RE: Toyota and Yamaha partner on hydrogen V8
Discussion
otolith said:
RE energy density, hydrogen looks great at 120MJ per kg compared to about 45MJ/kg for petrol.
Two problems there, though - firstly, a kg of compressed hydrogen takes up a lot of space, so the volumetric energy density is crap, secondly a tank to safely contain a relatively small amount of high pressure hydrogen is heavy.
If you look at the Mirai, the first gen one has 5kg of hydrogen in tanks with an internal volume of 120 litres. That gives 5MJ per litre which is somewhat less impressive compared to about 34MJ/l for petrol. Even less impressive if you consider that 120 litres is the internal volume of some pretty thick walled tanks. How thick walled is a petrol tank?
By weight then - the tanks weigh 87.5kg empty, so with 5kg of H in them that's about 6.5MJ per kg. Again, petrol is ~45MJ/kg for the fuel, bit less including the fuel tank, but petrol tanks are light - they certainly don't weigh 18 times what their content does.
TLDR - in the gen1 Mirai, 5kg of hydrogen in use takes up over 120 litres of storage and weighs 92.5kg and is matched in energy by 17 litres (13kg) of petrol plus whatever a 17 litre petrol tank weighs. This is the other reason why hydrogen ICE is a dead end.
It's the preserve of rich nations to pay more than petrol for less efficient fuel. Two problems there, though - firstly, a kg of compressed hydrogen takes up a lot of space, so the volumetric energy density is crap, secondly a tank to safely contain a relatively small amount of high pressure hydrogen is heavy.
If you look at the Mirai, the first gen one has 5kg of hydrogen in tanks with an internal volume of 120 litres. That gives 5MJ per litre which is somewhat less impressive compared to about 34MJ/l for petrol. Even less impressive if you consider that 120 litres is the internal volume of some pretty thick walled tanks. How thick walled is a petrol tank?
By weight then - the tanks weigh 87.5kg empty, so with 5kg of H in them that's about 6.5MJ per kg. Again, petrol is ~45MJ/kg for the fuel, bit less including the fuel tank, but petrol tanks are light - they certainly don't weigh 18 times what their content does.
TLDR - in the gen1 Mirai, 5kg of hydrogen in use takes up over 120 litres of storage and weighs 92.5kg and is matched in energy by 17 litres (13kg) of petrol plus whatever a 17 litre petrol tank weighs. This is the other reason why hydrogen ICE is a dead end.
It doesn't seem likely that these affluent nations can force developing nations to do this?
The reality is that they will remain burning fossil fuels until the affluent nations create a cheaper and as usable means to propel a vehicle which they can then switch to as a function of saving money.
I don't think people fully understand that there are only a few countries that can indulge themselves with paying more for fuel than is needed and that for most countries this is an insane non starter.
We aren't going to build a retail hydrogen fuelling structure for them, nor are we going to buy them millions of new cars. And they certainly haven't the means.
Especially as most of those countries will actually be bulldozed for our solar and wind farms so we can generate cheap electricity for ourselves on their land, ship it as hydrogen to our ports and convert it back to electricity for us to isa up the wall partying like it's 1999.
The other issue not oft considered is that the product of combining H2 with O2 is of course pure water. This is terrific when talking about tailpipe emissions, being a clean, colourless, non toxic compound, but rather less terrific when you consider it freezes solid at below 0degC, a temperature at which a lot of the automotive world fairly regularily operates at or below.. In a conventional ICE, the massive waste heat exhausted renders this reasonably irrelevant, but for a Fuel cell, having your exhaust freeze solid is a very real problem......
Max_Torque said:
The other issue not oft considered is that the product of combining H2 with O2 is of course pure water. This is terrific when talking about tailpipe emissions, being a clean, colourless, non toxic compound, but rather less terrific when you consider it freezes solid at below 0degC, a temperature at which a lot of the automotive world fairly regularily operates at or below.. In a conventional ICE, the massive waste heat exhausted renders this reasonably irrelevant, but for a Fuel cell, having your exhaust freeze solid is a very real problem......
Good job the hydrogen proponents want to burn it in ICEs not convert it to electricity. otolith said:
RE energy density, hydrogen looks great at 120MJ per kg compared to about 45MJ/kg for petrol.
