Ideas for Recharging battery trains

[D365]

The only energy that roof-mounted solar panels would generate, would compensate for the additional mass of the panels and electrical equipment. Absolute non-starter of an idea.

 

[Ken H]

The only energy that roof-mounted solar panels would generate, would compensate for the additional mass of the panels and electrical equipment. Absolute non-starter of an idea.

We keep adding mass to vehicles (rail and road). We seem to have lost sight of Newtons second law - F=ma. Force = mass times acceleration.

Add mass and you have to add force t=for acceleration to be constant.

What will a BEMU with transformer and pantograph, and also enough batteries to do useful work, weigh?

Its the same with cars. They used to weigh under a ton. Now are typically 1.5-2 tons. Dragging all the extra mass around must be costing a lot of energy.

(6 strong blokes used to be able to lift and carry a mini in the 60's/70's. We did. We moved a friends car around just for the laughs!)

 

[MotCO]

What will a BEMU with transformer and pantograph, and also enough batteries to do useful work, weigh?

What will all this extra weight do to the rail infrastructure? Some bridges may not be strong enough, or speed restrictions may need to be introduced. Track replacement may need to be done more often etc.

 

[Irascible]

I think the idea is eventually you build a significant amount of viehicle *from batteries*. Vehicle mass reduction is obviously a continual area of study. I think a lot of the extra mass in cars these days is just to meet current crash test standards.

 

[Nottingham59]

The pan would be heavy duty to manage the current transfer so wouldn't necessarily be suitable for running under 25kV.

If you wanted to use high voltage (~25kV) to recharge, I'd have three pantographs along the length of the power car, and feed them each with a different phase of the mains supply.

Three 5m bars in a line overhead (with insulating rods between them) could each be fed off a different phase of a standard 33kV AC supply cable with no transformer needed trackside. This would work well at Oban, which has a 33kV substation a mile or so from the station. You would need on board transformer(s) and rectifiers of course, able to handle 3 phases at that voltage.

And under standard 25kV OHLE, you would use just one pantograph, with an internal 25kV bus to distribute the power to the three on board transformer/rectifier units.

when the pan is static for a long period you will get localised heating of the carbon strips but it all depends on how much power is required to be transferred.

At a terminus, you could make the bus bar 5 or 10 or 20cm wide - however wide it had to be to spread the current across the carbon conductor strip.

 

[MattRat]

We keep adding mass to vehicles (rail and road). We seem to have lost sight of Newtons second law - F=ma. Force = mass times acceleration.

Add mass and you have to add force t=for acceleration to be constant.

What will a BEMU with transformer and pantograph, and also enough batteries to do useful work, weigh?

Its the same with cars. They used to weigh under a ton. Now are typically 1.5-2 tons. Dragging all the extra mass around must be costing a lot of energy.

(6 strong blokes used to be able to lift and carry a mini in the 60's/70's. We did. We moved a friends car around just for the laughs!)

Oh I understand things weigh too much nowadays, and I think the fuel cell will more likely be the future than batteries, but we are talking about batteries so they already weigh alot, so adding solar panels shouldn't add that much percentage wise.

 

[Nicholas Lewis]

Oh I understand things weigh too much nowadays, and I think the fuel cell will more likely be the future than batteries, but we are talking about batteries so they already weigh alot, so adding solar panels shouldn't add that much percentage wise.

Best solar panels are 20% efficient. Maximum radiation in Southern England, gets worse further North you go, is 500W/sqm for mid summer less than 200W/sqm in mid winter. So on a 24m coach x 2m you have 48sqm you might make 24kw max for a couple hours and thats if the sun is out but given topography of a railway its not going to be receiving sun all the time either. Whilst they don't weigh much I suggest they are best installed in static locations orientated to maximise energy production..

 

[GLC]

What will all this extra weight do to the rail infrastructure? Some bridges may not be strong enough, or speed restrictions may need to be introduced. Track replacement may need to be done more often etc.

