The Death Of Fossil Fuels

[jimbob]

One of my colleagues shared this. We have an interest in EVs as a lot of our 650V transistors are suitable for 400V power trains. I'm not an expert in the applications though
https://www.caranddriver.com/news/a6206 ... ar-coming/

[bjn]

It's a minor point, but those engine efficiencies are for ICE cars, though. You can do a fair bit better for marine diesel (55%) and jet engines (~40%) - such that you'd be competitive with hydrogen fuel cells for efficiency, and with much easier integration into existing systems.

Read the paper. It explicitly breaks out marine, rail, HGVs and aviation with seperate Sankey diagrams for each.

Here's the aviation Sankey.

[Gfamily]

It's a minor point, but those engine efficiencies are for ICE cars, though. You can do a fair bit better for marine diesel (55%) and jet engines (~40%) - such that you'd be competitive with hydrogen fuel cells for efficiency, and with much easier integration into existing systems.

But I assume a lot of that is because marine diesel and jet engines run most of their cycle at more or less the rate for which they're optimised. Pure ICE vehicles run at a massively wide range of rates, and you canna optimise for a verrrry wide range of rates Kirk. The best* is to use a hybrid engine where an optimised generator feeds the batteries that run the engine. But small generators tend not to have the same efficiency as big marine engines or jet engines.

Also no ICE engine can benefit from regenerative braking, though hybrids may.

* Caveat that this is a guess, rather than any hill I'd die on.

[dyqik]

It's a minor point, but those engine efficiencies are for ICE cars, though. You can do a fair bit better for marine diesel (55%) and jet engines (~40%) - such that you'd be competitive with hydrogen fuel cells for efficiency, and with much easier integration into existing systems.

But I assume a lot of that is because marine diesel and jet engines run most of their cycle at more or less the rate for which they're optimised. Pure ICE vehicles run at a massively wide range of rates, and you canna optimise for a verrrry wide range of rates Kirk. The best* is to use a hybrid engine where an optimised generator feeds the batteries that run the engine. But small generators tend not to have the same efficiency as big marine engines or jet engines.

Also no ICE engine can benefit from regenerative braking, though hybrids may.

* Caveat that this is a guess, rather than any hill I'd die on.

That's pretty much it, yes

[Martin Y]

It's interesting to see the scale of the difference to produce the same amount of thrust from aircraft engines by different technologies, though it is of course only part of the story as energy density means 1MJ of thrust in an electric plane full of batteries is not quite so effective as 1MJ of thrust in a jet which is on average half full of fuel.

[dyqik]

It's interesting to see the scale of the difference to produce the same amount of thrust from aircraft engines by different technologies, though it is of course only part of the story as energy density means 1MJ of thrust in an electric plane full of batteries is not quite so effective as 1MJ of thrust in a jet which is on average half full of fuel.

Miles per kg per MJ is a better measure, although non-linear, as getting to cruising altitude is far more fuel hungry than cruising.

Random thought - how much fuel savings would there be from using electric tugs to taxi airliners, and building them to accept tow line launches on the runway?

Even arrestor cables might be helpful to reduce reverse thrust use.

[Grumble]

It's interesting to see the scale of the difference to produce the same amount of thrust from aircraft engines by different technologies, though it is of course only part of the story as energy density means 1MJ of thrust in an electric plane full of batteries is not quite so effective as 1MJ of thrust in a jet which is on average half full of fuel.

Miles per kg per MJ is a better measure, although non-linear, as getting to cruising altitude is far more fuel hungry than cruising.

Random thought - how much fuel savings would there be from using electric tugs to taxi airliners, and building them to accept tow line launches on the runway?

Even arrestor cables might be helpful to reduce reverse thrust use.

The hooks used for the arrestor assembly on fighter jets have a limited number of uses. There has been a suggestion that planes could use electric power to take off and climb, jet fuel to cruise, and regen on the descent. I heard that off the Fully Charged Show rather than a paper or anything, so it might be a pipe dream.

[shpalman]

It's interesting to see the scale of the difference to produce the same amount of thrust from aircraft engines by different technologies, though it is of course only part of the story as energy density means 1MJ of thrust in an electric plane full of batteries is not quite so effective as 1MJ of thrust in a jet which is on average half full of fuel.

Miles per kg per MJ is a better measure, although non-linear, as getting to cruising altitude is far more fuel hungry than cruising.

Random thought - how much fuel savings would there be from using electric tugs to taxi airliners, and building them to accept tow line launches on the runway?

Even arrestor cables might be helpful to reduce reverse thrust use.

