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.
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.
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.
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.
We have the excess electricity already, but I’m not yet at the legally required amount of solar panels.
At work we are investing in energy storage, both batteries and heat storage and looking for more solutions.
For any but the largest commercial solar/wind providers, batteries and heat storage (or cold storage actually too!) are the best uses of overproduction of electricity. Batteries at your location are 90%+ efficient round trip, meaning for every 1kWh you shove into the battery, even after all the conversion and storage costs, you’ll be able to get 900Wh or more out of the battery when you have a use for it. Many PV tied batteries are upwards of 97% efficient even!
Heat storage is another great use, whether in water (to mitigate need for new energy expenditure to heat water for use), or in thermal batteries for space heating. Although the biggest downside to thermal batteries are their size. If you’ve got spare space then they can be effective in a home or business.
I’m looking at hydrogen, because it’s known tech and I dream of finding a way to use it in a more stable chemical form for storage.
I did the same looking at Hydrogen, and its pretty bleak. Not only is creating hydrogen safely (from electrolysis) difficult, but storage is a nightmare. Any kind of gaseous storage is incredibly difficult because of how small a molecule H2 is, and if you’re storage is inside a building that leakage creates explosion risks.
The safest way I saw to store and consume hydrogen is absorbed into a metal hydride. The problem there is that fillers (because of pressure) are expensive $2k for the cheapest one I saw, and you need many metal hydride cylinders to store any appreciable amount of hydrogen. So they end up being large, heavy and bulky or relatively little energy storage.
For home use, a regular lithium battery is so much more efficient and safe.
What it looks like this company is building would be partially compatible with that approach.
For the Haber-Bosch process needs input H2 (plus the atmospheric Nitrogen). 33% of what this company is building is an electrolyser. Further, the Sabatier reactor they’re using (another 33% of their process) could possibly be swapped out for a Haber-Bosch reactor.
I don’t know enough about the environmental conditions needed for handling ammonia vs methane to understand if there are any “gotchas” to creating ammonia in situ.
What are the other options you see for the excess electricity that would be more feasible than this methane approach?
This has the same problem as CO2 capture technologies, that is the relatively low CO2 concentration in the air.
You’re correct that the CO2 concentration in atmospheric air is low: 0.04%. Consider the following:
I would agree with you this would be a waste of time if the goal was CO2 sequestration, but it isn’t. The goal is to use otherwise 100% wasted electricity to produce something useful that can be stored long term that there is a market for, in this case methane.
The only way to make this even remotely feasible
What is your definition of “feasible” here? Economically compared to fossil based methane? Volume of production?
… are end of pipe solutions where you directly capture the exhaust of a fossile fuel combustion process. But that in turn is at best a temporary band aid.
The company agrees with you. They called out that being able to direct capture pure CO2 from an industrial application would be ideal, but as they also concluded, thats not where the excess electricity is that is really the primary economic driver of this technique.
LFP
Thank you for that.
Its odd calling LFP “new” and “a change is coming”. The first production EV to ship in the USA with an LFP was in late 2021 I think.
I would have thought this might be talking about cheaper chemistry Sodium Ion batteries, which are already on the road in small quantities in China.
Now, what ever happened to regularly riding horses around?
Besides the issue with horse excrement, other issues occurred (Hayden, 2016):
Dead horses often clogged city streets;
In New York City in 1880, 15,000 horses died on the streets, or 41 dead horses a day (which had to be removed);
Some place to stable the 100,000+ horses that operated within New York, and food to feed them;
On a per capita basis, 19th century horse-drawn vehicle accident rates were similar to those of the automobile in the 20th century.
Guess you’ve never heard of a fistulated cow before, they can totally connect tubing or pipes to cows to harvest methane straight out of their intestines.
And the cost for fistulating each cow? And how much methane will such a cow produce? How contaminated will the methane be? What methods would be required to refine it to pipeline grade? Further, can you feed a cow with the output overproduction of a PV solar panel?
This is what I meant when I said cows wouldn’t be economically viable sources of methane from electricity. If you think cows are they, then I won’t stop you though.
Confused, how is this useful?
