British boffins say aircraft could fly on trash, cutting pollution debt by 80% Sustainable aviation fuels (SAFs) made from sources other than fossil fuels have the potential to reduce emissions by up to 80 percent, UK researchers have found. Boffins from the National Centre for Atmospheric Science (NCAS) and the University of Manchester testing various blends of traditional jet fuel and SAF said …
I think the best part is-
SAFs are primarily made from corn and other crops, but waste resources have also been converted into synthetic jet fuel.
So another wizard wheeze to turn food into fuel, increasing the cost of both. And if it's like other biofuels, it'll reduce the efficiency as well. And sure, if you can seperate out other waste resources and feed them into digestors, that can work. Assuming you can get enough, at a low enough cost and they're clean enough. Alternatively, we could just be burning that in CHP plants and call it good. A much cheaper way to convert wast into power, but loony Greens don't want it because 'innovators' can't make as much money from it.
My local council's just given everyone 5 new wheelie bins because sorting waste into more categories that burns & doesn't burn is too easy.
And also "the UK would need to devote half of its existing farmland to SAF production".
Ummm, that sounds like a really bad idea, given there are large chunks of UK farmland that aren't suitable for growing crops like corn. We already import food because we don't grow enough to feed our population, so decreasing food production is going to *increase* the quantity of imported food and therefore make the situation worse, meaning more land needs to be converted into growing biofuel crops, and so on...
Synthetic fuels could well be the future of aviation, (and the future of keeping vintage ICE cars running) but biofuels from crops grown in fields are not the answer. What happened to the concept of fuel made from vat grown algae?
>> there are large chunks of UK farmland that aren't suitable for growing crops
It is ok, because there are vast swathes of land around the tropics that are basically unused... you know, they are simply covered with useless rainforest. Thanks to the increase in biofuel prices, clever enterpreneurs are turning these uselss lands into corn and oil palm plantations, which is sooo much better for the environment.
ANd just to add, anything based on processing "waste" is not a long term sustainable solution because we are all being told to waste less. Over time, the amount of waste should, in theory, reduce, so do you really want to base the continuation of major infrastructure or transport on yet another dwindling resource? And the agricultural waste is already recycled in one form or another as animal feed, compost etc. Using it for jet fuel will, as many have said, increase the value of the waste and divert it from the current uses.
Ummm, that sounds like a really bad idea, given there are large chunks of UK farmland that aren't suitable for growing crops like corn. We already import food because we don't grow enough to feed our population, so decreasing food production is going to *increase* the quantity of imported food and therefore make the situation worse, meaning more land needs to be converted into growing biofuel crops, and so on...
Joined up thinking isn't a feature of the Ecofreaks and Neo-Luddites. Here's one the Bbc carefully groomed & prepared earlier-
https://www.bbc.co.uk/news/uk-england-london-67136772
Fossil Free London posted on X, formerly known as Twitter: "Breaking - Greta Thunberg has just been arrested."
But being a multi-millionaire now, she can probably afford a lawyer.
But I digress. So we're supposed to turn millions of tonnes of corn and other crops into biofuels, be they liquid, gas or maybe even solid. We might also need to cover thousands of acres of farmland with bioreactors so algae can produce fuels. We're also told that we must stop eating meat, and eat vegetables (or bugs) instead. So thousands of hectares will be needed to grow that veg to feed us, or the bugs.
And like you say, a lot of farmland isn't suitable for growing avocados for Ecofreaks to 'smash' on their toast. Or quinoa, or any other food fad. Sure, there is land currently used to convert grass into proteins, and bugs could maybe do that as well. Yet we haven't evolved to eat bugs, so much of their protein is much less digestable than steak or bacon. And that land is often not suited to growing other crops. Especially not in the quantity needed to give 70m or so people in the UK a nutritious and balanced diet.
And then 'organic' food will have problems, because without livestock, there'll be less muck to spread on cropland to fertilise it. Or turn into syngas. Oh, and the Ecofreaks also want to ban fertilsers, pesticides and herbicides because that's just not Green. So crop yields will be reduced anyway. Plus cany farmers look at subsidies and figure growing solar panels or windmills can be much more profitable. Especially as you can later take the benefits of turning farmland into 'brownfield land' by a few seasons of growing solar, and then grow a housing estate instead. The Dutch, in a genius move fast-tracked this process by banning fertiliser, banning farming and replacing agriculture with housing for people they can't feed. But if you're a politician, think of the buy-to-let opportunities!
