Fueling change: FAQ on sustainable aviation and protecting our waters
FMR supporters always have good questions about complex topics. We put together this FAQ to make it easy to get the facts about the promise and potential pitfalls around sustainable aviation fuel.
Many industries, including aviation, are striving to reduce their carbon footprints. Airlines aim to significantly increase the production of lower-carbon sustainable aviation fuel (or "SAF") to tens of billions of gallons annually.
In fall 2024, the first SAF-fueled commercial flight departed from MSP airport. FMR was there in support, as the fuel utilized winter-hardy oilseeds that benefit Minnesota's landscape and waters.
But it's not a given that SAF will be made with this clean-water crop.
Public and corporate policymakers are currently deciding which SAF sources (referred to as "feedstocks") to support. Their choices will impact land use and water quality for generations to come.
We've created the FAQ below to help supporters, partners and policymakers understand SAF and FMR's engagement so far, and to advocate for choices that benefit the river, drinking water, Minnesotans and our environment.
Sustainable aviation fuel basics
What is sustainable aviation fuel, aka SAF?
Sustainable aviation fuel, or "SAF," is a substitute for petroleum-based jet fuel that (by law) emits at least 50% fewer greenhouse gases.
It can be created from a variety of sources (referred to as "feedstocks"), including crops like corn and oilseeds, forestry residues, hydrogen, rendered animal fats and even used cooking oil. It's a "drop-in" replacement that can be used in existing jets.
Of all the available options, FMR only supports SAF made from winter-hardy oilseeds.
Is sustainable aviation fuel safe?
Yes.
SAF undergoes extensive testing and certification to make sure it's as safe as — and performs as well as — petroleum-based jet fuel.
It's already being used in small volumes by some commercial operators. The European Union requires airports to use 2% SAF. By 2050, the minimum will increase to 70%.
In North America, the first commercial flight fueled in part by winter-hardy oilseeds took off from MSP in fall 2024, arriving safely and problem-free in New York.
Do we need sustainable aviation fuel?
If we want to bring down aviation emissions, and we want to do it sooner rather than later: Yes.
The vast majority — over 97% — of greenhouse gas emissions from flying come from fuel use. Which means to make a real impact, we have to address that root source of emissions.
Batteries won’t work for large airplanes; they would need to be so big that the plane would not be able to take off. And due to safety and testing constraints, developing wholly new technology would take more time than we have to start reducing emissions.
We need SAF as a near-term solution: a fuel that can be phased in to replace jet fuel, in the airplanes we already have, with lower emissions.
However it also needs to be the right kind of SAF.
If it's so important to reduce aviation emissions, can't we just fly less?
We all should minimize our carbon footprint, and we applaud people who opt to fly less. FMR also welcomes investments in high-speed rail and public transit.
But here’s the reality: Today, the global aviation industry makes up 2% of greenhouse gas emissions, equivalent to roughly Brazil’s total emissions. As more countries become wealthier and more people can afford to fly regularly, this number is expected to increase dramatically. In fact, the aviation industry projects more than double the air traffic by 2050.
We need to encourage behavior change while also implementing strategies to decarbonize aviation.
Additionally, SAF developed for commercial flights could be used for flights (cargo and military) beyond the realm of individual behavior change.
Will we lose habitat by converting land to grow crops needed for SAF?
If industry leaders and policymakers make the wrong choices: Yes.
But not if we use winter-hardy oilseeds as a source crop.
In addition to their water quality benefits, these oilseeds do not require new land. They are grown (over the fall, winter and spring) on the same acres as the primary summer crop (such as corn or soybeans).
They neither incentivize the conversion of Minnesota grasslands or forests into farmland, nor drive deforestation in other countries. (Researchers are even studying their potential to provide habitat for pollinators and other wildlife.)
This is a primary reason for their low carbon intensity, and it's what makes them a real outlier among near-term SAF options.
If we choose to incentivize corn and soybeans instead, when the SAF market takes off, so will corn and soy prices, upping demand for new farmland and the potential plowing of grasslands and forests.
Friends of the Mississippi River's position and role
Does FMR support all sustainable aviation fuels?
No.
FMR supports SAF made from two clean-water crops: camelina and pennycress. These crops are known as winter-hardy oilseeds because they’ve been developed to withstand the frigid climate of the upper Midwest.
We also support the development of green hydrogen and other technologies that meet our standards for future SAF creation.
Why is FMR involved? How does this relate to the river?
Millions of acres of cropland in Minnesota lie brown, barren and exposed to the elements for seven or eight months at a time, each and every year. This recurring "big brown spot" allows fertilizer and sediment to more easily flow into our rivers, streams and other waters, sometimes contaminating drinking water supplies.
