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United flies passenger flight on sustainable aviation fuel supplying one engine

106 points by hbarka 5y ago

vanusa 5y ago
Er... "using" 100 percent sustainable fuel ... in one of its engines. While in the other engine: 1. The plane didn’t actually use 100% SAF And it’s clear enough if you read the press release, as some of Twitter’s users did. In fact, one engine was running with 100% SAF and the other with traditional jet fuel. That’s because the US Federal Aviation Administration (FAA) allows for a 50% total of SAT to be used during a flight, United explains. For this reason, SAF is basically employed by airlines as a drop-in fuel that gets blended with the conventional one at a 50-50 ratio. United decided to fly its plane with one SAT-powered engine and one fossil fuel-powered to demonstrate that “there are no operational differences between the two.” https://thenextweb.com/news/twitter-vs-united-over-greenwashing-with-100-percent-sustainable-fuel-flight https://thenextweb.com/news/twitter-vs-united-over-greenwash...
- josephcsible 5y ago
  I assume that this rule will change once SAF builds up a long-term track record of safety and reliability.
- zucker42 5y ago
  So the FAA should change the regulation on the maximum concentration of SAF?
  - blankley 5y ago
    I am not sure the GP caught the article's statement that the regulatory cap on SAF is 50%, and that as a result this is arguably the most aggressive test UA could have run.
- ISL 5y ago
  It is a smart way to test. If it doesn't work, you still have another engine backed by roughly a century of experience.
  - vanusa 5y ago
    EDIT: My horrible, ostentatioous BAD! I mixed up the GE headline with the viral United Airlines tweet about the same exercise: https://twitter.com/united/status/1466045020473942020 https://twitter.com/united/status/1466045020473942020 In which they took care not to mention the second engine using standard fuel, going so far as to say (this time quoting correctly): Today, United will be the first in aviation history to fly a passenger flight using 100% sustainable aviation fuel (SAF). This flight will serve as a turning point in the industry's effort to combat climate change. So I definitely should have read the GE headline more closely (which doesn't make this obfuscation). But that's what happens when these companies keep lying, and lying, and lying - at some point your senses go numb, your eyes start to bleed... and you lose track of detail. But at the end of the day - my bad! Earlier, ill-thought transmission (from me) follows below, as-is: The point isn't the testing protocol, or that two different fuel types were used. It's that these companies are trying to play with our heads.
    - dijonman2 5y ago
      The modern media is at fault here, not nessecarily the company.
      - animal_spirits 5y ago
        Nothing about it being modern is relevant to them missing specific information here. That's happened for centuries. But I agree nonetheless, we shouldn't fault the company for having a fail-safe
      - thatguy0900 5y ago
        A little unfair to blame the company here, no? The fuel is 100% sustainable and it would be illegal to use more than 50% of it here
- jessriedel 5y ago
  Yes, misleading headline for sure. But as a testing strategy it certainly makes sense.
  - vanusa 5y ago
    The point is that the "headline" doesn't come from a news outlet. But from the company pushing the product.
    - tyingq 5y ago
      Unless they changed it, the headline on the page is: "United Flies World’s First Passenger Flight On 100% Sustainable Aviation Fuel Supplying One Of Its Engines" And it's in the url too.
    - jessriedel 5y ago
      The latter seems better to me.
- throwawayboise 5y ago
  I read it as meaning the fuel was 100% sustainable.
  - vanusa 5y ago
    Turns out it that's not true either. See the article linked to in my post.
    - deleted 5y ago
      [deleted]
    - throwawayboise 5y ago
      Well, who expects complete honesty in a marketing press release anyway?
- hbarka 5y ago
  EV batteries started this way with hybrids like the Prius. Look where we are.
  - chrischen 5y ago
    Actually Priuses use a completely different battery tech than EVs like Tesla.
    - hbarka 5y ago
      True. The point was that there’s a progression in the technology. Nickel Cadmium -> Lithium Ion -> ?Solid State. More importantly, there’s the cost curve improvement.
    - kijiki 5y ago
      True for pure hybrid Priuses, but Plug-in Priuses use Lithium-Ion batteries just like Teslas.
- p1necone 5y ago
  Seems like a perfectly reasonable test to me? This proves that an engine can run on this fuel at 100% concentration. The other engine is exactly the same, there's no reason that this result doesn't carry over to a flight with /both/ engines using this new fuel. This is just a safer test if there turned out to be problems with the experimental fuel. The article mentions this in the very first paragraph, I don't think there's anything to complain about here. I also don't think the headline is misleading either. The important thing being tested here is that the engine managed a flight with a 100% concentration of the new fuel, the other engine being a failsafe with known safe fuel doesn't make the outcome of the test any less useful. Edit: the headline on the page mentions the second engine using legacy fuel, I'm not sure why the HN headline was modified.
- staticassertion 5y ago