Oh, and then there's 'climate change'. Cows generally don't mind a bit of rain, crops do. Then again water is going to be an issue because most vegetables (and vegetarians) are 90%+ water.. So feeding 70m willing or unwilling vegetarians is going to need a lot of water that will end up as waste, and we don't really have anyway.
But such is 'progress' in the 21st Century!
"We're also told that we must stop eating meat, and eat vegetables (or bugs) instead"
If you want bugs, you can have them now. The cost approaches that of a meal on ISS. Bugs are often a vector for bad things so QC will be super important and a cost center. Humans haven't had diets that include lots of bugs so some have found that there can be interesting digestive issues when they give it a try.
The Greta dilemma:
If you've ever read the fine print from different countries you visit as a tourist, one of the restrictions is that you may not participate in protests or speak out in a negative way about the government when in the country. I expect there's also now the likelihood of being banned if you create negative videos and post them when you get home. I've done a lot of traveling for work and even way back when I was a roadie, we were all cautioned about political activities and breaking local laws. The short and sweet was, "get arrested, you're on your own. Good Luck". A performer I worked with couldn't get his piano player into Canada as he had a prior drink driving conviction. It didn't matter that he wouldn't be driving, Canada didn't want him in the country.
I eat less meat these days as the prices are through the roof. I've also learned recipes that stretch the meat I do eat much further. A meal with a steak and mushroom pie contains less meat than if I were to have steak and mash. There's a certain break even size for meat farmers too. If the market is restricted, only the largest producers will be able to stay in. Lots of farmland is already being paved over and turned into housing estates which I see as a crime. Good arable land should be used for food, not ghettos. I live in a desert and I'm finding that it's a good place for a home. The land isn't good for food production, we get lots of sun all year and it's cheap. Every year I'm adding more solar (PV and heating) and dropping my energy bills. While it does get below freezing in the winter, I haven't run the central heating in the house for 8 years. I'm hoping to raise the average indoor temp this winter a couple of more degrees. Initially the house was pretty cold. I do a lot more cooking in winter so heat from that warms the house in a co-gen fashion.
"Synthetic fuels could well be the future of aviation"
I'd rather see the future of overseas travel turn to ships. With good internet, I could even work while traveling. I'd just want a class that isn't being waited on hand and foot, but also not stuffed 4 to a room next to the engine compartment. I don't need housekeeping to make my bed and clean the bathroom every-single-day and the ice sculptures are very pretty, but massive (wasteful) buffets could go missing as well. As for the Elvis impersonator........
The "Looney Greens" don't want people flying at all. They want them to use electric trains powered by renewable energy.
Certainly some routes could be replaced with train services, but not all of them.
The people promoting this sort of stuff are greenwashers and people who's business plan is to raise money in investment rather than deliver an actual product.
"I'm not sure that they've really thought everything through."
Some of them certainly have not. Some are focused on one or two data points, not realizing that their proposals would be worse for the environment overall.
Last but not least, there is some evidence that some are naive rubes financed by people connected to the fossil fuel industry, with the intent of discrediting the entire green movement.
remember there are a least 50 shades of Green;
- the ones against planes
- the ones against turning farmland into greens
- the ones against using food to power cars
- the ones against building solar panel fields over unused land
- the ones against building nuclear plants
- the ones against building wind farms offshore
- the ones against building wind farms onshore
- ...
the only common thing being that they are against "something", especially when it is done in their backyard
Certainly some routes could be replaced with train services, but not all of them.
The overwhelming majority of trips made my plane are completely unnecessary and don't need replaced with anything. We need to wean ourselves as a species off long distance travel.
"Certainly some routes could be replaced with train services, but not all of them."
A lot of routes could be replaced with trains. California signed up for massive fraud via HSR, but a private company is adding a service from Los Angeles to San Francisco that will take several times longer. The advantage is that it's an overnight sleeper service and should be far less expensive. I'd be more interested in the overnight rather than the HSR (which will now go from nowhere to nowhere so one might as well just drive and be there faster). I always see needing to travel a few hundred kms as a travel day. I see an overnight train as zero days of travel since I have to get my head down anyway. Fortunately, I sleep like the dead on a train.
