The Anonymous Widower

Batteries On Class 777 Trains

In this article on Railway Gazette, which is entitled Merseyrail Class 777 arrives in Liverpool, there is this sentence.

There is space under one vehicle to house a battery weighing up to 5 tonnes within the axleload limit.

This matter-of-fact sentence, draws me to the conclusion, that these trains have been designed from the start to allow future battery operation.

Batteries are not an add-on squeezed into a design with great difficulty.

Battery Capacity

Energy densities of 60 Wh/Kg or 135 Wh/litre are claimed by Swiss battery manufacturer; Leclanche.

This means that a five tonne battery would hold 300 kWh.

Note that Vivarail find space for 424 kWh in the two-car Class 230 train, I wrote about in Battery Class 230 Train Demonstration At Bo’ness And Kinneil Railway, so it would appear that Stadler aren’t being over ambitious.

Kinetic Energy Of A Full Class 777 Train

The weight of a full Class 777 train is calculated as follows.

  • Basic empty weight – 99 tonnes
  • Battery weight – 5 tonnes
  • 484 passengers at 80 Kg – 38.72 tonnes

Which gives a total weight of 143.72 tonnes.

Intriguingly, the weight of a current Class 507 train is 104.5 tonnes, which is 500 Kg more than an empty Class 777 train with a battery!

If these weights are correct, I suspect Stadler have used some very clever lightweight design techniques.

For various speeds, using Omni’s Kinetic Energy Calculator, this weight gives.

  • 30 mph – 3.6 kWh
  • 40 mph – 6.4 kWh
  • 50 mph – 10.0 kWh
  • 60 mph – 14.4 kWh
  • 70 mph – 19.5 kWh
  • 75 mph – 22.4 kWh

Note.

  1. The average speed between Bidston and Wrexham General stations on the Borderlands Line is under 30 mph
  2. The operating speed on the Wirral Line is 70 mph
  3. The operating speed on the Northern Line is 60 mph
  4. The maximum speed of the trains is 75 mph.

Every time I do these calculations, I’m surprised at how low the kinetic energy of a train seems to be.

How Small Is A Small Battery?

One battery doesn’t seem enough, for a train designed with all the ingenuity of a product with quality and precision, that is designed to out-perform all other trains.

This is another paragraph from the Railway Gazette article.

According to Merseytravel, ‘we want to be able to prove the concept that we could run beyond the third rail’. By storing recovered braking energy, the batteries would help to reduce power demand and the resulting greenhouse gas emissions. All of the Class 777s will be fitted with small batteries to allow independent movement around workshop and maintenance facilities.

I am not quite sure what this means.

It would seem strange to have two independent battery systems in one train.

I think it is more likely, that the smaller battery can be considered the primary battery of the train.

  • After all in the depot, it looks after the train’s power requirement.
  • Does it also handle all the regenerative braking energy?
  • Is it used as a secondary power supply, if say the power is low from the electrification?
  • Could it be used to move the train to the next station for passenger evacuation in the event of a power failure?

I wonder if the power system is a bit like the average battery-powered device like a lap-top computer, smart phone or hybrid car.

  • The electrification and the regenerative braking charges the battery.
  • The battery provides the traction and hotel power for the train.

When the five tonne battery is fitted, does the train’s control system move power between the two batteries to drive the train in the most efficient manner?

I’ll return to factors that define the size of the small battery.

The small battery must be big enough for these purposes.

  • Handling regenerative braking at the operating speed.
  • Recovering a full train to the next station.
  • Keeping a train’s systems running, during power supply problems.
  • Moving a train around a depot

As the lines leading to depots are electrified, the train can probably enter a depot with a battery fairly well-charged.

As the new Class 777 trains have a maximum operating speed of 75 mph, I would suspect that the small battery must be able to handle the regenerative braking from 75 mph, which my calculations show is 22.4 kWh with a full train. Let’s call it 30 kWh to have a reserve.

Using Leclanche’s figures, a 30 kWh battery would weigh 500 Kg and have a volume of just under a quarter of a cubic metre (0.222 cubic metre to be exact!)

I suspect the operation of the small battery through a station would be something like this.

  • As the train runs from the previous station, the power from the battery will be used by the train, to make sure that there is enough spare capacity in the battery to accommodate the predicted amount of energy generated by regenerative braking.
  • Under braking, the regenerative braking energy will be stored in the battery.
  • Not all of the kinetic energy of the train will be regenerated, as the process is typically around eighty percent efficient.
  • Whilst in the station, the train’s hotel services like air-conditioning, lights and doors, will be run by either the electrification if available or the battery.
  • When the train accelerates away, the train’s computer will use the optimal energy source.

The process will repeat, with the battery constantly being charged under braking and discharged under acceleration.

Lithium-ion batteries don’t like this cycling, so I wouldn’t be surprised to see dome other battery or even supercapacitors.

A Trip Between Liverpool and Wrexham Central in A Class 777 Train With A Battery

The train will arrive at Bidston station with 300 kWh in the battery, that has been charged on the loop line under the city.

