“game-changing” and “10% efficiency” don’t seem to match that well…
I suspect that the ability to handle pure Sustainable aviation fuel (SAF) is the critical improvement here, but the article doesn’t provide the context that:
- current engines can only run with 5% SAF
- airlines are trying to get as much SAF as they can but struggle to find more at an affordable price
- how much SAF we could make based on current food trends and what is blocking us from reaching that level.
The announcement phrased as it is makes sense for professionals, which is why I understand RR PR department has phrased it that way, but the BBC shouldn’t expect its readers to know all that.
I agree that 5% efficiency justifies widespread adoption, but that didn’t require much more than a few hours of maintenance to set wingtips up.
I’m not sure that 10% would justify switching to a new engine, a new airplane type, and investing in re-qualifying all your pilots. I remember hearing hesitation around RISE and braced wings. Those would “only” save 20% fuel but required too many changes to be adopted before planes needed to be replaced.
On the other hand, working with a different fuel but with a similar power package, that could presumably be adopted before 2030, if the savings are indeed almost an order of magnitude of carbon footprint. This is why I think the article should have said a lot more about the supply chain and price of SAF.
> I agree that 5% efficiency justifies widespread adoption, but that didn’t require much more than a few hours of maintenance to set wingtips up.
Retrofitting winglets on an airliner costs a million+ upfront and grounds the plane for a week.
It’s not to the level of buying a new plane, but this is not a few hours work on the tarmac between two flights, they’re not airfoils off of wish you glue onto your rust bucket.
10% is close to the point where airlines would retire their planes earlier in order to reduce their fuel cost, as planes spend their value on fuel every 5 odd years.
Suppose you want to reduce carbon emissions by 50% but SAE cost 40% more. Replacing half your fuel with SAE = 0.5 * 140% + 0.5 * 100% = fuel costs go up by 20% and ticket prices go up by half that or 10%.
If instead you reduce total fuel need by 10%. 10% engines + 40% SAE + 50% normal = 50% carbon savings. But you’re paying 0.1 * 0% + 0.4 * 140% + 0.5 * 100% = 6% more on fuel and ticket prices only go up 3%.
On top of that you don’t need to carry as much fuel which further increases efficiency or let’s you increase cargo capacity.
I thought that aircraft could use much more than 5%, but that the maintenance regime was different - e.g. [1]. Current engines assume a proportion of impurities and are tuned to work with that, but could be modified to run with 100% SAF if it was available.
Just to add - 10% increase on the state of the art is nothing small!
The article explains briefly: fuel that is not from fossil sources. Essentially, organic waste converted to petrol-like hydrocarbons. Used frying oil from fast food is a large, consistent source. Ethanol from corn is also common in the US, but mostly for petrol meant for car. Not sure if there’s corn-based SAF but that would feel counter-productive (corn-based ethanol takes a lot of petrol to make).
There seems to be issue with the relative portion of octanes, so it cannot be used in large portion in both car and aviation: I remember reading something about lead in petrol and “knocking”, ie the air-petrol mix exploding too early. I’m assuming that this engine handles that problem better, somehow. Given that lead is still in aviation gas, that would be beneficial in many ways.
The important part to me: "The demonstator was powered by 100% Sustainable Aviation Fuel (SAF). This is derived primarily from waste-based sustainable feedstocks such as used cooking oils".
If McDonald's and other similar food joints of the world were be able to power not just trucks, but also airlines with used cooking oil, this would be something :)
Oh, and a 10% efficiency improvement over the current most efficient turbine engine, nice. This may be a bigger feat of engineering than the use of SAF, but looks less catchy.
The world ran out of waste cooking oils over a decade ago. 20 years ago used cooking oil was nearly worthless - there was some uses for it (makeup was a big one), but the total need was less than the supply, and a lot of it was dumped into a landfill (only a few landfills could take it). About 15 years ago biodiesel hit, and it wasn't long before that market exceeded the supply. These days talking about used cooking oil is a waste of time - there isn't any more to be had.
