Design for a universal Battery EMU for the GB rail network

[Nicholas Lewis]

So, if the battery trains are to recharge on existing electrified lines, you probably have to uprate the power supplies to those lines substantially, to cope with the extra trains all drawing full power all the time, not just during acceleration. This would likely be particularly costly in 3rd rail land, where lots of extra substations would be needed.

No such thing as a free lunch!

Remember the advantage of having onboard batteries is you can recuperate the majority of the braking energy into the batteries as long as there not fully charged of course so not all recharging would need to be met from the traction system although that depends on the duty of course ie closely spaced stations vs long distance running.

In respect of 3rd rail areas over half the Southern routes have uprated traction system to the "high current specification" so substation capacity shouldn't be an issue. What will need to be assessed is the increased demand on the grid supply points but given how few diesel services operate over third rail routes compared to the electric worked services all that would be required will be modest increases in firm service capacity at a handful of grid points.

 

[Basil Jet]

Making batteries modular makes them even heavier as you add packaging round the battery. (See the trend of portable devices to not have user-removable batteries).
Does carrying around more weight make much difference if the train has the performance needed? It would make diagramming more complex if you had trains with different capacities. Would you have to renumber into different subclasses each time to avoid putting a low capacity unit onto a diagram that needs more?

One might think so, but headlines like "A freight train powered by 18,000 lithium-ion battery cells" suggest that modularity might not carry significant overhead.

 

[Nottingham59]

All very well quoting miles of battery range and tailoring units to suit.
What happens when Battery degradation kicks in?

This question was posed on the MML electrification thread, but to avoid going off topic there, I thought I would try to discuss @Ploughman 's question here.

Obviously battery degradation will be an issue for BEMUs as it is for all EVs. I think the railway has a number of possible approaches:

• Specify that BEMUs should have a guaranteed range for say 10 years. Let the manufacturers accept the cost of over-providing battery capacity in the early years and/or taking the hit of replacing batteries when they degrade.
• Accept that after a certain time, batteries will have to be replaced.
• Plan to electrify the gaps in stages. As the batteries of a BEMU fleet degrade, the railway adds another mile or two or five of OHLE at one end of the gap, so that the length of the gap is reduced. This would require a degree of coordination between the infrastructure and rolling stock arms of the railway industry.
• Have a national fleet of BEMUs to one design which can be cascaded through the network. If a unit degrades so that it is unable to cross a 100-mile gap safely, then transfer it to a route that only has gaps of 70 miles or less. This is likely to be the cheapest option, but needs coordination between TOCs and a willingness to cascade. To help the process, I'd have a series of sub-classes: abc/1; abc/2; abc/3; abc/4 etc with guaranteed ranges of 35, 50, 70, 100, 140, 200 miles. So if an abc/6 can no longer guarantee 200 miles off the wires, it gets reclassified as abc/5.

 

[edwin_m]

This question was posed on the MML electrification thread, but to avoid going off topic there, I thought I would try to discuss @Ploughman 's question here.

Obviously battery degradation will be an issue for BEMUs as it is for all EVs. I think the railway has a number of possible approaches:

• Specify that BEMUs should have a guaranteed range for say 10 years. Let the manufacturers accept the cost of over-providing battery capacity in the early years and/or taking the hit of replacing batteries when they degrade.
• Accept that after a certain time, batteries will have to be replaced.
• Plan to electrify the gaps in stages. As the batteries of a BEMU fleet degrade, the railway adds another mile or two or five of OHLE at one end of the gap, so that the length of the gap is reduced. This would require a degree of coordination between the infrastructure and rolling stock arms of the railway industry.
• Have a national fleet of BEMUs to one design which can be cascaded through the network. If a unit degrades so that it is unable to cross a 100-mile gap safely, then transfer it to a route that only has gaps of 70 miles or less. This is likely to be the cheapest option, but needs coordination between TOCs and a willingness to cascade. To help the process, I'd have a series of sub-classes: abc/1; abc/2; abc/3; abc/4 etc with guaranteed ranges of 35, 50, 70, 100, 140, 200 miles. So if an abc/6 can no longer guarantee 200 miles off the wires, it gets reclassified as abc/5.

It's mentioned on the other thread that batteries shouldn't be routinely run right down, as they last much longer if they aren't. This actually provides a contingency for unforeseen circumstances such as a train having to sit for a period on heating and auxiliaries when there is a blockage ahead. In that exceptional situation you might accept running the battery much lower.