Two problems there, though - firstly, a kg of compressed hydrogen takes up a lot of space, so the volumetric energy density is crap, secondly a tank to safely contain a relatively small amount of high pressure hydrogen is heavy.
If you look at the Mirai, the first gen one has 5kg of hydrogen in tanks with an internal volume of 120 litres. That gives 5MJ per litre which is somewhat less impressive compared to about 34MJ/l for petrol. Even less impressive if you consider that 120 litres is the internal volume of some pretty thick walled tanks. How thick walled is a petrol tank?
By weight then - the tanks weigh 87.5kg empty, so with 5kg of H in them that's about 6.5MJ per kg. Again, petrol is ~45MJ/kg for the fuel, bit less including the fuel tank, but petrol tanks are light - they certainly don't weigh 18 times what their content does.
TLDR - in the gen1 Mirai, 5kg of hydrogen in use takes up over 120 litres of storage and weighs 92.5kg and is matched in energy by 17 litres (13kg) of petrol plus whatever a 17 litre petrol tank weighs. This is the other reason why hydrogen ICE is a dead end.
The 700 bar tanks will have an effective volume of maybe 75-80%, i.e. the amount of internal volume as a % of the external volume. Your 5 MJ/litre is more like 4 MJ/litre when you take this into account, and closer to 3-3.5 MJ/litre if the cylindrical shape creates un-utilised voids in the car when packaging the tanks. The packaging utilisation usually gets worse the more tanks you have, as you may have to put tanks side by side.Two problems there, though - firstly, a kg of compressed hydrogen takes up a lot of space, so the volumetric energy density is crap, secondly a tank to safely contain a relatively small amount of high pressure hydrogen is heavy.
If you look at the Mirai, the first gen one has 5kg of hydrogen in tanks with an internal volume of 120 litres. That gives 5MJ per litre which is somewhat less impressive compared to about 34MJ/l for petrol. Even less impressive if you consider that 120 litres is the internal volume of some pretty thick walled tanks. How thick walled is a petrol tank?
By weight then - the tanks weigh 87.5kg empty, so with 5kg of H in them that's about 6.5MJ per kg. Again, petrol is ~45MJ/kg for the fuel, bit less including the fuel tank, but petrol tanks are light - they certainly don't weigh 18 times what their content does.
TLDR - in the gen1 Mirai, 5kg of hydrogen in use takes up over 120 litres of storage and weighs 92.5kg and is matched in energy by 17 litres (13kg) of petrol plus whatever a 17 litre petrol tank weighs. This is the other reason why hydrogen ICE is a dead end.
To be fair though, it's a lot higher than a battery!
I'm not personally ready to write off HICE completely, but I think maybe it only makes sense as a very specialist car, with an exotic engine. I agree that a volume-production 2 litre 4 seater is most likely a dead end, the compromises are too significant.
I've thus been pondering for a while exactly how you would use the HICE V8 in an ultra-low-volume 2-seat road car. A sort of (semi) future-proofed LFA if you will.
The car would need to hold a minimum of 10 kg of hydrogen, and even then it's going to struggle to break 200 miles between refills.
To get an idea of the packaging task, we are talking 3-4 largish tanks similar to the largest one in the latest Mirai that sits in the transmission tunnel of that car.
A mid-engined layout might just work but it's difficult to see how you would store 10 kg of H2 in front of the passenger cell. You could possibly use the Mirai's main-tank-in-transmission tunnel arrangement with a long central tank and then two shorter tanks either side in front of the passengers, with the frunk above them, but I'm not convinced you can fit it all in and have sufficient frontal impact protection.
More likely to me is that the engine would be at the front, with a full height, full width lateral tank array behind the seats, and with the lowest tank split into two to create a gap for the prop-shaft. And maybe a reserve tank under the boot space to push the range up a bit. The weight of the tanks is going to be pushing 200 kg, which is not idea, but at least it's mostly contained between the front and rear axle.
Rearward visibility will also be non-existent but I guess that could be addressed with cameras. Anyone think I'm onto something or am I just pissing in the wind.
ETA: I realise that this idea forces the car to have a longer wheelbase, so it might end more of a GT.
