Battery powered EMUs

[Greybeard33]

The Bradford to Liverpool service was not a mandatory output from the Northern Hub as the Bradford to Manchester Airport service was. However the Manchester Hub Study, Executive Summary says:

and with Victoria becoming a through station, the example timetable showed 4tph to Manchester Airport, Liverpool, Wigan and Preston. There were contradictions in the Northern ITT documents in that the Franchise Consultation Response stated:

while the ITT and Service Specification mentioned nothing about a third train, specifying only 2tph extended to Manchester Airport and Chester. You would have expected bidders to seek clarification on whether this third tph was required or not and if so where the DfT expected it to go west of Manchester. Whether this contradiction was sorted out at the bid stage or during contract negotiation, the result was a third tph to Liverpool.

So as far as Calder Valley services go (including the via Brighouse service) the only major difference from the Hub example timetable is a service to Chester rather than Preston.

Good point regarding the specification of the third Bradford service. However, Victoria is not losing its east-facing bay platforms, so the third service could terminate there, with a connecting EMU service from Liverpool terminating at Stalybridge, as per the illustrative options in the CP5 HLOS jcollins linked above (this post-dates the Hub study):

Victoria (Northern)
Leeds via Bradford / Dewsbury and Rochdale to Victoria.
[snip]
Services from Liverpool, Southport, Wigan, Blackburn and Clitheroe extended to
Stalybridge or Rochdale and revised to match current patterns of demand.

 

[superkev]

The conclusions for the 379 were that the trial was technically feasible but that leasing maintenance charges and relative fuel costs with the current battery technology meant that it was uneconomic for squadron service by a very wide margin when compared with using a standard DMU on the non electrified service. I can't remember the exact cost but I think it was something of the region of 3.5 times the running cost of the DMU.

Ian Warmesly in modern railways said the leasing cost of the battery was similar to the cost of the rest of the train. Batteries need to get much much cheaper to do much more than provide short term acceleration.
To replace say a 100gal diesel tank needs around a 1600kw battery which using the figure quoted elsewhere on here of $200/kw would be $320000.
Needs replacement every 8 years or so not going to happen
K

 

[broadgage]

I feel that limited battery operation could be viable in many places, and despite the cost of the batteries could be worth pursuing.

Charging on an electrified main line is easy, and once on an a non electrified branch, energy could be conserved by lower speeds, and by reducing or even eliminating heating and air conditioning.
If the train is pre-heated or cooled, then the absence of heating or cooling for 20 minutes on the branch should be acceptable.

Charging the battery and providing hotel power at the terminus of a non electrified branch is relatively easy.
A simple connection to the existing 11KV network should be affordable. 11KV connections and new 500KVA substations are installed all the time.
To get the power from this new 500 KVA substation into the stationery train, I would use a short length of conductor rail. Although the HSE are opposed to new conductor rail installations, the risks may be managed in two ways.
Firstly, place the conductor rail between the running rails, and energise it only when a train is parked over it.
Alternatively, use conventional conductor rail but energised at only 110 volts DC. Voltage drop wont be a huge concern due to the very short distances involved. 500KW at 110 volts is less than 5000 amps and entirely doable for short distances.
Allowing 50KW for hotel power, that leaves 450KW for battery charging, plenty to top up a modest sized battery that will be fully charged on the main line.

 

[Emblematic]

Ian Warmesly in modern railways said the leasing cost of the battery was similar to the cost of the rest of the train. Batteries need to get much much cheaper to do much more than provide short term acceleration.
To replace say a 100gal diesel tank needs around a 1600kw battery which using the figure quoted elsewhere on here of $200/kw would be $320000.
Needs replacement every 8 years or so not going to happen
K

Even worse by my calculations:
450l x 35.8 MJ/l = 16,000MJ, x0.28 = 4500kWh
(to a first approximation, all fossil fuels are around 10kWh/kg, solids and liquids 10kWh/l.)

 

[superkev]

Even worse by my calculations:
450l x 35.8 MJ/l = 16,000MJ, x0.28 = 4500kWh
(to a first approximation, all fossil fuels are around 10kWh/kg, solids and liquids 10kWh/l.)