We already have bimodes carrying equipment for OHLE use, and diesel generators, going around the network. Weight of batteries on a BEMU is not materially different from the weight of the engines in a DEMU. Each V8 in a class 755 weighs over a tonne, and that’s before the weight of the alternator, fuel, coolant etc is included too

 

[Nicholas Lewis]

We already have bimodes carrying equipment for OHLE use, and diesel generators, going around the network. Weight of batteries on a BEMU is not materially different from the weight of the engines in a DEMU. Each V8 in a class 755 weighs over a tonne, and that’s before the weight of the alternator, fuel, coolant etc is included too

Good point carting around a tonne of diesel in a tank that has to be strengthened for crash resistance isn't insignificant although you get significantly more energy from a litre of diesel than from the equivalent volume of a battery. Lithium–titanate seem to be favoured chemistry for traction use and give about 60kwh/tonne. In comparison one litre of diesel has about 10kwh energy equivalent although actual productive energy would be c3-4kwh unlike a battery which is is much more efficient between charge / discharge cycles. So there is real challenge in deploying battery trains without recharging infrastructure.

 

[Ken H]

Good point carting around a tonne of diesel in a tank that has to be strengthened for crash resistance isn't insignificant although you get significantly more energy from a litre of diesel than from the equivalent volume of a battery. Lithium–titanate seem to be favoured chemistry for traction use and give about 60kwh/tonne. In comparison one litre of diesel has about 10kwh energy equivalent although actual productive energy would be c3-4kwh unlike a battery which is is much more efficient between charge / discharge cycles. So there is real challenge in deploying battery trains without recharging infrastructure.

what about the losses between the power station and the traction battery in the train.

 

[Nicholas Lewis]

what about the losses between the power station and the traction battery in the train.

losses average about 5% from point of generation to supply but the higher the voltage of the load the lower the losses so at 25kv c 2-3%.

 

[AndrewE]

Current is a lot lower at 25kV compared to transferring it at 750V DC though. Also when the pan is static for a long period you will get localised heating of the carbon strips but it all depends on how much power is required to be transferred.

If it is likely to be an issue (big if) you could easily have a pan on a sliding mounting that, when the train was recharging while stationary, just moved slowly forward and back a few 10s of cm. Big stagger on contact wire in the static location too. Not very complicated, unlikely to cause a problem if it worked when not intended either. (Or even a full pantograph-width contact for static charging.)
Where there's a will there's a way.

 

[Bald Rick]

Edit - I thought I posted this yesterday, but didn’t...

Well you'd have nearly the entire roof. And again, extend rather than fully power. It just needs to reduce the drain, not stop it.

At most you’d get 50 metres square of panels per coach, and of course the angle of the panels would be sub optimal. Let’s say there’s 4 coaches. If the train was running in Kent, on a sunny day in mid summer at 1300, it would generate around 10kWh in an hour, assuming no shade from cuttings, bridges, tunnels, buildings and trees. That would give the train less than a mile of range, in these perfect circumstances. However there would also be around 5 tonnes of panels, cabling and extra power electronics to cart around, including when it is cloudy, winter and night time. To get an extra mile of range from a battery, you’d need an extra 50kg of battery pack, which is about the same size as 2 boxes of cereal.

For almost all applications in this country, over the course of the year I suspect a roof full of solar panels would require more power to lug around than they would generate.

Oh I understand things weigh too much nowadays, and I think the fuel cell will more likely be the future than batteries, but we are talking about batteries so they already weigh alot, so adding solar panels shouldn't add that much percentage wise.

As above. A 4 car train covered in panels would weigh an extra 5 tonnes for, at the very best, a mile of range an hour.

5 tonnes of batteries buys you about 50 miles of range.

 

[MotCO]

Edit - I thought I posted this yesterday, but didn’t...


