Sustainable aviation fuel production remains nascent, but it is already clear that the feedstocks predominantly being used to make SAF today will not satisfy total future demand. Billions of gallons of SAF are needed, but only so much used cooking oil, waste fat, corn oil and soybean oil is available and unclaimed. A host of other feedstocks are plausible, but hard to convert, hard to find or hard to defend. These marketplace realities are drawing the SAF industry to an input that is ubiquitous, clean, understood and transformation ready: low-carbon ethanol.
Multiple airlines forged ethanol connections—some inking formal commitments—last year as interest in feedstocks and technologies of all types hit a near fever pitch and alcohol-to-jet was widely deemed both necessary and inevitable. In August, Congress passed the Inflation Reduction Act, which created an attractive federal tax credit for qualifying SAF, sparking intense questions about how, if at all, low-carbon corn ethanol might qualify. Almost all analyses of the legislation suggest corn ethanol is substantially hampered by the bill’s carbon math, but that hasn’t quelled ethanol producer enthusiasm for SAF, nor carbon reduction investments related to it. Corn ethanol producers are engaging in the play not as a result of SAF’s first big federal incentive, but almost despite being virtually excluded from it.
The federal SAF credit starts at $1.25 per gallon for qualifying biobased jet fuel that reduces carbon emissions by 50 percent, with one cent added for each additional percentage point of reduction, capping out at $1.75. SAF made from corn ethanol, experts say, has a difficult-to-impossible time qualifying since the law measures GHG reduction using the International Civil Aviation Organization’s CORSIA methodology rather than the Department of Energy-Argonne National Laboratory’s GREET model, which is more friendly to corn ethanol and believed by many experts to be the most appropriate lifecycle analysis methodology for the determination of SAF emissions.
In December, when the IRS issued guidance on the federal SAF tax credit—just a month after the DOE unveiled a roadmap for its SAF Grand Challenge—corn ethanol remained effectively sidelined as a result of the credit’s GHG methodology, despite the ethanol industry’s pleas for the adoption of GREET. In February, legislation signed into law in Illinois established a $1.50 per gallon tax credit for SAF.
Unlike the IRA, the state legislation allows SAF producers to qualify using either CORSIA or GREET, presumably putting low-carbon grain ethanol in the action. The bill was signed into law by Illinois Gov. J.B. Pritzker on Feb. 3 and becomes effective June 1. Not only has the Illinois SAF credit sparked excitement among conventional ethanol producers, but put more weight behind ongoing appeals to somehow work GREET into the IRA.
With or without the IRA credit, the ethanol industry is all over SAF, and the United States’ potential to be a major global producer of biobased jet fuel is undeniably tied to its massive ethanol production and delivery infrastructure. The International Energy Agency has, in fact, identified the U.S. as the country with the most “significant growth potential for SAF,” likely due to its existing biofuels production capability, the passage of the IRA and the DOE’s Grand Challenge, which calls for 3 billion gallons of SAF production and use by 2030, and completely replacing domestic jet fuel for aviation by 2050.
Marykate O’Brien, chief sustainability officer with Southwest Airlines, explains the demand for SAF, the feedstocks available and the technologies being deployed. “I think it’s a really great time for the SAF industry when you have the major players, the major off-takers saying they want to replace 10 percent of their fuel by 2030 and a hundred percent by 2050,” she says.
To replace all of the aviation fuel in the U.S. with a biobased counterpart, roughly 35 billion gallons of SAF will be needed. Worldwide, the demand is around 100 billion gallons. Southwest wants a tenth of its jet fuel to be SAF by 2030 and all of it by 2050. As of now, Southwest Airlines has offset around 0.05% of its overall jet fuel use, O’Brien explains. The company’s four pillars used to meet these goals: reduce, offset, replace and partner. “Reducing” involves implementing improved technologies that allow for more efficient use of fuel; “offsetting,” is about Southwest eventually scaling back and redirecting those efforts into replacing and partnering; “replacing” involves offtake agreements to substitute fossil fuels with SAF; and “partnering” is the R&D piece, involving some SAF offtakes and investment opportunities.