From my days of commissioning large diesel generators real world fuel consumption was always around half a pint a kw/hr which equates to 1 gal gives around 16kw of output for an hour.
There's a lot of energy in that stuff.
K.

 

[Emblematic]

From my days of commissioning large diesel generators real world fuel consumption was always around half a pint a kw/hr which equates to 1 gal gives around 16kw of output for an hour.
There's a lot of energy in that stuff.
K.

Of course you're correct, I've compared apples to oranges here as the battery is storing energy in a much more useable form. You would get probably 90% of the battery power as useful work at the rail, the diesel is doing well if it gets above 25%.
The battery can also benefit from recovering kinetic and potential energy by regeneration, a diesel loses all that to heat. So that reduces the battery requirements still further.
--- old post above --- --- new post below ---

I feel that limited battery operation could be viable in many places, and despite the cost of the batteries could be worth pursuing.

Charging on an electrified main line is easy, and once on an a non electrified branch, energy could be conserved by lower speeds, and by reducing or even eliminating heating and air conditioning.
If the train is pre-heated or cooled, then the absence of heating or cooling for 20 minutes on the branch should be acceptable.

Charging the battery and providing hotel power at the terminus of a non electrified branch is relatively easy.
A simple connection to the existing 11KV network should be affordable. 11KV connections and new 500KVA substations are installed all the time.
To get the power from this new 500 KVA substation into the stationery train, I would use a short length of conductor rail. Although the HSE are opposed to new conductor rail installations, the risks may be managed in two ways.
Firstly, place the conductor rail between the running rails, and energise it only when a train is parked over it.
Alternatively, use conventional conductor rail but energised at only 110 volts DC. Voltage drop wont be a huge concern due to the very short distances involved. 500KW at 110 volts is less than 5000 amps and entirely doable for short distances.
Allowing 50KW for hotel power, that leaves 450KW for battery charging, plenty to top up a modest sized battery that will be fully charged on the main line.

I think that's over complicating things a lot. The majority of cases where batteries will be of use is where a branch comes off an electrified main, or where there is a gap in electrification. If the services are continuing from the electric lines then charging occurs on the move. If the branch is run separately, or there's a mix (maybe off-peak shuttles and main line peak services) then you arrange for charging to happen at the mainline end, using the normal OLE. This might need some additional infrastructure at the mainline end, so you can run an additional unit to allow time for charging. You would need your batteries to handle the out and back trip on the branch without recharging.
What you might want to do is provide a shore supply at the branch terminus, so an extended or overnight layover can be accommodated, whether planned or because of disruption. This only needs to be hotel power though, so a standard 60A 415V three-phase cable and socket would be plenty, and inexpensive to arrange anywhere.

 

[coppercapped]

Of course you're correct, I've compared apples to oranges here as the battery is storing energy in a much more useable form. You would get probably 90% of the battery power as useful work at the rail, the diesel is doing well if it gets above 25%.
The battery can also benefit from recovering kinetic and potential energy by regeneration, a diesel loses all that to heat. So that reduces the battery requirements still further.

Seen as a traction system, the battery losses are a bit higher than that - the battery will store about 90% of the input electrical energy (e.g., from the overhead or from regenerative braking) as chemical energy. Then in the reverse direction about 90% of the chemical energy is converted back to electrical energy which means that one can recover about 80% of the energy put into the battery as useful work.

Batteries are direct current devices and modern electric traction uses 3 phase variable frequency motors. The IGBT traction power conditioning kit to convert the electricity from one form to the other is about 80% to 85% efficient, so losses will occur here as well - whether the input power comes from the overhead or from a battery. This also occurs in two directions - when the variable frequency AC from the motors is converted to DC for the battery during braking or whether the DC from the battery is converted to variable frequency 3 phase AC for the motors to power the train. So yet more losses. This means that for every 100 units of power coming from the motors while braking, only about 60% of that becomes useful traction power while accelerating.

This is not to say that using batteries to recover braking energy is not feasible - it obviously is - but the technique does have strictly limited applications and at the moment the economics are questionable.

