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zero emissions flying?

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 girlymonkey 14 Jul 2021

I presume the government are talking nonsense (they usually are) when they suggest that flying is going to be environmentally friendly in the near future? Is there any element of truth to this is or it all absolute nonsense? 

https://www.bbc.co.uk/news/business-57830168

 Lankyman 14 Jul 2021
In reply to girlymonkey:

Nonsense! Every time cabin pressure changes I'm farting for England.

 girlymonkey 14 Jul 2021
In reply to Lankyman:

Really?! That is an odd effect surely?! My ears pop but nothing else! lol

 wercat 14 Jul 2021
In reply to girlymonkey:

How can you think they are talking nonsense? All they are saying are that it will be Someone Else's Problem to solve the conundrum they have created (as usual) and Someone Else's Fault if their unrealistic vision does not come true.

You should know that by now!

 girlymonkey 14 Jul 2021
In reply to wercat:

Sorry, silly me. I am just not patriotic enough and too willing to doubt our highly moral and upright government! I look forward to a future of Someone Else making all well for us!!

 nikoid 14 Jul 2021
In reply to girlymonkey:

Since the government has not disclosed any detail or coherent plan as to how environmentally friendly flying will be achieved, other than "innovation" I think we have to assume the idea is BS. 

 Forest Dump 14 Jul 2021
In reply to girlymonkey:

You'll be able to look out and see a pig flying next to you

 girlymonkey 14 Jul 2021
In reply to nikoid:

Yes, that was certainly my assumption. I guess I hoped someone on here might have some knowledge of an up and coming innovation which showed real world potential, but it does seem like a long shot.

In reply to girlymonkey:

Seeing the rate of change in technology, it might not be completely impossible, but I suspect that as the target gets closer a greater reliance will be based on carbon-offsetting to hit the figures, rather than genuine emissions-reduction.

 Richard Horn 14 Jul 2021
In reply to girlymonkey:

In terms of achievability - 20/30 years is a long time. The world went from the Model-T Ford (before which almost no-one had private motorised transport) to landing on the moon in around 40 years. Look back 20 years, there were no smart phones or social media, back 30 years there was no internet. I would not be surprised if we have put a research lab on Mars in the next 20-30 years.

So I have plenty of belief that it could be achieved and the government will know that developing the technology here will mean companies abroad will come shopping when the effects of climate change develop even further and governments are forced to act. Think about it laterally, all a plane needs is a power source - it doesnt matter whether its fossil fuel, bio fuel, hydrogen or electricity. Hydrogen would appear to have a lot of potential (once the storage issues are resolved).

The contentious thing for me is that we probably want this a fair bit quicker than 20 or 30 years....

 wintertree 14 Jul 2021
In reply to girlymonkey:

My take:

There are plans to shoe-horn hydrogen power in to some propellor based, low capacity short hall flights using fuel cells and electric motors.  That's probably as fas as conversion of the existing fleet can go towards hydrogen.

Dedicated hydrogen aircraft can do better, but they require a ground-up redesign around cryogenic liquid hydrogen storage and hydrogen optimised engines.  Some interesting possibilities for in-atmosphere hypersonics using son-of-HOTOL engines - SABRE/LAPCAT.  But probably 20+ years away (optimistic) for commercial civil aviation.

Battery electric flight for civil aviation isn't going to be a thing until aluminium-ion battery technology is established and mature, probably 20+ years before it's in commercial service (optimistic) for civil aviation.

So, what's left?

  • Offsetting - reclaim a lot of desert and plant a lot of trees.
    • Better than nothing if travellers are made to pay the external costs (climate damage) of their flying and it's poured in to offsetting.  The instant collapse of budget airlines will also reduce demand
  • Greenwashing, er sorry biofuels...
  • Synthetic fuel
    • Holds promise, existing engines and aircraft can be re-certified for this, lots of R&D is going on, big players are invested.  It's only as green as the energy supply mix to the synthetic fuel plants, but as with BEVs, investment in the technology now will automatically benefit from all electricity decarbonisation work.

Edit: My solution - battery electric flight *now* with enough capacity for 30 minutes flight and landing, with take-off power and normal in-flight power supplied by microwave beaming, from ground terminals for takeoff and from orbital (geostationary) space based solar power arrays when in flight.  Or, rather than microwave beaming at takeoff, either electrically powered catapults (EMALS) or a scalextric style bushes-in-grooves system.

That should see the demand for aviation fall right off the scale...

Post edited at 09:34
 Duncan Bourne 14 Jul 2021
In reply to wintertree:

Wasn't there a thing about new designed airships a while back? Did that not get off the ground (sic)?

 jkarran 14 Jul 2021
In reply to girlymonkey:

> Is there any element of truth to this is or it all absolute nonsense? 

The timelines are nonsense.

We might have some very niche electric shorthaul by 2030, maybe a developing trend if the technology matures very very fast and there's a massive move by government (taxpayers) to incentivise it or to disincentivise investment in new fossil burning short-haul tech (which smells like an unaffordable trade war with Boeing or Airbus's hosts depending which falls behind). We could well see some niche 'ethical airlines' running routes on biofuels by then but there won't be anything like a wholesale switch.

Renewable or nuclear powered synthetic fuels could replace JetA1 without a requiring a whole new fleet and 30 years is a long time (not in the grid scale nuclear world mind). I'm a bit less sceptical of this one to be honest but I wouldn't bet on it. A lot can change in that time technologically and in public attitudes. Also, which generation holds the reins and purse strings. I suspect it might still be a decade or so on the optimistic side but we'll see.

jk

Post edited at 11:19
 wintertree 14 Jul 2021
In reply to Duncan Bourne:

A company called Hybrid Air Vehicles Limited have been chipping away at this for about 15 years now, with a hybrid twin-hulled lifting body design.  The idea is to have it not-quite neutrally buoyant when stationary to simplify landing with a hovercraft skirt that can switch to "suck" mode, removing the need for a ground tower and/or crew for landing.  Then the shape of the craft generates the lift needed for flight under forwards motion. 

They've had a few flights and FAA approval looms large for their next design. 

80 mph top speed, so it's not going to out-compete a continent spanning, integrated high speed rail system but might just cut it for ~1000 mile journeys in the real world.

2.5 days to get to California by one.  Imagine if I stepped off the airship feeling happy, refreshed, exercised, well fed, slept and having started to adjust my sleep schedule I'd take that over ~24 hours in the civil aviation system, turning up cramped, noise tormented, unslept, with a sore throat, sick of my fellow humans, stinking and miserable.  I'd pay over the odds for that - I haven't flown in 8 years and don't intend to set foot on another jet aircraft unless I accidentally end up obscenely rich and can have one to myself.

 If it can ride the jet stream, the return journey could be cut down to less than 1 day.

If they can get a bigger, better and faster one of the ground in the future, I look forwards to the glass bottomed swimming pool, and a small glass domned observatarium on the top between the two hulls, accessed by a Jeffries tube.

Requisite:  youtube.com/watch?v=Kq-N3_plNq8&

Realistically thought, airships have been on the cusp of a resurgence for most of my life, I hope to see it actually happen but optimism doesn't last for ever.

 SDM 14 Jul 2021
In reply to wintertree:

>  Imagine if I stepped off the airship feeling happy, refreshed, exercised, well fed, slept and having started to adjust my sleep schedule I'd take that over ~24 hours in the civil aviation system, turning up cramped, noise tormented, unslept, with a sore throat, sick of my fellow humans, stinking and miserable.  I'd pay over the odds for that 

I admire your optimism.

