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Ethanol’s Own SAF Runway

Luke Geiver

May 22, 2022

The world’s major airlines are racing to decarbonize air travel by backing and using sustainable aviation fuel. Much of it is now being produced via plant-based oils in tandem with renewable diesel. Soon, it may also come from ethanol.

The production of sustainable aviation fuel (SAF) is about to take off. Airline groups, government agencies and tech developers are all aligning to utilize low-carbon, biobased jet fuel for a market that currently requires 106 billion gallons per year. The U.S. Energy Information Administration predicts the demand for commercial jet fuel will surpass 230 billion gallons per year by 2050. In the near-term, aviation companies want to run SAF now. Headlines on the subject no longer focus on the mere possibility of sustainable feedstocks for air travel fuel—or test-flights flown with small amounts of SAF. Instead, news and discussion of SAF today includes headlines, press releases and announcements about SAF production plants breaking ground, and producers locking into long-term supply agreements with airline conglomerates. For SAF, it’s wheels up.

To date, multiple SAF production groups have focused on the use of triglycerides as feedstock for the in-demand, renewable drop-in fuel. In late March, Airbus performed the first A380 flight using 100 percent SAF. That flight, near France, utilized unblended fuel provided by TotalEnergies made from hydroprocessed esters and fatty acids. In the past six months however, the story on SAF has been shifting. A new SAF feedstock has gained the attention of Delta Airlines, British Airways and numerous other aviation giants.

Low- and potentially zero-carbon ethanol is now an SAF feedstock held in high regard. Speaking to the crowd at the National Ethanol Conference earlier this year, William Collings, mechanical engineer and consultant for 1898 & Co., said the use of triglycerides for SAF is slowing down because there is not a lot of it out there. “Maybe the next triglyceride isn’t a triglyceride at all,” he said. “Maybe it is ethanol.”

The U.S. Department of Energy has created the Sustainable Aviation Fuel Grand Challenge, to deal with the cost, sustainability and production of SAF. D3MAX, a fiber-to-ethanol production company with an operational system running at Ace Ethanol LLC in Stanley, Wisconsin, offers a glimpse into the merit in Collings’ assessment of ethanol as an SAF feedstock.

Earlier this year, Mark Yancy, chief technology officer at D3MAX, helped create a spin-off entity to focus on the SAF opportunity. SAFFiRE (Sustainable Aviation Fuel from Renewable Ethanol), will demonstrate reliable, low-greenhouse gas (GHG) production of SAF from corn stover in a fully integrated, 10-metric ton per day pilot-scale facility. Yancy and the SAFFiRE team will utilize funding from DOE’s SAF Grand Challenge. The company aims to commercialize a novel process first created and tested at the National Renewable Energy Laboratory in Colorado. NREL has already proven how well the low-temperature deacetylation and mechanical refining pretreatment process can work when combined with enzymatic hydrolysis and C5/C6 sugar fermentation—the platform SAFFiRE will use to make the cellulosic ethanol building block of bio-jet fuel. 

DOE selected SAFFiRE to prove its technology at pilot scale before ramping it up to produce commercial volumes of ethanol intermediate product. Along with other partners, Yancy’s team will be working with another SAF staple, LanzaJet. Later this year, SAFFiRE will begin verifying the data provided to the DOE. It’s not just government agencies, aviation entities or other SAF tech providers that want to engage with projects like SAFFiRE’s. Ethanol producers are now joining in as well. Lincolnway Energy LLC, a 50 MMgy dry mill corn-to-ethanol plant in Nevada, Iowa, will host the SAFFiRE project. Lallemand is providing the yeast products and Novozymes will provide enzymes. “We’ve already demonstrated that this process works,” Yancy says.

It isn’t hard to see why the DOE selected the project for multi-round funding. NREL has already calculated that SAF produced using the SAFFiRE approach will record an 85 percent reduction in carbon intensity score. One of the mainstays of the process relies on the pH of the corn stover biomass. While other processes have utilized dilute acid pretreatment with low pH balances, (most of which have failed to date), SAFFiRE will raise the pH in a pretreatment process of the biomass. Most corn-stover-to-ethanol plants have failed, Yancy explained, because the pretreatment requirements for the process often caused system failures in equipment not capable, within financial reason, to handle the high-pressures needed early in the process. SAFFiRE’s approach can utilize stainless steel equipment that is off-the-shelf and obtainable  quickly. “This project will have low technology risk,” Yancy says. “Data from this will help create the first commercial plant.”