Given all the carp that one must go through to fly, the actual flight needs to be several hours to amortize the not-flying parts. For me, the tie goes to the driver since I'd be at my destination with my car and could change my plans at any time without needing to also max out my credit card by having to purchase new plane tickets. Obviously, if I'm going from London to NY, driving isn't an option, but since my ultimate destination isn't going to be an airport, getting from there would be better on a train where uniformed government employees aren't trying to feel me up and a bottle of shampoo doesn't make me a terrorist.
@elsergiovolador
"What is better: feed the poor or have jet fuel so that the rich can fly their bottoms to St Barts to let go of all that stress of having so much money?"
Except the rich people are us, or at least people who like to travel (see the amusing picture of the just stop oil idiot on a plane). And the problem isnt the fuel, there is plenty of it, its the idiots insisting on blending food into it (just like our cars). Would be better to stop the blending nonsense with food and just leave it up to people and the markets to decide.
@elsergiovolador
"Are you not afraid of publicly expressing such extremist views?"
I am amazed at how such a short line of text can be so disconnected from reality but why should I be afraid of publicly expressing the very common and obvious truth (it isnt just the relatively rich of the UK who fill up UK airports for example) but also why you would consider my comment to be extremist? Assuming you mean the small part you quoted to be extremist I can only assume you are from the communist bloc? Possibly N.Korea?
For example you seemed to be pointing toward the government made problem of food going into fuel instead of feeding people. Which I agree is a problem and note it is caused by idiots (gov policy if it was unclear). The markets happily used fuel for fuel and food for food in general.
Maybe you can clarify what you think is extremist and why you feel I should be afraid?
There're already quite detailed, workable plans to decarbonise aluminium, steel and concrete production in the UK (not just by continuing to outsource the emissions overseas! - primarily by electrifying their energy usage). Air travel remains an outlier because you can't just wave wind turbines and battery storage at the bulk of the problem.
there isn't a plan to generate (in a carbon free manner) and distribute the vast amounts of electricity needed to decarbonise everything in sight, inclusive these energy intensive industries.
Oh - and detailed, workable, when dreamed up by academics, lobby groups, etc. more often then not excludes economically viable from the "workable" bit.
I mean government & industry plans - you know, the plans resulting from the goals set out in the Climate Change Act which makes it, not exactly difficult, but as difficult as feasibly possible for future governments to ignore the problem?
Of course there's a possibility those all amount to green-washing but somewhere between the expert input from industry, the scrutiny of the academics, and the rabble of the free press pandering to the electorate there is a danger something workable turns into reality and makes all the naysayers look foolish. High gas prices do not hurt the all-important economically viable aspect of it all.
"My last company put in its grand climate change plan that it will reduce its carbon footprint by getting the staff to drive EVs. That was basically the whole strategy."
Same here, and in common with many other companies, used the fig-leaf of "salary sacrifice" as a carrot to push people towards buying EVs. The problem is, the before-tax salary sacrifice scheme could only be used via certain suppliers who seemed to have prices just that bit higher than everyone else's such that not only was it not cheaper, but it was non-transferable if you decided to change jobs, leaving you with a more expensive EV that you are now paying for with your after-tax wages instead of your before-tax wages. It was notable that no one took up the offer in our company.
The thing that is hard to overcome is getting the metal from its raw, usually oxide, form into a metallic form.
Iron ore has traditionally been mixed with coke so that the oxygen swaps from the iron ore to the carbon in the coke. Aluminium has traditionally been an electric process and often co-located with hydroelectric plants however it still uses the same basic idea of a sacrificial carbon anode that binds with the oxygen leaving metallic aluminium.
Obvs recycling doesn't need this step.
"All air travel, passenger and cargo, is 2% of carbon emissions. Aluminium, steel and concrete production is 12-16%. Of course we should be reducing emissions everywhere we can but do you ever get the feeling like we're being misdirected?"