I will assume that the train is cruising at 50 mph between the twelve stops along the twenty-seven and a half miles to Wrexham Central station.

At each of the twelve stops, the train will use regenerative braking, but it will lose perhaps twenty percent of the kinetic energy. This will be two kWh per stop or 24 kWh in total.

I usually assume that energy usage for hotel functions on the train are calculated using a figure of around three kWh per vehicle mile.

This gives an energy usage of 330 kWh.

But the Class 777 trains have been designed to be very electrically efficient and the train is equivalent in length to a three-car Class 507 train.

So perhaps a the calculation should assume three vehicles not four.

Various usage figures give.

  • 3 kWh per vehicle-mile – 247.5 kWh
  • 2.5 kWh per vehicle-mile – 206 kWh
  • 2 kWh per vehicle-mile – 165 kWh
  • 1.5 kWh per vehicle-mile – 123.8 kWh
  • 1 kWh per vehicle-mile – 82.5 kWh

Given that station losses between Bidston and Wrexham Central could be around 24 kWh, it looks like the following could be possible.

  1. With a consumption of 3 kWh per vehicle-mile, a Class 777 train could handle the route, but would need a charging station at Wrexham Central.
  2. If energy consumption on the train could be cut to 1.5 kWh per vehicle-mile, then a round trip would be possible.

It should also be noted that trains seem to do a very quick stop at Wrexham Central station of just a couple of minutes.

So if charging were to be introduced, there would need to be a longer stop of perhaps eight to ten minutes.

But the mathematics are telling me the following.

  • The Class 777 train has been designed to weigh the same empty as a current Class 507 train, despite carrying a five tonne battery.
  • If power consumption can be kept low, a Class 777 train with a battery can perform a round trip from Liverpool to Wrexham Central, without charging except on the electrified section of line between Liverpool and Bidston.
  • Extra stops would probably be possible, as each would consume about 2 kWh

I feel that these trains have been designed around Liverpool to Wrexham Central.

Conclusion

Wrexham Central here we come!

Other routes are possible.

  • Hunts Cross and Manchester Oxford Road – 27 miles
  • Ormskirk and Preston – 15 miles
  • Headbolt Lane and Skelmersdale – 6 miles
  • Ellesmere Port and Helsby – 5 miles
  • Kirkby and Wigan Wallgate – 12 miles

Chargers will not be needed at the far terminals.

February 4, 2020 Posted by | Transport | , , , , , , , , | 18 Comments

Bidston Station And The Borderlands Line

Whilst in Liverpool, I took the Wirral Line to Bidston station, where the Borderlands Line to Wrexham Central station connects to the Merseyrail third-rail network.

This Google Map shows the location of the station.

Bidston Station

Bidston Station

Some things surprised me at Bidston station.

  • The station had the feeling of a rural junction in deepest Lincolnshire or Devon, rather than one a few miles from the centre of one of the UK’s biggest cities.
  • When the train arrived from Wrexham it was much busier than I expected.
  • The junction between the two lines was laid out in lots of space.
  • The state of the station, which considering its location was very good with a large waiting room.

I could also understand, why various bodies say that the Borderlans Line could be run by trains with an IPEMU capability or to put it simply – on-board energy storage or batteries. Wikipedia says this under Proposed Battery Trains for the line.

A trial of a converted Electrostar train using energy from overhead wires and batteries when on non-electrified sections of track was undertaken in January and February 2015 on the Mayflower line. The train can travel up to 60 miles on energy stored in the batteries also recharging the batteries via the overhead-wires when on electrified track, at stations and via brake regeneration. A month later in March 2015, the introduction of battery powered trains was proposed for the Borderlands line by Network Rail.

The document suggested that consideration had been given to electrification and to running services further into Birkenhead ceasing termination at Bidston for greater connectivity. However these options were expressed as offering low value for money. They proposed that using battery powered rolling stock precluding full electrification of the line, providing a cheaper method of increasing connectivity into the electrified Birkenhead and Liverpool sections of the Wirral line. From the document:

“In the longer term, potential deployment of rolling stock with the ability to operate on battery power for part of their journey may provide the ability in an affordable manner to improve the service offering between the Wrexham – Bidston route and Liverpool.
Trains could operate on batteries on unelectrified sections of the track and take power from an electric pick-up on the electrified sections. Adoption of these types of trains would preclude full line electrification.

My thoughts on this are as follows.

New Infrastructure

Obviously, I only looked at Bidston station, but it would appear that except for perhaps signalling and electrificastion changes, that the station could accept trains with an IPEMU-capability tomorrow.

For instance, there would need to be electrification for some distance down the Borderlands Line, so that a train arriving from that direction with low batteries, wou;dn’t get stalled, if another train had failed in the station.

I don’t know the answer, but as Merseyrail is an island of third-rail electrification, Merseyrail are probably capable of calling on competent third-rail experts, either in-house or from a regional contractor.

New Stations

Plans exist for new stations on the line.

Whether the line is fully-electrified or served by trains with an IPEMU-capability is irrelevant, with stations probably being designed to be suitable for either.