  Article headline: > United Flies World’s First Passenger Flight On 100% Sustainable Aviation Fuel Supplying One Of Its Engines Third sentence: > It was the first commercial flight with passengers on board to use 100% drop-in sustainable aviation fuel (SAF) for one of the aircraft’s two engines.
- dang 5y ago
  Ok, we've put one engine in the title above. The article title doesn't have this issue because it clearly says "Supplying One Of Its Engines". I wonder if they added after getting criticized or if it was there all along. Edit: probably the former, since the original press release omitted it: https://www.prnewswire.com/news-releases/united-to-become-first-in-aviation-history-to-fly-aircraft-full-of-passengers-using-100-sustainable-fuel-301435009.html https://www.prnewswire.com/news-releases/united-to-become-fi.... Pretty silly to think they could get away with that.
- Syonyk 5y ago
  ... and? If one engine works entirely fine on a 100% blend, with no ill effects in operation or in analysis afterwards (for weird deposits on the hot section), it's reasonable to conclude that one could run exclusively on it. There's a chunk of wisdom over in experimental aviation (the "You can build and fly whatever you want, please try not to kill anyone else in the process..." side of things): "Never test an experimental engine on an experimental airframe." If you're building a new airframe, use a proven engine. If you're trying a new engine, use a proven airframe. Otherwise you just end up with an explosion of possible issues, and "experimental engine plus experimental airframe" tends to lead to an alarmingly short lifespan. Running one engine on an experimental fuel, while keeping the other on something you know is entirely sane and will work fine, is entirely reasonable. You know the airplane can fly and land safely on one. You think the other one works fine - but there are some weird corner cases in aviation - British Airways Flight 38 was one of those things. In this particular, exceedingly difficult to reproduce case, water in the fuel iced up and clogged the fuel flow to both engines, leading to a crash short of the runway (no fatalities, mostly due to the skill of the pilots). The engines behaved absolutely fine, until short final, at which point they suddenly, and without any prior warning, refused to make power - because they couldn't get enough fuel. The entire point of testing is to work out as much of this sort of stuff as you can. If it turns out that after cruise, you've got weird fuel icing issues, it is far better to have that problem limited to one engine, where the other one can pick up the slack and haul you into a goaround if needed (twinjets are typically obscenely overpowered on two, because they need to perform well with an engine out). Doing it the way United did is entirely sane, reasonable, and rational for any sort of aviation testing. Doing it on both engines, without serious testing beforehand (of the "on one side" variety), would be insane in aviation.
pfdietz 5y ago
This appears to be the synthetic jet fuel from Virent. It is made from light carbohydrates and other small organic molecules by their "Bioforming" process. This removes oxygen from the molecules by reaction in solution with hydrogen gas and a ruthenium catalyst. The resulting hydrocarbon molecules are then put through a reforming process where they are linked together and isomerized to get the right distribution of molecular weights. I've followed this process for a while. It yields more energy than ordinary biomass approaches, since it can also incorporate the energy of the hydrogen input stream. This is good, because biomass has terrible efficiency at conversion of sunlight to fuel. No CO2 need be produced; the oxygen is carried away as water. One can think of the biomass as more of a carbon source than (just) an energy source. It also tolerates a wider variety of input molecules than enzyme-based approaches. https://www.virent.com/products/jet-fuel/ https://www.virent.com/products/jet-fuel/ https://www.virent.com/technology/bioforming/ https://www.virent.com/technology/bioforming/
- hbarka 5y ago
  I saw this news while on a public place watching NHK Newsline. Interestingly I couldn’t find it on Google search under News or All. The very interesting part is that the feed stock used to make the liquid fuel comes from common garbage waste. Have we finally found a place for the tons of household garbage we generate? The company cited as the supplier was Fulcrum Bioenergy in Reno Nevada. https://fulcrum-bioenergy.com/ https://fulcrum-bioenergy.com/
  - Reason077 5y ago
    > ”Have we finally found a place for the tons of household garbage we generate?” Fossil-derived plastics make up a significant portion of household waste. From a climate perspective, it might actually be better to bury plastics in landfills rather than burn them as fuel.
    - usrusr 5y ago