 

[Emblematic]

Seen as a traction system, the battery losses are a bit higher than that - the battery will store about 90% of the input electrical energy (e.g., from the overhead or from regenerative braking) as chemical energy. Then in the reverse direction about 90% of the chemical energy is converted back to electrical energy which means that one can recover about 80% of the energy put into the battery as useful work.

Batteries are direct current devices and modern electric traction uses 3 phase variable frequency motors. The IGBT traction power conditioning kit to convert the electricity from one form to the other is about 80% to 85% efficient, so losses will occur here as well - whether the input power comes from the overhead or from a battery. This also occurs in two directions - when the variable frequency AC from the motors is converted to DC for the battery during braking or whether the DC from the battery is converted to variable frequency 3 phase AC for the motors to power the train. So yet more losses. This means that for every 100 units of power coming from the motors while braking, only about 60% of that becomes useful traction power while accelerating.

This is not to say that using batteries to recover braking energy is not feasible - it obviously is - but the technique does have strictly limited applications and at the moment the economics are questionable.

I'd say your efficiencies are low-side estimates, the best Li-ion cells beat 90% cycle efficiency and 85% for the power conversion is woeful, I'd expect the high nineties.
That aside, what you would be best doing is adding a supercapacitor to the battery, to take the regenerated current and provide additional power during acceleration. That would reduce load and cycles on the battery as well as being inherently more efficient (albeit at cost.) Hybrid supercap-batteries, and supercapacitor-based regeneration systems for rail are already in commercial service.

 

[NSEFAN]

I'd say your efficiencies are low-side estimates, the best Li-ion cells beat 90% cycle efficiency and 85% for the power conversion is woeful, I'd expect the high nineties.
That aside, what you would be best doing is adding a supercapacitor to the battery, to take the regenerated current and provide additional power during acceleration. That would reduce load and cycles on the battery as well as being inherently more efficient (albeit at cost.) Hybrid supercap-batteries, and supercapacitor-based regeneration systems for rail are already in commercial service.

I was just thinking that supercaps may become a suitable option in the future for longer distance journeys. Improvements in capacity aren't happening very quickly, but charging times seem to be improving with caps being able to take much higher currents than previous generations of batteries. This would make them more suitable for absorbing regenerated power from braking, potentially improving the efficiency of BEMUs.

 

[coppercapped]

I'd say your efficiencies are low-side estimates, the best Li-ion cells beat 90% cycle efficiency and 85% for the power conversion is woeful, I'd expect the high nineties.
That aside, what you would be best doing is adding a supercapacitor to the battery, to take the regenerated current and provide additional power during acceleration. That would reduce load and cycles on the battery as well as being inherently more efficient (albeit at cost.) Hybrid supercap-batteries, and supercapacitor-based regeneration systems for rail are already in commercial service.

The cycle efficiency of all battery types depends on the duty cycle eccentricity, that is by how much the discharge current varies from a steady constant value. If the eccentricity is zero, that is the discharge current is constant, then cycle efficiencies of 90% for NiCads and around 93% for Li-Ion batteries can indeed be obtained.

However the further the duty cycle gets away from the ideal, then the cycle efficiency falls. At a degree of eccentricity where a NiMH has fallen to less than 70% cycle efficiency, Li-Ion and NiCads are still about 75%. Battery output currents will vary in a traction application, so I suggest the values I used are in fact reasonable real-life working values.

I attended a talk on Thursday evening arranged by the IET at Reading University where the topic was Crossrail in general and the design and maintenance of the trains in particular. The speakers were from Bombardier and Crossrail Ltd. It was clearly stated that the best state-of-the-art production IGBT power conditioning electronics reach an efficiency of 80% to 85% and these are being fitted to the Class 345. I have no reason to doubt the accuracies of their statements.

My original conclusion is still valid.

 

[Emblematic]

The cycle efficiency of all battery types depends on the duty cycle eccentricity, that is by how much the discharge current varies from a steady constant value. If the eccentricity is zero, that is the discharge current is constant, then cycle efficiencies of 90% for NiCads and around 93% for Li-Ion batteries can indeed be obtained.