There are still sources of vegetable oil to be had, but they are not used oil.
The whole point of the used cooking oil is that it has been also used for cooking.
Biodiesel is barely carbon-neutral if you're lucky; often it produces more carbon dioxide than you'd emit if you just used all the fuel directly, instead of fueling the agricultural machines, fertilizer factories, etc [1].
When all the harvesters and presses become 100% powered with renewables, direct production of biodiesel may make sense.
Some countries already recycle it from households. I guess the US is lagging behind as it doesn't have such a big bio-diesel industry (it's not far off Europe though):
The next step isn't to get more users of oil so there is more waste. The next step is bypass the waste oil and go directly to farmers to buy oil direct (actually the grain crushing plants). This what the biodiesel market started doing years ago, they can get a truckload from one place, instead of having to drive the truck around collecting a little bit from dozens of places. Plus the farmers can put in place quality controls that waste product can never meet.
Oh, this is a jet engine! Not a car engine. I was wondering if they’d be changing the electric vehicle game :)
Apparently this new engine is 10% more efficient, and also runs on “Sustainable Aviation Fuel” (SAF). I did some quick searching, and this source claims that SAF can reduce carbon emissions by “up to 80%”, and that this improvement might represent 65% of the necessary decarbonization of the aviation industry [1].
Rolls-Royce, the historical company, hasn’t made cars in several decades. The car brand is part of a German conglomerate.
Given the expected price point of the car brand, they can afford very interesting exploration in the EV space. They’ve revealed some prototypes but haven’t really owned the space the way they could: silent, heavy, and stately with surprising power if needed—EVs are a perfect match for their brand.
RR is the leading airplane engine manufacturer with Honeywell and Pratt & Witney. GE & Safran contribute a lot too, but usually for specialized (military) applications. Unless something goes wrong, this engine could easily equip the majority of Boeing and Airbus that fly in 2030. I’d agree with your implicit assumption that it could be on 80% the commercial aviation.
According to this source [1], as of 2019 GE and Safran’s joint venture (CFM) have a 39% share of the commercial engine market, and GE by themselves a further 16%. They have Pratt and Whitney at 35% and RR at 12%.
I’m not sure what their source is but it says this is the commercial market, excluding military and private aviation.
> GE & Safran contribute a lot too, but usually for specialized (military) applications.
GE and Safran is CFM (https://en.wikipedia.org/wiki/CFM_International), in late 2021 CFM claimed they had 72% of the narrowbody market. Literally all the 737 MAX mess was so they could re-engineer it for the LEAP and avoid falling too far behind the A320neo, and the CFM56 remains extremely popular despite its age.
Also things might get quite weird if RISE is a success.
Airplane bodies and engines are normally managed and maintained as separate assets and often exchanged AFAIK.
Not sure what fitting a different engine type would do to the (re)certification/airworthiness though, that might introduce a whole other bunch of bureaucratic difficulties.
Individual airliner airframes don't normally get re-engined.
Re-engining is a medium program requiring recertification (as lots of ancillary components need to be replaced to match, and the physical properties of the plane almost always change e.g. shape, size, and weight will change the plane aerodynamics), hence they generally include minor frame updates (e.g. A320neo), but can also require pretty major redesigns (737-NG, 737-MAX).
Plus it's common for the engine to be customised to the frame e.g. the CFM LEAP 1A is the variant for the A320 neo, the 1B for the 737 MAX, and the 1C for the COMAC C919. Similarly, the A220, A320neo, Embraer E2 and Irkut C21 all use different models of the PW1000G family.
Boeing had a patent 20-ish years ago for making engine interchange simpler on models that were certified for multiple engines. IIRC, it was originally implemented for 757 and 767. Might have been part of DCAC/MRM, but I’m not 100% on that bit.
