Primed for Commercialization

Sustainable aviation fuel set for explosive growth, offering a potential market for ethanol as feedstock.
By Susanne Retka Schill | June 07, 2021

Interest in sustainable aviation fuel (SAF) is taking off with all the renewed focus on reducing global greenhouse gases. Yet, while alcohol-to-jet fuel (ATF) is one of several approved processing options, it’s uncertain whether corn ethanol will be favored as a feedstock in what could be explosive SAF growth.

One ASTM-approved pathway has reached commercialization status—hydro processed esters and fatty acids (HEFA) using fats, oils and greases. A second ASTM-approved pathway—alcohol to jet (ATJ)—will reach commercialization in the next couple of years. Both pathways are approved for up to 50% blending, with work ongoing to expand the blend rate.

Counting the projects that have already been announced, Steve Csonka, executive director of the Commercial Aviation Alternative Fuels Initiative, says SAF capacity could reach 1 billion gallons by 2025, amounting to a 1% blend rate. “If you count work going on that hasn’t been publicly announced, we could maybe even get to 2% by 2026,” he says. Global aviation consumed just over 100 billion gallons of jet fuel in 2019, with expectations that total consumption will more than double by 2050.  

Coming Online
LanzaJet is one of the companies expected to bring commercial production of ATJ fuel online next year. Beginning this spring, Burns & McDonnell is engineering and installing utilities and infrastructure at LanzaTech’s Freedom Pines R&D and demo site in Soperton, Georgia. Engineering firm Zeton is simultaneously building the first 10 MMgy modular system at its factory, for the LanzaTech site. Burns & McDonnell’s site work is expected to be completed early next summer when the modules are scheduled to arrive.

The modular approach is efficient, says LanzaJet CEO Jimmy Samartzis. “When the module arrives, you’re not starting from scratch. The unit has been tested and commissioned in large part.” LanzaJet expects to use factory-built modules for facilities aiming at 10 to 30 MMgy production rates, and a mixture of stick-built plus modular construction for larger facilities, Samartzis says. “When you think about what we want to accomplish with ethanol as the feedstock and a focus on local or regionally sourced ethanol, keeping them at this size makes sense in terms of sustainability.”

LanzaJet’s ATJ modular approach complements parent company LanzaTech’s technology that uses carbon-rich gases to feed its microbial conversion process. Getting its start with biomass gasification, LanzaTech pivoted in 2011 to using steel mill flue gas as the carbon source. Its joint venture in China scaled up the process and has successfully reached 10 MMgy commercial scale producing ethanol and other biobased chemicals.

A year after beginning work in China, LanzaTech joined a collaboration led by the Pacific Northwest National Laboratory using waste-based ethanol as the feedstock for ATJ process development. LanzaTech acquired the technology in 2018 and formed LanzaJet to launch commercialization.

LanzaJet technology is based on the unique catalysts developed by the PNNL collaboration. The ATJ process starts with dehydration, running ethanol through a reactor with a catalyst to remove water. The resulting ethylene hydrocarbons are then combined using a second catalyst to build the range of carbon chains needed for jet fuel in a process called oligomerization. Another catalyst hydrogenates the carbon chains, which are then fractionated into synthetic paraffinic kerosene as renewable diesel and jet fuel.

The LanzaJet technology is unique among the handful of competing ATJ technologies, Samartzis says, in being able to produce up to 90% SAF and 10% renewable diesel, with no other products. If desired, the mix can be adjusted to produce as much as 75% renewable diesel and 25% SAF.

Launched in June 2020, LanzaJet has secured off-take agreements for all of the Georgia production with Suncor, British Airways and All Nippon Airways and attracted major investors.

“We are fortunate to have Suncor, Mitsui and Shell as investors because they all play in ethanol markets in different ways,” Samartzis says. “Mitsui is a pretty significant ethanol trader. Suncor has operations and involvement in ethanol in Canada and the U.S., and Shell, obviously has an interest.” Each of the partners brings a geographic interest, he notes, that will potentially result in projects in Japan, North America, the U.K., Europe and around the globe.

