The Anonymous Widower

Comparing An Aventra IPEMU With An Electrostar IPEMU

The Concept Of An IPEMU

This article in Rail Engineer, which is entitled An Exciting New Aventra, quotes Jon Shaw of Bombardier on onboard energy storage.

As part of these discussions, another need was identified. Aventra will be an electric train, but how would it serve stations set off the electrified network? Would a diesel version be needed as well?

So plans were made for an Aventra that could run away from the wires, using batteries or other forms of energy storage. “We call it an independently powered EMU, but it’s effectively an EMU that you could put the pantograph down and it will run on the energy storage to a point say 50 miles away. There it can recharge by putting the pantograph back up briefly in a terminus before it comes back.

I believe that once the concept of onboard energy storage is accepted, that Bombarduier’s engineers have found other ways to use it to the benefit of passengers, operators and Network Rail.

  • Regenerative braking energy can be stored on the train and used for a restart or other purposes, rather than just burning it off or returning it to the grid, through complicated transformers.
  • Onboard energy can be used to move a train to the next station, if the overhead or third rail power should fail.
  • Depots and stabling sidings don’t need to be fully electrified.
  • Onboard energy storage enables train features like remote wake up, which I discussed in Do Bombardier Aventras Have Remote Wake-Up?.
  • Trains can safely pass over short sections without electrification. Third rail trains can do this with contact shoes at both ends of the train.

Trains with onboard energy probably need to have intelligent current collection, so that pantographs and contact shoes can be intelligently deployed and retracted.

Take the simple example of a passing loop on a single track electrified branch line, which is needed for two trains per hour. The passing loop could be built without electrification and without altering the existing electrification, with just a set of points and appropriate signalling at each end.

  • Trains using the existing line and electrification would travel as now.
  • Electric trains using the loop would lower the pantograph a safe distance before the loop, go along the passing loop using onboard energy  and then once on the main line, raise the pantograph.

This technique could probably be used to simplify building of new stations or adding new platforms to existing ones.

Network Rail are going to love trains with onboard energy storage.

Electrostars and Aventras

Bombadier have shown that onboard energy storage is possible in an Electrostar and there is various articles on the web saying it can be fitted to the new Aventra.

As both Aventras and Electrostars seem to come in four- and five-car versions, I’ll do the calculations for both lengths of trains.

I’ll use these assumptions.

  • Electrostar cars weigh 40 tonnes and Aventra cars 32.5 tonnes.
  • Each car has 50 passengers weighing an average of 80 kilos.

The various types of IPEMU are shown in the next four sections.

Four-car Electrostar

This would have the following characteristics.

  • A mass of 160+16 = 176 tonnes.
  • A formation of DMOS+MOS+PTSO+DMOS
  • Braking from 100 kph would release 18.9 KWH.
  • Braking from 200 kph would release 75.5 KWH.
  • Onboard energy storage could be placed in probably the MSO or PTSO cars.

 

This could be created from a train like a Class 377, Class 378, Class 379 or Class 387 train.

We know that in the demonstration using a Class 379 at Manningtree, that that train could do 18.2 km. on the Mayflower Line, just by the use of battery power.

Five-car Electrostar

This would have the following characteristics.

  • A mass of 200+20 = 220 tonnes.
  • A formation of DMOS+MOS+PTSO+MOS+DMOS
  • Braking from 100 kph would release 23.6 KWH.
  • Braking from 200 kph would release 94.3 KWH.
  • Onboard energy storage could be placed in probably the MSO or PTSO cars.

Four-car Aventra

This would have the following characteristics.

  • A mass of 130+16 = 146 tonnes.
  • A formation of DMOS+MOS+PMSO+DMOS
  • Braking from 100 kph would release 15.6 KWH.
  • Braking from 200 kph would release 62.6 KWH.
  • Bombardier have stated that the MOS car is ready for onboard energy storage.

 

This could be created from a train like a Class 710 train.

Five-car Aventra

This would have the following characteristics.

  • A mass of 162.5+20 = 182.5 tonnes.
  • A formation of DMOS+MOS+PMSO+MSO+DMOS.
  • Braking from 100 kph would release 19.6 KWH.
  • Braking from 200 kph would release 78.2 KWH.

The five-car Aventra could have two sets of batteries or onboard energy storage.

Note this about all Aventras.

 

Bombardier have stated that the MSO car is ready for onboard energy storage, if the customer desires.

The MSO and PMSO cars can be considered a fixed pair of cars handling the electrical power for the train.

Can a PMSO and two MSOs be considered a trio on the five-car Aventra?

Aventras have a lot of motored cars, with lots of traction motor/generators.

The trains can have a remote wake-up feature, that would probably need some form of onboard energy. After all, your smart-phone doesn’t work if the battery is not fitted.

Can I draw any conclusions?

  • The Aventra with its pair of electrifical cars has been designed to have onbosrd energy storage.
  • The energy that needs to be handled is less with the lighter weight Aventra.
  • Stopping from 200 kph releases a lot more energy. Four times more than from 100 kph in fact.
  • The energy storage needed for 100 kph stop and restart operation, are within the battery size range of the battery in an electric car like a Nissan Leaf.
  • There could be advantages concerning reliability and battery size with the five-car Aventra with its possible two sets of energy storage.

Obviously, the weight of the battery would need to be factored into the calculations, but if say it was a tonne, it would only increase energy figures by less than one percent.

The Definitive IPEMU

I said that two two sets of energy storage in the five-car Aventra could give advantages.

  • Each set could be smaller.
  • Two sets will be more reliable than one.
  • The weight of the storage is shared between two MSO cars.
  • The two MSO cars in the five-car Aventra IPEMU would probably be identical.

In the extract from the Rail Engineer article that started this post Jon Shaw of Bombardier is quoted as saying this.

it will run on the energy storage to a point say 50 miles away.

Two sets of onboard storage would obviously help this, with each set needed to keep the train going for 25 miles. This is not the onerous task it could appear. Especially in an Aventra.

  • The train is designed to minimise aerodynamic losses.
  • The train is designed to minimise the very small rolling losses of steel wheel on steel rail.
  • All passenger systems like wi-fi, lighting and air-conditioning are designed to use minimum electricity.
  • Driving aids on the train will help the driver to drive in an energy efficient way.
  • When the brakes are applied, the energy is recovered and stored in the onboard energy storage.
  • The train will stop at a station using much less energy than a conventional train.

But the most important thing, is that the train has been designed from the wheels up as an efficient package.

Conclusions

I believe the following.

  • Five cars will be one of the most common lengths for Aventras. Abellio have already ordered eighty-nine.
  • The range on energy storage of a five-car Aventra with two sets of energy storage will be at least fifty miles.
  • Aventras with an IPEMU-capability will be used to reduce electrification work.
  • Aventras with an IPEMU-capability will be used to develop new electrified routes.
  • As the IPEMU technology develops, Bombardier will develop a solution, so that later Electostars will be able to store their own braking energy and travel a limited distance away from electrification.
  • All train manufacturers will look seriously at energy storage on trains.

If I was asked what would be the ultimate range of a train using this technology, I would say, that trains with an IPEMU-capability will within a few years be running the whole route between Waterloo and Exeter.

I

 

September 6, 2016 - Posted by | Travel | , , ,

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