A little skepticism is sometimes necessary to keep sustainability honest.
That is particularly true in aviation, where almost every new environmental initiative arrives wrapped in reassuring language: renewable feedstocks, lower-carbon flying, cleaner infrastructure, net-zero commitments, and partnerships designed to accelerate the future.
The message is usually simple: We are doing something sustainable. Therefore, we are helping the environment.
But the real world is rarely that simple.
Delta Air Lines (DL) recently celebrated the completion of a sustainable aviation fuel (SAF) blending facility at Flint Hills Resources' Pine Bend refinery in Rosemount, Minnesota. According to Delta's July 27 announcement, the facility is expected to be capable of blending as much as 30 million gallons of neat, or unblended, SAF each year and sending the resulting fuel through an existing pipeline to Minneapolis–Saint Paul International Airport (MSP).
That is an important logistical development. Delta says it uses approximately 250 million gallons of jet fuel annually at MSP. If the facility handled 30 million gallons of neat SAF in a year, and if all of it were allocated to Delta at MSP, that volume would equal 12% of the airline's stated annual fuel use at the airport.
Every clause in that sentence matters. Twelve percent is an arithmetic comparison, not a forecast. It does not establish how much SAF has been contracted, how fully the facility will be used, how much will go to Delta, or how much lifecycle carbon will be avoided.
The celebration should not end the conversation. It should begin one.
A Blending Facility Is Not a Production Plant
The first detail easily lost in the announcement is that Pine Bend is not presented as the plant making the SAF. Its disclosed function is to receive neat SAF, store it, blend it with conventional jet fuel produced by Flint Hills, and move the finished blend into the airport's fuel supply.
Delta's original September 2024 project announcement said Shell would supply the neat SAF. In July 2026, Delta separately announced a five-year agreement under which Shell will support neat and blended SAF deliveries at selected hubs and cities, including MSP.
That establishes a continuing role for Shell in Delta's SAF logistics. It does not answer every lifecycle question.
One likely production source has been identified outside the opening announcement. A July 1 MinnPost report said MSP's first batches would travel nearly 1,000 miles from Montana Renewables' plant in Great Falls, Montana. Delta and Montana Renewables also documented a separate 2024 proof shipment in which camelina-based SAF traveled from the Great Falls plant directly to MSP, before the Pine Bend facility opened.
It would therefore overstate the case to say that no producer has ever been identified. Montana Renewables is the best-supported likely initial source. But Delta's opening announcement does not confirm that plant as Pine Bend's supplier, and the public materials do not identify the feedstock for future Pine Bend batches, their pathway-specific lifecycle value, their process-hydrogen source, their transport mode, or whether the supply will later include other producers. Montana Renewables lists several possible feedstocks, including used cooking oil, tallow, distillers corn oil, camelina, canola, and soybean oil. Naming the plant narrows the question; it does not answer it.
Those distinctions matter because the tanks, pumps, and valves in Minnesota are unlikely to determine most of the fuel's lifecycle footprint. The larger questions sit upstream.
SAF Is a Category, Not a Carbon Score
We need to get into the weeds. SAF can be made from used cooking oil, animal fats, oilseed crops, agricultural and forestry residues, municipal waste, alcohols, and captured carbon, among other inputs. Different feedstocks can travel through different conversion processes, and each combination brings its own requirements for heat, electricity, hydrogen, water, transport, and land.
The International Civil Aviation Organization's (ICAO) lifecycle framework expressly counts emissions associated with feedstock cultivation or collection, processing, transport, conversion into fuel, distribution, combustion, and, where applicable, induced land-use change. ICAO therefore assigns different default lifecycle values according to feedstock, conversion process, and production region.
The spread is not academic. ICAO's November 2025 defaults give hydroprocessed esters and fatty acids (HEFA) fuel made from used cooking oil a core lifecycle value of 13.9 grams of carbon-dioxide equivalent per megajoule. U.S. soybean-oil HEFA carries a 40.4 core value plus a 24.5 induced-land-use-change value, for a total of 64.9. Against ICAO's fossil-jet baseline of 89, those figures imply reductions of roughly 84% and 27%, respectively.
Those are illustrative default values, not measurements of any Pine Bend batch. That is exactly why the disclosure matters. The acronym does not reveal the result.
Nor is the label completely unregulated in every context. Under the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), a fuel must satisfy sustainability criteria and receive independent certification before it can be claimed as CORSIA-eligible SAF. But a corporate announcement that calls a product SAF does not tell the reader whether that specific batch is CORSIA-certified, which default or actual lifecycle value applies, or who will claim its environmental attributes.
Ask Where the Hydrogen Came From
Hydrogen is a useful example of why process details matter.
The dominant commercial SAF pathway is HEFA. It uses hydrogen and catalysts to remove oxygen from fats, oils, and greases and convert them into hydrocarbons suitable for further finishing and blending. The International Air Transport Association (IATA) says waste fats, oils, and greases remain the most common feedstocks because HEFA is the most mature pathway.
The hydrogen source can change the carbon intensity of that process. The U.S. Department of Energy says 95% of hydrogen produced in the United States comes from natural-gas reforming, a high-temperature process that produces carbon dioxide. ICAO's current default tables even specify correction values for some HEFA pathways when coal-derived hydrogen or coal process heat is used.
None of that proves the fuel supplied to Minnesota will use fossil-derived hydrogen. It means the public should not be expected to assume the opposite.
