The basic problem is that “sustainable” aviation fuels, if based on biofuels, would substantially compete with food production. This limits their scale pretty significantly, so they can’t easily scale up to the levels that the airline industry wants, which means that the cost will remain quite high.
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I’ll preface this by saying that SAF by itself isn’t a silver bullet that solves all problems with carbon use in aviation. It can, however, be an important piece of a larger solution. Additionally, even in isolation without a larger plan it has a net benefit on carbon reduction which is a win in the battle against climate change.
The basic problem is that “sustainable” aviation fuels, if based on biofuels, would substantially compete with food production.
Certainly possibly, but not absolutely.
Virgin feedstocks (the stuff needed to feed in to make SAF) would support your position because the plants grown specifically for harvest to be turned into SAF would displace food crops, or possibly support destruction of other non-agricultrual land to grow net more crops. I agree with you that both of these situations would be a net negative to SAF.
However, virgin feedstocks aren’t the only nor even most desired feedstocks for SAF. There are many ways to produce the fuels that fall into the definition of SAF. Things that we would otherwise consider waste streams can be SAF feedstocks such as the following:
There are other pathyways being explored too such as the waste water runoff from dairy farms and beer breweries:
“To that end, the Argonne Lab scientists look to using carbon-rich wastewater from dairy farms (and breweries, for other reasons) as feedstock for SAF production. The study author at Argonne, Taemin Kim, said that the energy savings come in two ways. “Both [dairy farms’ and breweries’] wastewater streams are rich in organics, and it is carbon-intensive to treat them using traditional wastewater treatment methods. By using our technology, we are not only treating these waste streams, but [also] making low-carbon sustainable fuel for the aviation industry.””
Unless we as a global society choose to simply eliminate air travel for people and cargo, we have to accept that a better approach to energy used for air travel is needed to meet reality. SAF is an important part of that in my mind.
Are there really people who believe in “sustainable airplane fuel”?
Yes, I’m one.
Like most things, not one thing will fix a problem. SAF is one piece that measurable makes our situation better. The fact you can possibly fly on a plane today partially with SAF is an amazing achievement and the result of lots of hard work by lots of people trying to make a positive difference.
What is it made of?
Food. Food oils in particular.
It’s a real thing in the sense that you can produce it sustainably in small quantities, kind of like how California is turning 40% of US soybean oil into diesel fuel, thereby displacing ~40% of the state’s fossil diesel usage.
If we got rid of ethanol as a motor fuel in the US by electrifying passenger cars, we might be able to support 20% or so of current aviation using it.
Food. Food oils in particular.
While certainly possible technologically, for the main efforts in North America you are incorrect on the use of food (meaning something humans can eat) for SAF.
The largest producer of SAF in the USA is in California (and partially fuels LAX airport, BTW). This operation is using waste from other processes and not food that would otherwise be eaten.
Yes, they make a big PR thing about the fact that waste oils are incorporated into the final product. But at the end of the day, those are in quite limited supply. Any meaningful increase in the use of food-type oils for fuel results in their being removed from the food supply. There’s a fairly extensive government report documenting this from last year
First, that is a great link. I don’t follow biodiesel efforts very closely and always appreciate the data from a real world execution perspective.
That said, while the article contains a number of criticisms you’re pointing out, the article is mostly focused on biodiesel and not necessarily SAF, and even less applicability to California where the majority of North American SAF is produced. The article even called this out with the distinction that biofuels (SAF in this case) from virgin feedstocks doesn’t qualify for the Low Carbon Fuel Standards (LCFS) laws in California that make SAF economically viable. Meaning there is far lower incentive to try to produce SAF from virgin feedstocks, which I believe is your primary criticism of SAF.
“Additionally, the Producer’s Tax Credit, coupled with the California LCFS, will heighten the demand for lower carbon-intensity feedstocks like tallow, UCO, and corn oil. Under the LCFS, west-coast market demand is stronger for feedstocks that provide greater carbon-emission reductions than virgin vegetable oils like canola and soybean oil. These policies will continue to pull available global feedstocks into the California renewable diesel market, and boost U.S. import demand for feedstocks that make lower carbon-intensity biofuels that generate additional credits in the California market.”
The other point your article highlighted was the bottleneck to using less virgin sources was the need to increase the non-virgin sources of feedstocks. As in, the market is demanding more biofuel from non-virgin feedstock than can supplied. This is important as it goes back to the work identifying and introducing further non-virgin feedstocks that I linked in my other post on this topic here.
It doesn’t really matter whether you’re producing biodiesel or SAF; it’s a slightly different length of carbon chain coming out of the refinery. The same problem of competing with food is there because that’s where you’re sourcing carbon and hydrogen from.
There really aren’t other huge non-virgin feedstocks to bring in at this point; what’s left is largely doing things like intentionally contaminating palm oil to make it look like a waste product.
That is a very important question. SAF is a name for a bunch of different fuels produced from sustainable sources. I posted a larger reply to the main article that details some of the input feedstocks which answers your question here.