The hooks used for the arrestor assembly on fighter jets have a limited number of uses. There has been a suggestion that planes could use electric power to take off and climb, jet fuel to cruise, and regen on the descent. I heard that off the Fully Charged Show rather than a paper or anything, so it might be a pipe dream.

Jets basically glide down with the engines at idle, maybe using the airbrakes/spoilers only momentarily. I mean it's obvious, when climbing the energy is being mainly stored as height not as speed. (This isn't true of the final phases on landing, in which the slats and flaps create a lot of extra drag for the sake of having more lift at low speed.)

I'm not sure if it would be overall worth it to use regenerative braking, either with the wheels or the engines, on the runway.

But I note that whether they use wheel brakes or reverse thrust, the deceleration is supposed to be the same, it's just that reverse thrust means the brakes don't get so hot and they don't have to wait so long before it's safe to take off again (because the wheel brakes need to be ready to abort the takeoff if necessary, so they can't still be too hot from landing.)

[Sciolus]

Random thought - how much fuel savings would there be from using electric tugs to taxi airliners, and building them to accept tow line launches on the runway?

Even arrestor cables might be helpful to reduce reverse thrust use.

There's a detailed ACRP report on electric tugs for aircraft taxiing somewhere if you're really interested. Problems include: nosewheels aren't designed to be used like that; many busy airports don't have space for tugs to get back from runway to stand. But I think they are used at some airports by some airlines.

There have also been thoughts about having electric motors built into the nosewheel, but the extra weight is considered to outweigh the taxiing savings.

Most aircraft don't use reverse thrust above idle these days; brakes are usually good enough, or thrust-reversers are deployed with engines at idle if needed.

[bjn]

Dammit I've rabbit holed the morning when I should have taken the dog out.

Aviation will always be the right bugger to fully decarbonise because of the energy density of Jet-A. Unless magic happens, intercontinental flights will need some sort of hydrocarbon to operate. General aviation and regional flights are more amenable to electrification. This paper says regional flights are viable with batteries that have specific energies between 600Wh/kg and 750Wh/kg, Li-ion is somewhere around the 250Wh/kg at the moment. 600+Wh/kg will likely require some new battery chemistry, possibly solid state Li-Ion, Li-S or Li-Air, none of which are commercial yet (though solid state is close). Regardless, some companies have working electric aircraft for specific market segments, eg: the Pipistrel for trainers, Evation for short commuter and cargo hops (eg: between the islands and mainland off the NE coast of North America), and Beta looking to replace short helicopter flights.

A bonus of electric aviation is that you can use a range of tech not easily available to combustion engines. Distributed propulsion (lots of small propellers) makes flight much more efficient, NASA has built test aircraft that have demonstrated 20% reduction in power needed, along with other benefits like reduced noise and better control. They've also modelled other distributed propulsion configurations which yield up to 70%*(!) reduced fuel burn, depending on the exact technology. Boundary layer ingestion is another technique that reduces drag and increases efficiency.

So improving battery tech plus new airframe and propulsion design can enable electric aviation to start eating combustion aviation from below, and arguably has already started. The biggest hurdle is likely to be regulatory, big changes to how airframes and propulsion work will be a harder sell to regulators than swapping a petrol tank and ICE-motor for batteries and electric motor.

*70% is the N3-X concept, which uses gas turbines burning H2 to drive distributed super-conducting electric motors in a blended wing air-frame. There are other NASA airframe and propulsion designs that are less unobtainium laden that would yield 20-40% reductions in fuel burn.

[bjn]

More reading, the open goal for electric aviation seems to be air-taxis, replacing helicopters for short duration flights. This could open up new markets as helicopters are noisy expensive bastards in comparison which restricts where and who can use them. A whole bunch of companies are after that market.

https://www.scientificamerican.com/arti ... -up-on-us/

[Grumble]

This paper says regional flights are viable with batteries that have specific energies between 600Wh/kg and 750Wh/kg, Li-ion is somewhere around the 250Wh/kg at the moment. 600+Wh/kg will likely require some new battery chemistry, possibly solid state Li-Ion, Li-S or Li-Air, none of which are commercial yet (though solid state is close).

There are batteries at about 400Wh/kg which use a silicon anode. Not sure what type of flights that might enable.

[lpm]

More reading, the open goal for electric aviation seems to be air-taxis, replacing helicopters for short duration flights. This could open up new markets as helicopters are noisy expensive bastards in comparison which restricts where and who can use them. A whole bunch of companies are after that market.

https://www.scientificamerican.com/arti ... -up-on-us/

Air taxis, aka flying cars, are just another tech bro scam.

Sucked in cash from venture capital funds, promised flights by 2018. Failure all round.

Far too noisy, far too dangerous.