I expect the extra space would lead to them trying to cram more and more people in until you were spending 2.5 days in exactly the same conditions as as an economy class airplane.

Unless you were willing to pay thousands over the odds for a more luxurious journey.

In reply to wintertree:

A few years ago, I saw the latest Airlander flying over Bedfordshire whilst I was walking parallel to it in the Chilterns about ten miles to the south. It looked like one of the biggest white elephants (literally) I've ever seen. Against the headwind that day, it was hardly moving faster than my walking pace and seemed to be wallowing about and having difficulty maneuvering. 

Airships suffer from very low flying speeds, which are only several times greater than average airspeeds aloft, so their groundspeed when there is a head wind is pitiful. Long-distance travel in a westward direction is generally very slow even with circuitous flight plans. They are very expensive to run, one of the big costs being the helium...

In reply to girlymonkey:

Short haul battery airliners are likely to be viable in the not too distant future.  These would work pretty well for the likes of the Scottish Highland and island-hopper flights plus shorter European flights e.g. Gatwick-Amsterdam.

It's long haul that really poses a challenge, but I guess we should reduce long-haul travel anyway.  Biofuels perhaps with new designs of engine?  Jet A-1 is very similar to paraffin or diesel, so if you can do biodiesel...could enough rapeseed oil be grown?

Post edited at 13:25
 Timmd 14 Jul 2021
In reply to wercat:

> How can you think they are talking nonsense? All they are saying are that it will be Someone Else's Problem to solve the conundrum they have created (as usual) and Someone Else's Fault if their unrealistic vision does not come true.

> You should know that by now!

Technology and planting trees will solve things, apparently. The planting of trees in the wrong places can mean that snow cover isn't the same, stopping the heat from being reflected back up again. 

Post edited at 13:31
 gravy 14 Jul 2021
In reply to girlymonkey:

It means biofuels for the foreseeable future.

In reply to Neil Williams:

Is the energy density of the batteries really up to this? and with how many passengers?

Jet A-1 is paraffin (it's a mixture of paraffins in the C12 to C15 range), so I'm not sure what point you are making here.

 jimtitt 14 Jul 2021
In reply to Neil Williams:

Well United (and their leasing subsiduary)  have signed pre-contracts for 200 Heart ES19's which are 19 passenger electric planes with a range of 400km. Just got to see if the Swedes can actually deliver them! On the other hand they've also signed up for 50 supersonic airliners from Boom so maybe they are on drugs.

In reply to John Stainforth:

> Is the energy density of the batteries really up to this? and with how many passengers?

This is a good read on progress:

https://www.airbus.com/innovation/zero-emission/electric-flight.html

The answer is probably "not yet" but getting there.

> Jet A-1 is paraffin (it's a mixture of paraffins in the C12 to C15 range), so I'm not sure what point you are making here.

If biofuels are viable for other modes of transport they're viable for air, essentially.

In reply to Neil Williams:

> If biofuels are viable for other modes of transport they're viable for air, essentially.

Viable in terms of energy density but are they really much of a step forward in terms of sustainability?

Won't we just end up chopping down loads of forests in order to grow crops to fuel planes?

 wintertree 14 Jul 2021
In reply to Neil Williams:

> This is a good read on progress:

It looks like a page from a Marketing Department to me, with some rather confusing language.

To translate a bit of it, "2017 - Airbus Launches E-Fan X".  "Launches" does not mean launching an aircraft, but starting an R&D project; one that has apparently been cancelled purportedly because of Covid.

Some numbers to underline my skepticism of battery-electric for anything beyond the fringes of aviation and some mild hybrid stuff.  I've checked them but there could be a mistake.e

  • A 787 can carry a fuel load of ~10^5 kg (100 metric tonnes).
  • Kerosene has a specific energy of  ~40 MJ/kg 
  • That's 40 MJ/kg x 10^5 kg = 4 x 10^6 MJ of energy in the fuel (assuming ready access to atmospheric oxygen...)

A Tesla model 3 achieves about 1 MJ/kg of energy density in its batteries.

  • A full fuel load in a 787 would equate to (4 x 10^6 MJ) / (1 MJ/kg)
    • =4 x 10^6 kg
    • = 4000 metric tonnes of batteries
  • Fuel load is 100 metric tonnes, cargo capacity is 60 metric tonnes.
  • The battery electric approach might be a bit more efficient than a gas turbine engine, but not much.

Bit of a disparity there.  The theoretical gains in lithium-ion battery technology can get something like a 6x fundamental improvement, and there's some more from the packaging of the cells but it gets you nowhere near the more than 50 fold improvement needed to supplant kerosene.  Aluminium-ion can theoretically get a ~20x fold improvement over current batteries which at least puts it in the right ballpark. 

In reply to Me Me Me:

> Viable in terms of energy density but are they really much of a step forward in terms of sustainability?

> Won't we just end up chopping down loads of forests in order to grow crops to fuel planes?

I'll weep if we end up displacing forest to grow oil seed rape to fly people on £100 tickets to get mashed in Ibiza.  What's going on to fuel Drax is disgraceful enough.

Post edited at 17:32
In reply to wintertree:

The best thing that could happen long term is that flying on holiday becomes something most can only afford every 2 or 3 years and long haul holidays effectively end, there isn't really any justification for holidays to dubai, Maldives, Thailand etc..  simply to sit in the sun. 

In reply to summo:

> There isn't really any justification for holidays to dubai, Maldives, Thailand etc..  simply to sit in the sun. 

What about climbing rather than just sitting in the sun?

In reply to Robert Durran:

> What about climbing rather than just sitting in the sun?

Nope. I don't think it's justifiable anymore. Electric Sleeper trains maybe to countries within striking distance.

 Moacs 15 Jul 2021
In reply to wintertree:

> ...short hall...

Is that what they mean when you hear about air corridors?

 wercat 15 Jul 2021
In reply to summo:

plus mega cruiseships can go as well (unless they can be based on solae/windpower and become almost non polluting).  The sooner we move to a world not based on excess consumption the better

Post edited at 12:57
In reply to wercat:

Yes, these gross behemoths affect air quality of the towns where they park up, look totally out of place at destinations such as Venice, and create pressure to dredge channels through shellfish beds etc, but do you know what additional emissions they bring about over their lifetime, taking into account the emissions that are not happening in the lives of the passengers while they are aboard?

In reply to Neil Williams:

> Short haul battery airliners are likely to be viable in the not too distant future.  These would work pretty well for the likes of the Scottish Highland and island-hopper flights plus shorter European flights e.g. Gatwick-Amsterdam.

Lots of noise here about inter-island electric planes as the journey is only about 25 miles.  However, the problem is that of endurance- the planes need 40 minutes endurance for safety reasons even though the flight time is about 8 minutes. Batteries simply aren't up to that yet in a commercial setup. Wintertree's thoughts on launch catapults do actually make some sense because they remove the battery capacity required for taxiing and maximum power takeoff. The planes will be taken out from the terminal to the runway by tugs, clipped into the catapult and launched without engine use. Not needing batteries for takeoff reduces the mass of the plane, thus reducing the power required to keep it in the air, thus reducing the battery capacity required there.....

 Richard J 15 Jul 2021
In reply to wintertree:

I think the energy density argument is crucial here.  On this basis, I don't see how batteries will ever be viable for long-haul flight, nor, without a radical aircraft redesign, hydrogen.  I don't think there's a way of having zero-carbon long-haul flight in 2040 that doesn't involve liquid hydrocarbons.

So to make a zero-carbon replacement for kerosene, there are two choices.  Biofuel from vegetable oil is entirely viable technically, but I agree with you that the land area demands for growing enough oil-seed to power the aviation industry are unrealistic and unacceptable.

