Car Science #1.5: Sustainable fuels
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Hey,
It’s a bonus edition of Car Science (I know! Already! Sorry) and not to come over all driver-on-a-podium but I am super grateful that so many people subscribed to the first edition, especially given I hadn’t made it all fancy like and err, probably never will because I can basically write words (not very well) and that’s it.
So: edition 1.5. A sustainable fuels special because we’ll have to get into this some time. If you already know about sustainable fuel there’s probably not a lot for you here, hold tight for the proper science next Monday.
I might do these halfway versions just to cover off some background to make the main editions lighter on words and get through some themes like regeneration and what are composites, etc. This one basically started as next week's edition and then I realised it was just much, much too long (there's lots of sustainable fuel stuff coming on Monday though)
Rearranging hydrocarbons on the deck of the Titanic
Idk guys it’s quite hard not to feel like we’re living through the end times, isn’t it? There’s this drought cycle shutting everything down and I keep having to write about it and then think about how it’s getting worse. And there’s all this methane being released as the swamps cook dry and the sheet ice melts and maybe we’ve really well and truly fucked it? Like I’ve had this sense that we probably had ever since whenever I first got taught about global warming and the way no one was really doing anything about it but now it’s really bad.
Like the sirens are going off and the ship’s tilting and everyone’s putting together these very reasonable proposals to be carbon net zero by 2030 and I don’t know if I can take the world going out like a TED talk, to a ripple of polite sponsor applause. Not that I’d imagine I’ll have a choice in the matter.
Worst thing is nothing about writing that feels any better, does it? Anyway, I guess that’s part of why I’m writing this, to try and both cut through some of the BS around what’s called sustainable in cars and possibly find things that offer some sort of lifeline of hope I guess lol.
Which brings me to: sustainable fuel! I’ve been talking about this a lot lately. Mostly because people ask me perfectly innocuous things like “what is it” and then get a monologue.
What makes a fuel sustainable?
Well, variously:
it means it’s only partially or a significantly reduced amount from fossil fuels
it means it’s totally derived from re-growable resources like plant matter, hopefully not from agriculture
It means it’s made from waste materials
It means it’s made out of rearranging molecules to make a petrol
it might mean it’s close to (or, in real terms, a handwavy amount away from) carbon neutral
it might, very occasionally, mean it’s actually carbon negative but be cynical about that
Sustainable fuel isn’t a set mix of anything. It can be biodiesel (usually from cooking oil) or it can be a completely molecularly constructed petrol. It can be pure ethanol. It can be hydrogen that’s hopefully from a non-fossil source.
Oh, well that’s all clear then
“Sustainable” doesn’t mean zero emissions (although sometimes it is) - it’s just a catch-all term for non-fossil fuels. Which is why it bothers me that the new Formula 2 engine tender has an incredibly vague suggestion of 55% sustainable fuel compatibility for 2024. What does that mean? Absolutely nothing.
Sustainable fuel is what you make it. It can be made to suit any engine, to any spec - like was done with Sebastian Vettel’s recent outings in Nigel Mansell’s Williams and the first ever Aston Martin Grand Prix car. Neither was built to run on anything but dino-juice, so the fuel was made up to the engine’s spec.
What a tender like that could mean is: get ready to have valves and seals that can handle a high-ethanol mix. I don’t think that’s the direction for fuels for F1, which is what F2 will theoretically be acting as a testbed for but it might. There’s also the likelihood that sustainable fuels will have less energy than a pure fossil fuel petrol, so being able to maintain the other performance specs while running at a possibly very significantly reduced energy source could also be a factor.
So really what that line in the tender means is: ready to run F1’s 2026-grade spec fuel in a mix of up to 55% by 2024. Whatever that is. According to the 2026 power unit regulations the fuel source needs to be either non-food stock biological material or "genuine municipal waste" or from carbon capture so that the fuels won't use anything fossil derived, not adding any fossil carbon into the air. So, uhm, anything.
Which is where sustainable fuels get really confusing because people keep using that phrase and it doesn't really mean anything about a direction or a specific, ahem, formula. So let's run down some of the key types. For the sake of this only running to a reasonable length, I'm gonna keep to combustion fuels, so this isn't about anything that would run through a fuel cell stack to produce power for an electric motor.
