Hydrogen bus

[OxtedL]

Digging around in the bowels of TfLs internet presence recently, I came across this:
http://www.youtube.com/user/TransportforLondon#p/u/14/yz3Vt6rsjO0

I found a (very) passing mention of it on this forum in a locked thread, but felt it was important to give it a new airing so I could make a remark along the lines of "God, it's ugly."

Has anyone been on one?

 

[N Levers]

Are they safe...

If I shot at one of them (I am not going to shoot at one of them) would it go boom??

 

[SS4]

Are they safe...

If I shot at one of them (I am not going to shoot at one of them) would it go boom??

Perhaps if you shoot an incendiary bullet (but then you'd also blow up a petrol bus).

They are no more dangerous than a regular bus. I'm more concerned with how they're producing the hydrogen, if I remember back to my chemistry lessons then hydrogen is extract by steam reformation of methane - an endothermic reaction of what is essentially natural gas.

The development of the technology is good but IMO they need to produce a way of generating it by renewable means such as hydroelectric powering the electrolysis of a hydrogen compound (probably water).

 

[daikilo]

Digging around in the bowels of TfLs internet presence recently, I came across this:
http://www.youtube.com/user/TransportforLondon#p/u/14/yz3Vt6rsjO0

I found a (very) passing mention of it on this forum in a locked thread, but felt it was important to give it a new airing so I could make a remark along the lines of "God, it's ugly."

Has anyone been on one?

The bus seems to be at least 6 months old. I wouldn't call it ugly as it could have been much worse if the roof mounted elements were not shrouded. I would even say it is one of the best attempts at styling that I have seen, and possibly better than many low-floor trams.

I feel sorry for Kate Harland who apparently not only wears a stainless steel watch upside down on her right arm but also took a gulp of warm tasteless H2O (I hope she spit it out afterward).

 

[Xenophon PCDGS]

I remember the "locked" thread from reading back on such when I first joined the forum and a very lively technical debate on the actual cost of generating it ensued, mostly outside my knowledge and understanding, but interesting nonetheless.

 

[BestWestern]

Perhaps if you shoot an incendiary bullet (but then you'd also blow up a petrol bus).

They are no more dangerous than a regular bus.

Uh oh, it's time for Pedantry Corner, as they say in Private Eye!

All UK buses burn good old dirty diesel I'm afraid, rather than petrol. That's been the case for many decades now. So, if you were to shoot at one - not a particularly common occurence thankfully! - even if you hit the fuel tank, it wouldn't explode, Hollywood style. Diesel is nowhere near as volatile as good old petrol (I'm sure you knew that tho!). So, I suppose one might argue that a hydro bus might be tad more unstable, but then I know little about hydrogen so I might well be wrong!!

 

[N Levers]

Uh oh, it's time for Pedantry Corner, as they say in Private Eye!

All UK buses burn good old dirty diesel I'm afraid

[Pedant]

Some run on cooking oil

[/Pedant]

 

[BestWestern]

[Pedant]

Some run on cooking oil

[/Pedant]

You are quite right! I stand disgraced :cry:

 

[SS4]

You are quite right! I stand disgraced :cry:

You're not the only one :cry:

The only thing I can see hydrogen being more dangerous than diesel is due to it being liquefied (high pressure) but since it's lighter than air hydrogen won't pool on the ground

 

[BestWestern]

To be perfectly honest, in the vast majority of instances of buses catching alight for whatever reason, it's usually goodnight. Unless the fire brigade are there within the first few minutes, it'll take hold and the masses of plastic and fibreglass are well and truly gone. So in the grand scheme of things, it probably wouldn't make too much difference, everybody would bail out pretty damn quick either way I'd imagine!

 

[Goldfish62]

You're not the only one :cry:

The only thing I can see hydrogen being more dangerous than diesel is due to it being liquefied (high pressure) but since it's lighter than air hydrogen won't pool on the ground

The fuel cell buses (to use the correct term) use hydrogen gas and if any major fault is detected the gas is immediately evacuated upwards. Apart from finding enough space this is why the tanks are on the roof, giving the unusual styling.