However the further the duty cycle gets away from the ideal, then the cycle efficiency falls. At a degree of eccentricity where a NiMH has fallen to less than 70% cycle efficiency, Li-Ion and NiCads are still about 75%. Battery output currents will vary in a traction application, so I suggest the values I used are in fact reasonable real-life working values.

I attended a talk on Thursday evening arranged by the IET at Reading University where the topic was Crossrail in general and the design and maintenance of the trains in particular. The speakers were from Bombardier and Crossrail Ltd. It was clearly stated that the best state-of-the-art production IGBT power conditioning electronics reach an efficiency of 80% to 85% and these are being fitted to the Class 345. I have no reason to doubt the accuracies of their statements.

My original conclusion is still valid.

Bombardier state their IGBT traction packages are 95% efficient, improved from GTO which was around 90%. Power conditioning to return regenerated power to the grid is complex, and I can believe 80%, but that's AC to DC back to AC, and our BEMU avoids the last and most difficult step by regenerating to a stable DC load.

The duty cycle eccentricity is complex, and there will be some efficiency loss for real-world loads, that's unavoidable. Li-Ion is very much better than other technologies for eccentricity on the charge cycle, but I take your overall point. Adding a supercapacitor would address those issues, indeed the combination is used to make older battery technologies more competitive.

I don't think we'll see much happening with rail applications of batteries this decade, just on cost and availability of alternatives. I think supercapacitors will make more of an impression, most likely in diesel hybrids.

 

[coppercapped]

Bombardier state their IGBT traction packages are 95% efficient, improved from GTO which was around 90%. Power conditioning to return regenerated power to the grid is complex, and I can believe 80%, but that's AC to DC back to AC, and our BEMU avoids the last and most difficult step by regenerating to a stable DC load.

The duty cycle eccentricity is complex, and there will be some efficiency loss for real-world loads, that's unavoidable. Li-Ion is very much better than other technologies for eccentricity on the charge cycle, but I take your overall point. Adding a supercapacitor would address those issues, indeed the combination is used to make older battery technologies more competitive.

I don't think we'll see much happening with rail applications of batteries this decade, just on cost and availability of alternatives. I think supercapacitors will make more of an impression, most likely in diesel hybrids.

I think we are dangerously close to agreement! The Bombardier/Crossrail people were talking about the overall efficiency of the power conditioning electronic system, not just the IGBT inverter. This certainly does have efficiencies at the level you quoted, but the 'black box' (as it were) that was being referred to included the AC to DC rectifiers from the 25kV transformer to the DC link, the control circuits and the cooling pack. It may also have included the efficiency of the transformer as the two representatives then went on to talk about the thermal control of the tunnels which clearly has to cope with all the heat dumped from the train, whatever its source.

Now, to develop low-cost super-caps...I have one or two ideas, but first I have to make lunch!

 

[D365]

Pity, I would have liked to attend the Crossrail talk, alas Reading is too far to travel for one evening.

 

[HSTEd]

Still think that most branch lines would do better with just a low voltage conductor rail installation than anything fancy like battery packs.
At powers under a megawatt (which is reasonable for a two or three car train) the conductor rail really shines.

I wonder if anyone has ever done ~600Vac conductor rails..... It would eliminate the corrosion issue.

 

[Philip Phlopp]

Still think that most branch lines would do better with just a low voltage conductor rail installation than anything fancy like battery packs.
At powers under a megawatt (which is reasonable for a two or three car train) the conductor rail really shines.

I wonder if anyone has ever done ~600Vac conductor rails..... It would eliminate the corrosion issue.

You're trying to reinvent the wheel - what you want is an off-the-shelf tram-train design. The Vossloh Citylink unit would do what you want perfectly well, though you would need 750V DC OLE rather than third rail, which you won't get a safety case for (rightly so).

 

[HSTEd]

You're trying to reinvent the wheel - what you want is an off-the-shelf tram-train design. The Vossloh Citylink unit would do what you want perfectly well, though you would need 750V DC OLE rather than third rail, which you won't get a safety case for (rightly so).