 

[Nottingham59]

This actually provides a contingency for unforeseen circumstances such as a train having to sit for a period on heating and auxiliaries when there is a blockage ahead.

I agree. I can visualise NR developing "rules of the route" that required BEMU stock to have a nominal range off the wires eqaul to twice the longest gap. So a train could cross a gap to almost the point when the wires start again, and still have enough juice to return to base in case of blockage.

Either that or a "range extender" diesel engine, which would not be used in normal operations, but would be available to top up the batteries in emergencies. This would give effectively unlimited range if necessary, and the engine could be quite small and very efficient.

 

[edwin_m]

I agree. I can visualise NR developing "rules of the route" that required BEMU stock to have a nominal range off the wires eqaul to twice the longest gap. So a train could cross a gap to almost the point when the wires start again, and still have enough juice to return to base in case of blockage.

Either that or a "range extender" diesel engine, which would not be used in normal operations, but would be available to top up the batteries in emergencies. This would give effectively unlimited range if necessary, and the engine could be quite small and very efficient.

I think it would actually be a contingency expressed as time on maximum auxiliaries and/or additional range above what would be needed to run the route normally. Length of gap doesn't make sense, because even a small gap is big enough to get stranded in.

A diesel engine and associated hardware would take up a lot of space, which will be at a premium to accommodate batteries without reducing passenger capacity. It would also be a maintenance liability and the sort of thing that only gets used once in a blue moon - so when you needed it, it might well not work anyway. So best avoided I suggest.

 

[bib]

One of the tricky issues with battery trains is that the energy consumption of a train is highly variable depending on things like line speed, number of stops, gradient, loading. And then as discussed above you need to account for battery aging, and decide how much of a safety margin you need to leave if one becomes stranded etc, which raises all sorts of interesting questions such as how long do you need to be able run the lighting and heating for if the train gets stuck somewhere in the middle of winter? Can you rescue a BMU with another BMU? If a battery pack fails, is running slower to save energy acceptable? If the train is 5 mins late into a station where it is planned to sit and charge for 5 mins , can it leave on time or does it have to sit there for X mins?

So, just making up some numbers, the actual situation might be that you have a train that can trundle along empty in anglia for 150 miles at 20mph on batteries, but operator 1 decides that the useable battery range on their line is 50 miles, and operator 2 decides that on their line it's only 20.
I think you need to treat range figures you might see in the media similarly to how you treat 'official' car mpg figures, except its probably worse as I dont think theres any sort of standard test that can be used.
It would be interesting if there was a list somewhere of BMU/BEMUs that are actually in operation and what distance they actually run off the wires, as that would give an actual indication as to what practical ranges are achieveable, give or take some improvements in battery technology.

 

[HSTEd]

It seems highly likely that the most advisable situation would be to simply install as many batteries as you can fit in the unit and accept the additional cost for the assurance that the system will actually operate in adverse conditions.

 

[Nicholas Lewis]

One of the tricky issues with battery trains is that the energy consumption of a train is highly variable depending on things like line speed, number of stops, gradient, loading. And then as discussed above you need to account for battery aging, and decide how much of a safety margin you need to leave if one becomes stranded etc, which raises all sorts of interesting questions such as how long do you need to be able run the lighting and heating for if the train gets stuck somewhere in the middle of winter? Can you rescue a BMU with another BMU? If a battery pack fails, is running slower to save energy acceptable? If the train is 5 mins late into a station where it is planned to sit and charge for 5 mins , can it leave on time or does it have to sit there for X mins?

Batteries are very good at discharging at high power for short periods of time ie when accelerating so rated power isn't the main driver. As you rightly identify its the energy storage levels of the batteries that will determine the distance a train can travel. ie its WattHours not straight Watts that will determine journey duration. Standards will need to be established by RSSB over what the minimum time that heating/ventilation, lighting and safety systems need to be able to be sustained in perturbated situations. In respect of charging times off the electrified network they will have to be defined and built into the diagrams produced by the train planners. Ultimately though diesel has an energy density significantly greater than the best traction batteries so duration between recharging vs refuelling is going to worse for installed weight which is why we also need standards being developed for remote charging solutions that is supported by the electricity supply industry. Also lets not forget even diesel engines degrade and have to refurbished every few years depending on hours run.

