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Hitachi , Brush and Porterbrook have created the world's most powerful hybrid loco – and it works!
St Thomas Didymus is the Informed Sources patron saint of innovative technology. So on 3 May I set off for Quorn station on the Great Central Railway, to inspect Porterbrook Leasing's Hitachi/Brush hybrid IC125, in a sceptical, but open, frame of mind.
On the way to Loughborough (don't mention the ‘M' word) I ran a quick spread sheet to get a feel for the numbers involved. I made the kinetic energy of a 70 tonne Class 43 at 125 mile/h around 20 kilowatt hours (kWh). The ability of the hybrid system to recover and store this energy when braking would be my test case.
What Hitachi and Brush have done is to install the Lithium-ion battery, supplied by Hitachi Vehicle Energy Ltd, in a Mk3 Trailer Guard Second ( TGS ) which is coupled to the power car. The Class 43 has been fitted with new Hitachi alternating current traction motors rated at 300kW each.
Power to the traction motors is provided by inverters mounted underneath the TGS . The inverters can be supplied from the battery, the existing alternator on the power car's Valenta diesel engine, or both.
Hybrid technology stands or falls on the battery. That in the Class 43 is assembled from modules, each with a capacity of 1kWh and weighing 20kg.
With 48 modules the battery has a total capacity of 48kWh and weighs 960kg, just under a tonne. Specific capacity is thus exactly 50kWh/tonne – the current bench mark for Lithium-ion.
That said, Hitachi are keen to point out that battery technology is developing rapidly with significant reductions in weight and increases in storage capacity, driven by the demands of the automotive industry. But I didn't get an answer when I asked what the hybrid's battery cost.
So the 960kg battery is more than capable of storing the energy regenerated when braking the Class 43 electrically from maximum speed to standstill. What about reusing the recovered energy? The peak power output is an impressive 1 MegaWatt (MW) or 1,350hp for mechanical engineers.
For comparison, the Valenta in the power car has a rating of 1.68MW (2,250hp). However the off the shelf traction motors have derated the hybrid to 1.2MWfor traction at the wheels.
With these ratings and a fully charged battery, the power car could accelerate away at around 80% of the traction motors' full power for around 170 seconds. A couple of stops from 125 mile/h would then recharge the battery.
And to see a two power car plus three Mk 3 formation zip away silently like an EMU and then return at speed got everyone's attention. As English Electric knew – to sell something new build a demonstrator.
Why Hayabusa?
You may wonder why the hydrid demonstrator is called the Hayabusa – Japanese for Peregrine Falcon? Various bits of exciting kit share the name, from the Nakajima Ki 43 fighter plane to an unfeasibly fast motor bike and a space satellite. But why a 30 year old hybrid power car? Well, Ian Walmsley, the Porterbrook engineer originally responsible for the coordinating the project knows his history. Back in the days when I was sweating over hot diesel engines the equivalent of today's IEP contract was the British Rail requirement for 512 Class 47 locomotives. Three prototypes were built to the specification. Brush named theirs Falcon, the Brush factory at Loughborough being called Falcon Works. So Hayabusa is a gracious tribute to the two industrial partners in the Class 43 hybrid from the owner of the vehicles. But it gets better. To finish off the hybrid, Ian produced a replica of the original Falcon crest on D0280 plus a ‘Hayabusa' nameplate in the same lettering. I think the word is style. Also reproduced here is the calligraphy for ‘Hayabusa'. |
So the Hayabusa works. After further development testing, power car ad its TGS will be evaluated in Network Rail's New Maintenance Train (NMT) for at least six months. This will be a more demanding application than IC125 passenger service.
While all IC125 power cars experience binary driving, the NMT has to stay on the main line for obvious reasons. Since it can't be looped it has to follow what is in front, meaning regular braking and acceleration.
There is a limit to the rate at which the hybrid's battery can be charged. But if it can't accept all the braking energy, the surplus is dissipated in resistors, as with rheostatic braking. Trial running to date indicates that the battery can store most of the energy generated in the equivalent of Notch 2 braking.
Another issue to be explored is the relationship between battery life and capacity. Experience with hydrid cars suggests that battery life is maximised when the battery is kept charged to between 20% and 60% of its capacity.
Clearly, using that 1 MW for long periods could shorten battery life. And while Hitachi is coy on the cost of the tonne of battery it won't be cheap and you want it to last. But even staying within the optimum-life charging zone the hybrid power car will be able to brake its own weight and enable the NMT to arrive and depart at terminal stations without the engines running.
Of course, Hahabusa is not a perpetual motion machine. According to Hitachi 's project engineer, the internal losses of the battery mean that charging and discharging are each around 90% efficient, so only 80% of the regenerated energy is available for traction.
Initial estimates are that fuel saving with the hybrid system in operation will be of the order of 20%, similar to an electric g]train regenerating into the overhead line. But in a production hybrid the overall savings would be even greater.
First, the hybrid control system can blend in the battery power under acceleration so that instead of the diesel engine working at full power the engine management system keeps it at the point on the power/speed for optimum fuel consumption.
Second, with battery boost, the diesel engine can be made smaller which means that the cooler group can be smaller and lighter and the train can carry less fuel. The benefits should more than outweigh the extra mass of the battery.
It seems to me that the Porterbrook, Hitachi , Brush team have caught the EuroTrain manufacturers napping. I'm still pondering the application to the self powered (diesel) IEP, but in Diesel Multiple Units the virtuous spiral seems attractive.
Take a Class 22x vehicle. Take out the 750 hp 19 litre Cummins engine and fit the 14 litre engine as used in Electrostar. In addition to the smaller, lighter engine raft and fuel tanks you fit 250kg of batter. You then have a train with the economy of an Electrostar and the acceleration of a Voyager.
Overall, I arrived at Quorn a sceptic and went away, if not a believer, certainly convinced that hybrid technology has potential for diesel trains. Hitachi has three hybrid DMUs entering service in Japan which should give us some hard numbers to work on alongside the flying Falcon.