The last pillar, partnering, is the element behind Southwest’s investment in SAFFiRE Renewables (see page 16), O’Brien explains. “That’s where we think the opportunity is strong enough that we want to put some money down on the table to help advance that technology,” she says. “One big thing about our investment in SAFFiRE is that it is Southwest Airlines’ first investment in anything [outside of] an airline acquisition in our entire history as a company. So, that illustrates how important it is to us and how much potential we think this technology has to make a dent in the overall need for SAF.”
O’Brien sees ethanol as one of the feedstocks with high potential to yield the gallons needed to produce SAF, while also having some of the most advanced technology for conversion. “I think we have some really promising near-term pathways, and ... ethanol is certainly one of those, I think there are very few potential pathways that can claim the same maturity that ethanol has,” O’Brien says. “The infrastructure is there, the know-how is there, we still need some of the (alcohol-to-jet) buildout, but it’s proven technology at this point. I think, near-term, the ethanol industry has a huge opportunity to impact those initial gallons that we’re going to need.”
Freedom Pines Fuels
SAF company LanzaJet, has a 10 MMgy SAF and renewable diesel plant under construction in Soperton, Georgia. LanzaJet’s Freedom Pines Fuels will be the nation’s first alcohol-to-jet SAF production facility. The plant will use undenatured ethanol from a variety of feedstocks, including waste-based sources, to make 9 MMgy of SAF and 1 MMgy of renewable diesel. In January, the EPA approved LanzaJet to generate D4 RINs using sugarcane-based ethanol for its renewable diesel and SAF. This was a key milestone in the company’s EPA approval process, and the first approval of ethanol as a feedstock for SAF. LanzaJet is pursuing approval for ethanol made from other feedstocks as well, including novel and waste-based sources.
In December, LanzaJet hit another major project milestone with the completion of construction and fabrication, and the start of installation for its trademarked alcohol-to-jet technology. The plant is on track to be completed and begin startup later this year. “We’re most looking forward to seeing our sustainable aviation fuel from LanzaJet Freedom Pines Fuels serve as a compatible, drop-in replacement fuel for existing aircraft currently in use around the world that can significantly reduce aviation lifecycle emissions today,” Meg Whitty, vice president, corporate relations and marketing with LanzaJet, tells Ethanol Producer Magazine. “The facility is planning to fully transition to second-generation ethanol in the coming years as production develops and supply chains mature, establishing a new market for scalable ethanol from waste-based sources.”
Whitty explains that LanzaJet is simultaneously working on developing additional projects around the world. “We’re excited to play a significant part in building and scaling a new industry while enjoying the privilege of partnership with incredible public and private sector leaders that have supported the work on this journey,” she states.
LanzaJet signed a memorandum of understanding in 2022 with Marquis Sustainable Aviation Fuel to build an SAF plant in Illinois, while also receiving government grant funding in the U.K. to support the deployment of its technology there. In early 2023, the company announced a memorandum of understanding with Indian Oil Corporation to pursue a joint venture to produce SAF in India.
Blue Blade Energy
Green Plains, Tallgrass Energy and United Airlines announced a joint venture in January to pursue the commercial production of SAF by developing a novel technology that uses ethanol as its feedstock. Should the technology succeed, they plan to start construction on a pilot facility in 2024, followed by a commercial facility in 2028. The offtake agreement could provide enough SAF to supply 50,000 flights between United’s hub airports in Denver and Chicago.
“Our transformation to a true decarbonized biorefinery model has positioned Green Plains to help our customers and partners reduce the carbon intensity of their products by producing low-carbon proteins, oils, sugars and, now, decarbonized ethanol to be used in SAF,” said Todd Becker, president and CEO of Green Plains in a January press release announcing Blue Blade. “This partnership with world-class organizations like United Airlines and Tallgrass, shows the value creation that is possible with our low-carbon platform. The potential impact of this project is a gamechanger for U.S. agriculture, aligning a strong farm economy and a robust aviation transport industry focused on decarbonizing our skies.”