Pine Bend's Power Mix Needs Context
The same caution applies to electricity at the refinery.
Pine Bend has made substantial onsite-power investments. Flint Hills says the refinery operates a 45-megawatt solar installation and a 50-megawatt combined heat-and-power system. The company's 2024 community report says the two systems can satisfy as much as 70% of the refinery's power needs; Flint Hills' project fact sheet qualifies that figure as applying under optimal conditions.
That is meaningful. It is also easy to misread. The figures describe generating capacity and an optimal-condition share, not a verified annual renewable-energy percentage. Flint Hills says the combined heat-and-power system uses a natural-gas turbine and recovers heat that would otherwise be wasted. The solar installation is renewable; the gas turbine is not, even if cogeneration uses fuel more efficiently than producing heat and power separately.
The public project materials reviewed for this article do not disclose the blending equipment's expected annual electricity use, incremental emissions, or whether that load will be separately metered. As part of a large refinery, the equipment may draw from onsite solar, natural-gas cogeneration, and utility power at different times.
Blending itself may represent only a small fraction of the fuel's full lifecycle footprint. That does not weaken the argument; it sharpens it. The visible last step tells us little about the energy-intensive production steps that came before it.
Capacity Is Not Delivery
Transportation remains another unanswered part of the ledger. If MinnPost's report proves correct, the first supply will begin nearly 1,000 miles away in Great Falls. But will it reach Pine Bend by rail, truck, pipeline, or some combination? Will later batches come from the same plant? What will be required to move the feedstock to the producer and the finished SAF to Minnesota?
Then there is the word “capacity.”
Capacity is not production. It is not throughput. It is not delivery. It is certainly not a verified emissions reduction.
A facility capable of handling a lower-carbon fuel can be useful infrastructure. But the environmental benefit occurs only when qualifying fuel is produced, introduced into the supply system, and used in place of petroleum fuel—and when credible lifecycle accounting shows how much lower its emissions actually are.
This is where legitimate sustainability communication can risk sliding into greenwashing.
Greenwashing does not always require a sentence that is literally false. It can work through selective truth: spotlighting a renewable input without disclosing fossil process energy, announcing nameplate capacity without reporting actual throughput, or promoting a percentage reduction without showing the pathway and calculation behind it.
To be fair, Delta's Pine Bend announcement does not publish a project-specific percentage reduction. It says more generally that SAF can significantly reduce lifecycle emissions. That formulation is defensible, but it leaves the environmental performance of the fuel intended for this facility unresolved.
The most effective environmental marketing often consists of accurate facts presented without enough context to evaluate their significance.
Scrutiny Is Not Rejection
None of this proves the Pine Bend project is environmentally meaningless. The facility could help reduce aviation emissions. Existing pipeline access can avoid duplicating some distribution infrastructure, while local storage and blending can make SAF easier to introduce into the common fuel system at one of Delta's largest hubs.
Nor should skepticism become an excuse for paralysis. Current battery technology is better suited to small and short-range aircraft than to large, long-range transports, and NASA says larger, faster, longer-range aircraft still require fuel-powered or hybrid systems. Lower-carbon liquid fuels will therefore have an important role if aviation is to reduce its dependence on fossil petroleum.
Supply is also far from the scale the industry says it needs. IATA expects global SAF production to reach about 2.4 million tonnes in 2026, equal to only 0.8% of annual airline fuel consumption. Airways has previously examined the cost and supply constraints confronting the SAF market.
Supporting SAF, or any energy sustainability effort, should not mean surrendering our ability to question it.
For each major announcement, airlines and suppliers should publish the producer, production location, feedstock, conversion pathway, hydrogen source, process-energy mix, transport method, certification regime, pathway-specific lifecycle value, and actual delivered volume. If the lifecycle value is a regulatory default rather than a plant-specific calculation, say so.
Companies should also explain what, exactly, they are claiming. Was physical SAF delivered into the airline's fuel system? Were its emissions attributes allocated through a book-and-claim transaction? Which registry recorded the claim, and what controls prevent the same benefit from being sold twice?
Certificate-based accounting is not inherently illegitimate. Physical fuel and its environmental attributes do not always have to travel together for investment to support SAF use. IATA itself defines book and claim as a system in which the administrative record can move separately from the physical fuel. That flexibility makes transparent tracking more important, not less.
These are not fanciful data requests. Producers claiming the U.S. clean-fuel production tax credit must determine lifecycle emissions, and those SAF credit claims require third-party certification. CORSIA reporting can identify the producer, production location, feedstock, conversion process, lifecycle value, batch number, and mass. The industry's own accounting guidance emphasizes proof of delivery, batch-level links, transparent verification, and prevention of double counting.
Not every gallon will necessarily pass through each of those programs, and commercially sensitive details may limit immediate disclosure. But the systems show that the industry already knows how to collect and verify the information needed to substantiate a climate claim.
Aviation's environmental transition is too important to be reduced to ceremonial openings, executive quotations, and carefully framed photographs of pipes and storage tanks.
The new facility at Pine Bend may be a useful step. But a step toward sustainability is not the same as sustainability itself.
Before companies ask the public to applaud a cleaner fuel, they should show us where it came from, how it was made, what powered the process, how much entered the system, who owns the environmental benefit, and how much carbon it actually avoided.
Until then, the appropriate response is not rejection.
It is scrutiny.
Featured image: m01229 from US/CC BY 2.0
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