And 750V DC OlE is going to require numerous closely spaced feeder stations, or enormous bus bars on the track side near ground level.......
You can feed a branch line from one point (so you need only two small substations for the line to allow for outages) with third rail, but without enormous bus bars [the size of a conductor rail essentially] you can't hope for that using OLE.

And considering I would chose DC third rail before DC overheads - I do have the advantage of a standard already in railway use.

EDIT:

If we are going for a non standard system to ensure it used OLE it would be best to go for 1500v DC considering its various benefits and the fact it is still counted as low voltage for regulatory purposes.

 

[Philip Phlopp]

And 750V DC OlE is going to require numerous closely spaced feeder stations, or enormous bus bars on the track side near ground level.......
You can feed a branch line from one point (so you need only two small substations for the line to allow for outages) with third rail, but without enormous bus bars [the size of a conductor rail essentially] you can't hope for that using OLE.

And considering I would chose DC third rail before DC overheads - I do have the advantage of a standard already in railway use.

It makes no difference whether the 750V DC supply is overhead or third rail in terms of the supply that's required. Supply is going to be determined by demand, not by the method of electrification used.

 

[hwl]

Still think that most branch lines would do better with just a low voltage conductor rail installation than anything fancy like battery packs.
At powers under a megawatt (which is reasonable for a two or three car train) the conductor rail really shines.

I wonder if anyone has ever done ~600Vac conductor rails..... It would eliminate the corrosion issue.

No because the AC conductivity of something of the cross section of steel conductor rail is really bad compared with DC (circa 1/10th). See the Skin effect https://en.wikipedia.org/wiki/Skin_effect

 

[HSTEd]

It makes no difference whether the 750V DC supply is overhead or third rail in terms of the supply that's required. Supply is going to be determined by demand, not by the method of electrification used.

The resistance of OLE conductors is high enough that volt drop will be limiting on a low traffic branch line
--- old post above --- --- new post below ---

No because the AC conductivity of something of the cross section of steel conductor rail is really bad compared with DC (circa 1/10th). See the Skin effect https://en.wikipedia.org/wiki/Skin_effect

An AC conductpr rail would likely be an inverted u channel for this reason. It wouldn't look like a DC rail does

 

[edwin_m]

An AC conductpr rail would likely be an inverted u channel for this reason. It wouldn't look like a DC rail does

It would have to be different, because as Mr Phlopp mentioned further back a new third rail scheme is most unlikely to be approved unless an extension of an existing one. This is because safer alternatives exist in the form of OLE or bottom contact third rail, so the risk to track workers is not as low as reasonably practicable.

Bottom contact is more tricky to do. The pickups would have to be outside the normal loading gauge and therefore would have to retract within the gauge when not in use.

The skin depth is about 10mm at 50Hz in copper or aluminium, so with AC any part of a third rail more than about 10mm from the surface would be wasted. It's probably worse with ferrous metals dependign on what alloy is used.

 

[broadgage]

Still think that most branch lines would do better with just a low voltage conductor rail installation than anything fancy like battery packs.
At powers under a megawatt (which is reasonable for a two or three car train) the conductor rail really shines.

I wonder if anyone has ever done ~600Vac conductor rails..... It would eliminate the corrosion issue.

From a purely technical point of view, an AC conductor rail at say 600 volts is entirely doable, though it might have to be made of aluminium.
However the HSE are strongly opposed to any significant expansion of systems that use a lethal voltage exposed at ankle height.
Apart from very minor extensions of existing routes, we wont see any more conductor rail installations.
A possible exception would be short lengths for charging stabled battery trains as I earlier suggested, these could use either a relatively safe 110 volts, or could be interlocked and only rendered live when a train is parked over the live rail.

 

[Emblematic]

From a purely technical point of view, an AC conductor rail at say 600 volts is entirely doable, though it might have to be made of aluminium.
However the HSE are strongly opposed to any significant expansion of systems that use a lethal voltage exposed at ankle height.
Apart from very minor extensions of existing routes, we wont see any more conductor rail installations.
A possible exception would be short lengths for charging stabled battery trains as I earlier suggested, these could use either a relatively safe 110 volts, or could be interlocked and only rendered live when a train is parked over the live rail.

