London has just purchased 2 new hydrogen buses at ~£700k a pop. A equivalent diesel single is ~£130-140k. Even in London these can only be purchased after receiving environmental grants ... some of which come from EU. Fuel cells are not cheap!
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BiMode Hydrogen power?
- Thread starter Flying Phil
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London has just purchased 2 new hydrogen buses at ~£700k a pop. A equivalent diesel single is ~£130-140k. Even in London these can only be purchased after receiving environmental grants ... some of which come from EU. Fuel cells are not cheap!
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I guess not.
matacaster
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The currently suggested method of hydrogen power is via fuel cells.
Would it be practical to use on-board electrolysis to split water into hydrogen and oxygen utilising overhead power when train is running under OHLE, capturing, compressing and storing the hydrogen and then using it as the power source when off the electrified network. Clearly when under the wires traction would be by normal electric power?
There may be practical problems here such as the size of equipment required, danger, process too slow to be viable, too expensive.
Thoughts anyone?
Would it be practical to use on-board electrolysis to split water into hydrogen and oxygen utilising overhead power when train is running under OHLE, capturing, compressing and storing the hydrogen and then using it as the power source when off the electrified network. Clearly when under the wires traction would be by normal electric power?
There may be practical problems here such as the size of equipment required, danger, process too slow to be viable, too expensive.
Thoughts anyone?
D365
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How does that offer any improvement over a li-ion (or other compound) battery?
HSTEd
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Hydrogen is not really a practical energy storage method unfortunately.
It has very good energy to weight ratio, but even cryogenic hydrogen has a density of only 80kg per cubic metre.
As to reliable batteries for railway applications - I think NiFe are worth looking at again, whilst they are heavy they are also effectively bulletproof.
It has very good energy to weight ratio, but even cryogenic hydrogen has a density of only 80kg per cubic metre.
As to reliable batteries for railway applications - I think NiFe are worth looking at again, whilst they are heavy they are also effectively bulletproof.
They appear to be absolutely rubbish in terms of energy density and specific energy (about a factor of 10 less than Li-Ion on both counts). I think the bigger concern for rail at the moment is a battery that will provide sufficient range rather than additional reliability, surely.
D365
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Energy storage capacity is the weakness of any kind of battery technology and has been for some time. Development isn’t moving fast enough for any IPEMU to be a serious contender for diesel replacement for a number of years yet.
InTheEastMids
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Personally, I think hydrogen as fuel will be confined to a "special situations" niche, I can't see it being a mainstream solution for the rail industry.
If you're going to make green hydrogen, there's a stack of things against you
1. The "surplus electricity" thing will not happen as often as people think as EVs and electric heating could lead to a tripling of electricity demand by 2050
2. You then have electrolysis and compression losses to make it a usable fuel at very high pressure, making it look expensive compared to power
3. Rail would depend on other users (far from certain) to roll out a national hydrogen infrastructure to get fuelling points (or will it be trucked around?)
4. Need to solve all the fuel storage issues on the train
5. The train is still likely to be dependent upon batteries for peak power and regenerative braking.
Batteries plus discontinuous electrification could be what "electrification" looks like in 10 years.
The bits of electriciation that are done are basically a BEMU charging infrastructure. This means the range doesn't have to be a whole day/hundreds of miles between refuelling, but tens of miles across gaps in the wires. This instantly knocks down the energy capacity requirement by a factor of ten, and the weight penalty for batteries is down to a few tonnes per vehicle.
Of course this has implications for ensuring capacity of the wires and substations to deliver that current, but even so, sounds cheaper than all the piling and structural works to get conventional electrification to every mile of a route.
If you're going to make green hydrogen, there's a stack of things against you
1. The "surplus electricity" thing will not happen as often as people think as EVs and electric heating could lead to a tripling of electricity demand by 2050
2. You then have electrolysis and compression losses to make it a usable fuel at very high pressure, making it look expensive compared to power
3. Rail would depend on other users (far from certain) to roll out a national hydrogen infrastructure to get fuelling points (or will it be trucked around?)
4. Need to solve all the fuel storage issues on the train
5. The train is still likely to be dependent upon batteries for peak power and regenerative braking.
Batteries plus discontinuous electrification could be what "electrification" looks like in 10 years.
The bits of electriciation that are done are basically a BEMU charging infrastructure. This means the range doesn't have to be a whole day/hundreds of miles between refuelling, but tens of miles across gaps in the wires. This instantly knocks down the energy capacity requirement by a factor of ten, and the weight penalty for batteries is down to a few tonnes per vehicle.
Of course this has implications for ensuring capacity of the wires and substations to deliver that current, but even so, sounds cheaper than all the piling and structural works to get conventional electrification to every mile of a route.
HSTEd
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Yes, but they will last the entire lifetime of the multiple unit they are fitted to. Li-Po will most certainly not, then there are the safety implications of having batteries that have no structural elements in them in a rail accident.
And range can be fixed by simply fitting more batteries.
D365
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379013 proved that fitting Li-ions to an EMU is just fine.
And that is very much contingent on finding more room below the solebar.
themiller
Member
379013 was to prove the concept. Unless I'm mistaken, the trial was a success as far as the basic concept was concerned but there are still aspects of the technology to be solved such as power density and weight. The lack of orders for Battery Electric Multiple Units suggest that the BMU's time has not yet come. Don't forget that Northern have a franchise which requires them to trial an Independently Powered Multiple Unit on the Windermere branch. I suspect that, given the state of the technology, this will not happen any time soon.
superkev
Established Member
I think it's all down to cost as both hydrogen or battery powered trains are perfectly feasable.
Witness Hull and Reading converting there hybrid buses back to straight diesel when the batteries need replacing at £35k each which is more than a 7+ year bus is worth. Modern Railwatys said the battery leasing cost of the battery emu exceeded the leasing cost of the whole train.
Hydrogen is still waiting for someone to do find way of producing it economically and environmental frendily as well as the cost of fuel cells.
How the costs compare with the dreadnought class GW electrification system I'm not sure.
K
Witness Hull and Reading converting there hybrid buses back to straight diesel when the batteries need replacing at £35k each which is more than a 7+ year bus is worth. Modern Railwatys said the battery leasing cost of the battery emu exceeded the leasing cost of the whole train.
Hydrogen is still waiting for someone to do find way of producing it economically and environmental frendily as well as the cost of fuel cells.
How the costs compare with the dreadnought class GW electrification system I'm not sure.
K
HSTEd
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How long was the trial?
What is the projected life of a hard-cycled Li-Po battery pack versus the lifespan of a multiple unit.
A lot of Li-Po's advantage starts to fade away once you consider they have some serious restrictions on deep-cycling.
EDIT:
To be honest, the only way we are going to get battery units in mass use is if someone gets one of those proposed aluminium-air rechargeable batteries to work properly.
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