The Anonymous Widower

Bombardier Bi-Mode Aventra To Feature Battery Power

The title of this post is the same as this article in Rail Magazine.

A few points from the article.

• Development has already started.
• Battery power could be used for Last-Mile applications.
• The bi-mode would have a maximum speed of 125 mph under both electric and diesel power.
• The trains will be built at Derby.
• Bombardier’s spokesman said that the ambience will be better, than other bi-modes.
• Export of trains is a possibility.

Bombardier’s spokesman also said, that they have offered the train to three new franchises. East Midlands, West Coast Partnership and CrossCountry.

In some ways, I am not surprised about what is said in this article.

Another article on Christian Wolmar’s web site, is entitled Bombardier’s Survival Was The Right Kind Of Politics.

This is said.

Bombardier is not resting on its laurels. Interestingly, the company has been watching the problems over electrification and the fact that more of Hitachi’s new trains will now be bi-mode because the wires have not been put up in time. McKeon has a team looking at whether Bombardier will go into the bi-mode market: ‘The Hitachi bi-mode trains can only go 110 mph when using diesel. Based on Aventra designs, we could build one that went 125 mph. This would help Network Rail as it would not have to electrify everywhere.’ He cites East Midlands, CrossCountry and Wales as potential users of this technology.

The article was published in February 2017 and mentions, 125 mph on diesel and two of the companies in the recent article.

The Design Of The Trains

My thoughts are as follows.

The Starting Point

I’m pretty certain that if you wanmt to create a 125 mph bi-mode train, you start with a 125 mph electric train, if you want a high degree of commonality between the two trains.

Bombardier haven’t yet built any of their Aventras for West Midland Trains, but as they will use the West Coast Main Line extensively, will they be 125 mph trains and not 110 mph trains, as is said in Wikipedia?

Aventras And Battery Power

I will believe until Bombardier say I’m wrong, that Crossrail’s Class 345 trains, which are Aventras, use batteries for the following purposes.

• To handle regenerative braking.
• To limp the train out of the tunnel or to the next station or safe exit point, if there should be a catastrophic power failure.
• To lessen the amount of electricity fed to the trains in the tunnels.
• To allow features like remote wake-up, which need a train to have some form of power at all times.
• To move trains in sidings and depots without having live electrification.
• To run passenger features, when the power fails.

Effectively, the Class 345 trains have electricity as a main power source and batteries for energy storage and a secondary or emergency power source.

I talked to one of their staff, who was training drivers on Crossrail’s Aventras. The conversation went something like this.

• Me: “What happens, when the Russians hack the power supply?”
• Driver-Trainer: “We switch the train to emergency power!”
• Me: “You mean batteries?”
• Driver-Trainer: (Pause, then something like) “Might be!”

Can anybody think of another way to have emergency power on the train?

Electric Traction, Regenerative Braking and Batteries

Bi-mode trains and Alstom’s hydrogen-powered Coradia iLint are electrically powered at all times.

This means that under electric, diesel or hydrogen power, the traction motors can generate electricity to brake the train.

On an electric train, this electricity is returned through the overhead wire or third rail to power other nearby trains. This electricity could also be stored in an onboard battery, just as it is in a hybrid or battery-electric vehicle.

Driving A Bi-Mode Train With Batteries

The bi-mode Aventra could have electricity from one of four power sources.

• 25 KVAC overhead electrification.
• 750 VDC third-rail electrification.
• An onboard electricity generator powered by diesel fuel or hydrogen.
• Batteries

So will the driver need to keep switching power sources?

I am a Control Engineer by training and optimising the best power to use is a typical problem for someone with my training and experience.

The train’s computer would take all the information about the route, timetable, signal settings, battery charge level, train loading, weather and other factors and drive the train automatically, with the driver monitoring everything thoroughly.

Aircraft have been flown in a similar fashion for decades.

I look in detail, at the mathematics of a bi-mode Aventra with batteries in Mathematics Of A Bi-Mode Aventra With Batteries.

I came to the following conclusions.

I am rapidly coming to the conclusion, that a 125 mph bi-mode train is a practical proposition.

• It would need a controllable hydrogen or diesel power-pack, that could deliver up to 200 kW
• Only one power-pack would be needed for a five-car train.
• For a five-car train a battery capacity of 300 kWh would probably be sufficent.

From my past professional experience, I know that a computer model can be built, that would show the best onboard generator and battery sizes, and possibly a better operating strategy, for both individual routes and train operating companies.

Obviously, Bombardier have better data and more sophisticated calculations than I do.

Note, that everything I proposed, is well within the scope of modern engineering, so other companies like CAF and Stadler, who are actively involved in rail application of battery technology, could join the party.

This picture is a visualisation of a Stadler Class 755 train, which they are building for Greater Anglia.

Note the smaller third car, which contains the diesel engine of this hybrid train. Is there room for batteries as well?

I can’t find any information on the web about the power train of the Class 755 train, but this article in the Railway Gazette, describes another Stadler bi-mode Flirt, that Stadler are building for Italy.

This is said.