      The mirror argument is that from a climate perspective, as long as we are still burning low energy-per-co2 fossils like lignite for energy (spot the embarrassed German) it might be a net reduction if we burn those high energy future landfills instead. Plastics are very useful, perhaps we should consider it wasteful to leave any well-to-atmosphere paths where the carbon did not go through a stage of making itself useful as plastics? Hard to find any numbers, because the CO2/MWh stats of incineration plants always contain a considerable fraction of renewable on the input and that would have to be removed from the equation an all sides (input, CO2 output, energy output) for a useful answer. I'm not enough of a chemist, but I suspect that the process the article is about could also habe potential for the creation of raw materials from bio stocks for plucking into the conventional plastics pipeline? This, combined with landfills (instead of incineration/highly processed incineration) could end up being the most viable carbon capture approach: instead of jumping through hoops trying to capture for the sake of it, it would harness our insatiable demand for plastics consumption. Are there any plant-based plastics already that don't don't with the friendly "degradable" label?
boringg 5y ago
A step in the right direction. Would be interested to know what the comparative energy ghg lifecycle costs for this fuel vs conventional fuel - and what prohibits them from using both engines. Is it just a liability / pilot test on the first go and then switch to both engines? Or are there concerns about going fully SAF?
- throwawayboise 5y ago
  Aviation is extremely conservative when it comes to adopting any new technology. It is tested and tested and tested again. Allowing only 50% (or 100% on one engine) seems like exactly what they would do. Make a small change, test it for a while, tear down some engines and look for anything unusual, etc. If it's a drop-in replacement for Jet A, it needs to work in the newest modern engines as well as the 30 year old ones that are still in service. Look how long it took to get unleaded gasoline approved as an aviation fuel for piston-engined aircraft.
  - sokoloff 5y ago
    Part of the difficulty is that the certifications for the (high-compression piston) engines were to run on 100LL, not to run on “a fuel with a lean mixture knock value of X and a rich mixture knock value of Y” and the specification for 100LL (ASTM D 910) is a formulation specification which includes tetraethyl lead rather than being a performance specification. Maybe the FAA could have been more aggressive in allowing a replacement fuel to be certified, but various fuels have been tested for over a decade now in experimental category aircraft, meaning they were not holding up development activities, just holding what seems like an objectivity reasonable hurdle for all-model STC approval (which still hasn’t been granted; we’re at the “many model” approval level right now).
oliv__ 5y ago
I wonder if this fuel could be produced in sufficient quantities to power cars? I love my combustion engines
- colechristensen 5y ago
  There are a few methods out there for synthesizing gasoline equivalents. This fuel: no (possibly in diesel engines, jet fuel has been used but there are issues).
- fy20 5y ago
  Most diesel engines can run on kerosene just fine, so I expect this would be the same. In fact kerosene is often blended with diesel in cold climates as regular diesel below -25C/0F will start to get thick. The reason why you don't want to use straight kerosene is that it is too pure - diesel has additives that lubricate the engine, without which you will cause more wear and tear on the engine. If that's all you have it'll probably work though, especially if you mix it with a little engine oil.
tims33 5y ago
One interesting aspect buried deeper in the release is that United has gone out to make extensive financial commitments to get this fuel produced at greater scale. Putting these fuels to use is more than just testing.
woeirua 5y ago
Anyone know what the cost is per gallon for SAF versus conventional jet fuel?
HWR_14 5y ago
I do like that the CEOs of both GE aviation and United were on the flight. I respect dog fooding.
- hbarka 5y ago
  Skin in the game. United CEO Scott Kirby is invested in SAF. https://youtu.be/XQtNEvVWPLc https://youtu.be/XQtNEvVWPLc
- ec109685 5y ago
  These planes can run on one engine, so risk was small.
  - taspeotis 5y ago
    That’s a 737 MAX which uh, doesn’t fly with both engines…
    - mike256 5y ago
      Doesn't need both engines to fly...
      - taspeotis 5y ago
        The 737 MAX has had a tendency to crash despite having two working engines. Thus the joke: it doesn’t fly with both engines.
- lbriner 5y ago
  I can't really see what the risk would have been. It's just liquid fuel and will mostly work or not work. They would have already tested heat generation and build-up of deposits etc. for many months.
nunez 5y ago
> Sustainable aviation fuel can be made from any of 60 different feedstocks — among them plant oils, algae, greases, fats, waste streams, alcohols, sugars, captured CO2 and other alternative feedstock sources and processes. The Department of Energy estimates that the United States alone has the resources to produce 50–60 billion gallons of SAF per year. For context, commercial airlines will use about 57 billion gallons of fuel by the end of 2021, down from a peak of 95 billion gallons in 2019, according to Statista. By switching from petroleum to SAF — when you take into consideration the entire life cycle of the fuel — the aviation industry could reduce its carbon contribution from fuel by up to 80%, according to industry associations the Air Transport Action Group and the International Air Transport Association. This is massive. Aircraft are some of the biggest CO2 pollutants out there.
- jillesvangurp 5y ago