 

[MCR247]

Nottingham has a few on "trial" running on Ethanol

When I say trial, it was supposed to be an 18 month one, starting 3 years ago...

 

[bb21]

The hydrogen technology has so far proved unreliable, with prohibitive set-up costs. At least at the moment, they're unlikely to be produced en masse. Likewise with fuel cell technology. The amount of pollution caused by the disposal of used battery is eye-watering. I don't really understand the objection to the good old trolleybus though. They're as clean as hydrogen buses insofar as emission is concerned, and they run successfully in many countries. In inner-city traffic conditions where stop-start is frequent, they cause less pollution and are faster starting up than conventional diesel buses too. We seem obsessed with inventing new technology when there is something that actually works currently being ignored.

 

[NLC1072]

The fuel cell buses (to use the correct term) use hydrogen gas and if any major fault is detected the gas is immediately evacuated upwards. Apart from finding enough space this is why the tanks are on the roof, giving the unusual styling.

It's also on the roof to stop it being crashed in to by other road users, its expensive stuff to repair!

 

[Deerfold]

I'm not sure if this is an indication of their reliability but I often see buses that are not intended for use on RV1 running on it (including double deckers), presumbly in lieu of a hydrogen vehicle.

Though to be fair I often see many buses on route RV1 as it runs near my office. I don't often see unusal types on the other routes I see regularly though.

 

[exile]

During the war some buses ran on town gas, which is mainly hydrogen.

 

[LE Greys]

Well, imagine that they did develop a means for electrolysing water cheaply (producing all sorts of other stuff as well, especially from seawater) then that would mean they would have to generate a lot of electricity. However, to cut out the huge inefficiencies, perhaps they could simply send the electricity direct to the buses via overhead wires. Maybe they could call it a trolleybus.

 

[exile]

We'd still need buses and minibuses where the capital cost of building tram lines and putting up trolley poles etc for trolleybuses ouldn't be justified.

That said, the benefits of hydrogen cars and buses seem to be overstated. It's just a - not particularly convenient, due to its low density - method of storing energy that has to be generated by some other means.

 

[LexyBoy]

During the war some buses ran on town gas, which is mainly hydrogen.

Ah yes, I remember seeing a hilarious photo of such a contraption! The best I could find online is this one (pic too large to embed). Don't forget that town gas is ~10% carbon monoxide too

Anyway, my view on hydrogen is that in general it's a bit of a gimmick in most applications - and it must be remembered that hydrogen is not a fuel, but a way of storing energy. We don't have any particularly efficient way of storing it (though scale is on your side here) and it's a less efficient way of storing energy than using batteries. For buses, the benefit is in having no (point of use) emissions - which is only really a concern in cities, where frequent, short services are the order of the day - i.e. ideal for trolleybus/tram operation, or battery electric vehicles.

That said, the "zomg but it burns!!1!!1" response that always crops up is slightly annoying. Hydrogen is so light it'll be well out of the way, unless an accident happens in an enclosed space. Big crash & fire with petrol/diesel vehicle = everyone concerned is left in a pool of burning fuel; same thing with hydrogen vehicle = fireball racing into the sky, well away from everyone concerned. (Oversimplified I know, but people do tend to forget that they're driving around with gallons of highly flammable liquid in their tanks when they talk about hydrogen being dangerous).

 

[LE Greys]

Ah yes, I remember seeing a hilarious photo of such a contraption! The best I could find online is this one (pic too large to embed). Don't forget that town gas is ~10% carbon monoxide too

Anyway, my view on hydrogen is that in general it's a bit of a gimmick in most applications - and it must be remembered that hydrogen is not a fuel, but a way of storing energy. We don't have any particularly efficient way of storing it (though scale is on your side here) and it's a less efficient way of storing energy than using batteries. For buses, the benefit is in having no (point of use) emissions - which is only really a concern in cities, where frequent, short services are the order of the day - i.e. ideal for trolleybus/tram operation, or battery electric vehicles.