See also airships.

ETA see also hyperloop, supersonic, Theranos, vertical farming, blockchain, drone delivery services...

[bjn]

This paper says regional flights are viable with batteries that have specific energies between 600Wh/kg and 750Wh/kg, Li-ion is somewhere around the 250Wh/kg at the moment. 600+Wh/kg will likely require some new battery chemistry, possibly solid state Li-Ion, Li-S or Li-Air, none of which are commercial yet (though solid state is close).

There are batteries at about 400Wh/kg which use a silicon anode. Not sure what type of flights that might enable.

Even better!

[bjn]

More reading, the open goal for electric aviation seems to be air-taxis, replacing helicopters for short duration flights. This could open up new markets as helicopters are noisy expensive bastards in comparison which restricts where and who can use them. A whole bunch of companies are after that market.

https://www.scientificamerican.com/arti ... -up-on-us/

Air taxis, aka flying cars, are just another tech bro scam.

Sucked in cash from venture capital funds, promised flights by 2018. Failure all round.

Far too noisy, far too dangerous.

See also airships.

I'm not at all convinced I'll be swapping a black-cab for an air-taxi, but short duration helicopter flights are a thing. Electric aviation should be able to eat into that and be able to be used more broadly. They are less noisy than helicopters, though relative safety has admittedly yet to be demonstrated. Helicopters are already much more prone to crashing than cars or planes, so it might not be that hard given the redundancies built into e-vtol craft.

[lpm]

Evidence needed.

Puff pieces from the scammers PR team don't count.

[bob sterman]

Miles per kg per MJ is a better measure, although non-linear, as getting to cruising altitude is far more fuel hungry than cruising.

Random thought - how much fuel savings would there be from using electric tugs to taxi airliners, and building them to accept tow line launches on the runway?

Even arrestor cables might be helpful to reduce reverse thrust use.

The hooks used for the arrestor assembly on fighter jets have a limited number of uses. There has been a suggestion that planes could use electric power to take off and climb, jet fuel to cruise, and regen on the descent. I heard that off the Fully Charged Show rather than a paper or anything, so it might be a pipe dream.

Jets basically glide down with the engines at idle, maybe using the airbrakes/spoilers only momentarily. I mean it's obvious, when climbing the energy is being mainly stored as height not as speed. (This isn't true of the final phases on landing, in which the slats and flaps create a lot of extra drag for the sake of having more lift at low speed.)

I'm not sure if it would be overall worth it to use regenerative braking, either with the wheels or the engines, on the runway.

But I note that whether they use wheel brakes or reverse thrust, the deceleration is supposed to be the same, it's just that reverse thrust means the brakes don't get so hot and they don't have to wait so long before it's safe to take off again (because the wheel brakes need to be ready to abort the takeoff if necessary, so they can't still be too hot from landing.)

shpalman clearly knows plenty about aviation.

But a few additional points...

- Arrestor cables not really an option unless you want to give 300+ folk in the back an involuntary rhinoplasty with each landing.
- Tow lines (or catapults) on the runaway? No ejector seats on civilian aircraft so you need to be able to abort take-offs. You can turn off an engine and stick it in reverse. Not so easy to stop a tow line or catapult flinging you in one direction.
- In any case, cables and fixings that could break off and create scraps of metal that could fly about and get stuck in unwanted places - not a good mix with civil aviation. E.g. Air France Flight 4590.

For some informed discussions take a look at PPRuNe. E.g.

https://www.pprune.org/tech-log/625944- ... sions.html

https://www.pprune.org/jet-blast/658907 ... uit-2.html

Just never ever ever ask on there about runway conveyor belts. You have been warned!

[Grumble]

Interesting episode on geologic hydrogen from Catalyst
https://www.latitudemedia.com/news/cata ... c-hydrogen

In this episode, Shayle talks about geologic hydrogen with Pete Johnson, CEO of Koloma. Early estimates suggest vast quantities of the gas could be tapped for far cheaper than other production methods. That is, if some major challenges are solved, like finding economically viable reserves, managing leakage, and building infrastructure. In these early days, those are all big ifs.

[shpalman]

Interesting episode on geologic hydrogen from Catalyst
https://www.latitudemedia.com/news/cata ... c-hydrogen

... vast quantities of the gas could be tapped for far cheaper than other production methods. That is, if some major challenges are solved, like finding economically viable reserves...

"hydrogen could be cheap if we find some cheap hydrogen"

[Grumble]

Interesting episode on geologic hydrogen from Catalyst
https://www.latitudemedia.com/news/cata ... c-hydrogen

... vast quantities of the gas could be tapped for far cheaper than other production methods. That is, if some major challenges are solved, like finding economically viable reserves...