  It's important because planes are expensive and have operational lives measured in decades. So, even though companies like Boeing and Airbus are looking at alternative forms of propulsion now (e.g. hydrogen and electric), it would take well into the second half of the century to replace the existing fleet with their newer, more sustainable versions. Realistically production for that kind of plane won't even start until the 2030s at the earliest (and probably in low volume initially). Synthetic fuels will allow the existing fleet to be operated in a more sustainable way during this time. It will probably have a higher cost though. Long term, the low cost sustainable alternatives will probably take over. But as electricity production cost drops in the next decades, so will the cost of using electricity for producing synthetic fuels.
supernova87a 5y ago
I hope this is part of a new positive development. But to me it sounds like one more in a series about biofuel that has generally gone nowhere or hit some limit that is not getting better. I say that because this same story pops up every ~2-3 years, but the important question that never gets conveniently ignored in the articles is, they flew using plant-based fuel at what price? Price is what determines everything for our behavior, including airlines deciding to fly planes all over the place. Reporters (and of course the press release) seem allergic to addressing such questions. If you read a story about biofuels and it has no mention of the price of the fuel, you can bet it's pretty much a meaningless piece of news. There is not a single $ sign in the story. It always turns out the fuel costs like $25 per gallon to produce. The basic concept that you can make fuel from biomass is not challenging. And flying it in a plane's gas tank is not new. Manufacturing it at a competitive price is. What will happen is that this will go nowhere, because neither United Airlines nor any other carrier will pay that per gallon compared to the $6-7 they usually pay. Unless it's continuously subsidized. Or until a technology comes along to make the price much more economical. Past examples: 2008: https://abcnews.go.com/Technology/story?id=4338149&page=1 https://abcnews.go.com/Technology/story?id=4338149&page=1 2010: https://www.scientificamerican.com/gallery/military-green-us-air-force-flies-on-biofuel/ https://www.scientificamerican.com/gallery/military-green-us... 2011: https://www.npr.org/2011/09/26/140702387/air-force-and-navy-turn-to-bio-fuels https://www.npr.org/2011/09/26/140702387/air-force-and-navy-... 2016: https://www.biofuelsdigest.com/bdigest/2016/10/02/american-airlines-hires-ocean-park-to-assist-with-renewable-jet-fuel-evaluation/ https://www.biofuelsdigest.com/bdigest/2016/10/02/american-a... 2018: https://www.theguardian.com/environment/2018/jan/30/qantas-uses-mustard-seeds-in-first-ever-biofuel-flight-between-australia-and-us https://www.theguardian.com/environment/2018/jan/30/qantas-u... Not a peep heard from these practically since. Sorry this is a little negative. But if there is to be any informed / useful understanding of the topic (which I think this place is about), and not just feeling good after reading a story for 30 seconds, this is the key issue, not just the nice headline. Otherwise you go away for a couple years and wonder "hey what happened to that good news about achieving biofuels?" It's like if I told you I demonstrated that we could run your car on biofuels. Great. At $25/gallon? Not so impressive.
ya_throw 5y ago
This is completely bogus. The ever-increasing global demand for soy foodstock is already accelerating the destruction of tropical rainforests - how is it all sustainable to burn huge amounts of foodstock that so we can enjoy making the world "a smaller and better place" [1]? Just for fun - an acre of soy produces 70 gallons of "biofuel", so a square mile of soy plantation can produce around 45,000 gallons of fuel, or enough to fly a 747 for about 10,000 miles. After slashing and burning a patch of rainforest, you get about 3 years of crops, before you need to leave it for around 10 years to "regrow". If all of the Amazon rainforest (2,000,000 sq miles) was slashed and burned for soy plantations, and assuming it can magically regrow in those 10 years, we will get enough fuel over one 13-year cycle to fly 5 billion miles. That is about 1/10th the total airplane mileage in one year. [2] [1] https://www.virent.com/products/jet-fuel/ https://www.virent.com/products/jet-fuel/ [2] https://www.quora.com/How-many-miles-do-airplanes-fly-in-the-world-each-year?share=1 https://www.quora.com/How-many-miles-do-airplanes-fly-in-the...
- wutwutwutwut 5y ago
  From the article: > Sustainable aviation fuel can be made from any of 60 different feedstocks — among them plant oils, algae, greases, fats, waste streams, alcohols, sugars, captured CO2 and other alternative feedstock sources and processes. The Department of Energy estimates that the United States alone has the resources to produce 50–60 billion gallons of SAF per year.
  - ya_throw 5y ago
    By "article", you mean "marketing blub from someone trying to sell you something". Ultimately, all of those "sustainable" feedstocks will have to be grown. As my quick maths points out, the size of the field we're going to need is just staggering. >The Department of Energy estimates that the United States alone has the resources to produce 50–60 billion gallons of SAF per year. I'd like to know where from. Actually, I looked it up. It's the "Billion Tonne Plan". It involves "thinning" all US forests, and planting practically every available acre with crops for biofuel. Basically, dedicating all of the available plant matter grown in the US to burning for transportation.