Winter-hardy oilseeds could be grown on existing farm acres that also grow corn, soy and other crops, turning the "big brown spot" green and significantly reducing water pollution.
And because they can be grown on current agricultural lands, we can protect natural areas and habitat.
(See above: "Will we lose habitat by converting land to grow crops needed for sustainable aviation fuel?")
What is FMR doing?
We — FMR, our River Guardians and many partners — have been advocating for a suite of “clean-water crops” for years, supporting their research and development, market development and farmer adoption.
Winter-hardy oilseeds, the main SAF feedstock we advocate for, are part of this suite of crops. They offer significant environmental benefits, including reducing nitrogen loss, soil erosion and greenhouse gas emissions.
We’re also actively engaging with public and private decision-makers, advocating for the most socially and environmentally responsible approach in order to steer SAF toward actual sustainability (and away from potentially damaging choices).
Is SAF truly sustainable?
It depends.
The risks and consequences of a poorly managed transition to SAF are significant.
In 2024, with partners The Nature Conservancy and Fresh Energy, we released guiding principles to help define and advocate for the most socially and environmentally responsible approach.
We continue to inform policymakers and industry leaders at the state and federal levels of these principles, urging them to make the right choices for the near term and generations to come.
Carbon footprints
What is SAF’s carbon footprint?
This depends on a lot of factors
SAF can be made from a wide variety of feedstocks, and the carbon footprint of the final product depends on the materials and processes used to produce it.
SAF made from corn ethanol has a high carbon footprint in part because corn needs a lot of fertilizer.
SAF made from winter-hardy oilseeds already has a much lower carbon footprint because of how and when farmers grow these crops. And it will drop even further. Forever Green researchers continue to breed better varieties, decreasing fertilizer use while improving yields — driving the carbon footprint even further downward.
Are zero-emission fuel options available?
Not yet.
SAF created from "green hydrogen" has the potential for near-zero emissions if it's produced with renewable energy and captured carbon. However, this technology is still in very early development and is not expected to come online until at least the 2040s.
It also requires a lot of clean energy. If we wanted to use green hydrogen (also called "power to liquid SAF") to replace all of the jet fuel at Minneapolis-St. Paul Airport, we would need to double the number of solar panels and wind farms in Minnesota.
Why winter-hardy oilseeds?
Why winter-hardy oilseeds?
Winter-hardy oilseeds have many significant advantages over other potential SAF source crops such as corn, soybeans and canola.
They improve water quality by providing ground cover during the fall and spring, when agricultural lands lose nutrients and topsoil to the elements.
If farmers grow these oilseeds back-to-back with soybeans, they can produce 50% more vegetable oil from the two crops on the same acreage.
They have a much lower carbon intensity than other commodity crops, resulting in lower greenhouse gas emissions.
Perhaps most importantly, they can be grown on existing farmlands with other crops, meaning that they will not create the demand for new farm acreage that other SAF feedstocks will likely create.
(See above: “Will we lose habitat by converting land to grow crops needed for sustainable aviation fuel?”)
Can’t we just use corn and soybeans?
Farmers in the U.S. typically plant 90-95 million acres of corn every year in order to meet all of our current needs (including human food, animal feed and fuels).
To produce the Department of Energy’s goal of 35 billion gallons of SAF entirely using corn-ethanol, we would need 114 million acres of corn — just for jet fuel.
We don’t have the space for that much new corn. Where would we put it?
Going this route would incentivize the conversion of grasslands, forests and wetlands into farmland. It would require planting in poor-quality farmlands that have to be supplemented with more fertilizer and more pesticides. The environmental impact of such land conversion would drastically outweigh any carbon benefits from SAF.
The production of fertilizer (which is usually nitrogen-based) also has a sizable carbon footprint. After it’s applied, spring snowmelt or a heavy rain carries any excess fertilizer into our waters. (In part because 97% of Minnesota cropland acres do not use cover crops.) This can lead to serious nitrate pollution problems like those we’re seeing in southeastern Minnesota (more from FMR, more from PCA).
Winter oilseeds are new. Can they be a major source of aviation fuel right now?
SAF and winter-hardy oilseeds are both in their early development phases. If we incentivize winter-hardy oilseeds as a feedstock, then SAF and oilseeds will scale up together.
Winter oilseeds are at the beginning of a years-long journey to becoming a high-volume feedstock. Although it may be hard to imagine, soybeans were once a novelty on the landscape. It took government and industry investments in research, development and supply chains to facilitate their now-widespread adoption.
So just like soybeans or corn, winter-hardy oilseeds can get there.
FMR’s Putting Down Roots analysis found that by 2035, winter camelina and pennycress could reasonably be integrated into 1.2-3 million acres of row crop production here in Minnesota.
FMR is currently working with partners to create a blueprint for reaching the first million of those acres.