Your difficulty here is not so much the regulator but the law itself. Both The Health and Safety at Work etc. Act 1974 and The Electricity at Work Regulations 1989 require that employees and the general public are not exposed to danger, with the qualification so far as is reasonably practicable. So this is not an absolute requirement, but any risks must be justifiable and mitigated. For an existing third rail system, the justification is that replacing both trains and infrastructure is not reasonable. Mitigation in the form of barriers, signage and safe systems of work suffice.
For a new system, this cannot be argued, as neither train nor infrastructure exist. It is foreseeable that someone may fall and contact the live rail, and safer systems, such as OHLE and insulated shore supplies, are available.
110V is still too high to be deemed a safe voltage, as well as being far too low to deliver sufficient power for rapid charging. Even 50V, the commonly accepted safe limit for an exposed conductor, is established on the basis of someone reacting and removing themselves from contact in under 3 seconds. Someone falling onto a rail may be unable to do that.

 

[HSTEd]

When was the last time someone was actually electrocuted by contact with a conductor rail who was not immediately hit by a train or similar anyway?

Additionally with these relatively low voltage systems the track can obtain significant voltages relative to Earth - so you can obtain shocks from the running rail if you are not careful.

The HSE legislation essentially reduces an already very low risk at the cost of impeding electrification of the railway - which increases injuries from pollution and from alternative forms of travel.

 

[Bald Rick]

When was the last time someone was actually electrocuted by contact with a conductor rail who was not immediately hit by a train or similar anyway?

About three weeks ago.

 

[HSTEd]

About three weeks ago.

Really? Huh - didn't hear anything about that.

How many fatalities are there a year as a result of conductor rail electrocutions, then we have to adjust per track mile. And how many fatalities are there a year from electrocutions from 25kV supplies, again adjusted per track mile?

Thanks to major problems in the electrification programme and the inherently high costs of 25kV schemes we are going to be stuck with a lot of diesel operation for a very long time.

 

[TheKnightWho]

Thanks to major problems in the electrification programme and the inherently high costs of 25kV schemes we are going to be stuck with a lot of diesel operation for a very long time.

Remember that there are multiple things that will improve this:

1) There have been the standard teething problems, which are being ironed out as we speak.

2) Issues such as unmarked signalling cables will become moot when ERTMS is rolled out wholescale in the next 30 years, which will be far quicker than electrification roll out.

3) There is increasing pressure to electrify due to environmental regulations anyway, which means we'll likely see a larger workforce specialising in this.

4) Bimodes provide good stop-gaps, especially when they can be converted to fully electric traction as and when necessary.

5) Existing mainlines are far more difficult to electrify than branches or smaller rural lines. The number of electrified route-miles possible with equivalent man-hours is higher with these smaller lines for numerous reasons.

 

[The Ham]

5) Existing mainlines are far more difficult to electrify than branches or smaller rural lines. The number of electrified route-miles possible with equivalent man-hours is higher with these smaller lines for numerous reasons.

A few I can think of are:

- Fewer tracks (i.e. single or double tracks vs double or more tracks)

- Fewer junctions/crossovers

- Less intensively used making busification during works easier and viable for longer (i.e. longer time to do work over night at weekends).

- Less disruptive for fewer passengers (i.e. closing the line between Reading and Didcot causes more problems and impacts on more people then between Basingstoke and Salisbury)

 

[edwin_m]

How many fatalities are there a year as a result of conductor rail electrocutions, then we have to adjust per track mile. And how many fatalities are there a year from electrocutions from 25kV supplies, again adjusted per track mile?

Don't know the answer to that but it's probably buried in the RSSB website somewhere, or one of its logon-only adjuncts.

However I'd also point out that it's much easier to come into contact with a third rail by "accident", such as trackside workers or people falling off platforms (even if the third rail is on the far side, the shoes on both sides of the train are live). Electrocution from overhead line is proportionately much more likely to result from attempting something illegal such as climbing on a train or dangling a rope over a bridge. This may not make any quantitative difference because the risk assessment framework makes no distinction in the value of different lives, but I think there is a moral argument here.