At most you’d get 50 metres square of panels per coach, and of course the angle of the panels would be sub optimal. Let’s say there’s 4 coaches. If the train was running in Kent, on a sunny day in mid summer at 1300, it would generate around 10kWh in an hour, assuming no shade from cuttings, bridges, tunnels, buildings and trees. That would give the train less than a mile of range, in these perfect circumstances. However there would also be around 5 tonnes of panels, cabling and extra power electronics to cart around, including when it is cloudy, winter and night time. To get an extra mile of range from a battery, you’d need an extra 50kg of battery pack, which is about the same size as 2 boxes of cereal.

For almost all applications in this country, over the course of the year I suspect a roof full of solar panels would require more power to lug around than they would generate.




As above. A 4 car train covered in panels would weigh an extra 5 tonnes for, at the very best, a mile of range an hour.

5 tonnes of batteries buys you about 50 miles of range.

Much easier to just make sure you only build downhill railways (smiley emoji)

 

[Tester]

Much easier to just make sure you only build downhill railways (smiley emoji)

Well it certainly worked in North Wales

 

[MattRat]

Much easier to just make sure you only build downhill railways (smiley emoji)

Actually, you may be onto something, as going downhill, the motors can be turned into generators.

 

[MarkyT]

Oh I understand things weigh too much nowadays, and I think the fuel cell will more likely be the future than batteries, but we are talking about batteries so they already weigh alot, so adding solar panels shouldn't add that much percentage wise.

Just to note that all fuel cell vehicles built so far also have some kind of traction battery in a hybrid configuration. Although the battery can be a lot smaller than for the equivalent range with battery only, the electric traction system floats on that battery at all times just like a pure battery electric vehicle, and it is topped up automatically as required by the fuel cell, even while stationary, like certain hybrid car designs with small range-extender IC engines. The battery can also be topped up from regenerative braking, and from 'plug in' charging sources, including plausibly in motion from OHLE/3rd rail supply, if equipped with the requisite pick-up devices and where that infrastructure exists, so as to minimise use of expensive and space-consuming hydrogen.

 

[mike57]

In December, a Stadler Flirt AKKU achieved 225km on battery power. Their guaranteed range off the wires is 80km. https://www.railtech.com/rolling-st...ld-record-for-battery-only-range/?gdpr=accept

80km is not enough for Settle-Carlisle, but there are many many branches lines in Britain less than 80km away from the juice.

The great thing about battery charging is that it can use a balanced 3-phase supply, so you don't need massive 400kV transformers to accommodate single-phase OHLE.

Personally, I'd investigate using a 750V DC overhead busbar at branch terminus platforms feeding a dual-voltage pantograph, like you get on a dual-voltage tram-train.

But I'm not an expert (which is why I opened this thread!)

I suggested 1.5kV DC for the same reason, easier to provide a high power supply from a 3 phase grid connection, to get a balanced load. You could convert that 1.5kVDC derived from a 3 phase grid supply electronically to 25kV AC single phase, but that introduces further conversion losses, and its going to be converted back to DC on the train to charge the batteries anyway. The reason for suggesting 1.5kV DC is that it is already in use and there should be quite a few designs/equipment which will work 'out of the box' or only require minor mods. The French use 1.5kV DC overhead conductor bar on some of their lines. Short (half mile ish) sections around each station would be fairly easy to do, and rather than getting into major reconstruction just finish before any challenging bridge or tunnel.

If the units never need to operate on 25kV then the weight of the transformer can be lost, maybe have a design that allows a 25kV package to be fitted and removed simply in the workshops.

As with a lot of battery system designers tend to paint the best picture rather than real world, so the 225km is a publicity stunt, but as you say 80km would cover an awful lot of the UK. If you took my idea and provided short sections of power at stations I suspect you easily add another 25 miles to the 50 mile range.

I would also not bother about routes such as the S&C, Far North line, West Highland line etc. They are low frequency services, and their contribution to emissions on a UK scale must be minimal, and they present challenges which are currently beyond the technology without significant additional infrastructure, and any meaningful electrification of these lightly used routes is not going to happen. Go for the low hanging fruit first.