The units will be rated at 2 600 kW with a maximum speed of 160 km/h when operating from 3 kV DC electrification, and 700 kW with a maximum speed of 140 km/h when powered by the two Stage IIIB compliant Deutz TCD 16.0 V8 diesel engines.

There is provision to add up to two more cars if required to meet an increase in ridership. Two more engines could be added, or the diesel module removed if only electric operation is needed.

Note.

• The Deutz diesel engines are rated at 520 kW.
• As 700 kW is the power of the train, I suspect each engine generator creates 350 kW of power.
• 160 km/h would be ideal for the Great Eastern Main Line
• 140 km/h would be more than adequate for roaming around East Anglia

I suspect that if batteries were used on this train, that the engines would be smaller.

We will see in May 2019, when the trains enter service.

Diesel Or Hydrogen Generator

Electricity generation using a diesel generator and electricity generator from a hydrogen fuel cell, each have their own advantages.

• Diesel fuel has a higher energy density than hydrogen
• Diesel engines create a lot of noise and vibration and emit carbon dioxide, noxious gases and particulates.
• Hydrogen fuel cells can be silent and only emit water and steam.
• Ballard who are a Canadian company and a leading manufacturer of hydrogen fuel-cells,  manufacture one for use in rail applications which has an output of 100 kW, that weighs 385 Kg.
• MTU make the diesel engine for a Class 800 train, which has an output of over 600 kW, that weighs 5000 Kg.
• Hydrogen storage is probably heavier and more complicated than diesel storage.
• Both generators can be fitted into convenient rectangular power packs.

I would envisage that in the future,  hydrogen electricity generators will get more efficient, lighter in weight and smaller in size for a given power output.

I don’t think it is unreasonable to believe, that within a reasonable number of years, hydrogen generators and their hydrogen storage tank, will be comparable in weight and size to current diesel generators and fuel tanks.

Accelerating A Bi-Mode Train With Batteries

The major use of electricity on a 125 mph train, will be in accelerating the train up to line speed. The energy needed will be.

• Proportional to the mass of the train. This is why your car accelerates better, when it’s just you in the car  and you don’t have your overweight mother-in-law in the back.
• Proportional to the square of the velocity.

I have calculated that a five-car bi-mode Aventra, carrying 430 passengers and travelling at 125 mph, will have a kinetic energy of 91.9 kWh.

Obviously, using electricity from electrification is the best way to accelerate a train.

• Electricity from electrification is probably cheaper and more convenient, than that from an onboard electricity generator.
• If diesel is not used to power the train, there is no noise and vibration from an onboard diesel generator.
• A route with a lot of running on onboard fuel, means more fuel has to be carried.

Using electricity stored in batteries on the train, is also a good way to accelerate a train, but the batteries must have enough charge.

The onboard electricity generator will be used, when there is no electrification and the power stored in the batteries is approaching a low level.

|When Bombardier’s spokesman says, that the ambience will be good, control of the train’s power sources has a lot to do with it.

Could he have been hinting at hydrogen, as hydrogen fuel cells do not have high noise and vibration levels?

Cruising A Bi-Mode Train With Batteries

Newton’s First Law states.

Every body continues in its state of rest or uniform motion in a straight line, unless impressed forces act on it.

If you have a train on a railway track moving at a constant speed, the following forces are acting to slow the train.

• Aerodynamic forces, particularly on the front of the train.
• Rolling friction of the steel wheel on a steel rail.
• Bends and gradients in the track.
• Speed limits and signals.

So the driver and his control system will have to feed in power to maintain the vrequired spreed.

I have sat on the platform at Stratford, whilst an Aventra has gone past at speed. I wrote about it in Class 345 Trains Really Are Quiet!

This was my conclusion.

Bombardier have applied world class aviation aerodynamics to these trains. Particularly in the areas of body shape, door design, car-to-car interfaces, bogies and pantographs.

Remember too, that low noise means less wasted energy and greater energy efficiency.

In addition steel wheel on steel rails is a very efficient way of moving heavy weights. Bombardier have a reputation for good running gear.

Once a train has reached its cruising speed, appropriate amounts of power will be fed to the train to maintain speed.

But compared to the power needed to accelerate the train, they could be quite small.

For small amounts of power away from electrification, the control system will use battery power if it is available and can be used.

The onboard electricity generator would only be switched in, when larger amounts of power are needed or the battery power is low.

Slowing A Bi-Mode Train With Batteries

The regenerative braking will always be used, with the energy being stored in the batteries, if there is free capacity.

Imagine the following.

• A bi-mode making a stop at Leicester station on the Midland Main Line.
• It is doing 100 mph before the stop on the main line.
• It will be doing 100 mph after the stop on the main line.

The energy of the train after Leicester will be roughly the same as before, unless the mass of the train has changed, by perhaps a large number of passengers leaving or joining the train.