That leaves synthetic hydrocarbons made using zero-carbon forms of energy.  This is entirely technically doable.  You need hydrogen made from either (a) electrolysis driven by wind or solar electricity, (b) process heat from high temperature nuclear reactors, or (c) steam methane reformation with carbon capture and storage.  Then you need carbon dioxide extracted from the atmosphere by "direct air capture", again technically doable but needs a source of zero-carbon energy to overcome the second law.  After a "shift reaction" to produce carbon monoxide from the hydrogen + carbon dioxide, then you can use Fischer-Tropsch chemistry to get whatever hydrocarbon you want (the technology essentially invented in Germany in WW2 by IG Farben).

This could be done now, but it's expensive, so it needs lots of process R&D to drive the costs down - as well as a general scaling up and reduction in cost of zero-carbon electricity.  I think Rolls-Royce are very interested in this (as they know something like this needs to happen in order for them still to have an aero-engine business in 2050), as are some of the big oil companies.  But even after the processes are perfected the fuel is still likely to be significantly more expensive than the stuff that comes out of the ground, so it will need (a) an acceptance that aviation will be relatively more expensive, and (b) international agreement and regulation to outlaw petroleum based fuel.

 jkarran 15 Jul 2021
In reply to Toerag:

I can totally see taxi tugs being a thing whatever powers the aircraft, part cost reduction, part local air quality issues.

I don't see catapults happening. If the aim is to get you up to rotation speed with a burried catapult like US carriers then the gains are marginal, the re-engineering enormous and I suspect the structure added around the undercariage would cost more fuel than skipping part of the acceleration phase would save.

Winch launching works for gliders and doesnvt require digging up a runway but it's messy and really quite hazardous in a number of ways. It's also stressful for the airframe so again, add weight, decrease cruise efficiency. It's also a wild ride! Flat out nope for commercial opperations. 

Jk

Post edited at 13:47
In reply to wercat/mbh:

>do you know what additional emissions they bring about over their lifetime, taking into account the emissions that are not happening in the lives of the passengers while they are aboard?

I've just read a paper on emissions from cruise ships in Norwegian waters. The emissions per passenger per trip are just over half a tonne, plus whatever is emitted by the ship elsewhere, plus emissions during port stops - about 52h per trip.

So going on a cruise is a 25t+ emissions per year lifestyle. The paper also looked into NOx and particulate matter emissions.

It also said, though, that the cruise industry contributes just 5% of global shipping emissions. That was in 2019.

 S Ramsay 15 Jul 2021
In reply to jkarran:

Cat and Trap systems are already on the way out for aircraft carriers, the US's newer carriers now use an electromagnetic launch system which has the advantages of putting much less stress on the airframes and being able to cope with a much larger range of aircraft weights so while I'm not betting on these being installed under commercial runways its not totally implausible.

-

Even if someone develops a super light battery or functional hydrogen plane (hydrogen doesn't seem that unlikely) the costs of flight will shoot up dramatically. We are unlikely to have as much energy as we do now in 2050 if it is all to be from renewable sources. This isn't a total disaster as we can make do with a bit less but it does mean that price of electricity will be high as there is likely to be more demand than supply. Jet fuel is currently crazy cheap relative to electricity and diesel/petrol due to a combination of abundance and no taxes. I haven't done the exact sums but the cost of buying renewable electricity to turn into hydrogen, an inefficient process, and using that to power planes is likely to be high enough to virtually kill, or at least substantially reduce, the tourist market. Who is going to want to fly to Southern Europe for beach/climbing holidays in 2050 anyway as the Sahara starts to take over Madrid?

 jimtitt 15 Jul 2021
In reply to Toerag:

> Lots of noise here about inter-island electric planes as the journey is only about 25 miles.  However, the problem is that of endurance- the planes need 40 minutes endurance for safety reasons even though the flight time is about 8 minutes. Batteries simply aren't up to that yet in a commercial setup. Wintertree's thoughts on launch catapults do actually make some sense because they remove the battery capacity required for taxiing and maximum power takeoff. The planes will be taken out from the terminal to the runway by tugs, clipped into the catapult and launched without engine use. Not needing batteries for takeoff reduces the mass of the plane, thus reducing the power required to keep it in the air, thus reducing the battery capacity required there.....

Not so sure, the Heart runs 4 x 400kW engines and a proposed top speed of 400km/hr and range of 400km (presumably going slower) which using Tesla batts means 6 tons of weight (it can weight 8.6tons). However even car makers worked out the battery can also be the structure and there's plenty of work being done on carbon nano-tube structural batteries. Since in aviation money isn't such a concern as building cars I can well imagine they will get close for short-haul applications. At a price.

 wintertree 15 Jul 2021
In reply to jimtitt:

Have you seen their projected lifetimes for the batteries?  They reckon on needing to change the full pack every year due to degradation; there's such a large requirement for safety reserves in aviation and the batteries are so limited, that they're going to have to cycle them from 100% which doesn't help.  

You'd be better off putting the aircraft's lifetime supply of batteries in to a couple of hundred extra BEVs and offsetting the oil usage that way.

> and there's plenty of work being done on carbon nano-tube structural batteries.

Glad to see you coming round to my views that the exciting things in the R&D pipeline are going to transform battery electric power for all sorts of vehicles - as if they can solve problems for aviation, ground based vehicles are sorted.

 wintertree 15 Jul 2021
In reply to Richard J:

> I think the energy density argument is crucial here.

Ye canna change the laws of Physics.  Really optimised aluminium-ion packs could just about cut it with all the other efficiency gains across aircraft design rolled in, but it's going to be a pretty major rethink, probably getting in to blended wing designs as well. 

>   I think Rolls-Royce are very interested in this (as they know something like this needs to happen in order for them still to have an aero-engine business in 2050), 

I imagine you've met some of their ideas people in a professional capacity?  I've met a couple, and they were definitely shaped by Gerry Anderson in their formative years.  I wonder if any of them are looking at their SMR concept and getting ideas...  I can't see it ever happening for civil aviation, but with the resurgence of interest in small reactors for terrestrial power and for interplanetary rocketry and mars surface power, someone must at least be running the numbers...

Then there's induced gamma emission as a potential high density energy source, it does rather suffer a credibility gap in terms of published research, having had a New Scientist article about it with a daft name put out about it.

In reply to jkarran:

> Winch launching works for gliders and doesnvt require digging up a runway but it's messy and really quite hazardous in a number of ways. 

It's fun though; imagine doing that kind of take-off in a commercial jetliner.   I spent a long time on the Intamin built, winch launched roller coaster at Knott's Berry [1].  That would totally scale to jetliners - just don't watch the "cable snap" video on YouTube, slices through the cars like a knife through butter.

Bonus design feature for a battery electric aircraft - the winch cable could supply power until it detaches.  

[1] https://en.wikipedia.org/wiki/Xcelerator

 jimtitt 15 Jul 2021
In reply to wintertree:

> Have you seen their projected lifetimes for the batteries?  They reckon on needing to change the full pack every year due to degradation; there's such a large requirement for safety reserves in aviation and the batteries are so limited, that they're going to have to cycle them from 100% which doesn't help.  

> You'd be better off putting the aircraft's lifetime supply of batteries in to a couple of hundred extra BEVs and offsetting the oil usage that way.

> > and there's plenty of work being done on carbon nano-tube structural batteries.

> Glad to see you coming round to my views that the exciting things in the R&D pipeline are going to transform battery electric power for all sorts of vehicles - as if they can solve problems for aviation, ground based vehicles are sorted.