One suggestion is for a new station at Woodchurch close to Junction 3 of the M53.

This Google Map shows the motorway junction.

Junction 3 Of The M53

Junction 3 Of The M53

Note how, the Motorway and the Borderlands Line go either side of the North Cheshire Trading Estate.

There is also plans for a station at Deeside Industrial Park, which looks like it could have a railway line already.

Another possibility would be to improve Shotton station, so that it was a genuine interchange between the Borderlands Line and the North Wales Coast Line.

This Google Map shows the area.

Shotton Stations

Shotton Stations

Note Hawarden Bridge station on the other side of the River Dee, which is also on the Borderlands Line.

Capacity In Liverpool On The Wirral Line

The single-track loop of the Wirral Line under Liverpool, that serves James Street, Moorfields, Lime Street, Central and James Street agin, is soon to be relaid with new track to go along with its recently-refurbished station, that can handle two three-car Class 508 trains, running as a six-car unit.

With modern signalling, it would probably have a limit of upwards of twenty trains per hour (tph), giving a train under the Mersey in both directions at least every three minutes.

Currently, the service on the Wirral Line includes.

  • 4 tph to Chester
  • 2 tph to Ellesmere Port
  • 4 tph to New Brighton
  • 4 tph to West Kirby

Capacity seems to be adjusted to that needed by running a mixture of three and six-car trains.

But there is undoubtedly spare capacity in Liverpool’s loop of stations.

And if more capacity is needed between Birkenhead and Liverpool, then running extra trains to new destinations on the West side of the Mersey is a simple way to increase it.

Wrexham would be an ideal destination, especially if at least two tph were provided on the route.

Freight Issues

There would appear to be a few freight trains, but none of a high frequency.

Wrexham to Liverpool Timings

Currently Wrexham Central to Bidston takes a couple of minutes over the hour. West Kirby trains, also take 34 minutes to go from Bidston round the loop under Liverpool

So this would probably mean that if you got the timings right, you could get from Wrexham Central to Liverpool Lime Street in about eighty minutes.

As Chester to Liverpool Central takes forty-one minutes, eighty minutes is rather slow between Wrexham and Liverpool.

So could electric trains do the route in under the hour?

If the line was fully electrified, judging on the Chester timings, that this is certainly the case.

Trains Needed Between Liverpool And Wrexham

As the round trip to and from Liverpool would probably take two hours, it would appear that two trains would be needed to provide an hourly service, with four trains nbeeded for 2 tph.

As there is a short platform at Wrexham Central station, trains would probably have a maximum length of three-cars.

IPEMU Range

Wrexham Central to Bidston stations, is about thirty miles, so based on Bombardier’s rumoured figures of sixty kilometres a charge, going out and back to Wrexham might be a bit on the long side.

So I wouldn’t be surprised to see the single-track line between Wrexham General and Wrexham Central stations given third-rail electrification, to make sure that trains with an IPEMU-capability can work the line.

If extra stations are added to the Borderlands Line and Shotton station is rebuilt as an interchange with North Wales, I could see that the extra cost of third-rail electrification to Shotton would have a high value.

As Shotton is only about twenty miles from Wrexham, it might be possible to bridge the gap between Shotton and Wrexham using onboard power.

Costs

This is said about electrification costs of the Borderlands Line in Wikipedia.

Network Rail’s conclusion was that full line electrification is only feasible if it could be delivered for less than £100,000 for each km per single track. The twin track line would be £200,000 per line km, giving a total figure of £8.7 million, which is far below the estimate of full line electrification of £66 million. Another consideration is whether a new pattern of service delivers significant net benefits.

The new Stadler trains being purchased for MerseyRail are costing £460 million for 52 trains, according to this article in the Railway Gazette, which works out at about nine million pounds a train.

So if two trains are needed to provide an hourly service to Wrexham, the cost of the extra trains will be significant.

The Railway Gazette article also says this about the trains.

At 99 tonnes, the EMUs will be lighter than the current 105 tonne trains, and energy consumption is expected to be 20% lower, including regenerative braking; options for energy storage are to be studied.

The 750 V DC third-rail EMUs will be capable of conversion to dual-voltage operation for use on 25 kV 50 Hz lines with a view to serving Skelmersdale, Warrington and Wrexham in the longer term.

So I suspect, it’s put up the money and take your choice.

Conclusion

It would certainly be possible to electrify the Borderlands Line either using third-rail or overhead and I’m certain that any prudent transport authority would go for an optimal solution, especially as extending to Wrexhan will need extra trains.

I could see an holistic solution being applied to the Boasderlands Line.

  • At least two tph to Wrexham Central station.
  • New stations at Beechwood, Deeside Industrial Park and Woodchurch.
  • A rebuilt Shotton station.
  • Partial third-rail electrification.
  • Use of onboard energy storage to power trains on lines without electrification.

As it would be a project, where benefits were to both Merseyside and North Wales, funding would probably have several options.

 

 

 

 

 

December 17, 2016 Posted by | Uncategorized | , , , | 4 Comments