Analysis
Manufacturers are devoting more time and energy into a future for hybrid trains, but challenges centred on costs and efficiency will need to be resolved, says PHILIP HAIGH
The options for powering tomorrow’s trains.
NOT since British Rail phased out steam traction has rolling stock been subjected to the level of change now taking place.
For BR, diesel replaced steam across much of Britain. There were pockets that switched to electric trains - chiefly in South East England, across the Pennines via Woodhead, and around Glasgow. The West and East Coast Main Lines would receive electric trains over the following few decades.
Now train operators are faced with a UK government that wants to see straight diesel trains gone by 2040, and no more electrification.
What fills the gap? Hybrids, in their various forms.
Best known are Hitachi’s bi-mode, electro-diesel multiple units now in service with Great Western Railway, and which start working for Virgin Trains East Coast from December.
They are the result of a procurement exercise that the Department for Transport started a decade ago. The resulting trains, labelled IEP, are electric multiple units (EMUs) fitted with a number of diesel engines to allow them to run beyond the end of overhead wires. (Some IEP trains are straight electric multiple units.)
Government claims bi-mode trains bring the benefits of electrification without the costs of erecting wires. This is important as rising costs have tarnished electrification, leading the Government to ditch a plan to wire the Midland Main Line as well as cutting back other projects in northern England - including that to wire Leeds-Manchester via Diggle.
However, critics claim that IEP on diesel cannot perform as well as in electric mode. Government says that London-Sheffield on diesel will be one minute slower than on electric, but Network Rail told RAIL that the difference would be more like five minutes.
Nevertheless, the coming of Hitachi’s bi-mode trains has sparked wider interest in the benefits of drawing traction power from multiple energy sources. Network Rail and Bombardier tested an Electrostar EMU that was equipped with batteries several years ago. This concept might apply to a service that runs on an electrified main line before running onto a short, unwired branch. The batteries would provide sufficient power for the trip to the branch terminus and back, then be recharged once again under the wires.
Battery electric multiple units (BEMUs) now sit on the cusp of passenger service. Bombardier expects to have Talent 3 EMUs running with batteries very soon, following a German government award of 3.6 million euros in 2016. It plans to use its Primove batteries, which weigh just over a tonne for a 90kWh unit. These have already proved successful in hybrid buses and trams, although both have lower energy needs than trains.
Converting a Talent 3 EMU involves adding four batteries, which weigh 7.5 tonnes and contain 300kWh. Bombardier reckons the resulting trains will be able to run at 160kph (100mph) under overhead wires and 120kph (75mph) away from wires - or ‘catenary free operation’ (CFO) as the company calls it. Range will initially be around 40km, but Bombardier says that will become 100km.
It estimates that a three-car Talent 3 BEMU will cost 6-7 million euros, compared with 4.5 million euros for an equivalent diesel train. It predicts energy costs at 0.65euro/ km, against diesel’s of around one euro per kilometre. Maintenance costs will be lower without the cost of servicing and overhauling diesel engines.
Talent 3 EMU has also provided the basis for Bombardier to estimate that initial costs comprise 40% whole life costs, followed by 30% for energy and 30% for maintenance. Energy costs can be cut by using less fuel. This is made possible by equipping trains with dynamic brakes that convert and then store in batteries a train’s kinetic energy (speed). This increases the life of brake pads because they are used less, which cuts maintenance costs.
Further savings come from using batteries overnight rather than leaving trains stabled with their pantographs raised, which generates losses from main transformers. Bombardier is also taking advantage of tighter noise regulations to redesign traction motors to run more quietly and more efficiently.
The exact cost savings from these improvements depends on the cost of energy, but for Talent 3 Bombardier estimates that improved dynamic brakes come with a pay back period of 12-17 months.
The changes increase the purchase price of the train. But, measured over its whole life, the savings outweigh the higher initial price.
Train operating companies (TOCs) will need to carefully consider the costs of their fleets and prospective fleets. This is because under increasingly popular ‘train service agreements’ for rolling stock, the manufacturer takes responsibility for maintenance and will benefit from savings there.
TOCs will also need to insist that their traction electricity is metered rather than simply calculated by Network Rail on a mileage basis, otherwise it will be NR that benefits from lower train fuel consumption.
Higher capital and lower maintenance and energy costs are a feature of Alstom’s move into hydrogen hybrid trains. Here, Alstom UK Business Development and Marketing Director Mike Muldoon reckons it takes less than a decade for the higher price of hydrogen trains to be countered by lower operating costs.
Not that Muldoon has any hydrogen trains in operation yet. The first should be running in Lower Saxony (Germany) this June. They will be iLint multiple units, and Alstom has been testing the concept and prototypes for several years.
Britain might have to wait until 2021 before hydrogen trains arrive. Muldoon’s ambition is to have one running on test with fleet service fairly rapidly afterwards, depending on Alstom’s success in taking its train through approval processes. His target market is Britain’s diesel lines and those fleets of regional diesel multiple units (DMUs) that governments wants gone by 2040.
“I want to see multiple deployments - not a side show, not a freak show,” he tells RAIL.
He will need a compelling product and story if he’s to tempt move to rail producing less carbon.
Over at Siemens, there’s reticence about revealing what the company is up to. Spokesman Emma Whitaker says: “We are doing some interesting work in this area, but we are not in a position yet to talk in detail.”
Siemens is working with fuel cell company Ballard, power management company Actia, and Toshiba to develop a hybrid XEMU (dubbed Mireo) which combines fuel cell and battery - similar to Alstom’s iLint. Ballard is developing a 200kW fuel cell for Mireo multiple units, funded in part with a German government grant of 12 million euros (£10.36m).
Siemens reckons the most efficient way of delivering power to a traction motor is catenary (80%), batteries (65%), then hydrogen/ diesel (25%). Batteries currently deliver a range around 80km. Trains will be more expensive than DMUs but have lower operating costs, which means whole life costs might be 25% lower, according to Siemens. Using similar techniques to those of Bombardier and lighter carbodies, Siemens reckons to save 25% on energy consumption