Rather than "misdirected", I'd say distracted. There IS much lower hanging fruit that could be implemented if there were any political will. Elon has train to get employees to the Tesla plant in Germany. Mr "I'm going to save the world" is using a diesel-electric Bombardier Talent when there is already a version of that loco that's fully electric. Only the spur from the main train tracks to the Tesla plant are not electrified. Charging the train at the plant via overhead lines from on-site solar would obviate needing to install overhead lines along the whole spur or they could put up the lines (extending from the main tracks) and not need a battery pack in the loco at all. Many passenger tracks could be electrified in the US where doing the same for freight tracks might pose problems for oversize load (maybe not). The ever-proposed train from Los Angeles to Las Vegas travels through vast stretches of useless scrub land that could be covered in solar panels and battery backup stations. Other than some difficult parts getting out of the LA basin, nearly all of the track could be electric and self-sufficient. But n00000000, every time this comes up, some shmuck gets the politicians hard up over HSR and the whole thing falls through (too expensive). A train that could do 125mph could do the trip in just over 2 hours. The real bonus is it would do the trip in just over 2 hours on a Friday afternoon and again on a Sunday evening if it wasn't stopping every 5 miles. Instead, there's huge amounts of private cars backed up on the freeway taking 4-8 hours depending on weather and accidents. There used to be passenger service from LA to Vegas but I believe all of the cheap flights killed it off. With all of the 9/11 faff now, it could be faster to take the train than to get through a TSA line.
I think I prefer that situation to the rampant consumerism of "own everything while owing everything to your creditors". Under that scenario, I would net-own nothing -- possibly negative due to interest -- and the things I "own" will still "pwn" me (already do).
(Need a "thinking deeply about it" icon.)
"Oh, look - a red herring. If you've got debt issues, that's your problem, not mine."
I do have a little sympathy for those who've grown up and only every experienced low interest rates and cheap, easy borrowing. Not much, but some. I have less sympathy for those allowing themselves to be led down the garden path by their noses to a "own nothing, rent/subscribe for life" lifestyles though and now finding they can no longer afford some of the nice stuff.
@My other car WAS an IAV Stryker
"I think I prefer that situation to the rampant consumerism of "own everything while owing everything to your creditors"."
Why? People maintain private property better than public in general (public property or commercial 'service'). People care more about what they own, use it wiser and utilise it in ways that serve them. The own nothing and be happy crowd live a fantasy utopia which falls over when people value things at nothing.
The "own nothing" crowd are part big industry who are rent-seeking. As an IT website, we're all aware of the software-as-a-service and other subscription models that are being pushed on the customer. This thinking goes beyond IT, for example MaaS - mobility as a service (attacks on private car ownership). Add in this generation's "property is theft" ideologues, who have more of an "in" to the levers of power than they did when I were a lad.
@Dan 55
"This is a new business model being forced onto people as the old business model is retired from the market or prIced out of reach, not a lifestyle choice."
I dont disagree (dunno who downvoted but here's an upvote). The own nothing crowd to me range from governments to private business trying to 'provide' a 'service' against what the people want. I see it as a next step from vendor lock in where they made it difficult to move from one to another.
"The own nothing and be happy crowd live a fantasy utopia which falls over when people value things at nothing."
It falls over when they get older, can't work as much/as hard and start not getting called back for as many interviews for jobs. By owning nothing and renting everything, they have no buffer. I own my house outright and my car as well. I have a kitchen full of gadgets that let me cook just about anything I desire. I have a shed full of gardening tools so I can grow a portion of my own food (the expensive stuff usually). I have shelves full of books, DVD's, casettes, CD's that I can draw from for some entertainment. I keep adding solar (PV and heat) to lower my energy bills and fiddle about with projects to reduce my monthly outgoing and increase efficiency. If I had to, I could cover my monthly nut with a minimum wage job or work something part time at wages more in line with my knowledge and experience. At my age, I'd be in real trouble if I hadn't worked towards owning my residence and being as debt free as possible.
"Before we’re reduced to the rural lifestyle being planned by our betters."
I think cheap flights have kept people from embracing where they live. Everybody is jetting off to some foreign country rather than exploring the country they are in. I'm not saying that foreign travel is bad, it's just that it can be just as fulfilling to visit the far reaches of one's own country and not risk being served something for dinner that could be rather disagreeable (but you have to eat otherwise your host would take offense). At least you know you are covered for medical, speak the language and the money isn't odd.
Burning something in a gas turbine has a much better energy per unit mass of fuel compared to a battery. For the foreseeable future, aircraft will be burning fuel rather than running on batteries, except for some "short hop" routes, like small planes operating between closely spaced islands. The alternative is to build a lot more high speed rail, including tunnels that are thousands of miles long under the oceans, and that's not going to happen, because the delay between the money spent to build it and recovering the costs will be more than a human lifetime for long routes.
"If you're burning something to do a thing, you're doing it wrong."
Whatever.