There are many MANY useful applications of carbon neutral methane. The most beneficial and obvious to me are:
You can get methane out of a cow’s ass all day long
You cannot get pipeline grade methane out of cows ass, and even if you could, you wouldn’t have the technology to capture it for use in the marketplace in any quantity that would be cost effective against fossil fuel based methane. As in, even if you could (and you can’t), it would cost so much that no one would buy it and instead just pull more out of the ground. The solution proposed here is on the path to being worth skipping the fossil fuel route for methane and using this instead.
and methane is a greenhouse gas,
So is the CO2 that is being used as the feedstock to create the methane. This would be reducing atmospheric CO2, which I hope you would agree is a useful element when directly combating climate change from C02 emissions.
I thought we wanted less methane, not more.
This wouldn’t be producing net more methane. The market is already consuming all of methane it demands. This would replace some of the supply that is currently being fulfilled by carbon positive fossil fuel sources.
I didn’t see anything in the article at all regarding speculation or futures markets of electricity with the one exception being a mention of some industrial operators signing long term contracts to buy oversupply.
Can you refer me to the section of the article you’re responding to?
I think the “swapping” may be a different use case the author is talking about. I don’t think the author was referring to an end-user executed swap to simply put in a charged battery.
This would be a service center option where a mechanic would have to take tools and removed panels and connectors to make the swap. Something done maybe only a few times, if ever, for a car during its life.
A structural battery pack is constructed to not be serviced in parts. The author calls this out with his comments on “replacing a single bad cell”. He’s right that this is a concern for structural battery packs. Here’s a Tesla structural battery pack when it was attempted to be disassembled:
There was more of that pink foam wrapping around the cells now exposed. All of that pink foam is needed for strength and its thermal properties because the battery pack is part of the structure of the vehicle carrying load forces.
Clearly replacing a bank of cells would be difficult to do if there was a cell failure, and no wear near cost effective for a consumer to have done on their car. The author is suggesting having some of THIS type of battery, but also another part of the battery in the standard hard plastic modular cases where the whole module could be removed and replaced (“swapped”)
The author is suggesting SOME of the battery be the pink foam type that is unserviceable, and SOME of the battery be behind panels in cases that a technician can swap at a service center when the module has reached the end of its life.
I had spare batteries for my smartphone for events like all-day conferences/conventions to swap batteries in the afternoon.
Sure, but how often are you going to all-day conferences. Once a year? Twice? Is it worth having the possibly 20% less battery capacity the other 363 days a year for that swapability?
Something seems missing from the description. What would make the most sense with the articles description is if there were two packs each with different chemistries. One cheap and low density, such as NA-Ion (Sodium-Ion) that could take care of 90% of EV driving needs for trips under, say, 100 miles. The second pack being a much higher density chemistry like NMC (Nickel, Manganese, Cobalt) which could add significantly more range for the same cubic cm of volume in the vehicle, but the battery would have far fewer cycles compared to other chemistries.
The idea being, beat the heck out of the Sodium Ion battery and make it easily serviceable/replaceable at the cost of range for the same volume consumed, while the NMC battery would be gently cared for and only called on in the more extreme demands of range.
If that’s what the author was trying to say, it was not clear.
This article is a bit confusing because its talking about the theoretical use cases of structural battery packs in EVs, the possible problems, and possible mitigations.
The Tesla Model Y has been using a structural battery pack for over 2 years (since 2022 model year, I think). While Hyundai/Kia may make different choices, the pros and cons from Tesla’s choices can be used as at least one path for what Hyndai/Kia want to keep or what they would want to change from Tesla’s choices.
Here’s the articles cited problems:
However, placing cells inside load-bearing components would also make them hard to replace, offsetting this practice.
In practice almost no service of the battery is done at the shop where the car is. If there is a fault anywhere in the pack, from a cell to a BMS component, the entire pack is swapped.
Most EV drivers rarely use all of their battery range; they only need it on long trips. Therefore, batteries built into load-bearing automotive components would not be needed for daily use; they could be maintained at the ideal charge level for the battery formulation and rarely used except for long trips.