As I said, at a cost!

Car builders are already well past any real savings using batteries as structural members and for HGV's there's no chance but aircraft have an enormous surface area to be used. At a price!

 Richard J 15 Jul 2021
In reply to wintertree:

> I imagine you've met some of their ideas people in a professional capacity?  I've met a couple, and they were definitely shaped by Gerry Anderson in their formative years.  I wonder if any of them are looking at their SMR concept and getting ideas...  I can't see it ever happening for civil aviation, but with the resurgence of interest in small reactors for terrestrial power and for interplanetary rocketry and mars surface power, someone must at least be running the numbers...

I think the people I've talked to aren't quite as (ahem) visionary.  But I do think Rolls-Royce's recent resurgence of interest in civil nuclear is connected.  Their current SMR design is very conventional old technology, but I do think their interest in a high temperature advanced modular reactor is directly linked to the prospect of using one to power a zero-carbon synthetic aviation fuel factory, supplying both the electricity and the process heat to power all the steps, from making the hydrogen and capturing carbon dioxide from the air, to making the hydrocarbons.  

 Si dH 15 Jul 2021
In reply to wintertree and Richard J:

> > I think the energy density argument is crucial here.

> Ye canna change the laws of Physics.  Really optimised aluminium-ion packs could just about cut it with all the other efficiency gains across aircraft design rolled in, but it's going to be a pretty major rethink, probably getting in to blended wing designs as well. 

> >   I think Rolls-Royce are very interested in this (as they know something like this needs to happen in order for them still to have an aero-engine business in 2050), 

> I imagine you've met some of their ideas people in a professional capacity?  I've met a couple, and they were definitely shaped by Gerry Anderson in their formative years.  I wonder if any of them are looking at their SMR concept and getting ideas...  I can't see it ever happening for civil aviation, but with the resurgence of interest in small reactors for terrestrial power and for interplanetary rocketry and mars surface power, someone must at least be running the numbers...

As I used to work for RR and still have lots of friends that do, I tend to keep my eye out a bit for what they're working on. I noticed they are notionally collaborating with a couple of the groups (incl Boom) wanting to develop supersonic aircraft and the aim there is to use synthetic fuels...no idea how much they are investing though. It must be seen as significant as they recently announced an MoU with Shell:

https://www.rolls-royce.com/media/press-releases/2021/30-06-2021-sustainability-shell-and-rr-sign-agreement-to-accelerate-progress-towards-net-zero.aspx

On the nuclear side, their SMR is based on conventional PWR fuel and coolant so as to have a fighting chance of getting a few on the grid early enough and at an acceptable cost. However this means it's not great for hydrogen production (I'm no expert in H2 production but I think you need higher temperatures like you might get from a HTGR to be able to produce it at a good efficiency). Having said that, RR might pursue something even if the efficiency is bad because there are circumstances in which you want a nuclear plant to flex, and being able to easily bypass the turbine and still make use of the steam can sometimes be a better alternative to dropping primary power. We'll see.

There is some public info about their SMR design in the IAEA brochure if interested (although I don't think it's been updated since I left.) https://aris.iaea.org/Publications/SMR_Book_2020.pdf

I think you were hinting at nuclear-powered planes? Definitely not an application for a PWR but the Russian's built one based on a molten salt reactor in the 50s. It got canned after one or two test flights I think. The US also developed one but I think cancelled the project before it was ever run, I think primarily because they couldn't fit enough shielding and it still take off. Unfortunately gamma shielding needs lots of mass. And obviously most of the public would probably prefer not to get on a plane with a reactor aboard anyway.

To add, RR do have an electric plane project too, which is nearing it's first flight. It's a single seat technology development platform though.

https://www.rolls-royce.com/innovation/accel.aspx

Post edited at 20:00
 wintertree 15 Jul 2021
In reply to Richard J:

> But I do think Rolls-Royce's recent resurgence of interest in civil nuclear is connected.  Their current SMR design is very conventional old technology, but I do think their interest in a high temperature advanced modular reactor is directly linked to the prospect of using one to power a zero-carbon synthetic aviation fuel factory, supplying both the electricity and the process heat to power all the steps, from making the hydrogen and capturing carbon dioxide from the air, to making the hydrocarbons.  

It's good that they can take this long term view on sustaining their engine business; it could solve a few other problems in the process...   The atmospheric extraction is a really interesting area, such a wide diversity of thoroughly different approaches.  I imagine the US military would pay a fortune for this stuff, keeping their forwards bases supplied with kerosene is a major expense and security risk; I recall stories about looking at a fuel plant for their carriers.

It's suddenly getting very interesting in energy, as well as the SMRs, at least 4 of the private fusion consortiums having achieved major funding - $1Bn in to TAE, $0.2Bn in to General Fusion, £0.1Bn in to to Tokamak Energy and it seems like MIT's effort have a similar level of funding to TAE secured contingent on the test item of their coil design passing tests.  I think serious interest is rising  for orbital solar-to-microwave power arrays as well; the UKSA are running a small project and rumour has it the questions they're asking the technology people are really quite insightful...

In reply to Si dH:

>  I noticed they are notionally collaborating with a couple of the groups (incl Boom) wanting to develop supersonic aircraft and the aim there is to use synthetic fuels..

It's interesting how SST fever is breaking out in a few places now; I'm not sure what's changed to make the proposition much better than it used to be.  The funkier tail designs reducing the booms, better engines and lighter materials, but is that enough?  These days you can save more time by having a mega-rich person's short cut through airports than with supersonic planes...

> I think you were hinting at nuclear-powered planes? 

Yes, but in a very non-serious way.  It's flabberghasting that anyone ever thought that was good idea, let alone with the technology of the era.  I hadn't appreciated small PWR concept isn't flight suitable.

Post edited at 20:09
In reply to mbh:

> I've just read a paper on emissions from cruise ships in Norwegian waters. The emissions per passenger per trip are just over half a tonne, plus whatever is emitted by the ship elsewhere, plus emissions during port stops - about 52h per trip.

Yeah it's a joke. There are some Scandinavian cruises by several companies that just hop around the coast: Oslo, gothenberg, Copenhagen, etc.. day excursion in each place. They should be banned, electric trains run everywhere already. Pollution is a real issue in the Baltic sea because the water mixes exceedingly slowly, but has high ship traffic, and a lot of off land pollution from some states that don't care what goes into the sea. 

 Si dH 15 Jul 2021
In reply to summo:

> Yeah it's a joke. There are some Scandinavian cruises by several companies that just hop around the coast: Oslo, gothenberg, Copenhagen, etc.. day excursion in each place. They should be banned, electric trains run everywhere already. Pollution is a real issue in the Baltic sea because the water mixes exceedingly slowly, but has high ship traffic, and a lot of off land pollution from some states that don't care what goes into the sea. 

That's a shame, the Baltic is about the only place I'd really like to go on a cruise. Being able to wake up and go to a different city each day without finding new accomodation is a big attraction. I did it with an inter rail ticket in my youth, but... creature comforts.

Can't see the point of cruises just to sit on the boat as if you were on the beach or round the pool.

On the plus side, a cruise ship definitely is something that you could put a nuclear reactor in relatively easily

Post edited at 20:32
 Si dH 15 Jul 2021
In reply to wintertree:

> Yes, but in a very non-serious way.  It's flabberghasting that anyone ever thought that was good idea, let alone with the technology of the era.  I hadn't appreciated small PWR concept isn't flight suitable.

