Battery electric trains or Hydrogen Trains?

[randyrippley]

But why not add a carbon atom to the mix and get the benefits of a gas without the risk of toxic exposure?

You could, and to do so may help control the combustion temperature in the turbine more easily.
Its just that doing so involves burning carbon and would upset the ultra-greens. It would be commercially safer to burn a non-carbon fuel, even if it came from a recoverable source

 

[najaB]

You could, and to do so may help control the combustion temperature in the turbine more easily.
Its just that doing so involves burning carbon and would upset the ultra-greens.

Not if that carbon atom was already going to be released - either because you're capturing methane from existing sources (bio gas) or you've made the methane from atmospheric CO2 in the first place.

 

[edwin_m]

The energy density of hydrogen is pretty poor. I'd go with LPG.

As far as I can tell LPG has most of the storage risks of hydrogen or methane, with the considerable extra risk that it is heavier than air. Therefore any leak will settle near ground level rather than dissipating into the atmosphere. Also I guess the longer hydrocarbons are more difficult to make than methane is from non-fossil sources. The fact that people are familiar with it from camping stoves etd doesn't necessarily make it safer.

Nobody has yet answered the question about the local emissions of a turbine - how is it for NOx and particulates?

 

[najaB]

Nobody has yet answered the question about the local emissions of a turbine - how is it for NOx and particulates?

When run at peak efficiency, on methane or LPG: very good - way better than diesel.

 

[xotGD]

As far as I can tell LPG has most of the storage risks of hydrogen or methane, with the considerable extra risk that it is heavier than air. Therefore any leak will settle near ground level rather than dissipating into the atmosphere. Also I guess the longer hydrocarbons are more difficult to make than methane is from non-fossil sources. The fact that people are familiar with it from camping stoves etd doesn't necessarily make it safer.

Nobody has yet answered the question about the local emissions of a turbine - how is it for NOx and particulates?

NOx: Burning natural gas in a GT you can use dry low-NOx burners and usually meet NOx limits without the need for post treatment of the flue gas. ( Selective non-catalytic reduction (SNCR) or Selective catalytic reduction (SCR) ) There shouldn't be an issue with particulates using natural gas in either a GT or an internal combustion engine.

With hydrogen, however, there are a couple of issues:

1. The high flame speed of hydrogen means that you have to use conventional diffusion burners rather than low-NOx

2. Higher flame temperature from burning pure hydrogen results in even higher NOx formation - this can be overcome by using nitrogen as a diluent; fine in a power station, more of a chew-on on a train.

So more likely to require SNCR / SCR.

However, hydrogen would be used in fuel cells on trains, not in GTs, so these points are academic.

 

[themiller]

Given that there is no distribution network for hydrogen at this time, it's probably better to inject it into the domestic gas system as it becomes available rather than store it at train refuelling depots. This would have the benefits of reducing pollution from burning pure natural gas in urban areas whereas most relevant trains tend to spend time between urban conurbations where it's currently not so polluted per unit of area compared with built up areas and eliminate the bulk storage of pure hydrogen.
https://eandt.theiet.org/content/ar...cent-of-natural-gas-in-the-uk-research-shows/

 

[Andy25]

Given that there is no distribution network for hydrogen at this time, it's probably better to inject it into the domestic gas system as it becomes available rather than store it at train refuelling depots. This would have the benefits of reducing pollution from burning pure natural gas in urban areas whereas most relevant trains tend to spend time between urban conurbations where it's currently not so polluted per unit of area compared with built up areas and eliminate the bulk storage of pure hydrogen.
https://eandt.theiet.org/content/articles/2018/06/hydrogen-could-easily-replace-30-per-cent-of-natural-gas-in-the-uk-research-shows/?utm_source=Adestra&utm_campaign=New EandT News - Automation FINAL - MEMBER&utm_medium=Newsletters - E&T News&utm_content=E&T News - Members&utm_term=https://eandt.theiet.org/content/articles/2018/06/hydrogen-could-easily-replace-30-per-cent-of-natural-gas-in-the-uk-research-shows/

On the whole I'd agree but from the looks of it most potential routes being looked at are deliberately close to chemical industries where hydrogen is a byproduct. So they're reasonably choosing areas where infrastructure requirements are minimal. So far they've mentioned Merseyside and North East.

 

[HSTEd]

Why would you use electricity to make hydrogen just to burn it to make heat later on?

Surely storage heaters would be a far simpler system and eliminate combustion products in the chain entirely.
There are proposals to build giant industrial storage heaters to provide heat to industrial facilities to supplement coal and gas firing and they come out very cheap as most of the material required are simple firebricks.

 

[InTheEastMids]

Why would you use electricity to make hydrogen just to burn it to make heat later on?

Surely storage heaters would be a far simpler system and eliminate combustion products in the chain entirely.
There are proposals to build giant industrial storage heaters to provide heat to industrial facilities to supplement coal and gas firing and they come out very cheap as most of the material required are simple firebricks.

It depends... hydrogen is a lot more valuable than heat for starters. Although of course heat storage is a lot cheaper. This meant one upshot of renewables in the EU was a burst of investment in very large heat stores that allowed large CHP units to store heat so they didn't have to run when the power prices was low or negative.

One reason why some are very excited by hydrogen grids is that gas networks give a lot of inertia/short-term storage to energy systems to cope with spikes in demand (e.g. the pickup in heat demand at 6am on a winter's morning). Secondly it means heating systems might be decarbonised with minimal fuss. Finally, if heat goes electric then gas companies like Cadent are sitting on a colossal stranded asset.