Edited by GT9 on Monday 7th March 18:49
That's not going to help consumption is it.
Despite me saying earlier that the volumetric energy density of H2 tanks is much higher than batteries, once you factor in the energy efficiency deficit between a large capacity HICE and a BEV, there's probably actually nothing in it in real terms, in the sense that the mileage you can achieve per unit volume of energy storage ends up similar.
And you have to carry around a 5 litre engine, gearbox, prop shaft, diff and exhaust system.
A full 'storage+drivetrain' volumetric comparison between the two won't favour the HICE in my opinion.
A weight comparison will probably favour the HICE, but whatever extra weight the BEV carries it compensates for this with regen, lower CoG and lower polar MoI.
I'm not giving up yet though!
Despite me saying earlier that the volumetric energy density of H2 tanks is much higher than batteries, once you factor in the energy efficiency deficit between a large capacity HICE and a BEV, there's probably actually nothing in it in real terms, in the sense that the mileage you can achieve per unit volume of energy storage ends up similar.
And you have to carry around a 5 litre engine, gearbox, prop shaft, diff and exhaust system.
A full 'storage+drivetrain' volumetric comparison between the two won't favour the HICE in my opinion.
A weight comparison will probably favour the HICE, but whatever extra weight the BEV carries it compensates for this with regen, lower CoG and lower polar MoI.
I'm not giving up yet though!
GT9 said:
That's not going to help consumption is it.
Despite me saying earlier that the volumetric energy density of H2 tanks is much higher than batteries, once you factor in the energy efficiency deficit between a large capacity HICE and a BEV, there's probably actually nothing in it in real terms, in the sense that the mileage you can achieve per unit volume of energy storage ends up similar.
And you have to carry around a 5 litre engine, gearbox, prop shaft, diff and exhaust system.
A full 'storage+drivetrain' volumetric comparison between the two won't favour the HICE in my opinion.
A weight comparison will probably favour the HICE, but whatever extra weight the BEV carries it compensates for this with regen, lower CoG and lower polar MoI.
I'm not giving up yet though!
Seems like a whole lot of effort for a handful of cars when we already have petrol ICE for a couple more decades and synthetic petrol probably phasing in before that. By which time I suspect the ICE will be so completely outclassed in every area that hopefully the number of us anoraks wanting to run them will be so tiny no one will care about us any more than they care about people keeping horses.Despite me saying earlier that the volumetric energy density of H2 tanks is much higher than batteries, once you factor in the energy efficiency deficit between a large capacity HICE and a BEV, there's probably actually nothing in it in real terms, in the sense that the mileage you can achieve per unit volume of energy storage ends up similar.
And you have to carry around a 5 litre engine, gearbox, prop shaft, diff and exhaust system.
A full 'storage+drivetrain' volumetric comparison between the two won't favour the HICE in my opinion.
A weight comparison will probably favour the HICE, but whatever extra weight the BEV carries it compensates for this with regen, lower CoG and lower polar MoI.
I'm not giving up yet though!
otolith said:
I think that to approach any semblance of practical usability an HICE would need a drivetrain more like a Prius an LFA - at which point, really, who cares?
I've got zero interest in a run of the mill FWD HICE car, it would need to have a small capacity frugal (read boring) engine and will be totally outclassed by the equivalent BEV, yet expensive to run for what it is. It has no real reason to exist IMO. A high revving NA large-capacity V8 HICE is worth pushing the boat out for, albeit as an irrelevance in the grand scheme. There's a very slim possibility that it might just slip through the net as a 'hydrogen car' rather than a banned ICE.
I don't have a lot of faith in widespread availability of synthetic fuels for road cars in the UK, but I do expect a 700 bar hydrogen refuelling set up that could support a modest fleet of fuel cell cars.
A tiny number of HICE cars could masquerade as one of those.
Hydrogen internal combustion engines (and now jet engines) represent a much more flexible and useful green renewable low pollution and zero carbon solution than batteries. What they need to become mainstream is refuelling networks. Motor sport getting behind them as well would really speed things up. Once they start mass producing them existing car manufacturers will be able to produce cars more cheaply and most existing ICE vehicles could be converted to hydrogen, saving huge amounts over the cost of buying a new vehicle. Elon Musk apparently called them 'hydrogen fools', I would say to him that he is an electric flatliner. I have written a book about all forms of renewable energy (available on Amazon) and for me hydrogen is the best option for the future of our civilization. Big oil and established industrial engineering companies have been resisting it, promoting inferior processes and spreading falsehoods for over thirty years now because the potential scares the hell out of them.