I'm pretty sure it was just another part of the race for nuclear weapons supremacy before submarines with ICBMs became the dominant thing. The concept of having a plane that could stay in the sky as long as the pilot could last would have been very attractive.

 Richard J 16 Jul 2021
In reply to Si dH:

> On the nuclear side, their SMR is based on conventional PWR fuel and coolant so as to have a fighting chance of getting a few on the grid early enough and at an acceptable cost. However this means it's not great for hydrogen production (I'm no expert in H2 production but I think you need higher temperatures like you might get from a HTGR to be able to produce it at a good efficiency).

That's right - you need 700 *C or more to do direct thermochemical water splitting to hydrogen, so a light water reactor like the current Rolls design won't help.  You'd need a high temperature gas reactor, or liquid salt, or liquid metal.  There's a good explainer of all this stuff in this report from the Royal Society - https://royalsociety.org/topics-policy/projects/low-carbon-energy-programme/nuclear-cogeneration/.  (The group that put this report together included RR"s head of civil nuclear).

 Richard J 16 Jul 2021
In reply to girlymonkey:

> I presume the government are talking nonsense (they usually are) when they suggest that flying is going to be environmentally friendly in the near future? Is there any element of truth to this is or it all absolute nonsense? 

To return to the original question, I don't think the government is talking complete nonsense, in the sense that net-zero compatible long-haul aviation is possible in principle on a 20-30 year timescale.  But they aren't doing very much concrete to make it happen - and if you were serious about that goal, you'd need to be starting some very serious and expensive development work right now.

 Siward 18 Jul 2021
In reply to Si dH:

Not perhaps surprising in a world where bazooka launched tactical nukes were a thing! 

 jkarran 19 Jul 2021
In reply to mbh:

> I've just read a paper on emissions from cruise ships in Norwegian waters. The emissions per passenger per trip are just over half a tonne, plus whatever is emitted by the ship elsewhere, plus emissions during port stops - about 52h per trip.

Given they don't run cruise ships empty if at all possible the majority of what's burned is burned for (and responsibility shared by) guests. 500kg of CO2 per person per trip is basically a round trip to Font in your car, it's not that extravagant for an occasional holiday especially if your cruise is from and to a 'home' port cutting out flights. I suspect cruises attract as much ire on here as they do in large part because the people on them aren't 'us'.

I'm not saying there aren't problems associated with cruises but the CO2 emissions aren't absurd.

jk

 mutt 19 Jul 2021
In reply to jkarran:

> Given they don't run cruise ships empty if at all possible the majority of what's burned is burned for (and responsibility shared by) guests. 500kg of CO2 per person per trip is basically a round trip to Font in your car, it's not that extravagant for an occasional holiday especially if your cruise is from and to a 'home' port cutting out flights. I suspect cruises attract as much ire on here as they do in large part because the people on them aren't 'us'.

> I'm not saying there aren't problems associated with cruises but the CO2 emissions aren't absurd.

> jk

isn't that 500Kg Co2 more than the planet sustain? We were talking about zero emission I think up above here. Seems to me that the physics is obvious. mgh, 1/2 mv^2 will always prevent battery flight. In your car you generally have 1/2 mv^2 at much lower v. The need for speed to keep the aircraft aloft means V^2 is immense.

There are ofcourse efficiency savings to be made in engines but I'd have thought that Rolls Royce have mastered all of those already. 

but never the less we are aiming for 0 C02 emissions and so the vast majority of this claim will be net C02 from offsetting. Offsetting of course is a sham. Its money paid to forest and woodland management to buy carbon credits for doing what they would have been doing anyway. it doesn't constitute a bigger sink for carbon and so they shouldn't be allowed to claim it. However 'green' energy companies routinely use norwegian carbon credits. Those credits being generated from the Hydro power plants in norway that have been operating for 50 years. its absolutely bonkers to claim that this is a carbon sink anyway but thats what the airlines are thinking. 

There is no alternative other than ceasing flying and cruise shipping immediately unless we are prepared to pay for massive adaptation and clearups. Just look at how much merkle has promised for rebuilding after their recent floods ( that have also killed 150 or so europeans). And its worth also noting that the adaptation costs are born by us all, every taxpayer, where as the vast majority of flights are taken by a tiny majority of rich people. It just isn't fair.

Post edited at 17:46
 jimtitt 19 Jul 2021
In reply to mutt:

Ryan Air, rich people????

 mutt 19 Jul 2021
In reply to jimtitt:

> Ryan Air, rich people????

https://www.inequalityintransport.org.uk/sites/default/files/uploads/Inequality-indices-for-great-britain-air-travel.jpg

shows indeed that the rich fly vastly more than the poor, but yes the uptick in the lowest ventile is perhaps due to Ryan air. The richest ventile take 8 times as many flights as the lowest, and most likely they are flying further too (long haul rather than short)

This quote addresses low cost airlines directly

"The advent of the low-cost airlines in the 1990s has added a new complexity to the picture, as it has both increased seat availability and potentially widened the market. Air travel has become more affordable, but as noted above this has not resulted in more people flying, as those levels have remained stable at around 50 per cent of the adult population. The 26 per cent who make two or more flights a year account for about 80 per cent of all flights, and just 6 per cent make 40 per cent (2010 and based on Rutherford, 2011 and DfT, 2014a). It seems that the low-cost airlines have allowed those who are already flying to fly more frequently and possibly to save money."

Post edited at 19:57
 jkarran 19 Jul 2021
In reply to mutt:

> isn't that 500Kg Co2 more than the planet sustain?

Depends how many people are doing it and how frequently. Given where we are it's a small part of a big problem that's not sustainable medium term. I'm not arguing for cruises, I'm cautioning people in glass houses about throwing stones.

> We were talking about zero emission I think up above here. Seems to me that the physics is obvious. mgh, 1/2 mv^2 will always prevent battery flight. In your car you generally have 1/2 mv^2 at much lower v. The need for speed to keep the aircraft aloft means V^2 is immense.

There's nothing about the physics of flight per se precluding electric drive. Yes, switching a modern airliner from JetA1 to batteries is a non-starter but metal tube-and-wing transonic airliners are just our current solution, there have been other dominant technologies in the past and there is no reason to suspect aviation is a technological dead end.

Even my wrinkly old wooden glider only releases ~4kW of GPE to sustain 70mph, you can halve that for the best modern designs. At relatively modest speeds and with efficiency as the be all and end all of the design you do not need much power to fly. Current battery technology is already sufficient to power light aircraft already in production, it's still niche but likely to become dominant for flight training at least before automation and simulation kills that sector.

As weather prediction improves we'll be far better able to exploit the energy gradients which exist in the atmosphere. Hobbyists are years ahead of commercial operators here exploiting the environment's energy, gliders can cover thousands of kilometers in a day or soar to the stratosphere powered indirectly by the sun. At smaller scales they can sustain airspeeds in excess of 500mph. Solar-electric aircraft can circumnavigate the globe. While these absurd extremes of research and niche sports may seem nothing more, it's worth remembering this isn't just curiosity, it's how an Albatross can cross an ocean on a few wingbeats.

Will we soar off on holiday like birds in the lea of ocean waves, no. We will however get much better at exploiting the energy gradients around the upper atmospheric streams to cut fuel burn and we may very well see routes developed to exploit continent scale mountain waves once they can be better imaged and forecast.