My ethanol production and use in ICE equipment is a net carbon sink. A good portion of the carbon in corn comes out of the atmosphere in the first place; returning it would be net zero. Secondly, the bulk of the carbon in the plants is left behind in the fields, where it gets ploughed under (I'm building up the organic content of the top 18 inches of soil, or thereabouts). So overall, I'm actually sequestering carbon while still using internal combustion engines. The greens hate that, go figure.
>If you're burning something to do a thing, you're doing it wrong.
If you're burning fossil something, you're certainly doing it wrong (because it's adding carbon into the cycle that wasn't there before).
If you're burning something that was in the atmosphere until a few years ago, you may or may not be doing it wrong. On the carbon front, it's neutral, yay! On the energy front, it's somewhat tricky - if you grew it in the sun, it's solar, and it competes with photovoltaics. On the land usage front, it competes with food production. On the "other pollutants" front, particulates and such, it's a mess and I wouldn't know where to start - but that's also important and should be considered.
Overall, I'd be wary of speaking in absolutes on the topic of sustainability.
"because it's adding carbon into the cycle that wasn't there before"
Well it may not have been there recently but the last time I looked at fossil fuel creation it was from sequestered atmospheric carbon in a atmosphere generally similar to ours, albeit richer in carbon.
On a geological time scale, yes. On a time scale that has any sort of meaning for humans, no.
I find that the kind of events of which paleontologists say "but then life adapted, as it always does, and eventually thrived and diversified again" are not the kind of events I want myself, or my kids, or indeed my species, to have to live through, if there's any way at all to avoid it.
Of course a sustainable aviation future is possible although one doubts it will happen. Has everyone forgotten the zeppelins? The Hindenburg came to a spectacularly bad end of course, but the Graf Zeppelin made hundreds of flights in the 1920s and 1930s including regular mail and passenger service between Germany and Brazil in the mid-1930s. Puitting on my green glasses which make the improbable possible and everything look far easier than it is, It is easy to envision lighter than air aircraft built with modern materials and fueled by "green hydrogen" driving hydrogen-air fuel cells replacing hydrocarbon fueled jets on all but the longest routes. Of course, they'll be a bit slow, -- maybe 30-40 hours across the Atlantic, Much longer between Australia and just about anywhere And it'd be a good idea to keep them away from strong storms. But they can (on paper at least) lift and move a lot of mass cheaply and move it fairly quickly. Especially compared to ships.
I suppose that they might occasionally incinerate a payload. But airliners do that from time to time. And current EVs and large scale grid storage batteries spontaneously combust every now and then. No one seems to care all that much.
Will that happen? IMHO -- Two chances -- slim and none.
But it COULD happen.
Velcocys shares have absolutely collapsed. That's the market telling you about the future value of the company...
https://www.google.com/search?sca_esv=573962864&q=LON:+VLS&stick=H4sIAAAAAAAAAONgecRozi3w8sc9YSm9SWtOXmPU4OIKzsgvd80rySypFJLiYoOyBKT4uHj00_UNjcoKMyzTStJ4FrFy-Pj7WSmE-QQDABKVkctHAAAA&sa=X&ved=2ahUKEwjd2-X82vyBAxXimGoFHbfRAPAQsRV6BAhKEAM&biw=1912&bih=932&dpr=1
Interesting comment.
The article does not mention Velcocys anywhere.
Care to explain why you mention a company with a dismal stock price as a counterargument when said company has not been referenced by the article ?
I mean, Renault isn't doing too well at the moment either, but I fail to see how that has anything to do with potentially making fuel out of trash.
Because if we can make jet fuel out of trash and lower our carbon emission, I'm all for it. It'll help solve two problems at once.
Not holding my breath though . . .
Corn-based biofuels can take more fossil fuel to make than they can replace. Maybe it's just the way they do it in the US, but I get twitchy when someone suggests something that could lead to an expanded use of that particular boondoggle. Any sane use of this idea needs to somehow exclude that, and any other means which makes the problem worse IMO.
"Corn-based biofuels can take more fossil fuel to make than they can replace."
They certainly CAN, but they don't have to.
I'm a small operation, and quite selfish. The ethanol we make is for my farm's internal use only.
My fertilizer is produced with cows, sheep, hogs, horses and chickens.
I pull the seed-drill with an ethanol converted Farmall Model M. Cultivating is minimal, using the same Model M. At the moment, harvest is done with a smallish ethanol converted combine, but this is still very much a work in progress.
Distillation heat is provided by a GSHP. The circulation pumps are PV/battery powered.