This is such a strange description. This isn’t how EV batteries are used at all today, as far as I know, because it would be very inefficient in regular use. You wouldn’t want to put extra strain/stress/charge/discharge on specific cells in the battery. That would lead to unbalanced packs. Further it would be much less efficient and slower to charge the segregated pack that the article is describing. The more full a cell gets of charge, the harder/more power you need to work it to take additional charge. Also, deep discharge of cells significantly shortens their life. The author’s design description of a segregated pack would also experience much worse cold weather range reduction.
if the carmaker were to use modular battery packs, it would reduce the related cost of repairs across all of the car batteries; if they had better batteries, the need to replace them would be substantially reduced
Several automakers have tried making modular packs the way the author is describing them here. They turn out to be a bad choice because of all the extra stuff you have to do to make it flexible to accept fewer or more modules. This same thing happened to mobile phones. You used to have a removable battery, which was nice. However to make the battery removable, you had to add spring contacts, a separate tray to hold the battery, and a battery door. All of these things took space. The only time you’d ever use these, practically, would be years into the phone’s life you’d open it up to replace the battery once, maybe twice in the phone’s entire life. Manufacturers could just put a larger battery in and make it cheaper. Many phones don’t live long enough to ever kill their first battery.
The author of the article is well credentialed and has worked in the tech and automotive industry for years, so I’m very confused as to the content of this article. Its almost like it was written 3 years ago, even though it is showing a Feb 14th 2025 dateline.
there are multiple scenarios and budgets that can support these initiatives. In fact, many of the ideas I’ve proposed have already been implemented quickly in places I’ve lived:
All of those things still require dense urban environments. There’s a whole bunch of the world that doesn’t apply to that ICE vehicles rule. EV replacement of any of those ICE vehicles is a net gain for the CO2 reduction movement.
We could even argue that the carbon footprint associated with the early replacement of functioning vehicles, driven by fear of ICE vehicle restrictions, should be considered in the total cost.
That would be a valid argument if the replaced ICE vehicles were immediately going to the scrapyard, but I think you’d agree with me that isn’t what is happening with a replaced ICE vehicle. Further, I stipulated that I wasn’t advocating for people with nearly new ICE vehicles to immediately got out and buy an EV, but instead when they are planning on replacing their ICE with another ICE, and EV would be a better choice for the environment.
Here’s some data. 6.8% of new cars in the USA are EVs. That 6.8% replaced otherwise ICE vehicle purchases. I think if you’d ask most climate scientists if nearly 7% of new cars no longer running on fossil fuels they would say thats a substantial improvement.
Okay, I think I understand your position better, thank you.
The biggest flaw that I see in your approach is that nearly all of those changes require the population to decide to make the changes together. If that agreement isn’t there, the only other way to implement most of those would be with authoritarian decrees. There are places in the world where that is possible, but I wouldn’t call that a recommended solution to apply. A number of your suggestions would require additional funding too. That has to come from somewhere and the origin of that funding is also likely a contentious debate. Without everyone agreeing on the need for these things, few, if any will be implemented and that means more CO2 being emitted.
For example, ADEME (a French organization) estimates that: “A reduction in average meat consumption of 10 grams per day per person leads to a decrease of approximately 200 square meters in land footprint, as well as a 5.2% reduction in total greenhouse gas emissions.” (Source).
This is a good one that can be done at an individual level. It requires no agreement other than the person making the choice for themselves. This definitely resonates well on the “punk” of solar punk.
The meat reduction is the closest thing EVs for your cited solutions. Its an individual choice on the part of the consumer that can have the intended positive impact. That makes it extremely realistic as far as a component on the path to a full solution.
First, I see your post before mine was downvoted. That wasn’t me. I share a different opinion than yours, but your opinion is equally valid in this discussion. I see nothing in your post which is insulting or takes away from the discussion to deserve a downvote.
It seems way more sensible to act on what we know works now rather than hoping for future discoveries to save us.
So I don’t put words in your mouth, what do we “know works now” in your opinion that could be implemented in a faster time frame than EVs that would have a positive impact on the reduction of CO2?
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.”
from your provided source
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.