Synthetic fuels
As you might imagine, this means fuels created entirely through synthesis. The basic ingredients are carbon and hydrogen, that are then rearranged into a string that forms petrol. Ideally, it's all done using clean energy and the carbon comes from capture, so it's carbon neutral by the time it's burned.
Some car companies, particularly Porsche, are investing a lot in these and it's the direction that former F1 guy Paddy Lowe's Zero Petroleum is going in. The reasons to be cynical about it are the high amount of energy involved in making it and the fact it's (currently) very expensive to do, so not hugely scalable. It might be in the future but right now it's
By its nature, the synthetic fuel should be the easiest to make to order, in the sense you're literally rearranging it on the molecular level. However, that's not really the case as whatever the specific process is that's used to catalyse the hydrogen and carbon together will make whatever it comes out with. Which should be consistent (it's not as straightforward as that all the time though) but also tends to be 'we found this way and we're doing that because what comes out is acceptable fuel.' So this is actually one of the most prescriptive sustainable fuels you can get, as things stand.
Additives and subsequent messing around could make a fuel more compatible to an engine but generally speaking it's more, with synthetic fuels as they currently are produced, that the engine needs to be built to be compatible with whichever the selected synthetic fuel is.
Biofuels
This is stuff made of anything from a biological source. In theory, it should be something like waste chippings from wood or the runoff from a food production process (stuff leftover from making wine got used at Le Mans this year) but that's often a more intensive process, resulting in potentially a less high energy fuel or a more difficult conversion, than going straight for using something like corn starch.
Usually, what happens is that there's a fermentation process to turn the biological stuff into ethanol or methanol and then that's combined with (more) hydrogen to rearrange it into something more like petrol or diesel. Ethanol or methanol itself is a burnable fuel, too (IndyCar used to use pure methanol, now uses a high-ethanol gasoline mix) but engines need to be specially adapted to use it and methanol, in particular, has invisible flames which isn't entirely ideal for safety.
These are probably the most customisable fuels, although they're still energy intensive to make. You're always going to get less energy out of a fuel than went into making it - the reason fossil fuels are so energy dense is it was all put there a very long time ago, over a very long time with forces like gravity and pressure doing a lot of the work. For fuels to be made faster than the distance between prehistory and the present, you have to put that energy in at a higher intensity.
So some of the energy comes from the original bio-matter (and from the growth processes that made that bio-matter) and then each process it's put through adds some more. It's not, ironically, as efficient as taking something out the ground and refining it but it does mean that we're not digging up more carbon and adding it to the air.
It's fairly likely - and definitely currently true - that the majority of synthetic fuels will be biofuels of some form or another.
There's also bio-diesel, which is either a mix of natural fats (animal fat, old cooking oil, etc) with oil-based diesel or just straight up fats. It's not especially high-energy but it does emit less CO2 than regular diesel and have the advantage of not adding any (or as much) fossil carbon to the air.
Straight-up hydrogen
Hydrogen can be a combustion fuel that doesn't emit CO2. Unfortunately, if it burns at high temperatures it does generate NOx which is not great but in theory otherwise the byproduct is water.
It has all the regular problems of hydrogen (it's a bit tricky to make unless you get it from fossil fuels, it's annoying to store) and also some of the problems of other sustainable fuels in that it's not massively energy dense, definitely compared to eg: LPG. But you can combust it in a diesel engine with only pretty minimal adaptation (a few valve changes and stuff) and that's pretty good, as an alternative to pollutive diesel engines so maybe hydrogen does have some uses after all.
(even if climate change wasn't a thing, the particulate pollution from diesel engines is literally lethal and we may still be understating the effects)
Of course, there's a bunch of sustainable fuels that fit some other description or which are a combination of those types. But basically it's generally some combination of things that fit those descriptions. Then whatever comes out will be whatever comes out - it could be something that fits a modern engine or something more designed for a 1922 F1 car's because fuel isn't really that specific. Even the range of 'petrol' as a concept is very broad. Once you've got the fuel, too, you can separate it further and refine it into other types like you would a fossil product .
So there's no specific formula for what makes a fuel a sustainable fuel or, in principle, any reason why it should chemically differ from a fossil fuel. It just doesn't involve as much or any dinosaur gunk.
Right, that's enough talking about sustainable fuel. Time to go and do the same thing at my dearest friends in the pub until they lob me into a bin.
Hazel
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