One thing to consider is lines where there is currently no electrification as the range quoted would allow one journey, but then a layover would be needed to recharge. It would be interesting to see how many routes could be converted without making huge changes given some sensible application of current technology. a 100 mile route where 50miles are on battery would be doable, but a 50 mile route completely on battery would present some challenges.

 

[CdBrux]

What will a BEMU with transformer and pantograph, and also enough batteries to do useful work, weigh?

What is the comparison between the weights of:
1. EMU
2. BEMU
3. DMU, including average fuel weight (running Diesel under wires)
4. Hybrid MU to run electric under wires and diesel off wires

 

[Nottingham59]

It would be interesting to see how many routes could be converted without making huge changes given some sensible application of current technology. a 100 mile route where 50miles are on battery would be doable,

I would suggest a good aspiration for BEMU designs in the UK would be Liverpool - Norwich. If battery trains could manage that route, they could go just about anywhere. Recharging will be possible (eventually) at Liverpool; Manchester to Hazel Grove; Dore-Sheffield (reverse)-Alfreton; Nottingham; Grantham to Peterborough; Ely (reverse); Norwich. You might have to extend electrification East and West from Ely a bit.

 

[Ken H]

I would suggest a good aspiration for BEMU designs in the UK would be Liverpool - Norwich. If battery trains could manage that route, they could go just about anywhere. Recharging will be possible (eventually) at Liverpool; Manchester to Hazel Grove; Dore-Sheffield (reverse)-Alfreton; Nottingham; Grantham to Peterborough; Ely (reverse); Norwich. You might have to extend electrification East and West from Ely a bit.

or Birmingham - Stanstead. Pan up at Birmingham NS, at Nuneaton, hopefully through Leicester soon, Peterborough and Ely thence to Stanstead. Some little bits of wiring could help. Helpston - Stamford, perhaps. or even New St - Water Orton.

(Not sure whats wired at Nuneaton these days TBH.)

 

[D365]

What is the comparison between the weights of:
1. EMU
2. BEMU
3. DMU, including average fuel weight (running Diesel under wires)
4. Hybrid MU to run electric under wires and diesel off wires

Not sure about 3 and 4, but a battery-equipped electric vehicle typically weighs between five and eight tonnes more than a "pure" electric vehicle.

 

[AM9]

Not sure about 3 and 4, but a battery-equipped electric vehicle typically weighs between five and eight tonnes more than a "pure" electric vehicle.

So, given that a 319 inherits about 8 tonnes of genset and fuel per end car to become a 769, BEMUs and future diesel-electric bimodes should have similar gross weights.

 

[gingertom]

With electrification from Haymarket to Dalmeny being rolled out it would appear Scotrail/TS's strategy is for BEMUs to be charged up on the move from OLE. TS has committed the Levenmouth reopening to be with electric rolling stock, and I believe there's plans for the branch to be electrified. Thornton jnc looks to be a good place for a power feed point, with national grid close by. To be really useful the wires ought to go as far south as the next station, Kirkcaldy. A southbound unit would have plenty of battery charge to reach Dalmeny, where it would pan up and recharge. Some of the Fife trains work through to Tweedbank. Charging from Dalmeny to Newcraighall ought to pick up enough charge to enable the train to work to Galashiels. A short section of OLE through to Tweedbank should be enough to allow the return journey to Newcraighall. If that's not enough then extend the wires south from Newcraighall to Gorebridge. At the north end extending the wires to Ladybank would allow Perth and Dundee to be reached.

Could the same approach be used elsewhere? Definitely. Take the West Highland. Extend the wires west from Craigendoran jct to Helensburgh Upper to facilitate the changeover. Wire from Ardlui to Tyndrum Upper and Lower. Connel Ferry to Oban, Fort William to Spean Bridge & Corpach/Banavie, Arisaig to Mallaig (Glenfinnan viaduct gets left well alone). Grid feed point at Crianlarich.

 

[Bald Rick]

Grid feed point at Crianlarich.

Inverarnan, a few miles south would be the place for that. if it was to happen, which is very very unlikely.