The Anonymous Widower

Electroflex Battery EMU Plan To End Southern Diesel Operation

The title of this post is the same as this article on Railway Gazette.

This is the introductory paragraph.

An electric multiple-unit is to be equipped with batteries for ’first of a kind’ testing which could lead to the end of diesel traction on the Ashford – Hastings and Oxted – Uckfield routes.

The train to be converted is a Class 377/3 train.

  • These are three car trains.
  • There are twenty-nine trains.
  • They have 176 seats.
  • They were built in 2001/2002.

The article gives some details of the conversion.

  • The trains would have a range of 60 km.
  • They could be charged in eight minutes.
  • There would be an emergency mode to keep systems running for an hour. Sounds very much like a Class 345 train.
  • Between twenty-five and thirty trains would need to be converted to replace all the diesel trains. Twenty-nine?

The article also says that the General Election has delayed the sign-off.

In August 2018, I wrote Battery Trains On The Uckfield Branch. I was proposing Aventras as they are obviously a more efficient train. The article details a lot of the mathematics involved.

Some Observations

These are my observations on various topics.

Uckfield Branch

The section without electrification on the Uckfield Branch is forty kilometres long.

A train with a full battery can go from one end to the other.

As the train takes eleven minutes to turn round at Uckfield, there is enough time to recharge the batteries.

Would the route be run by three Class 377/3 trains, running as a nine car unit?

Trains would be charged en route between London Bridge and Hurst Green stations and if required at Uckfield.

Would charging at Uckfield be a length of third-rail electrification in the long platform?

It sounds that there is a feasible solution for Uckfield.

Capacity On The Uckfield Branch

Consider

  • Three Class 377/3 trains running together have a capacity of 528 seats.
  • Five Class 171 trains running together have a capacity of 535 seats.

I think that the capacity would be enough.

Number Of Trains Needed For The Uckfield Branch

The round trip on this route takes three hours, so to run an hourly service will need three nine-car trains or nine three-car trains in total. Two trains per hour (tph) will need a total of eighteen trains.

The Marshlink Line

The Marshlink Line is also forty kilometres long and both ends are already electrified.

Services on the route terminate at Eastbourne in the West and Ashford International in the East.

As the route between Ore and Eastbourne stations is fully electrified, charging at the Western end of the route, will be en route and trains will arrive at Ore with a full battery.

The platform at Ashford International is electrified using third rail and there is adequate time in the turnround to charge the battery, so that it leaves Ashford full.

Train Length On The Marshlink Line

There are some shorter platforms across the Romney Marsh and these may restrict the length of train that can be used. But as they are generally two-car trains at present, even a three-car train is an over fifty percent increase in capacity.

I suspect Southern would probably want to run six-car trains between Ashford and Eastbourne.

Number Of Trains Needed for the Marshlink Line

The round trip on the route takes three hours, so to run an hourly service will need three trains. If they were six cars, then six three-car trains would be needed.

Total Number Of Trains Needed For Both Routes

If nine-car half-hourly trains are run on the Uckfield Branch and hourly six-car trains on the Marshlink, this will need twenty-four trains. As there are twenty-nine trains available for conversion, this would appear to be very convenient.

The article stated that between twenty-five and thirty would need to be converted. So there is probably enough trains to allow for a spare and a couple in maintenance.

What Size Battery Will Be Needed On Each Train?

I will now attempt to estimate the size of battery needed for the train.

The Kinetic Energy Of A Full Train

This is important for two reasons.

  • When a train accelerates from rest, the battery must have enough stored energy to bring that train to the operating speed.
  • When a battery train brakes, the energy of the train, recovered by regenerative braking, must be capable of being stored in the battery.

Note that regenerative braking loses perhaps ten to fifteen percent of the energy at each station stop.

This is the calculation for the kinetic energy.

  • The weight of the empty train is 133.1 tonnes
  • The train has around two hundred passengers, who each weigh 90 kilograms with baggage, bikes and buggies.
  • This adds a surprising 18 tonnes.
  • The total train weight 151.1 tonnes.

The kinetic energy of the train can be calculated for various speeds using Omni’s Kinetic Energy Calculator.