The technology Blue Blade plans to use was initially developed by Pacific Northwest National Laboratory. Tallgrass will manage the research and development of the technology, including development of the pilot plant, as well as managing construction of the production facility. Green Plains will supply low-carbon ethanol to the SAF plant and manage its operation. United will assist with SAF development, fuel certification and “into-wing” logistics. The airline company has agreed to buy up to 2.7 billion gallons of SAF produced from the joint venture (over 20 years), according to the press release.
“The production and use of SAF is the most effective and scalable tool the airline industry has to reduce carbon emissions and United continues to lead the way,” said United Airlines Ventures President Michael Leskinen. “This new joint venture includes two expert collaborators that have the experience to construct and operate large-scale infrastructure, as well as the feedstock supply necessary for success. Once operational, Blue Blade Energy has the potential to create United’s largest source of SAF, providing up to 135 million gallons of fuel annually.”
SAFFiRE Renewables is partnered with Southwest to make cellulosic SAF with an ultra-low CI score, using corn stover as a feedstock. Mark Yancey, chief technology officer with D3MAX and SAFFiRE (an acronym for Sustainable Aviation Fuel from Renewable Ethanol) explains the potential of corn stover and other agricultural residues as feedstock. “Since corn is the biggest crop in the U.S., it is the biggest agricultural residue available by far, bigger than anything else,” he says. “It just makes sense for SAFFiRE to start with corn stover, but I see us moving to wheat straw, energy crops, switchgrass and other fast-growing crops down the road. But with corn stover alone, I think we could conceivably produce seven-and-a-half billion gallons of SAF with SAFFiRE technology. Theoretically, it could approach 10 billion gallons based on how much stover is out there.”
SAFFiRE’s cellulosic SAF will have an estimated CI score of 15, without the addition of renewable energy and carbon capture and sequestration technology, which would lower the CI score further.
With matching funding from the DOE’s SAF Grand Challenge, SAFFiRE aims to commercialize a low-temperature deacetylation and mechanical refining pretreatment process first created and tested at the National Renewable Energy Laboratory in Colorado. The process combines enzymatic hydrolysis and C5/C6 sugar fermentation to make cellulosic ethanol. DOE selected SAFFiRE to prove its technology at pilot scale before ramping it up to produce commercial volumes of ethanol as a biointermediate feedstock for SAF.
The company is in the mid-to-late stages of what it calls Phase One, which involves completing the plant design, permitting, updating lifecycle analysis, working on the business plan, updating the financial analysis and more, Yancey explains. With the project’s first phase scheduled for completion by the end of August, pending DOE reviews, SAFFiRE will move into Phase Two.
“Once the design package is completed, there will be another validation step with the DOE and the third-party engineering company,” O’Brien explains. If they look at the package and think everything looks promising and reasonable—the technology is there, the due diligence is there—then we will move on to further finalizing design, construction and operation. So that will be the exciting piece, when we get into Phase Two of this, which would be completing construction and operating the pilot plant for a year.”
Multiple key partners have been contracted to make the plant a reality, including engineering firm Advance Bio (to design the plant); Equinox (to handle feedstock procurement); Novozymes (to provide enzymes to the pilot plant) and Lallemand (to provide yeast).
The pilot plant, when built, will produce roughly 800 gallons of cellulosic ethanol per day, or the capacity to produce and ship 8,000 gallons of SAF every 10 days. The construction of commercial-scale SAF biorefineries would eventually follow.
Gevo: Net-Zero 1
Technology company Gevo has its Net-Zero 1 project underway in Lake Preston, South Dakota. The project will utilize ethanol made from low-carbon corn as the feedstock for SAF, oxygenated blendstocks for gasoline and renewable premium gasoline. Gevo broke ground in September at its 240-acre location in Lake Preston. According to a January update from the company, the facility is projected to produce 65 MMgy of renewable liquid hydrocarbons, including 55 MMgy of SAF. This volume is part of the roughly 375 million gallons of SAF Gevo is contracted to provide to the airlines it has signed agreements with, including Virgin Atlantic, Iberia Airlines, Qatar Airlines, Delta, Japan Airlines and others.
The Net-Zero 1 plant will utilize regenerative agriculture, carbon capture and sequestration, biogas, green hydrogen and renewable energy to reach net-zero carbon emissions as calculated with the GREET model.