"hydrogen could be cheap if we find some cheap hydrogen"

We know hydrogen is produced geologically but we don’t yet know if there are major exploitable reserves. We’re in the exploration phase currently. Potentially it could be comparable to natural gas, per unit volume, is one of the points made early on.

[Grumble]

The closure of Ratcliffe on Soar coal power station later today is a true “death of fossil fuels” moment. And enables a truly accurate response to idiots who persist in thinking that evs are powered by coal. At least in the UK.

[bjn]

Excellent mastodon thread by Jenny Chase of BNEF, she’s their senior analyst for solar power.

We’ve got the tools and tech decarbonise the first ~85% of electricity generation, the last bit will be harder. Solar is stupidly cheap and is unstoppable, but it’s not the whole answer, wind is needed as well. Storage is zooming off. Plus other good points.

https://mastodon.green/@solar_chase/113214911341855405

[shpalman]

I imagine you've all already seen https://m.xkcd.com/2992/

He calculates that "The UK... dug up and burnt and average of 3 inches of their country".

[Grumble]

I imagine you've all already seen https://m.xkcd.com/2992/

He calculates that "The UK... dug up and burnt and average of 3 inches of their country".

In recent years the coal has been imported, because UK coal has too high a sulphur level, but that probably doesn’t affect the calculation by that much.

[IvanV]

BBC gives credibility to the idea that more renewable electricity will make it cheaper. It justifies this with quotes from a guy from at Imperial College, called Iain Staffell. He is a Senior Lecturer in Sustainable Energy at the Centre for Environmental Policy.

There is general acknowledgment that renewables are intermittent. But the approach to making a reliable supply out of intermittent sources of energy is just hand-wavy, and no appreciation that it might be very expensive, and is currently unproven. Maybe it will eventually work out that renewables are cheap, including the energy storage to cover us when there isn't much wind or sun. But maybe such innovation will not occur, or will still cost quite a lot of money. I think saying so definitely that electricity will get cheaper as renewables are used more is a hostage to fortune.

The prospect for electricity getting cheaper with more renewables is currently a lot better than it used to be. And that's because electricity is a lot more expensive than it was a short while ago. It always seemed likely that electricity should become more expensive with decarbonisation than it was before that recent increase. But maybe it has increased so much just recently that in fact it is now temporarily more expensive than the renewable future. But I don't think anyone can really know, because they don't know what our renewable future looks like or what it costs. Especially that conversion from renewable sources to reliable supply. It still seems a hostage to fortune

There is the usual complaint that electricity is currently so expensive because gas drives the price of electricity at almost all moments in Britain, because we just can't turn gas off, as the electricity system stands in Britain. Many other countries do not rely on gas to make its electricity system work to the extent Britain does. The wholesale price of electricity is driven by the most expensive technology in the market at the moment. That's how electricity markets work - indeed all markets it could be said. If it doesn't work like that, it isn't a market. It is not unique to Britain. It is true across the EU (possibly excepting some parts of SE Europe whose electricity market is not integrated) and many parts of the US. Yet electricity is cheaper in many of those places.

What is less common is our particular reliance on gas. So that now that gas is so expensive we still need it at all moments and cannot keep our electricity system safe and reliable with some cheaper form of generation. Even when there is too much wind and sun at a moment, we still have to keep the gas on and constrain off the wind first. We are increasingly finding ways to do with of a safety margin of gas, and we need to evolve to doing without it. But at the moment we always need some, unlike continental countries. They can use other technologies such as hydro for system reliability, either because they have enough of them, or they are part of a synchronised grid with neighbours which have enough. The DC links from Britain to the continent fail to provide that benefit to us, because we are not synchronised. And it is difficult to expand hydro sufficiently in Britain to do that job here.

Interestingly, Norwegian domestic customers are even more exposed to wholesale prices than British domestic customers. Mostly this is beneficial to them because most of the time the price of electricity is low in Norway - heavily related to their massive hydro resources. But increasingly that is being sold in an international market, and Norwegian domestic customers are increasingly exposed to the situation in the Germany market, which is a lot worse than it ought to be because of poor decisions they made there. They turned off nuclear plants, and subsidised solar and wind in place with not much sun or wind. It's becoming a similarly difficult problem in Norway.

There is a point I feel the need to explore. With the high price of gas, increasingly wind is generating at times when the wholesale price is higher than their CfD - the guarantee price that the government provided to get them to build the wind farm. When this happens, the wind farm should have to pay out to the government. What is happening to the government's CfD profits? Are they holding down the price of electricity? Or disappearing into the Exchequer's pocket?