106 points by hbarka 5y ago

Er... "using" 100 percent sustainable fuel ... in one of its engines. While in the other engine: 1. The plane didn’t actually use 100% SAF And it’s clear enough if you read the press release, as some of Twitter’s users did. In fact, one engine was running with 100% SAF and the other with traditional jet fuel. That’s because the US Federal Aviation Administration (FAA) allows for a 50% total of SAT to be used during a flight, United explains. For this reason, SAF is basically employed by airlines as a drop-in fuel that gets blended with the conventional one at a 50-50 ratio. United decided to fly its plane with one SAT-powered engine and one fossil fuel-powered to demonstrate that “there are no operational differences between the two.” https://thenextweb.com/news/twitter-vs-united-over-greenwashing-with-100-percent-sustainable-fuel-flight https://thenextweb.com/news/twitter-vs-united-over-greenwash...

josephcsible 5y ago
I assume that this rule will change once SAF builds up a long-term track record of safety and reliability.
zucker42 5y ago
So the FAA should change the regulation on the maximum concentration of SAF?
- blankley 5y ago
  I am not sure the GP caught the article's statement that the regulatory cap on SAF is 50%, and that as a result this is arguably the most aggressive test UA could have run.
ISL 5y ago
It is a smart way to test. If it doesn't work, you still have another engine backed by roughly a century of experience.
- vanusa 5y ago
  EDIT: My horrible, ostentatioous BAD! I mixed up the GE headline with the viral United Airlines tweet about the same exercise: https://twitter.com/united/status/1466045020473942020 https://twitter.com/united/status/1466045020473942020 In which they took care not to mention the second engine using standard fuel, going so far as to say (this time quoting correctly): Today, United will be the first in aviation history to fly a passenger flight using 100% sustainable aviation fuel (SAF). This flight will serve as a turning point in the industry's effort to combat climate change. So I definitely should have read the GE headline more closely (which doesn't make this obfuscation). But that's what happens when these companies keep lying, and lying, and lying - at some point your senses go numb, your eyes start to bleed... and you lose track of detail. But at the end of the day - my bad! Earlier, ill-thought transmission (from me) follows below, as-is: The point isn't the testing protocol, or that two different fuel types were used. It's that these companies are trying to play with our heads.
  - dijonman2 5y ago
    The modern media is at fault here, not nessecarily the company.
    - animal_spirits 5y ago
      Nothing about it being modern is relevant to them missing specific information here. That's happened for centuries. But I agree nonetheless, we shouldn't fault the company for having a fail-safe
    - thatguy0900 5y ago
      A little unfair to blame the company here, no? The fuel is 100% sustainable and it would be illegal to use more than 50% of it here
jessriedel 5y ago
Yes, misleading headline for sure. But as a testing strategy it certainly makes sense.
- vanusa 5y ago
  The point is that the "headline" doesn't come from a news outlet. But from the company pushing the product.
  - tyingq 5y ago
    Unless they changed it, the headline on the page is: "United Flies World’s First Passenger Flight On 100% Sustainable Aviation Fuel Supplying One Of Its Engines" And it's in the url too.
  - jessriedel 5y ago
    The latter seems better to me.
throwawayboise 5y ago
I read it as meaning the fuel was 100% sustainable.
- vanusa 5y ago
  Turns out it that's not true either. See the article linked to in my post.
  - deleted 5y ago
    [deleted]
  - throwawayboise 5y ago
    Well, who expects complete honesty in a marketing press release anyway?
hbarka 5y ago
EV batteries started this way with hybrids like the Prius. Look where we are.
- chrischen 5y ago
  Actually Priuses use a completely different battery tech than EVs like Tesla.
  - hbarka 5y ago
    True. The point was that there’s a progression in the technology. Nickel Cadmium -> Lithium Ion -> ?Solid State. More importantly, there’s the cost curve improvement.
  - kijiki 5y ago
    True for pure hybrid Priuses, but Plug-in Priuses use Lithium-Ion batteries just like Teslas.
p1necone 5y ago
Seems like a perfectly reasonable test to me? This proves that an engine can run on this fuel at 100% concentration. The other engine is exactly the same, there's no reason that this result doesn't carry over to a flight with /both/ engines using this new fuel. This is just a safer test if there turned out to be problems with the experimental fuel. The article mentions this in the very first paragraph, I don't think there's anything to complain about here. I also don't think the headline is misleading either. The important thing being tested here is that the engine managed a flight with a 100% concentration of the new fuel, the other engine being a failsafe with known safe fuel doesn't make the outcome of the test any less useful. Edit: the headline on the page mentions the second engine using legacy fuel, I'm not sure why the HN headline was modified.
staticassertion 5y ago
Article headline: > United Flies World’s First Passenger Flight On 100% Sustainable Aviation Fuel Supplying One Of Its Engines Third sentence: > It was the first commercial flight with passengers on board to use 100% drop-in sustainable aviation fuel (SAF) for one of the aircraft’s two engines.
dang 5y ago
Ok, we've put one engine in the title above. The article title doesn't have this issue because it clearly says "Supplying One Of Its Engines". I wonder if they added after getting criticized or if it was there all along. Edit: probably the former, since the original press release omitted it: https://www.prnewswire.com/news-releases/united-to-become-first-in-aviation-history-to-fly-aircraft-full-of-passengers-using-100-sustainable-fuel-301435009.html https://www.prnewswire.com/news-releases/united-to-become-fi.... Pretty silly to think they could get away with that.
Syonyk 5y ago
... and? If one engine works entirely fine on a 100% blend, with no ill effects in operation or in analysis afterwards (for weird deposits on the hot section), it's reasonable to conclude that one could run exclusively on it. There's a chunk of wisdom over in experimental aviation (the "You can build and fly whatever you want, please try not to kill anyone else in the process..." side of things): "Never test an experimental engine on an experimental airframe." If you're building a new airframe, use a proven engine. If you're trying a new engine, use a proven airframe. Otherwise you just end up with an explosion of possible issues, and "experimental engine plus experimental airframe" tends to lead to an alarmingly short lifespan. Running one engine on an experimental fuel, while keeping the other on something you know is entirely sane and will work fine, is entirely reasonable. You know the airplane can fly and land safely on one. You think the other one works fine - but there are some weird corner cases in aviation - British Airways Flight 38 was one of those things. In this particular, exceedingly difficult to reproduce case, water in the fuel iced up and clogged the fuel flow to both engines, leading to a crash short of the runway (no fatalities, mostly due to the skill of the pilots). The engines behaved absolutely fine, until short final, at which point they suddenly, and without any prior warning, refused to make power - because they couldn't get enough fuel. The entire point of testing is to work out as much of this sort of stuff as you can. If it turns out that after cruise, you've got weird fuel icing issues, it is far better to have that problem limited to one engine, where the other one can pick up the slack and haul you into a goaround if needed (twinjets are typically obscenely overpowered on two, because they need to perform well with an engine out). Doing it the way United did is entirely sane, reasonable, and rational for any sort of aviation testing. Doing it on both engines, without serious testing beforehand (of the "on one side" variety), would be insane in aviation.