In January, Ethanol Producer Magazine reported that Net-Zero 1 is on track to startup in 2025. At the time, Gevo had nearly completed front-end engineering design work and selected an engineering, procurement and construction contractor for the project. Gevo plans to develop other facilities for the production of SAF and has signed letters of intent with existing ethanol plants that are good candidates to develop alcohol-to-jet technologies, while other projects would be greenfield facilities. “We remain on track with our projects and I am very optimistic about the future of Gevo’s 1-billion-gallons-per-year goal of Net-Zero fuels,” Patrick Gruber, CEO of Gevo, stated in a January project update. “We have multiple attractive sites that we are considering for Net-Zero 2 and beyond. Our process to raise project financing is underway and going well. I believe that momentum is going our way.”
Gruber went on to point out the significance of the federal SAF tax credit and the new Illinois SAF credit. “This bill allows for the use of Argonne GREET, inclusive of agricultural practices and CCS, to measure carbon intensity score,” he said, suggesting that Gevo's low-carbon corn ethanol SAF could qualify for the state incentive.
Honeywell: Ethanol to SAF Technology
Technology development company Honeywell has developed an alcohol-to-jet technology that produces SAF with an 80 percent carbon reduction over fossil-based jet fuel, according to the comapny. “The new technology that we’re launching right now ... takes ethanol, processes it and converts it into aviation fuel” says Kevin O’Neil with Honeywell UOP.
O’Neil explains that the company sees the market for this technology coming from several places including existing ethanol plants, oil refiners and project developers. According to O’Neil, Honeywell has the capability to modularize its plants, building the pieces off-site and then delivering SAF plants to ethanol producers for on-site installation. “The [process] can be very simple and very quick, and you can save a lot of time that way, you can also save a lot of cost, you don’t need large pools of labor out in the middle of rural areas to construct a plant, you can do it in a shop where that labor already exists,” O’Neil says.
Honeywell’s process starts with dehydrating the ethanol to make ethylene, which is then run through oligomerization, and finishes with hydrogenation to saturate the olefin molecules in hydrogen. The SAF is essentially finished after this step, but it is run through a final refining step to ensure it meets ASTM standards.
“We’ve been talking to a lot of producers who are looking for alternate uses for their ethanol, and asking, 'What can I do if the gasoline market starts to slow down or starts to get less profitable.' And ... adding a little bit of processing to convert their ethanol to SAF is a very attractive option to basically every ethanol producer we’ve talked to,” O’Neil says.
In a world where around seven million barrels of aviation fuel are used each day across the planet, O’Neil believes that the progress being made with SAF is going to make a big impact. “We’ve developed something that we think is robust and ultimately will serve the market with the lowest possible cost,” he says.
BASF: Catalyst for Bio-Ethylene from Ethanol
BASF has brought its CircleStar dehydration catalyst to the market, which assists in dehydrating ethanol for conversion into ethylene. Kerstin Hoffman, global communications officer with BASF, explains that CircleStar enables lower temperature operation of the E2E process and helps further decrease the footprint of bio-ethylene by 10 percent while maintaining the same performance. The development of this product is part of BASF’s role as a “key enabler” in attaining a net-zero transformation.
“We understand the challenges of the traditional E2E catalyst, [for example] high pressure drop in the reactor, byproduct formation and coking due to mass transfer limitation,” Hoffman explains.
“Therefore, we developed CircleStar to solve those challenges and to support the commercialization of bio-ethylene with lower PCF.”
Bio-ethylene is a crucial component of many chemical processes, including the production of SAF. This catalyst provides producers with a variety of different benefits, including reduction in energy costs for the dehydration process, less mechanical wear out and more.
A September press release explains that the catalyst’s performance is due to its novel star shape “that maximizes the active geometrical surface area for the reaction.”
With a growing demand for SAF, both Gen 1 and Gen 2 ethanol producers have an opportunity to put their product into a new market in line with the mission they've shared for decades: reducing carbon emissions.
SAF producers and developers agree that ethanol is a key feedstock that will help advance the SAF industry and meet the decarbonization goals set in both the private and public sector.
Author: Katie Schroeder
Printed in the April 2023 issue of Ethanol Producer Magazine