The Anonymous Widower

Tri-Mode Stadler Flirts

I would expect that these trains are very similar to the bi-mode Stadler Flirt DEMUs, but that the power-pack would also contain a battery.

As an Electrical and Control Engineer, I wouldn’t be surprised that the power-pack, which accepts up to four Deutz diesel engines, can replace one or two of these with battery modules. This could make conversion between the two types of Flirt, just a matter of swapping a diesel module for a battery one or vice-versa.

Note that the three-car Class 755 trains for Greater Anglia have two diesel engines and the four-car trains have four engines.

This document on the KeolisAmey web site details their plans for the new Wales and Borders Franchise.

It gives a few extra details about the Tri-Mode Stadler Flirts

The KeolisAmey document gives extra a few extra details.

• The tri-mode trains are instended for Rhymney/Coryton <> Penarth/Barry Island/Bridgend via the Vale of Glamorgan Line.
• Main power source 25 KVAC overhead line with battery and diesel engine.
• 100% electric operation on transferred metro network.

I assume the following.

• That 100% electric operation includes battery operation.
• Batteries will certainly be used in the mile-long Caerphilly tunnel.
• Batteries will be charged when running on electrified lines or by capturing regenerative breaking energy whilst descending to Cardiff.
• The diesel engine will be used for primary power on the Vale of Glamorgan Line, which is without electrification and nearly twenty miles long?

There will be a lot of commonality between the two types of Flirts and I suspect driver and other staff training for the two variant will be the same.

How Big Will The Batteries Need To Be?

Consider a three-car Tri-Mode Stadler Flirt

• I reckon, that the weight of the train will be around 130 tonnes.
• Rhymney has an altitude of 287 metres.
• I will assume 150 passengers at 80 Kg. each, which gives a weight of 12 tonnes.

This means that the train has a potential energy of 111 kWh at Rhymney station.

On the way down the hill from Rhymney the regenerative braking will convert this potential energy into electricity, which will be stored in the battery.

But also consider.

• There will be losses in energy conversion in the regenerative braking process.
• Energy will be used running the train’s systems.
• Energy will be used stopping and starting the train at each station.
• Energy will be used bringing the train through some sections without electrification.
• Energy will be used keeping the crew and passengers comfortable.
• Energy can be burned off using braking resistors on the roof of the train.

When you consider that the battery on a London New Routemaster bus, has a capacity of 75 kWh, I think it is highly likely, that Stadler can design a battery module to fit one of the two spare engine positions in the power-pack.

Now, consider a four-car Tri-Mode Stadler Flirt

• I reckon, that the weight of the train will be around 150 tonnes.
• Rhymney has an altitude of 287 metres.
• I will assume 200 passengers at 80 Kg. each, which gives a weight of 16 tonnes.

This means that the train has a potential energy of 130 kWh at Rhymney station.

Looking at the weight of Bombardier’s 50 kWh batteries, I suspect that it would be possible to design a battery module with the following characeristics.

• 100 kWh capacity
• A weight less than that of the Deutz engine, which is around 1.3 tonnes.
• Plug compatibility with the diesel engine.

Doing this calculation with real data, is the sort of mathematics that I relished doing in my twenties.

How Far Would A Full 100 kWh Battery Take A Three-Car Flirt?

In an article in the October 2017 Edition of Modern Railways, which is entitled Celling England By The Pound, Ian Walmsley says this in relation to trains running on the Uckfield Branch, which probably has a terrain not much different to the lines to the South and West of Cardiff.

A modern EMU needs between 3 and 5 kWh per vehicle mile for this sort of service.

This would mean that a 100 kWh battery would take a three-car train between six and ten miles. It might even take the train from Cardiff to Barry Island or Penarth and back..

Conclusion

It looks a very interesting concept.

• Most of the energy is provided by the electrification, which would power the train up the hill.
• Coming down the hill, the batteries would be recharged using the regenerative braking.
• Battery power would used to take the train on routes without electrification to the West and South of Cardiff.
• When the battery power was low, the diesel engines would cut in.

Energy efficiency would be high.

June 8, 2018 - Posted by AnonW | Transport/Travel | Diesel/Electric/Battery Hybrid Trains, Stadler, Stadler Flirt, Tri-Mode Stadler Flirt