Sparkyb69 said:
Hydrogen internal combustion engines (and now jet engines) represent a much more flexible and useful green renewable low pollution and zero carbon solution than batteries. What they need to become mainstream is refuelling networks. Motor sport getting behind them as well would really speed things up. Once they start mass producing them existing car manufacturers will be able to produce cars more cheaply and most existing ICE vehicles could be converted to hydrogen, saving huge amounts over the cost of buying a new vehicle. Elon Musk apparently called them 'hydrogen fools', I would say to him that he is an electric flatliner. I have written a book about all forms of renewable energy (available on Amazon) and for me hydrogen is the best option for the future of our civilization. Big oil and established industrial engineering companies have been resisting it, promoting inferior processes and spreading falsehoods for over thirty years now because the potential scares the hell out of them.
Existing engines cannot be converted to hydrogen, they need substantial changes. They are not zero carbon either, they use multiples more energy to power (and therefore produce more CO2. They also produce local tailpipe emissions and you would t be able to package rear seats and have a range above 80 miles at the same time. NextSparkyb69 said:
Hydrogen internal combustion engines (and now jet engines) represent a much more flexible and useful green renewable low pollution and zero carbon solution than batteries.
This is all very well if you look at it from a layman’s perspective. If however, you actually study the physical properties of hydrogen, the end-to-end conversion efficiencies of ANY hydrogen based pathway, and the availability and source of materials required for the pressurised hydrogen storage then it is simply impossible for hydrogen to be the mainstream form of energy supply in our society. It can only act as a supporting role to direct electrification, the maths and physics are non-negotiable aspects that have not changed for 11 billion years. They aren’t about to change any time soon.
H2 GR Corolla race car will make a few show laps in this year Le Mans (not in a race obv). Toyota will also reveal their sporty h2 concept car.
Also h24 hydrogen race car should be in Road to le mans cup this year.
A lot of going for h2 in both road mobility and motorsport.
Btw, Honda, Kawasaki etc are going to develop h2 ice. Honda kind of admitted that Toyota was right and they were wrong 😉
https://forecourttrader.co.uk/latest-news/japanese...
A research association to develop hydrogen combustion engines for small mobility has been set up by Yamaha, Honda, Kawasaki and Suzuki.
Also h24 hydrogen race car should be in Road to le mans cup this year.
A lot of going for h2 in both road mobility and motorsport.
Btw, Honda, Kawasaki etc are going to develop h2 ice. Honda kind of admitted that Toyota was right and they were wrong 😉
https://forecourttrader.co.uk/latest-news/japanese...
A research association to develop hydrogen combustion engines for small mobility has been set up by Yamaha, Honda, Kawasaki and Suzuki.
LasseV said:
H2 GR Corolla race car will make a few show laps in this year Le Mans (not in a race obv). Toyota will also reveal their sporty h2 concept car.
Also h24 hydrogen race car should be in Road to le mans cup this year.
A lot of going for h2 in both road mobility and motorsport.
Btw, Honda, Kawasaki etc are going to develop h2 ice. Honda kind of admitted that Toyota was right and they were wrong ??
https://forecourttrader.co.uk/latest-news/japanese...
A research association to develop hydrogen combustion engines for small mobility has been set up by Yamaha, Honda, Kawasaki and Suzuki.
Toyota got it right? Is that the car company selling a hydrogen car that nobody buys, and has announced multiple BEV cars are in development Also h24 hydrogen race car should be in Road to le mans cup this year.
A lot of going for h2 in both road mobility and motorsport.
Btw, Honda, Kawasaki etc are going to develop h2 ice. Honda kind of admitted that Toyota was right and they were wrong ??
https://forecourttrader.co.uk/latest-news/japanese...
A research association to develop hydrogen combustion engines for small mobility has been set up by Yamaha, Honda, Kawasaki and Suzuki.
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