This article is frustratingly light on details and it almost sounds like an ad. I wish we could swap the link for a better source because I would like to know more about this new engine.
Flying consumes a lot of energy, and flying by carbon combustion emits CO2 high up in atmosphere. As good as incremetal improvements like this neither really get fixed by technology like this.
Very roughly a plane emits CO2 equivalent of using 1MW of electricity per passenger in economy. So an intercontinental return flight can be equivalent to a whole's years worth of electricity usage....
You seem to get downvoted but I’m totally unimpressed by this news for the same reason. If we want a sustainable future, the first step is banning private jets, and the second one is to restrict and reduce all air travel. That would have a huge impact on people but I think it’s the moral thing to do.
I know, yet I think the conclusion to draw here is that those other polluters are really terrible, not that the aviation is something to ignore because it’s a relatively small part of the pie.
Kudos to RR engineers, but when I read that this engine is "powered by 100% Sustainable Aviation Fuel (SAF)" and that it "is derived primarily from waste-based sustainable feedstocks such as used cooking oils" I am dissapointed. Maybe there is enough used cooking oil in the world to power all the jets (now and in the future) but it first needs to be gathered. And that is expensive. Which will lead to unused cooking oil to be used. And, in the end, it will raise food prices as that oil is needed for human food preparation.
It's pretty shocking how giant that engine is. Is that really how big they are on the biggest jumbo jets? Or is it for one of those super giant planes that carry tanks for the military or whatever?
The 747 actually had rather small engines. First of all, it had 4 and they were older-style with low bypass ratio. The 777 isn't that far from 747 capacity, but only sports 2 gigantic engines, they not only need to be more powerful, but have high bypass ratios to improve efficiency. They are even wider than the body of a 737.
It’s pretty normal for modern turbofans to look huge, they’re so-called “high bypass” turbofans: the power is provided by a turboreactor-ish core, but that drives a large ducted fan which pushes air through, most of that air bypasses the core (hence high-bypass).
A model turbofan might have a bypass ratio of 10, aka for every kilo of air going through the core 10 are pushed around it by the fan.
That applies to all airliners e.g. the reason for the 737 max’s issues is that the plane is very low to the ground, so it didn’t have room under the wings for modern turbofans.
The 2nd and 3rd gen 737 (Classic and NG) worked around it with peculiar flattened nacelles (they’re circular on every other plane), and moving some of the components to the sides (from their usual position at the bottom).
For the Max Boeing wanted even wider engines, and there was no way to flatten things further, so they moved the engines forwards and using long struts (check out comparison pics from the side).
The result however is that the thrust vectors are different than on “normal” 737 giving the aircraft a tendency to pitch up in certain conditions, which is what the MCAS was supposed to automatically remedy.
For reference, the original 737 had engines with a width of ~1m (40 inches), the second generation (“classic”) had fans 1.5m (60in) in diameter, the 737-NG is a minor bump to 1.55m (61in).
The Max’s CFM Leap has a 1.76m (70in) fan. And that’s a specially reduced and less efficient version, on the 320neo the same engine has a 2m (78in) fan.
Notable: The fan is driven through gearing from the low-pressure turbine stage.
> ... with its power gearbox and Advance3-based core, represents a radical shift away from the traditional three-shaft designs that have been the hallmark of Rolls-Royce’s large engine configurations since the 1960s.
That engine is massive! This will need new air frames to keep those engines from scraping the ground. Seems like it will be a while before this is used commercially.
I suspect that the ability to handle pure Sustainable aviation fuel (SAF) is the critical improvement here, but the article doesn’t provide the context that:
- current engines can only run with 5% SAF
- airlines are trying to get as much SAF as they can but struggle to find more at an affordable price
- how much SAF we could make based on current food trends and what is blocking us from reaching that level.
The announcement phrased as it is makes sense for professionals, which is why I understand RR PR department has phrased it that way, but the BBC shouldn’t expect its readers to know all that.