You can't decarbonise domestic heat with storage heaters. Firstly you'd need to probably quadruple the size of the electricity system to delivery 400 GW of electricity, and secondly replace gas central heating with storage heaters, which consumers won't do.

 

[HSTEd]

It depends... hydrogen is a lot more valuable than heat for starters. Although of course heat storage is a lot cheaper. This meant one upshot of renewables in the EU was a burst of investment in very large heat stores that allowed large CHP units to store heat so they didn't have to run when the power prices was low or negative.

Yes, but the vast majority of use of natural gas in the UK is for heat of various types (including heat used for electricity production).

One reason why some are very excited by hydrogen grids is that gas networks give a lot of inertia/short-term storage to energy systems to cope with spikes in demand (e.g. the pickup in heat demand at 6am on a winter's morning). Secondly it means heating systems might be decarbonised with minimal fuss.

Going electric is not particularily troublesome compared to many other options for decarbonisation, and it has the advantage that you would no longer have to maintain two seperate energy distribution infrastructures that supply a large fraction of teh total number of dwellings in the country.

Finally, if heat goes electric then gas companies like Cadent are sitting on a colossal stranded asset.

Well if electric heat is cheaper then we would expect this to happen. And if hydrogen is being used as the heating medium, electric heat will be cheaper.

You can't decarbonise domestic heat with storage heaters. Firstly you'd need to probably quadruple the size of the electricity system to delivery 400 GW of electricity, and secondly replace gas central heating with storage heaters, which consumers won't do.

Electricity distribution costs are primarily a function of the number of subscribers and their geographic distribution. Costs are extremely non-linear in relation to the amount of electricity actually distributed as many studies have concluded in the past.
A 2MW substation does not cost twice as much in life-cycle terms as a 1MW substation.
In fact the easiest way to reduce the cost of electricity per unit is to double the amount of electricity being consumed.

In addition, the use of modern electronically controlled storage heaters would allow them to soak up off-peak electricity, whenever those peaks occur in real time, essentially converting all electricity demand into baseload demand.

At that point, even replacing all gas boilers with CCGTs and resistive heaters would only be 25% or so more carbon emitting than the current system, add in some use of heat pumps and non-carbon intensive energy generating sources and that figure falls precipitously. And we all know of a power generation tech that doesnt produce carbon dioxide and is very very very good at baseload generation.

ANd consumers will do many things when they realise they can save substantial amounts of money by going electric, and new construction would certainly go entirely electric. Likewise with phase change heat stores built into the walls and floor and simple underfloor heating, or by adopting heat pumps with heat stores.

 

[Kneedown]

I’d love it if 25kV was a perfect answer. The problem isn’t the electrical costs, it’s the civils involved in enabling overheads to be put up.

True, but once the civils are done, they're done. They won't have to be done again. The issue isn't the cost as such, it's that no government want's to be the one who pays for it.

 

[D365]

True, but once the civils are done, they're done.

Unless the ORR changes their mind again during the next large-scale electrification programme.

 

[InTheEastMids]

Going electric is not particularily troublesome compared to many other options for decarbonisation, and it has the advantage that you would no longer have to maintain two seperate energy distribution infrastructures that supply a large fraction of teh total number of dwellings in the country.

I agree it's that electrification of the heat and mobility sectors will happen, but it will be troublesome. It is troublesome - there's been basically no progress on heat decarbonisation in the last decade, for reasons that are not simply technical and are way too far off-topic. The most basic tecnical issue is encapsulated by this picture - http://www.lolo.ac.uk/wp-content/uploads/2015/10/images.png. To move towards an electrically heated world using direct electric heating, you need to move the electricity system capacity from the blue line to the sum of red+blue. Then whack on EV demand...

In fact the easiest way to reduce the cost of electricity per unit is to double the amount of electricity being consumed.

I'll challenge your thinking here - because the main driver of electricity system cost is the cost of capacity - i.e. fixed cost. So cost per unit falls if you can sweat the system for another kWh without having to invest in capacity. However, the transformation we believe in requires very significant investment in system capacity, which will add to kWh cost if that's how the system is paid for. It's exactly like the rail network where the cost of adding more seats is actually pretty low until you bump into capacity issues.

Bringing this back on topic, this fixed cost issue that applies to normal electrification also (IMHO) leads to a horses-for-courses approach to low-CO2 rail. Everything where the traffic is dense and/or power is high will probably get nearly-continuous OHLE - the low operating costs of intensive services trumps the high capital cost. Battery trains will dominate shorter branch lines because electricity is cheaper than hydrogen etc, and full electrification is too high capital cost. Biofuels or low carbon gas (including hydrogen) will be pushed out to longer secondary routes because the electricity infrastructure won't cover its costs, and a battery train would basically have no room for anything but batteries. Or it might get batteries with hybrid fast-charging electrification. But each of these approaches are in competition with each other in terms of costs and risk, so it's a fool's game and actually pretty pointless to try and pick a winner for what NR should do with a specific route in some far-off Control Period.

 

[snowball]

Although of course heat storage is a lot cheaper. This meant one upshot of renewables in the EU was a burst of investment in very large heat stores that allowed large CHP units to store heat so they didn't have to run when the power prices was low or negative.

Sorry to drift away from rail, but what form did these heat stores take and who owned them? Did it happen in the UK?