pfdietz 5y ago

This appears to be the synthetic jet fuel from Virent. It is made from light carbohydrates and other small organic molecules by their "Bioforming" process. This removes oxygen from the molecules by reaction in solution with hydrogen gas and a ruthenium catalyst. The resulting hydrocarbon molecules are then put through a reforming process where they are linked together and isomerized to get the right distribution of molecular weights. I've followed this process for a while. It yields more energy than ordinary biomass approaches, since it can also incorporate the energy of the hydrogen input stream. This is good, because biomass has terrible efficiency at conversion of sunlight to fuel. No CO2 need be produced; the oxygen is carried away as water. One can think of the biomass as more of a carbon source than (just) an energy source. It also tolerates a wider variety of input molecules than enzyme-based approaches. https://www.virent.com/products/jet-fuel/ https://www.virent.com/products/jet-fuel/ https://www.virent.com/technology/bioforming/ https://www.virent.com/technology/bioforming/

hbarka 5y ago
I saw this news while on a public place watching NHK Newsline. Interestingly I couldn’t find it on Google search under News or All. The very interesting part is that the feed stock used to make the liquid fuel comes from common garbage waste. Have we finally found a place for the tons of household garbage we generate? The company cited as the supplier was Fulcrum Bioenergy in Reno Nevada. https://fulcrum-bioenergy.com/ https://fulcrum-bioenergy.com/
- Reason077 5y ago
  > ”Have we finally found a place for the tons of household garbage we generate?” Fossil-derived plastics make up a significant portion of household waste. From a climate perspective, it might actually be better to bury plastics in landfills rather than burn them as fuel.
  - usrusr 5y ago
    The mirror argument is that from a climate perspective, as long as we are still burning low energy-per-co2 fossils like lignite for energy (spot the embarrassed German) it might be a net reduction if we burn those high energy future landfills instead. Plastics are very useful, perhaps we should consider it wasteful to leave any well-to-atmosphere paths where the carbon did not go through a stage of making itself useful as plastics? Hard to find any numbers, because the CO2/MWh stats of incineration plants always contain a considerable fraction of renewable on the input and that would have to be removed from the equation an all sides (input, CO2 output, energy output) for a useful answer. I'm not enough of a chemist, but I suspect that the process the article is about could also habe potential for the creation of raw materials from bio stocks for plucking into the conventional plastics pipeline? This, combined with landfills (instead of incineration/highly processed incineration) could end up being the most viable carbon capture approach: instead of jumping through hoops trying to capture for the sake of it, it would harness our insatiable demand for plastics consumption. Are there any plant-based plastics already that don't don't with the friendly "degradable" label?