That said, the "zomg but it burns!!1!!1" response that always crops up is slightly annoying. Hydrogen is so light it'll be well out of the way, unless an accident happens in an enclosed space. Big crash & fire with petrol/diesel vehicle = everyone concerned is left in a pool of burning fuel; same thing with hydrogen vehicle = fireball racing into the sky, well away from everyone concerned. (Oversimplified I know, but people do tend to forget that they're driving around with gallons of highly flammable liquid in their tanks when they talk about hydrogen being dangerous).

That also means that leaks are less of a concern. An LH2 tank with a hole in it will turn into a tank full of air over a prolonged period of time, but the hydrogen will not remain on the floor like petrol would, it would evaporate and disperse. Hydrogen also has a higher spontaneous ignition temperature than either petrol or diesel.

 

[LexyBoy]

You'd want to make sure your vehicle is stored somewhere with good ventilation though, as hydrogen has one of the widest explosive ranges with air of anything, so whilst it will disperse upwards if given a chance, it could get dangerous if it doesn't have the opportunity. And unlike natural gas, I don’t think there will be anything added to hydrogen to give it a smell (the sulfur compounds used in natural gas would quickly poison the catalysts used in fuel cells I’d think). BTW hydrogen is generally stored as a compressed gas rather than liquid (in fact I think it can’t exist as a liquid at ambient temperatures). Storing liquid hydrogen requires very low temperatures so isn’t very practical for long-term storage of small amounts.

 

[LE Greys]

You'd want to make sure your vehicle is stored somewhere with good ventilation though, as hydrogen has one of the widest explosive ranges with air of anything, so whilst it will disperse upwards if given a chance, it could get dangerous if it doesn't have the opportunity. And unlike natural gas, I don’t think there will be anything added to hydrogen to give it a smell (the sulfur compounds used in natural gas would quickly poison the catalysts used in fuel cells I’d think). BTW hydrogen is generally stored as a compressed gas rather than liquid (in fact I think it can’t exist as a liquid at ambient temperatures). Storing liquid hydrogen requires very low temperatures so isn’t very practical for long-term storage of small amounts.

Depends on what you want it for. As I understand it, fuel cells prefer liquid fuel, so the hydrogen in question would have to be in cryogenic storage before being fed to the fuel tanks. Most of what I know about this comes from the way they stored and handled Space Shuttle fuel, and that's not much. It needs careful handling and heavy insulation to prevent boil-off, and to avoid it coming in contact with skin (being hit by liquid at -450F can be very hazardous to health) and the process of cooling it must use a lot of power, although it is one possible option for use of the boil-off gases. However, it's practical for large volumes, because the larger the tank, the more likely it is to maintain a stable temperature. The real problem is keeping it cold when it is in the bus, especially in traffic on a hot day, when radiators don't work well. One option would be to refuel buses a lot more regularly, hourly if possible, to reduce the boil-off rate. Another might be to store it under pressure, preventing the liquid from boiling. I don't really know.

 

[Zoe]

Depends on what you want it for. As I understand it, fuel cells prefer liquid fuel, so the hydrogen in question would have to be in cryogenic storage before being fed to the fuel tanks.

Would you not need a LOX tank also then?

 

[LE Greys]

Would you not need a LOX tank also then?

I've never been sure about that. Is O2 for fuel cells scavenged from the air, or do you bring your own?

 

[OxtedL]

I would be very surprised if they used liquid hydrogen for a bus! It's one thing doing it for the space shuttle, and quite another doing it on a public road... And carrying around LOX on a bus doesn't seem sensible either. It ain't a rocket.

And having said that, I'm off to do some actual research...