels from forest industry residues and municipal solid waste. And according to Velocys, their fuels yield net greenhouse gas emission reductions of 60% compared to their petroleum derived counterparts.
In Maine, annual harvests of nearly 12 million green tons per year produce forest residues and low-grade pulpwood that seeks new markets. Much of our forest residue that lacks markets could be used to produce renewable jet fuel. In fact, Velocys has indicated that it prefers the type of wood that Maine has available (e.g., softwood) for use in its technology.
So why aren’t we seeing any facilities in Maine to manufacture renewable jet fuel from woody biomass? Part of the reason is because it is still unclear whether Maine’s woody biomass qualifies as “renewable biomass” under the U.S. Environmental Protection Agency-administered national Renewable Fuel Standard as amended by the Energy Independence and Security Act of 2007 (RFS2).
The way the RFS2 is written, it is unclear whether woody biomass harvested from Maine’s naturally-regenerating forests qualify as feedstock eligible to produce biofuels that could receive federal subsidy. The regulations are written to give preference to plantation-grown trees, not trees from naturally-regenerating forests. Without the federal RFS2 subsidy, it will be difficult for Velocys or any other biofuel company to seriously consider Maine’s woody biomass as a feedstock for renewable fuels. Biofuels could still be made, but they would not be cost-effective or able to compete in the market against fuels eligible for the federal subsidy.
Biobased Maine has learned that some forest industry stakeholders in Maine are working on revising the way EPA interprets the RFS2, and we hope this issue gets resolved quickly so that Maine can help speed the transition from fossil-fuel derived aviation fuel to renewable aviation fuel made from sustainably grown and harvested second-generation feedstock.