Alaska Airlines Sustainable Biofuel
A 20% Wooden Blend Chemically Indistinguishable From Jet Fuel
The headline conjures up images of a train’s steam engine being fueled by a tender full of wood.
While the title is correct, it fails to explain how new technology is using renewable energy sources to fire Alaska Airlines‘ engines. On November 14, 2016, an AS flight between Seattle-Tacoma International Airport and Reagan National Airport, flew using fuel in which wood was a source of its energy. Technically, the plane used a 20 percent blend of sustainable aviation biofuel, “chemically indistinguishable from regular Jet A fuel.”
Washington State University-led Northwest Advanced Renewables Alliance (NARA) used forest harvest residuals to make aviation biofuel and co-products. Joe Sprague, Alaska Airlines’ senior vice president of communications and external relations, explained that the flight was the “latest milestone in Alaska’s efforts to promote sustainable biofuels is especially exciting since it is uniquely sourced from the forest residuals in the Pacific Northwest.” The airline put the potential of this alternative biofuel’s Green value in concrete terms with this example: “If it replaced 20 percent of its total fuel supply at Seattle-Tacoma, greenhouse gas emissions would be slashed by roughly 142,000 metric tons of CO2, equivalent to taking 30,000 passenger vehicles off the road for an entire year.”
What is different about this NARA initiative is that unlike previous biofuels efforts, the WSU consortium recognizes that its “fuel” must be producible at a price point which is competitive. Its website states this goal pointedly: “To do that, NARA seeks to improve the efficiency for each supply chain step from forestry operations to conversion processes; create new bio-based products; provide economic, environmental and social sustainability analyses; engage stakeholder groups; and improve bioenergy literacy for students, educators, professionals and the general public.”
The first step in the NARA game plan is to capture forest harvest residues. Currently those “chips” are collected in slash piles and are burned. Instead of “wasting” these residues, they could be a potential feedstock for biofuels and co-products. This broad strategy has been articulated into practical tactics:
- “Feedstock (forest harvest residuals) specifications for optimum conversion to biojet fuel.
- An improved model and equations to better predict future forest residual supplies.
- Forest slash chemical compositions from diverse landscapes in the Pacific Northwest.
- Distribution, availability, and chemical characterization of wood-based material from recycling facilities in ID, OR, MT, and WA.
- A GeneChip used by tree breeders to introduce softwoods with improved traits for biofuel processing.
- Computer models to help forest landowners efficiently process and transport forest residuals.
- Logging utilization, harvest trends, and timber product output data for ID, OR, MT, and WA.”
Here’s the NARA research library supporting these steps:
Berg, E., Morgan, T., Simmons, E., Zarnoch, S. & Scudder M. (2016). Predicting logging residue volumes in the Pacific Northwest. For. Sci., 62(5), 564-573. doi: http://dx.doi.org/10.5849/forsci15176
Marrs, G., Zamora-Cristales, R. & Sessions, J. (2016). Forest biomass feedstock cost sensitivity to grinding parameters for bio-jet production. Renewable Energy, 99, 1082-1091. doi.org/10.1016/j.renene.2016.07.071
Zamora, C.R., Sessions, J., Murphy, G., & Boston, K. (2013). Economic impact of truck–machine interference in forest biomass recovery operations on steep terrain. Forest Products Journal, 63(5/6), 162-173. doi: 10.13073/FPJ-D-13-00031
Step #2 NARA integrates this supply chain into a conversion pathway that is effective, economical, of scale, and adaptable to existing facilities in the Pacific Northwest. NARA work has resulted in:
- An adaptable and scalable sulfite-based pretreatment and fermentation system that converts forest residuals into isobutanol.
- An economic blueprint to project the costs and potential revenues associated with a biorefinery that converts forest residuals into biojet fuel and co-products.
- Alternative pretreatment technologies such as wet oxidation and wood milling.
The 3rd point in the outline is the chemical conversion into Jet A. Here are the studies which explain this process:
Alvarez-Vasco, C., Guo, M. & Zhang, X. (2015). Dilute acid pretreatment of Douglas fir forest residues: pretreatment yield, hemicellulose degradation, and enzymatic hydrolysability. BioEnergy Research, 8(1), 42-52. doi:10.1007/s12155-014-9496-7.
Gu, F., Gilles, W., Gleisner, R. & Zhu, J.Y. (2016). Fermentative high titer ethanol production from a Douglas-fir forest residue without detoxification using SPORL: high SO2 loading at a low temperature.Ind. Biotechnol., 12(3),168-175. doi: 10.1089/ind.2015.0028
Garrett, B.G., Srinivas, K., & Ahring, B.K. (2014). Design and optimization of a semi-continuous high pressure carbon dioxide extraction system for acetic acid. J.of Supercritical Fluids, 95, 243-251. doi:10.1016/j.supflu.2014.08.029
NARA and select partners employed the feedstock specifications and conversion technologies developed by NARA to produce 1,000 gallons of biojet fuel made from Pacific Northwest forest slash.
“NARA’s accomplishments and the investment of the U.S. Department of Agriculture provide another key in helping Alaska Airlines and the aviation industry reduce its carbon footprint and dependency on fossil fuels.”
This is the sort of story which merits repetition. The more that the general public knows about this sort of greening of aviation, the debate over airline environmental efforts will become more fact-based.