Economics
Are winter-hardy oilseeds more expensive than traditional cover crops?
Production costs are about the same — but oilseeds can be harvested and sold for a profit.
Most Minnesota farmers who use traditional cover crops simply terminate or kill them in the spring, before planting a primary crop like corn.
This benefits soil health and long-term soil productivity, but even with taxpayer subsidies for cover crops, it’s an investment with up-front costs for farmers.
Winter-hardy oilseeds are likewise grown in rotation in fields with another primary crop, but they are in demand as a harvested crop, meaning that purchasers help bear the costs of production.
Profit is the key that unlocks scale. Today, only about 3% of MN’s cropland acres use cover crops. If we incentivize winter-hardy oilseeds, we create a win-win situation: Winter cover crops on tens of millions of acres of existing farm fields in our region, benefiting our environment and farmers alike.
Will a farmer lose money trying to grow winter-hardy oilseeds?
Long-term, as camelina and pennycress scale up, the market will make sure these crops are profitable.
Overall farm incomes are expected to decline over the next decades. If SAF is made from winter-hardy oilseeds, winter camelina and pennycress could be important additional revenue streams for farmers. If SAF is made from winter-hardy oilseeds, winter camelina and pennycress could be important additional revenue streams for farmers.
During this early or pilot stage of commercialization, farmers in Minnesota are supported by a Forever Green program that protects against losses and rewards ecosystem services. It also includes secure purchase agreements from a major agribusiness.
Will growing winter-hardy oilseeds hurt the yield of other crops?
Winter-hardy oilseeds can cause what’s called “yield drag” on the following crop (such as soybeans), reducing the summer harvest. But the overall yield of a camelina-soybean system is up to 50% more than growing soy alone, meaning it’s a net win. Researchers are also continuing to drive drag further down and increase profits.
Does winter oilseed aviation fuel cost more than SAF from other feedstocks?
For now, yes.
SAF makers or processors currently pay a premium for winter-hardy oilseeds compared to other feedstocks like corn. But winter camelina and pennycress are in the early stages of breeding and commercialization. As they mature, they will reach the yields and economies of scale that drive costs down over time.
This is why public investments are needed in the early commercial stage of development. Much like taxpayers subsidized wind and solar to encourage energy companies to invest in renewables, airlines rely on tax credits to keep costs comparable between conventional jet fuel and SAF. (This encourages airlines to buy and use SAF without needing to hike ticket prices.)
What do you mean by "public investments?" What does that entail?
A few things.
There are tax credits, for example. Current federal tax credits are sliding-scale and reward higher emissions reductions, so winter-hardy oilseeds should have a much bigger bang for taxpayers’ and passengers’ bucks. The state of Minnesota can also shape SAF by offering tax credits with important environmental guardrails.
And we need to continue to invest in research and farm safety-net programs to level the playing field between oilseeds and less advantageous (and potentially damaging) SAF feedstocks.
Do we need to subsidize winter-hardy oilseeds for SAF?
If we want clean water in Minnesota, then yes, we should subsidize the use of winter-hardy oilseeds for SAF.
Subsidies are a part of agriculture. The real choice is not whether we subsidize but what we subsidize. Even the two most-grown crops (corn and soybeans) benefit from public subsidies — and at a scale that dwarfs both the current and potential future costs for winter-hardy oilseeds.
FMR is a member of the National Sustainable Agriculture Coalition, where we’re rethinking how taxpayer dollars can promote conservation and equity in the sector.
We believe taxpayers have a responsibility to share the costs of transitioning to greener systems.
Where would the solar and wind industries be today without early and ongoing support from the public? There’s a clear difference between subsidizing coal plants and subsidizing renewable energy, and the same principles apply here.
And today, wind and solar energy, which used to be extremely expensive, are cheaper than coal.
Profit is the key that unlocks scale. Today, only about 3% of MN’s cropland acres use cover crops. If we incentivize winter-hardy oilseeds, we create a win-win situation: Winter cover crops on tens of millions of acres of existing farm fields in our region, benefiting our environment and farmers alike.
How can I help?
Without environmental advocates at the table, sustainable aviation fuel could take off in the wrong direction. We're in this not only to protect the river from the worst outcomes, but to push toward a solution that could help restore our waters.
If you’re with an organization that would like to be more deeply involved, you can learn more by viewing our other SAF-related content and downloading the landmark report "Putting Down Roots." This report lays out a realistic path to cleaner waters and more profitable farms through the use of continuous living cover. If you still have questions, feel free to reach out to us as well at safquestions@fmr.org. We'll update this page as needed.
If you're an individual, please sign up to be a River Guardian. We alert our River Guardian advocates when there's a chance to shape sustainable aviation fuel policy to benefit climate, farmers, wildlife and our waters. See our latest action alerts.
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