Gevo, a long-running, successful advanced biofuel, biochemicals and bioplastics producer, is also in the mix with top SAF pursuers. In February, Gevo signed a five-year, 200 MMgy deal with the Oneworld Alliance, a network of world-class airlines, for Gevo’s version of SAF. In March, Gevo added another major deal to its timeline. Delta Airlines signed a 75 million gallon per year offtake agreement with Gevo, also for its SAF. Through its partnership with Archer Daniels Midland Co., one of the leading ethanol producers in the world, Gevo has shown how feasible and possible ethanol-based aviation fuel is. ADM has pledged to use up to 900 million gallons of its ethanol production output with Gevo to produce aviation fuel, more than half of ADM’s yearly ethanol production volume. From that amount, Gevo and ADM expect to produce more than 500 million gallons of SAF and other sustainable products.

“SAF is one of those products that everyone understands the need for,” according to Patrick Gruber, CEO of Gevo. “It is energy dense. They have to be exact drop-ins. They have to be safe and proven. We are making jet fuel from carbohydrates and driving down the carbon footprint.”

To do that, Gevo is in the midst of developing what it calls a Net Zero Project. Located in Lake Preston, South Dakota, the project will produce energy-dense liquid hydrocarbons for use in ground and air transportation. Gruber says Gevo will be building an ethanol plant and then converting it to an alcohol-to-jet fuel plant. “All of it is going to be renewable.” The plant’s carbon intensity score will be reduced by minimizing or eliminating the use of on-grid energy in the form of electricity or fossil-based natural gas. The ethanol will be converted to ethylene and then to jet fuel. “The whole value proposition is about driving down the carbon footprint.”

Gruber has already experienced the demand and interest from major airlines, and he has the agreements to prove it. The company intends to deliver fuel in 2025 with more expansion along the way.

LanzaJet has also made headlines in the space this year. A spin-off of LanzaTech, the company formed in 2020 specifically to address the need for SAF. Last fall, LanzaJet hosted a tour of its first-ever sustainable fuels plant. This year, the company has already received $50 million in funding through the Microsoft Climate Innovation Fund. Recently, LanzaJet signed a deal with Marquis Sustainable Aviation Fuel to build an integrated SAF plant at a new sustainable energy site hosted by Marquis in Illinois. The memorandum of understanding between the two entities will create a 120 MMgy SAF plant. The plant will also include on-site carbon capture and sequestration and renewable energy to produce SAF, resulting in a lifecycle greenhouse gas reduction of more than 70 percent compared to conventional jet fuel.

Opportunities In SAF

Understanding the true opportunity for sustainable aviation fuel derived from ethanol or other renewable sources starts with CAAFI, the Commercial Aviation Alternative Fuels Initiative. CAAFI was formed in 2006, the same year the price of aviation fuel to the airline industry became an issue. In 2006, petroleum prices caused fuel to become the single largest component of U.S. airline operating costs for the first time in history, according to CAAFI. Since then, the initiative has been working to drive down the cost of aviation fuel while making it more environmentally friendly and sustainable. As a whole, commercial aviation in the U.S. drives 6 percent of the nation’s gross domestic product and just under 9 percent of national employment, according to CAAFI.

In 2020 alone, CAAFI leadership participated in more than 60 workshops, seminars and project discussions across the globe to push for SAF. In 2021, CAAFI had a banner year. And that excitement has spilled into 2022, with a slew of SAF announcements already made or coming soon. On the global scene, the U.S. and EU have both set lofty goals for SAF use. By 2030, the pair hope to use at least 4 billion gallons of SAF per year. By 2050, that number jumps to 45 billion gallons. Most producers believe the number is both achievable and possibly low, given the continued push for lower carbon fuel— which can only come from feedstocks like ethanol and other renewable sources.

Although the GHG reduction of SAF produced from companies like SAFFiRE can reach up to 85 percent (or 100 percent in some calculations by Gevo), the cost of the fuel is still an issue. Yancy says rough calculations show jet fuel currently costs in a range between $2.50 to $3.50 per gallon. SAF however, ranges in price from $6 to $8 per gallon. “The aviation industry not only needs billions of gallons of SAF,” Yancy says. “They need it at a lower price.”

Providing that fuel more cost-efficiently   may sound limiting to the developers of any production facility, but in many ways, it is a win-win for all involved. In the case of SAFFiRE, the corn stover it will need to produce SAF using its process will create an economic plus for corn farmers, Yancy says. Ethanol yields generally increase. So do corn yields, on a bushel-per-acre basis. For each pound of corn produced, a field creates a pound of corn stover. The corn stover-to-jet fuel process is a great solution to the excess corn stover, Yancy says. “This would be a huge amount of income to farmers. We project $80 a ton of stover. This would create economic development in rural communities.”

Gruber echoes Yancy on the benefit of SAF production to rural communities. Gevo is planning or already in discussions with several rural  ethanol plants to co-locate its net zero projects. Interested ethanol plants just need to know that Gevo will buy their product over the fence. “We are taking all of this into our own hands,” Gruber says of the push to lower carbon intensity scores. “We will go build our own infrastructure. The rural economy will benefit from us.”

Author: Luke Geiver


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