It would be interesting if there was a list somewhere of BMU/BEMUs that are actually in operation and what distance they actually run off the wires, as that would give an actual indication as to what practical ranges are achieveable, give or take some improvements in battery technology.

Japan East Railways have been running a fleet of BEMUs for several years now and Germany is investing in BEMUs in a number of areas. However, there are many tram systems around the world with battery running to draw experience from.

Ultimately if we to decarbonise the industry we will need to find solutions and work within the constraints. Mind you given rail is a miniscule contributor to greenhouse emissions in the UK its hardly the main priority currently so can afford to wait to see how the various technologies evolve before making significant commitments.

 

[Nottingham59]

It would be interesting if there was a list somewhere of BMU/BEMUs that are actually in operation and what distance they actually run off the wires, as that would give an actual indication as to what practical ranges are achieveable, give or take some improvements in battery technology.

There is some information in this thread, unfortunately now closed:

Battery trains in passenger service in Germany (and elsewhere)

This article says that Alstom tested its regional BEMU in September 2021, and that "The BEMU will enter passenger service in Baden-Württemberg and Bavaria when the new timetable comes into effect in December 2021. It will be the first battery-powered train to be approved for regular passenger...

www.railforums.co.uk

EDIT: I discovered that Hitachi and Eversholt Rail are developing a battery version of the Class 802, to be trialled by GWR: https://eversholtrail.co.uk/news/2003-2/

"Hitachi and Eversholt Rail develop battery for a GWR intercity battery hybrid train trial
Hitachi Rail and Eversholt Rail are in the advanced stages of designing and
engineering an electric-diesel-battery (tri-mode) train, with plans to trial on a Great
Western Railway (GWR) Class 802 train in 2022."

I can't tell from the press release what sort of capacity these battery packs will have or what range that might deliver off the wires. The possibility of converting EMR class 810s to battery or tri-mode operation would have interesting implications for the investment case for MML electrification.

Does anyone know what progress is being made on the proposed trial? And what range off the wires will a single battery pack provide?

 

[Nicholas Lewis]

There is some information in this thread, unfortunately now closed:

Battery trains in passenger service in Germany (and elsewhere)

This article says that Alstom tested its regional BEMU in September 2021, and that "The BEMU will enter passenger service in Baden-Württemberg and Bavaria when the new timetable comes into effect in December 2021. It will be the first battery-powered train to be approved for regular passenger...

www.railforums.co.uk

EDIT: I discovered that Hitachi and Eversholt Rail are developing a battery version of the Class 802, to be trialled by GWR: https://eversholtrail.co.uk/news/2003-2/

"Hitachi and Eversholt Rail develop battery for a GWR intercity battery hybrid train trial
Hitachi Rail and Eversholt Rail are in the advanced stages of designing and
engineering an electric-diesel-battery (tri-mode) train, with plans to trial on a Great
Western Railway (GWR) Class 802 train in 2022."

I can't tell from the press release what sort of capacity these battery packs will have or what range that might deliver off the wires. The possibility of converting EMR class 810s to battery or tri-mode operation would have interesting implications for the investment case for MML electrification.

Does anyone know what progress is being made on the proposed trial? And what range off the wires will a single battery pack provide?

well with 7 weeks left of 2022 we will find out soon or maybe its another project that is all talk and no action as DfT haven't authorised it

 

[Bald Rick]

well with 7 weeks left of 2022 we will find out soon or maybe its another project that is all talk and no action as DfT haven't authorised it

Pedantically, 8 weeks and 2 days.

(I don’t want anyone to shorten my life!)

 

[Sm5]

expanding this idea a standardised spec for Multible units espically with conversion and interopribility in mind would go a long way
e.g. like the 4TC units you could serve unelectrified branches with BMU's that could couple up to EMU's once they reach the mainlines and are easy to convert to EMU's once said line is electrifed

In that sense the class 73/9 is the perfect scenario…

Use the excess space where the caterpillar now goes, could be holding batteries, instead of concrete.

Think about your electric tools…, like Machita..
you have a charger, and a battery, which work with all other compatible products.

So now you have a Battery bank on wheels, which charges on 3rd rail, or overhead, or at a Charging station. It has driving cabs to it can be used to self propell, or pull a train, but also act as a power supply powering an EMU which is off grid.

Next step is a standard way of connecting (coupling and power ), to the existing EMU fleet be it 3rd rail or overhead... 379’s could goto Oxted this way.