We also need to remember the burning of fuel isn't the problem, the fossil source is. Ok, there are problems associated with burning hydrocarbons in the upper atmosphere but run-away global heating needn't be one of them. Like it or not, carbon offsetting is going to be the front runner in approaching nett zero in the short-medium term and sure much of it is currently a bit of a sham but it needn't be, that's a choice, we can potentially benefit from finding ways to meaningfully and safely sink carbon. Longer term I expect we'll see aviation shift to synthetic, renewable/nuclear derived hydrocarbon fuel, it's a conservative sector with huge capital investment in oil-burning and they're just the tip of the oil economy pyramid. 'Clean oil' of some sort is the path of least resistance to sustainability for aviation and while it's not certain to beat battery-electric, I'd bet on it for the next 50 years.

Personally I doubt lithium batteries will fly many passengers and I doubt we'll see more than incremental efficiency increases from tricky atmospheric exploitation before zero carbon fuel becomes cheap enough the salami slicing is paused but I could be wrong. There are ways we can keep flying, quite differently, with much less impact.

> There are ofcourse efficiency savings to be made in engines but I'd have thought that Rolls Royce have mastered all of those already.

It's not the engines though they are massively improved, it's how and where you fly, what energy you convert to get and keep you there.

> There is no alternative other than ceasing flying and cruise shipping immediately unless we are prepared to pay for massive adaptation and clearups.

Well short of the collapse of our technological civilisation that isn't going to happen so we are just going to have to figure out alternatives. Hair shirts won't fix climate change, technology, economics and politics will or our civilisations die trying.

jk

Post edited at 00:00
In reply to mutt:

Define rich? Those who might have flown to a Costa for a summer holiday now also fly to Riga or Prague for a stag do, then Paris, barcrlona or Rome for a romantic city break.(pre covid) Cheap flights have increased air travel for everyone. If you are genuinely wealthy, a flight costing £50 or £200 is effectively in the same price bracket. 

 mutt 20 Jul 2021
In reply to summo:

> Define rich? Those who might have flown to a Costa for a summer holiday now also fly to Riga or Prague for a stag do, then Paris, barcrlona or Rome for a romantic city break.(pre covid) Cheap flights have increased air travel for everyone. If you are genuinely wealthy, a flight costing £50 or £200 is effectively in the same price bracket. 

erm ... I don't have to do I? The data is collated by ventile by income. That makes the top ventile 20 times as rich as the bottom ventile. I'd say that was rich by anyones measure although there is a huge variation in the income of that top ventile and I not very much in the bottom (due to the social security system). And the summary that follows points out that its not 'air travel for everyone' its air travel for the same 50% of people who flew before Ryan air came on the scene.  i..e those who could afford it before it became democratically cheap. 

 mutt 20 Jul 2021
In reply to jkarran:

> Depends how many people are doing it and how frequently. Given where we are it's a small part of a big problem that's not sustainable medium term. I'm not arguing for cruises, I'm cautioning people in glass houses about throwing stones.

I get where you are coming from, but perhaps we should look in more detail at the net Zero by 2050. Firstly C02 that is emitted now from whatever source will continue to warm the climate for at least 20 years and perhaps 200 years. It will eventually be absorbed by the oceans where it will acidify, destroying the marine ecosystem. So I argue that there is no safe level of C02 emissions even today. I single out flights and cruising as the two most egregious activities because we require neither of them. Flying abroad is not a necessity by any reasonable standard, and neither is cruising. So anyone who participates in those makes a choice to f*ck up the atmosphere and the ocean for their own leisure, Nothing else apart from perhaps eating meat falls into that category of egregious vandalism. Most other major Co2 emissions are built into our lives and are much harder to live without. We can all do without flying (just as the other 50% of people do).

> There's nothing about the physics of flight per se precluding electric drive. Yes, switching a modern airliner from JetA1 to batteries is a non-starter but metal tube-and-wing transonic airliners are just our current solution, there have been other dominant technologies in the past and there is no reason to suspect aviation is a technological dead end.

> Even my wrinkly old wooden glider only releases ~4kW of GPE to sustain 70mph, you can halve that for the best modern designs. At relatively modest speeds and with efficiency as the be all and end all of the design you do not need much power to fly. Current battery technology is already sufficient to power light aircraft already in production, it's still niche but likely to become dominant for flight training at least before automation and simulation kills that sector.

That's exactly the same argument that applies to Airships, The number of passengers is too small for economies of scale so flights are only for the very rich. I have no problem with that other than its grossly unfair.

> As weather prediction improves we'll be far better able to exploit the energy gradients which exist in the atmosphere. Hobbyists are years ahead of commercial operators here exploiting the environment's energy, gliders can cover thousands of kilometers in a day or soar to the stratosphere powered indirectly by the sun. At smaller scales they can sustain airspeeds in excess of 500mph. Solar-electric aircraft can circumnavigate the globe. While these absurd extremes of research and niche sports may seem nothing more, it's worth remembering this isn't just curiosity, it's how an Albatross can cross an ocean on a few wingbeats.

You are actually wrong . I worked for a few years on one of those stratospheric souring aircraft. To fly under only solar power required the aircraft to be lightened to the point of structural failure. Indeed recently built versions crashed and were destroyed because they were too light to land. They certainly can't carry human payloads. In fact for persistent flight only 5kg of payload is possible, 

The round the world solar plan transported 2 people but had to have a full battery replacement on every landing. Not just a recharge, it had to be so deeply discharged the batteries went in the bin every time it landed. And the charge in the replacement was obtained from carbon power generation. That is no answer.

> Will we soar off on holiday like birds in the lea of ocean waves, no. We will however get much better at exploiting the energy gradients around the upper atmospheric streams to cut fuel burn and we may very well see routes developed to exploit continent scale mountain waves once they can be better imaged and forecast.

And I call up birds as an indicator of what is possible with environmental energy. There are no heavy birds that fly even though they have chemical energy storage that is more efficient by weight than batteries. So why is that? is it a quirk of evolution or does evolution favour birds that can actually take off when the cat turns up.

> We also need to remember the burning of fuel isn't the problem, the fossil source is. Ok, there are problems associated with burning hydrocarbons in the upper atmosphere but run-away global heating needn't be one of them. Like it or not, carbon offsetting is going to be the front runner in approaching nett zero in the short-medium term and sure much of it is currently a bit of a sham but it needn't be, that's a choice, we can potentially benefit from finding ways to meaningfully and safely sink carbon. Longer term I expect we'll see aviation shift to synthetic, renewable/nuclear derived hydrocarbon fuel, it's a conservative sector with huge capital investment in oil-burning and they're just the tip of the oil economy pyramid. 'Clean oil' of some sort is the path of least resistance to sustainability for aviation and while it's not certain to beat battery-electric, I'd bet on it for the next 50 years.

I wont argue point by point but you seem to be very concerned about the continuity of a few companies. Why should I care if BP, British Airways, Rolls Royce go to the wall? It wont be the end of flying, When sustainable flight is available it will come off the back of some innovation that is totally unrelated to flight as we know it. (And if you are preparing to say that our pension funds are tied up irretrievably with these companies then I respond that many people and organisations have already divested their investments from polluters and that will continue so do so yourself or find yourself trying to live off stranded assets.)

> Personally I doubt lithium batteries will fly many passengers and I doubt we'll see more than incremental efficiency increases from tricky atmospheric exploitation before zero carbon fuel becomes cheap enough the salami slicing is paused but I could be wrong. There are ways we can keep flying, quite differently, with much less impact.

> It's not the engines though they are massively improved, it's how and where you fly, what energy you convert to get and keep you there.

> Well short of the collapse of our technological civilisation that isn't going to happen so we are just going to have to figure out alternatives. Hair shirts won't fix climate change, technology, economics and politics will or our civilisations die trying.