boringg 5y ago

A step in the right direction. Would be interested to know what the comparative energy ghg lifecycle costs for this fuel vs conventional fuel - and what prohibits them from using both engines. Is it just a liability / pilot test on the first go and then switch to both engines? Or are there concerns about going fully SAF?

throwawayboise 5y ago
Aviation is extremely conservative when it comes to adopting any new technology. It is tested and tested and tested again. Allowing only 50% (or 100% on one engine) seems like exactly what they would do. Make a small change, test it for a while, tear down some engines and look for anything unusual, etc. If it's a drop-in replacement for Jet A, it needs to work in the newest modern engines as well as the 30 year old ones that are still in service. Look how long it took to get unleaded gasoline approved as an aviation fuel for piston-engined aircraft.
- sokoloff 5y ago
  Part of the difficulty is that the certifications for the (high-compression piston) engines were to run on 100LL, not to run on “a fuel with a lean mixture knock value of X and a rich mixture knock value of Y” and the specification for 100LL (ASTM D 910) is a formulation specification which includes tetraethyl lead rather than being a performance specification. Maybe the FAA could have been more aggressive in allowing a replacement fuel to be certified, but various fuels have been tested for over a decade now in experimental category aircraft, meaning they were not holding up development activities, just holding what seems like an objectivity reasonable hurdle for all-model STC approval (which still hasn’t been granted; we’re at the “many model” approval level right now).

oliv__ 5y ago

I wonder if this fuel could be produced in sufficient quantities to power cars? I love my combustion engines

colechristensen 5y ago
There are a few methods out there for synthesizing gasoline equivalents. This fuel: no (possibly in diesel engines, jet fuel has been used but there are issues).
fy20 5y ago
Most diesel engines can run on kerosene just fine, so I expect this would be the same. In fact kerosene is often blended with diesel in cold climates as regular diesel below -25C/0F will start to get thick. The reason why you don't want to use straight kerosene is that it is too pure - diesel has additives that lubricate the engine, without which you will cause more wear and tear on the engine. If that's all you have it'll probably work though, especially if you mix it with a little engine oil.

tims33 5y ago

One interesting aspect buried deeper in the release is that United has gone out to make extensive financial commitments to get this fuel produced at greater scale. Putting these fuels to use is more than just testing.

woeirua 5y ago

Anyone know what the cost is per gallon for SAF versus conventional jet fuel?

HWR_14 5y ago

I do like that the CEOs of both GE aviation and United were on the flight. I respect dog fooding.

hbarka 5y ago
Skin in the game. United CEO Scott Kirby is invested in SAF. https://youtu.be/XQtNEvVWPLc https://youtu.be/XQtNEvVWPLc
ec109685 5y ago
These planes can run on one engine, so risk was small.
- taspeotis 5y ago
  That’s a 737 MAX which uh, doesn’t fly with both engines…
  - mike256 5y ago
    Doesn't need both engines to fly...
    - taspeotis 5y ago
      The 737 MAX has had a tendency to crash despite having two working engines. Thus the joke: it doesn’t fly with both engines.
lbriner 5y ago
I can't really see what the risk would have been. It's just liquid fuel and will mostly work or not work. They would have already tested heat generation and build-up of deposits etc. for many months.

nunez 5y ago

> Sustainable aviation fuel can be made from any of 60 different feedstocks — among them plant oils, algae, greases, fats, waste streams, alcohols, sugars, captured CO2 and other alternative feedstock sources and processes. The Department of Energy estimates that the United States alone has the resources to produce 50–60 billion gallons of SAF per year. For context, commercial airlines will use about 57 billion gallons of fuel by the end of 2021, down from a peak of 95 billion gallons in 2019, according to Statista. By switching from petroleum to SAF — when you take into consideration the entire life cycle of the fuel — the aviation industry could reduce its carbon contribution from fuel by up to 80%, according to industry associations the Air Transport Action Group and the International Air Transport Association. This is massive. Aircraft are some of the biggest CO2 pollutants out there.

jillesvangurp 5y ago
It's important because planes are expensive and have operational lives measured in decades. So, even though companies like Boeing and Airbus are looking at alternative forms of propulsion now (e.g. hydrogen and electric), it would take well into the second half of the century to replace the existing fleet with their newer, more sustainable versions. Realistically production for that kind of plane won't even start until the 2030s at the earliest (and probably in low volume initially). Synthetic fuels will allow the existing fleet to be operated in a more sustainable way during this time. It will probably have a higher cost though. Long term, the low cost sustainable alternatives will probably take over. But as electricity production cost drops in the next decades, so will the cost of using electricity for producing synthetic fuels.