  • 30 mph – 3.8 kWh
  • 40 mph – 6.7 kWh
  • 50 mph – 10.5 kWh
  • 60 mph – 15.1 kWh
  • 70 mph – 20.6 kWh
  • 100 mph – 42.0 kWh

I have included the last figure, as that is the cruising speed of the train.

When I first calculated train energy figures, I thought these figures were too low, when you consider that according to Ovo Energy, the average electricity consumption of a UK dwelling is about 10 kWh.

Regenerative Braking Losses

If we assume that at each stop fifteen percent of the energy of the train is not recovered, then for a train travelling at 60 mph, then 0.15 * 15.1 or 2.3 kWh will be lost at each stop.

The Uckfield Branch has seven intermediate stops so will lose 15.9 kWh under braking and this will need to be in the battery at the start of the electrification-free run.

The Marshlink Line has six intermediate stops, so will lose 13.6 kWh.

Energy Needed To Maintain Speed And Run The Train

A train needs power for the following purposes.

  • Overcome friction and aerodynamic loses, whilst travelling at the operating speed. When you are riding a bicycle, you need more energy to accelerate, but then you need to keep pedalling to maintain speed.
  • To power the various electrical systems on the train, like air-conditioning, doors, lights and toilets.
  • To power the control systems of the train.

It is generally accepted, that a simple way of expressing the power needed by the train is between 2 and 5 kWh per vehicle-mile.

So power needed by a three-car Class 377 train over the twenty-five miles of both routes will be.

  • 2 kWh per vehicle-mile – 150 kWh
  • 3 kWh per vehicle-mile – 225 kWh
  • 4 kWh per vehicle-mile – 300 kWh
  • 5 kWh per vehicle-mile – 375 kWh

This energy will be taken from the battery.

An Estimate Of Energy Used And Battery Size Required

This calculation is for the Uckfield Branch and I am assuming the following.

  • A cruising speed of 60 mph.
  • Regenerative braking is 85 % efficient.
  • 3 kWh per vehicle mile is used in the cruise.

Energy use will be as follows.

  • Initial acceleration to cruising speed – 15.1 kWh
  • Regeneration losses – 7 * 0.15 * 15.1 -15.9 kWh
  • Energy needed to run train – 225 kWh

This gives a total of 256 kWh

There will also need to be a reserve to cater for.

  • Trains stopping because of a problem like cows on the line.
  • Recovery of the train to the nearest station.

The article talked about an emergency mode of an hour.

I wonder if a battery of between three hundred and four hundred kWh would be sufficient.

Note that Vivarail find space for 424 kWh in the two-car train, I wrote about in Battery Class 230 Train Demonstration At Bo’ness And Kinneil Railway.

I have various Excel spreadsheets that can model various scenarios.

I’m sure Bombardier have much better information, than I do and can do better than this crude estimate.

Conclusion

This could be the first of many conversions of existing Bombardier Electrostars and Siemens Desiros to battery-electric operation.

January 22, 2020 - Posted by | Transport | , , , , ,

3 Comments »

  1. i can see the need for a new delay announcement.

    ‘This train is being delayed due to charging batteries’

    On a more serious note if it can charge whilst in 3rd rail traction mode, even if at reduced rate, that ought to make them suitable to run the Gatwick to Reading services.

    Comment by Nicholas Lewis | January 22, 2020 | Reply

    • They will do most of their charging in 3rd rail traction mode between London ridge and Oxted and Ore and Eastbourne.
      Bombardier ran a successful test using overhead between Manningtree and Harwich a few years back.
      There are lots of routes, where the trains could be used. Gatwick and Reading is a good one. I can see GWR converting some of their 387 trains to battery-electric Gatwick Expresses for the route. They’re already converting some for the Heathrow Express.

      Comment by AnonW | January 22, 2020 | Reply

  2. […] Porterbrook and Southern are proposing to convert a number of Class 377/3 trains to battery operation for the Uckfield Branch and the Marshlink Line, as I wrote about in Electroflex Battery EMU Plan To End Southern Diesel Operation. […]

    Pingback by Raw Material For Southern’s Battery Trains « The Anonymous Widower | January 27, 2020 | Reply


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