Let’s assume that the energy at 100 mph in the train is X kWh

• When the train brakes for Leicester this energy will be transferred to the train’s batteries, if there is capacity.
• On accelerating the train, it will need to acquire X kWh. It couldn’t get all of this from the batteries, as for various reasons the overall efficiency of this sort of system is about seventy to ninety percent.
• The onboard electricity generator will have to supply a proportion of the energy to get the train back up to 100 mph.

But in a diesel train it will have to supply all the energy to get back to 100 mph.

Where Would I Put The Batteries?

Aventras seem to have a lot of powered-bogies, so to keep cable runs short to minimise losses and maximise the efficiency of the regenerative braking, I would put a battery in each car of the train.

This would also distribute the weight evenly.

Where Would I Put The Electricity Generators?

Diesel engines always seem to be noisy, when they are installed under the floor of a train. I’ve travelled a lot in Bombardier’s Turbostars and although they are better than the previous generation, they are still not perfect.

I’ve also travelled in the cab of a Class 43 locomotive, with a 2,250 hp diesel engine close behind me. It was very well insulated and not very noisy.

As I said earlier, the most intensive use of the onboard generators will come in accelerating a train to operating speed, where no electrification or battery power is available. There is only so much you can do with insulation!

Stadler, who are building the Class 755 train for Greater Anglia, have opted to put a short diesel generator car in the middle of the train.

This was an earlier train, where Stadler used the technique.

There are reports in Wikipedia, that the ride wasn’t good, but I’m sure Stadler has cracked it for their new 100 mph bi-mode trains.

Creating a bi-mode by adding an extra motor car into the middle of an electric train could be a serious way to go.

• The dynamics are probably better understood now
• A powerful diesel engine could be fitted.
• Batteries could be added.
• Insulating passengers and staff from the noise and vibration would surely be easier.
• There could be a passage through the car, to allow passengers and staff to circulate.

In an ideal world, a four-car electric train could be changed into a five-car bi-mode train, by adding the motor car and updating the train software.

In Mathematics Of A Bi-Mode Aventra With Batteries, I came to the conclusion, that if the batteries are used in conjunction with the power-pack, that a single power-pack of about 200 kW could be sufficient to power the train. This would be smaller and lighter in weight, which would probably mean it could be tucked away under the floor and well-insulated to keep noise and vibration from passengers and staff.

In this article in Global Rail News from 2011, which is entitled Bombardier’s AVENTRA – A new era in train performance, gives some details of the Aventra’s electrical systems. This is said.

AVENTRA can run on both 25kV AC and 750V DC power – the high-efficiency transformers being another area where a heavier component was chosen because, in the long term, it’s cheaper to run. Pairs of cars will run off a common power bus with a converter on one car powering both. The other car can be fitted with power storage devices such as super-capacitors or Lithium-ion batteries if required.

This was published six years ago, so I suspect Bombardier have refined the concept.

So could it be that Bombardier have designed a secondary power car, that can be fitted with a battery and a diesel engine of appropriate size?

• Using a diesel engine with batteries means that a smaller engine can be used.
• The diesel engine could also be replaced with a 200 kW hydrogen fuel cell.

I won’t speculate, but Bombardier have a very serious idea. And it’s all down to the mathematics.

What Would Be The Length Of A 125 Mph Bi-Mode Aventra?

Long distance Aventras, like those for Greater Anglia and West Midlands Trains, seem to be five and ten car trains.

This would fit well with the offerngs from other companies, so I suspect five- and ten-cars will be the standard lengths.

Could There Be A Bi-Mode Aventra for Commuter Routes?

The London Overground has ordered a fleet of four-car Class 710 trains.

The Gospel Oak to Barking Line is being extended to a new Barking Riverside station.

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 London.

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

The new extension is about a mile, so this would need 20 kWh each way.

This could easily be done with a battery, but supposing a small diesel engine was also fitted under the floor. Would anybody notice the same 138 kW Cummins ISBe diesel engine that is used in a New Routemaster hybrid bus?

I doubt it.

It is a revealing to calculate the kinetic energy of a fully-loaded Class 710 train. I estimate that it under 50 kWh, if it was travelling at 90 mph, which would rarely be achieved on the Gospel Oak to Barking Line.

Could Bombardier Be Serious About Exporting Bi-Mode Aventras?

In my opinion, the Aventra is a good train an it seems to sell well in its electric form to train operating companies in the UK.

But would it sell well in overseas markets like the United States and Canada, India and Australia?

They obviously know better than I do, so we should take their statements at face value.

The Prospective Customers

The Rail Magazine article mentions three prospective customers.

I deal with them and other possiblilities in Routes For Bombardier’s 125 Mph Bi-Mode Aventra.

This was my conclusion.

If Bombardier build a 125 mph bi-mode Aventra with batteries, there is a large market.

It looks like the company has done a lot of research.

Conclusion

Bombardier are designing a serious train.

 

March 31, 2018 - Posted by AnonW | Energy Storage, Transport/Travel | Aventra, Bi-Mode Train, Bombardier, CrossCountry Trains, East Midlands Franchise, High Speed Bi-Mode Aventra, High Speed Two, Lithium-Ion Battery, West Coast Main Line, West Coast Partnership