supernova87a 5y ago

I hope this is part of a new positive development. But to me it sounds like one more in a series about biofuel that has generally gone nowhere or hit some limit that is not getting better. I say that because this same story pops up every ~2-3 years, but the important question that never gets conveniently ignored in the articles is, they flew using plant-based fuel at what price? Price is what determines everything for our behavior, including airlines deciding to fly planes all over the place. Reporters (and of course the press release) seem allergic to addressing such questions. If you read a story about biofuels and it has no mention of the price of the fuel, you can bet it's pretty much a meaningless piece of news. There is not a single $ sign in the story. It always turns out the fuel costs like $25 per gallon to produce. The basic concept that you can make fuel from biomass is not challenging. And flying it in a plane's gas tank is not new. Manufacturing it at a competitive price is. What will happen is that this will go nowhere, because neither United Airlines nor any other carrier will pay that per gallon compared to the $6-7 they usually pay. Unless it's continuously subsidized. Or until a technology comes along to make the price much more economical. Past examples: 2008: https://abcnews.go.com/Technology/story?id=4338149&page=1 https://abcnews.go.com/Technology/story?id=4338149&page=1 2010: https://www.scientificamerican.com/gallery/military-green-us-air-force-flies-on-biofuel/ https://www.scientificamerican.com/gallery/military-green-us... 2011: https://www.npr.org/2011/09/26/140702387/air-force-and-navy-turn-to-bio-fuels https://www.npr.org/2011/09/26/140702387/air-force-and-navy-... 2016: https://www.biofuelsdigest.com/bdigest/2016/10/02/american-airlines-hires-ocean-park-to-assist-with-renewable-jet-fuel-evaluation/ https://www.biofuelsdigest.com/bdigest/2016/10/02/american-a... 2018: https://www.theguardian.com/environment/2018/jan/30/qantas-uses-mustard-seeds-in-first-ever-biofuel-flight-between-australia-and-us https://www.theguardian.com/environment/2018/jan/30/qantas-u... Not a peep heard from these practically since. Sorry this is a little negative. But if there is to be any informed / useful understanding of the topic (which I think this place is about), and not just feeling good after reading a story for 30 seconds, this is the key issue, not just the nice headline. Otherwise you go away for a couple years and wonder "hey what happened to that good news about achieving biofuels?" It's like if I told you I demonstrated that we could run your car on biofuels. Great. At $25/gallon? Not so impressive.

ya_throw 5y ago

This is completely bogus. The ever-increasing global demand for soy foodstock is already accelerating the destruction of tropical rainforests - how is it all sustainable to burn huge amounts of foodstock that so we can enjoy making the world "a smaller and better place" [1]? Just for fun - an acre of soy produces 70 gallons of "biofuel", so a square mile of soy plantation can produce around 45,000 gallons of fuel, or enough to fly a 747 for about 10,000 miles. After slashing and burning a patch of rainforest, you get about 3 years of crops, before you need to leave it for around 10 years to "regrow". If all of the Amazon rainforest (2,000,000 sq miles) was slashed and burned for soy plantations, and assuming it can magically regrow in those 10 years, we will get enough fuel over one 13-year cycle to fly 5 billion miles. That is about 1/10th the total airplane mileage in one year. [2] [1] https://www.virent.com/products/jet-fuel/ https://www.virent.com/products/jet-fuel/ [2] https://www.quora.com/How-many-miles-do-airplanes-fly-in-the-world-each-year?share=1 https://www.quora.com/How-many-miles-do-airplanes-fly-in-the...

wutwutwutwut 5y ago
From the article: > Sustainable aviation fuel can be made from any of 60 different feedstocks — among them plant oils, algae, greases, fats, waste streams, alcohols, sugars, captured CO2 and other alternative feedstock sources and processes. The Department of Energy estimates that the United States alone has the resources to produce 50–60 billion gallons of SAF per year.
- ya_throw 5y ago
  By "article", you mean "marketing blub from someone trying to sell you something". Ultimately, all of those "sustainable" feedstocks will have to be grown. As my quick maths points out, the size of the field we're going to need is just staggering. >The Department of Energy estimates that the United States alone has the resources to produce 50–60 billion gallons of SAF per year. I'd like to know where from. Actually, I looked it up. It's the "Billion Tonne Plan". It involves "thinning" all US forests, and planting practically every available acre with crops for biofuel. Basically, dedicating all of the available plant matter grown in the US to burning for transportation.