1 acre here produces 175 bushels of corn (average, I have 50 acres split between corn and soy, alternating yearly. I sell my beans to an artisan tofu maker). One bushel of corn can produce about 2.75 gallons of ethanol. Doing the maths for you, I can currently make about 12,000 gallons of ethanol per year for fuel. I leave all the trash in the field, till it under, and plant winter cover crops (which get tilled under in in the spring[0]), all of which help to sequester more carbon. The spent corn, sometimes called DDGS ("dried distillers grains with solubles") is a high protein supplement for animal feed, thus re-starting the entire process.
[0 I'm playing with both cereal rye and rye grass, and clover on a few acres as harvestable animal feed, instead of just plowing the cover-crop under. I'm not no-till (yet?), the soil here is volcanic and alluvial river bottom ... very fertile, but not very high in organic mater. Once I get a good 18" of topsoil built up I might look into no-till again. Maybe. Seems to be a lot of religion involved in that, though.
"Maybe it's just the way they do it in the US"
I'm in the US.
I suspect for your farm you probably can produce enough bioethanol from waste matter. This is also common in rural France where the tractors (and the farmers) will run on pretty much anything.
The bigger problem is when areas are devoted to crops for bioethanol and other products for fuel. These schemes almost invariably involve using synthetic fertilisers, made from petrochemicals, which means they're effectively obfuscating the source of the fuel, and negating any notional carbon offsets. As these schemes are nearly always subsidised they can also drive up land prices as subsidised corn for fuel has higher returns than corn for food. This is certainly the case with E5 / E10 in Europe, something to which some Greens – notably Robert Habeck in Germany – have belatedly noticed, but proposals to scrap the schemes were knocked back by an industry grown fat on subsidies. Similar things are also happenin with solar farms, even though mixed use (raise panels over crops) and in many cases even desirable.
Sigh, the field of good intentions…
"The bioethanol lobby in the US is HUUUUGE!"
Of course. There is a certain market for corn as a food product and that's not going to change that much. If you are a farmer and have invested in the machinery to grow corn (and paid the fees to Monsanto for the privilege), leveraging those machines by being able to run them several hundred more hours every season to produce crops is a great thing. With gov mandated biofuel, the world is your mollusk. Chances are that you'll get the subsidies and tax credits whether you sell the alcohol or not. You just have to show production and Bob's your uncle. Of course, the military is still hooked on good, old fashioned petroleum based fuel or the government might want to stop by and pick up any excess.
""Corn-based biofuels can take more fossil fuel to make than they can replace."
They certainly CAN, but they don't have to.
I'm a small operation, and quite selfish. The ethanol we make is for my farm's internal use only."
Could you scale up to provide fuel for 3x the size that you are now and still be net energy positive? 100x?
It sounds like you are looking at a solution that takes in the whole thing end to end from an energy perspective. It might work out to be more financially rewarding to come up with a method that isn't net energy positive. If the government gets involved and mandates non-petroleum fuels, big companies will only be looking at issue from a financial standpoint. In all likelihood, there will be subsidies and tax credits to help gloss over the most difficult issues in the chain.
It may also be that to scale up, ethanol isn't a good way forward and battery electric machinery or hybrid is the way to go. Some things don't scale and sometimes it takes being at a certain minimum level to make another technology more efficient.
jet fuel is nothing like diesel. Except at the " they're both hydrocarbons" level - and strangely you need to drill deeper than that to devise an industrial strategy.
You can stick almost anything in a diesel engine. You have to be very careful indeed as to what you stick in an aero engine.
True, but that's a function of processing.
We already have multiple very large plants around the world that are capable of refining waste cooking oil into jet fuel with appropriate adjustments.
They aren't doing that because it's much cheaper to refine fossil oil at the moment - mostly due to transport & collection costs. Pipelines are cheaper than trucks.
That is certain to change eventually, though it remains an open question as to whether there will still be sufficient market for it to be worth bothering.
You can stick almost anything in a diesel engine. You have to be very careful indeed as to what you stick in an aero engine.
Can also be risky with diesels. Reading Council did an experiment switching their buses to biofuel and ended up giving lots of people headaches and making the air quality worse. There can be lots of nasty VOCs (Volatile Organic Compounds) in biodiesel exhaust that are arguably worse for air quality than traditional diesel.
Fueling jets with municipal solid waste reminded when I was a student many years ago of someone suggesting jumbo jets (Boeing 747s) could fly on coke (as in steel making not the Columbian sort.) I can imagine academia being what it is, this individual has clambered up the greasy pole and might be responsible for this.