A European project launched in December targets operations beginning in 2024, Samartzis adds. The FLITE (Fuel via Low Carbon Integrated Technology from Ethanol) consortium received a 20 million-euro EU grant to build an ATJ plant using LanzaJet technology. Site selection and other details will be announced in the coming months.

The European Union and U.K. have a strong focus on waste-based feedstocks, Samartzis says, although ethanol from any feedstock is suited for the LanzaJet process. “For us, a lot comes down to what are the supporting policies for sustainable aviation fuel and what is required to participate in those mechanisms? It’s also about what end users want to fly on.” In some cases, it’s not the feedstock that is the concern, but the country of origin.

“In the right markets, our gallons of SAF get close to being competitive with conventional jet fuel, but that is enabled by policy,” he says, adding that there’s a reason the majority of SAF in the U.S. is used in California, where the value of carbon credits under the Low Carbon Fuel Standard creates favorable economics.

Sustainability Scoring
The aviation industry has its own carbon scoring and development mechanism as part of a broad policy framework developed by the International Civil Aviation Organization. Under the carbon offsetting and reduction scheme for international aviation (CORSIA), the default analysis of U.S. corn ethanol for ATJ scores at 55.8 grams/megajoule, Csonka says. Another 22 grams is added for land use change, resulting in only a 12.5% reduction in carbon relative to jet fuel’s baseline. “U.S. airlines are primarily interested in greater levels of reduction, although there may be some airlines in some parts of the world that might accept such scores,” he says. CORSIA does allow petitions to replace the default value with assessments that use actual data to potentially lower the carbon intensity, he adds.

Corn ethanol faces hurdles, Csonka admits. “I know folks have asked EPA to go back and do a reassessment on what the baseline life cycle analysis looks like for corn ethanol today. I hope that work gets done. Having worked with some of the folks providing technology in this space, I agree that they’ve made leaps and bounds over the past few years.”

Discussions around sustainability with nongovernmental organizations go beyond carbon intensity scores to include issues around water quality, land use change and food versus fuels. “There are things out there that can be done to make ethanol production look more attractive to everyone involved,” Csonka says, citing cover crops as an example.

Csonka is particularly interested in new oilseed cover crops such as pennycress or carinata. “One of the ways to lower the life cycle analysis for ethanol and biodiesel is to introduce a winter cover crop. It’s more work, but it addresses multiple things: an incremental revenue source with three crops in two years instead of two, no new equipment, and addresses issues with pesticides, herbicides, nematode control, pollinator habitats, water quality, erosion control and soil carbon sequestration.”

Expanding oilseed crops and tapping into ethanol producers’ corn oil coproduct would actually be the fastest way of ramping up SAF production, Csonka explains. As the most mature technology, the HEFA pathway converting lipids into SAF is beginning to drive down costs. Furthermore, the supply chain for oilseed crops is established and adaptable to new crops alongside existing soy and canola feedstocks. Supplying distillers corn oil will likely be the way corn ethanol producers will first participate in SAF, he says.

In preliminary modeling, LanzaJet ATJ fuel sees an 80% reduction in carbon intensity relative to conventional aviation fuel when using waste-based feed sources. Much depends upon the market and the model used to calculate carbon intensity, Samartzis says. “With the California Low Carbon Fuel Standard, it’s one thing and with EPA, it’s different and it depends upon the feedstock. Our process itself adds some carbon intensity to the overall equation, but it’s not a lot. The bulk of the carbon intensity impact is from the ethanol itself,” he says. “We’re still in the middle of modeling that out with different feedstocks and different markets.”

An advantage for LanzaJet is that the ethanol feedstock needed for its ATJ process is produced at commercial volumes around the globe. Samartzis does not rule out any ethanol source. “We’re also talking to corn ethanol producers in the U.S.,” he says. “There are some terrific stories of low-carbon corn ethanol opportunities. I don’t want to discount that. I think it’s a matter of keeping all these various interests in mind and aligned as we move these technologies forward.”

Author: Susanne Retka Schill
Freelance Journalist

Published in July 2021 issue of Ethanol Producer Magazine