> jk

In reply to mutt:

The difference is how often folk flew before covid. In the 70s and 80s yeah the so called middle class might have gone to Spain etc.. a much smaller number skied somewhere in the alps. Compared to today, you only have to look at the rather annoying adoption of stay cation meaning holidaying in the uk, the concept of flying abroad at least once a year has become the norm for a very large proportion of society. It's became much cheaper than many UK train tickets.

 mutt 20 Jul 2021
In reply to summo:

sure, but that's because we don't pay for the damage we do (unless you count the cost of HS2). If we had to pay for the removal or mitigation of the effects of C02 in our fares I think we'd all staycation a little closer to home. 

And don't get me started again on the sham that is offsetting. Its just their to greenwash the flight operators. No benefit comes from buying carbon credits. 

In reply to mutt:

> sure, but that's because we don't pay for the damage we do (unless you count the cost of HS2). If we had to pay for the removal or mitigation of the effects of C02 in our fares I think we'd all staycation a little closer to home. 

Of course. That day is coming, slowly.

> And don't get me started again on the sham that is offsetting. Its just their to greenwash the flight operators. No benefit comes from buying carbon credits. 

Indeed, wonder what folk will think when everyone has allegedly planted enough offsetting trees to fill two planets, yet they still can't see any extra forest!

In reply to summo:

It would be interesting to see an analysis of cost. My Grandparents, low income working class, where flying to holiday abroad from the late 60s.

In reply to jkarran:

> Given they don't run cruise ships empty if at all possible the majority of what's burned is burned for (and responsibility shared by) guests. 500kg of CO2 per person per trip is basically a round trip to Font in your car, it's not that extravagant for an occasional holiday especially if your cruise is from and to a 'home' port cutting out flights. I suspect cruises attract as much ire on here as they do in large part because the people on them aren't 'us'.

> I'm not saying there aren't problems associated with cruises but the CO2 emissions aren't absurd.

Where do you get the 500kg from?

It's hard to find figures but here it says about 0.83 tons per passenger (https://blogs.griffith.edu.au/institute-for-tourism/how-much-carbon-does-cruise-ship-tourism-emit/).

Driving to Font and back in my Berlingo is about 1300 miles and 0.4 tons if I was stupid enough to do it by myself. Much more likely that there would be 4 of us in the car so 0.1 ton per passenger.

I'm not saying that climbers are all perfect in terms of CO2 (far from it, many take multiple flights per year) but I think the idea that the CO2 emissions from cruises aren't that bad is in itself absurd.

 mutt 21 Jul 2021
In reply to summo:

> Of course. That day is coming, slowly.

So my position is that we should all be acting as if we did have to pay for the damage we do, because of course we will do but just in the future. Act as if carbon has a carbon cost that far outweighs the cost of the fuel. And if anyone thinks that they can't live without their carbon freedoms then look around, I don't have to look very far to find people whose ethnicity, location, income or social status deny them access to those freedoms. It is perfectly possible to act like them.

In reply to mutt:

> So my position is that we should all be acting as if we did have to pay for the damage we do, because of course we will do but just in the future. 

Most will say it's their right to fly on holiday. There isn't much hope. 

 jkarran 21 Jul 2021
In reply to MeMeMe:

> Where do you get the 500kg from?

From mbh's post on the 15th. Half ton, 500kg.

> It's hard to find figures but here it says about 0.83 tons per passenger (https://blogs.griffith.edu.au/institute-for-tourism/how-much-carbon-does-cruise-ship-tourism-emit/).

Different paper, similar figure.

> Driving to Font and back in my Berlingo is about 1300 miles and 0.4 tons if I was stupid enough to do it by myself. Much more likely that there would be 4 of us in the car so 0.1 ton per passenger.

Change the car, change to occupancy figures... you still get figures that are of the same order of magnitude. Sure, we're not all equally bad but we are all in the glass house together.

> I'm not saying that climbers are all perfect in terms of CO2 (far from it, many take multiple flights per year) but I think the idea that the CO2 emissions from cruises aren't that bad is in itself absurd.

I agree and disagree. My point is not that they're not bad, it's that they're not disproportionately bad compared to things 'we' do but they attract near universal scorn on here because cruising is something 'we' don't do because of the site demographic.

jk

 jkarran 21 Jul 2021
In reply to mutt:

> I get where you are coming from, but perhaps we should look in more detail at the net Zero by 2050. Firstly C02 that is emitted now from whatever source will continue to warm the climate for at least 20 years and perhaps 200 years. It will eventually be absorbed by the oceans where it will acidify, destroying the marine ecosystem. So I argue that there is no safe level of C02 emissions even today.

And you're probably right but you might as well be arguing the moon should stop.

> That's exactly the same argument that applies to Airships, The number of passengers is too small for economies of scale so flights are only for the very rich. I have no problem with that other than its grossly unfair.

> You are actually wrong . I worked for a few years on one of those stratospheric souring aircraft. To fly under only solar power required the aircraft to be lightened to the point of structural failure. Indeed recently built versions crashed and were destroyed because they were too light to land. They certainly can't carry human payloads. In fact for persistent flight only 5kg of payload is possible, 

Which claim is wrong? I double checked each of my examples and I was careful not extrapolate too far from what are, by my own admission the extremes of niche aviation development. I'd expect for every success there to be several failures, that's what happens at the edges of engineering, it happened to what we now consider 'normal' aeroplanes too.

Perlan 2: has reached the stratosphere in Andean mountain wave

Solar impulse 2: did circumnavigate earth.

Transonic DP: Sustained, atmospherically powered flight >500mph youtube.com/watch?v=4eFD_Wj6dhk&

> The round the world solar plan transported 2 people but had to have a full battery replacement on every landing... That is no answer.

No, it's an early technology demonstrator for a technology I don't expect to see in commercial aviation, I've said as much up thread but every journey starts with a small step. Frankly a solar circumnavigation is quite a big first step as first steps go.

> And I call up birds as an indicator of what is possible with environmental energy. There are no heavy birds that fly even though they have chemical energy storage that is more efficient by weight than batteries. So why is that? is it a quirk of evolution or does evolution favour birds that can actually take off when the cat turns up.

We can make things light enough to fly at widely differing scales, we solved that problem. My point regarding birds is that they show us there are sources of atmospheric energy which can sustain flight we have yet to learn to exploit. The phenomena Albatross exploit to soar endlessly exists at different scales elsewhere in the atmosphere.

> I wont argue point by point but you seem to be very concerned about the continuity of a few companies. Why should I care if BP, British Airways, Rolls Royce go to the wall?

Actually I don't much care either way, I'm not sure where you got that impression. What I know is their investors and leaders do care so they will fight tooth and nail to stay profitable and relevant, they also have the resources to credibly try. This makes me think they stand a reasonable chance of achieving it, crowding out (or buying up) startups. Could go either way as with Tesla* but my medium term bet would be on continuity over revolution.

Not to imply Tesla is revolutionary, they're still basically a car maker.

> It wont be the end of flying, When sustainable flight is available it will come off the back of some innovation that is totally unrelated to flight as we know it.

That's possible but I doubt it. Not that there aren't revolutionary innovations possible but that we will destroy then rebuild the aviation industry from ashes.

> (And if you are preparing to say that our pension funds are tied up irretrievably with these companies then I respond that many people and organisations have already divested their investments from polluters and that will continue so do so yourself or find yourself trying to live off stranded assets.)

I'm not defending oil and aero companies, I'm just being realistic about the pace of change we are willing and able to accept in our democratic capitalist society. I have nothing invested in this, you're swinging at a strawman.

jk

Post edited at 14:25
In reply to jkarran:

> Change the car, change to occupancy figures... you still get figures that are of the same order of magnitude. Sure, we're not all equally bad but we are all in the glass house together.