I would thought the local chippy's used frying oil might be a better bet. In most parts of the world it would be vegetable oil so by definition a biofuel. (Some independence minded parts of the UK might use solid paraffin.)
He had probably read about prof. Lippisch coal powered jet interceptor https://en.wikipedia.org/wiki/Lippisch_P.13a.
However, the way I read his memoirs, prof. Lippisch mainly used this project as a means to keep his students from being sent to the front until Germany collapsed.
Do note that, once they had figured out the problem with the rounded leading edges, this project lead straight to today's delta winged aircraft, so it was not all for naught.
Ultafine black carbon is a result of burning hydrocarbons in air to convert the hydrogen to water and leave the carbon behind. For the next 100 years it will give the polluters asthma and shorten their life expectancy.
Burn the stuff properly and the carbon is converted to CO2, a greenhouse gas that will heat the planet for the next 1,000 years and ensure that your children's children's children don't even get to be born.
Please place your !votes.
It's very difficult to burn hydrocarbons completely efficiently, though modern turbines are very good. However, the idea behind SAFs is that the carbon comes from the atmosphere so the CO2 will eventually be recycled. Lots of caveats, but significantly better than burning fossil fuels.
Carbon released into the upper atmosphere will not cause breathing problems for us on the ground but the carbon does act as a seed for contrails, which are the biggest problem associated with aircraft emissions.
Don't think anybody here is against sucking in SAF in preference to burning more fossils.
But your particulate science is way off beam. Sure they cause contrails but, as Wikipedia remarks, "Starting from the 1990s, it was suggested that contrails during daytime have a strong cooling effect". Contrails are not a problem in their own right, though the timing of them can matter. And after 20 years of churn, even high-altitude particulates are making it into your ground-level lungs - and vice versa. Never cherry-pick your science to make a point, best to pull your points out of the science. Ciao!
I don't think that's just an approvals issue.
Lead was added to gasoline to improve its apparent octane rating, and prevent knocking. It's easy to get the same effect by refining the fuel to be higher octane, it just makes it more expensive but should not, in itself, require new approval.
A bigger problem is that the lead in fuel has a lubricant effect on the valves, and manufacturers found that they could machine valve seats from softer metal if the engine ran on leaded fuel. Phasing out the lead means reworking the engines or waiting until the older engines reach end-of-life, and I'd guess that the expected life of an aviation engine is many times that of one in a car. Until most engines can run on unleaded Avgas they can't phase out the leaded version.
"the lead in fuel has a lubricant effect on the valves"
Valve lubrication is provided by engine oil. What tetraethyl lead does[0] is provide a barrier (some people erroneously call it a cushion) between valve and valve seat, preventing micro welding which sloughs off material at a micro level, which eventually leads to so-called "burned" valves. Modern engines with hardened valve seats have no need for the additive, nor do older engines rebuilt with hardened valve seat inserts.
"manufacturers found that they could machine valve seats from softer metal if the engine ran on leaded fuel."
Wrong way around. They discovered that adding lead made the seats last longer in the early days. Hardened seats came later.
[0] Aside from the octane boost, obviously.
"Aero engines solved."
Not really, considering the dry weight of a Merlin is roughly the same as the gross weight of my A152 ... And note that even though the rebuilt engine in my little plane is perfectly capable of running on pump gas, the airframe as a whole is NOT certified to run on it. The FAA and the EPA have completely different agendas when it comes to fuel additives.
Burning fuels made from corn, trash or cooking oils you are still emitting CO2, an unavoidable result of combustion. Not seeing the benefit of carbon emissions from biomass, trash or whatever being more beneficial or less damaging than carbon from fossil fuels. A lot of pseudo-scientific and climate change nonsense!! IMO
I don't see an entry on the energy density per cubic volume of solid municipal waste. I sort of expect it to be pretty low meaning that it will take a heck of a refining process to get it to the point to compete with hydrocarbon liquid fuels. Jet-A also has additives to keep it from atomizing as well as not freezing into a solid in fuel pipes on aircraft. There was an issue way back with super-cooled jet fuel gelling and clogging up pipes as an aircraft descended from a long flight. The propensity to atomize was a problem when tanks were ruptured and the fuel droplet size was so small that there would be big fuel-air explosions. Any reformulated fuel will also need to have the same characteristics for safety.
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