I think it shows how hard it is to determine these figures because of the huge numbers of variables which sometimes makes it hard to make decisions. Although on the other hand having lots of variables means you've probably got the opportunity to tune them (don't drive to Font by yourself in your Porsche).

> I agree and disagree. My point is not that they're not bad, it's that they're not disproportionately bad compared to things 'we' do but they attract near universal scorn on here because cruising is something 'we' don't do because of the site demographic.

I kind of agree and disagree also. It's difficult to get your emissions from a cruise to a low level no matter what you do, it is possible to take climbing trips in a relatively low carbon way, it's a question of whether people do or not! 


I also agree with your 'us' and 'them' point, vilifying particular individual choices is a mine field and probably not a good way to change behaviour.

 jimtitt 21 Jul 2021
In reply to MeMeMe:

> I also agree with your 'us' and 'them' point, vilifying particular individual choices is a mine field and probably not a good way to change behaviour.

Indeed, I've no intention of ever taking a cruise so ban them. I've also no intention of driving to Font in a Berlingo (or anywhere else in one) so ban them as well!

In reply to MeMeMe:

> Where do you get the 500kg from?

>From mbh's post on the 15th. Half ton, 500kg.

I got that number from this paper:

Simonsen, M., Gössling, S. and Walnum, H. J. (2019) ‘Cruise ship emissions in Norwegian waters: A geographical analysis’, Journal of Transport Geography. Elsevier, 78(December 2018), pp. 87–97. doi: 10.1016/j.jtrangeo.2019.05.014.

They came up with a figure for cruise ships in their waters of 589 kg CO2 per passenger for a 1 week trip, plus the roughly 15% of emissions that occur in port, which are of particular concern to the port residents, not least because of the NOx, sulphur and particulate matter emissions.

That may not seem horrendous, but is, as I said above, a 25 t CO2 a year lifestyle. Oops, make that 35 t. This is a shockingly extravagant lifestyle at a time when we need to decarbonise quickly and are clutching at ever more improbable straws as to how to do so. It is more than double the per capita emissions in the USA, one of the most profligate nations on Earth- I got that from the World Bank) and more than 7 times the global per capita average these days. Global emissions this year are expected to be 33 billions tonnes CO2e, or about 5 tonnes CO2e per person across the planet. 

Hey, a cruise is only for a week, but that does not make it right when drastic reduction is what we need. Can't we take our holidays in some way that doesn't need us to build some of the largest ships ever? 

In reply to mbh:

> Hey, a cruise is only for a week, but that does not make it right when drastic reduction is what we need. Can't we take our holidays in some way that doesn't need us to build some of the largest ships ever? 

Having never been on a cruise, nor ever wanting to, I'm happy to do that.

As a climber I'm not _happy_ to give up flying but barring some extraordinary advance in aviation it's a choice between flying and contributing substantially to climate catastrophe or not flying and contributing less to climate catastrophe so reluctantly I don't see how flying is justifiable either.

At least not for me.

 mutt 23 Jul 2021
In reply to jkarran:

Can you find any current fuel source that has the energy density of hydrocarbons? For every additional 70kg needed to meet the same energy demand of an airliner you will obviously have to boot off a passenger.

power required to keep a Boeing 737-300 flying at a constant altitude and speed is 7.2 × 10^6 watts so over 10 hours of flight required 2x10^11 joules (neglecting take off and landing).

Jet fuel energy density is 2.3x10^7 j/kg so it burns 8.7x10^3 kg of jet fuel.

lithium iron batteries store 4.6x10^5 j/kg so requires 4x10^5kg of batteries.

the difference in weight then is equivalent to 6x10^3 passengers.

the Boeing 737-300 in fact only caries 1.4x10^2 passengers so exactly 0 passengers can fly to california on an electric 737-300 should it exist, and the same argument works for any other destination

Please find me an sustainable fuel that can match the energy density of jet fuel. I suspect you won't be able to. 

There is a place for optimism in building a sustainable future but realism I am afraid is going to be needed if we are going to make flight based tourism happen. 

whatever form of aircraft emerges, every pilot will have to fully recertify to pilot it. that is enough of a challenge in and of itself to sink every carrier company financially. I don't see how the existing industry can survive without being excepted from the goal zero objectives. And two do so makes a complete mockery of goal zero. 

Sustainable mass transport on land and sea is much more achievable.

 jimtitt 23 Jul 2021
In reply to mutt:

Luckily sythetic hydrocarbons are simple to make and carbon neutral.

 jkarran 24 Jul 2021
In reply to mutt:

> the Boeing 737-300 in fact only caries 1.4x10^2 passengers so exactly 0 passengers can fly to california on an electric 737-300 should it exist, and the same argument works for any other destination

Where have I given the impression a battery-electric 737 type aircraft is viable? It clearly isn't with lithium batteries! Time will tell what other battery chemistries deliver but however good they get, they're unlikely to be powering a transonic metal tube with wings flying great circle routes from point to distant point.

> Please find me an sustainable fuel that can match the energy density of jet fuel. I suspect you won't be able to. 

Jet fuel, just not fossil derived jet fuel. It's good stuff so why change it? The problem is the source of the carbon in it.

> There is a place for optimism in building a sustainable future but realism I am afraid is going to be needed if we are going to make flight based tourism happen.

You think your idea to just stop people flying until new technology arrives is realism?

I'm a pessimist to my core, I don't feel my thoughts on this are remotely optimistic! With one exception, where I've considered timelines for meaningful change, my inclination would be to add 20 years but I suspect the times and attitudes are changing quite quickly now.

> whatever form of aircraft emerges, every pilot will have to fully recertify to pilot it. that is enough of a challenge in and of itself to sink every carrier company financially.

A type conversion, the sort of thing most pilots do several times in a career? That's about the least of the barriers imaginable to greening aviation. The reality is our desire to see the world will remain, as costs associated with greening aviation grow we won't stop flying and airline companies won't all suddenly up and disappear, we'll fly less, new middle classes will fly more, the companies will keep merging and consolidating, growing, failing, relaunching and evolving their business models as they ever have through changing times.

> I don't see how the existing industry can survive without being excepted from the goal zero objectives. And two do so makes a complete mockery of goal zero. 

I can see how it could. Public attitudes drive regulatory change, costs go up, investment in lobbying to buy time grows, progress slows, carbon is 'cut' through offsetting which starts out scammy and gets better with time while we shift through greenwash bio/fossil-fuel mixes into synthetic fuels over the next 30-40 years. Battery electric aircraft and cryo-hydrogen power begin fill niches at the margins of the industry.

> Sustainable mass transport on land and sea is much more achievable.

Yes.

jk

Post edited at 12:47
 wercat 24 Jul 2021
In reply to jkarran:

I raised cruises in the first place not because of anything to do with site demographics but because I don't like the effect of such a concentration of particulates and other emissions for the duration of port visits in areas where people have no choice but to inhabit.  Nothing to do with any kind of judgement on the kind of people who want to cruise EXCEPT that it is a form of excessive consumption in concentrated form.

Your journey to Font (which i've never made anyway)  is in no way comparable qualitatively as the benefit of your harmful emissions is distributed over the whole journey rather than running a monstrosity of power consumption invading the breathing space of poorer folk

I remain of the opinion that we could live somewhat less consumptive lives and still enjoy a reasonable standard of life.  Fly drive holidays from the south of England to the Highlands typify this "convenience consumption".

Post edited at 13:29

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