Hitachi Rail's bold experiment with battery-electric bi-mode units

In this article:

• Retrofit Testing: Hitachi Rail tested a Class 802 train retrofitted with a powerful battery, replacing one diesel engine, aiming to explore sustainable inter-city travel.
• Trial Results: The trials exceeded expectations, achieving up to 50% fuel cost savings, 75mph on eco mode, and efficient station handling.
• Prospects: Hitachi Rail plans further development, addressing costs, infrastructure, and scaling retrofitting for broader adoption.

In May, Hitachi Rail began testing a five-carriage TransPennine Express Class 802 bi-mode unit that had been retrofitted with a battery, after one of its diesel engines had been taken out.

It was a bold plan, designed to bring innovation to a train operating company which has struggled to operate - let alone innovate - over the past few years, as well as to a train manufacturing company which has been growing its presence since it entered the UK market in 2009, enhancing its reputation across the globe as an innovator in battery-train operations.

As well as those two companies, the Class 802’s owner Angel Trains has been part of the project, ensuring that it has cross-industry support.

Meanwhile, Sunderland-based Turntide Technologies has supplied the battery, making sure that any future rollout has its roots in the UK.

The battery fitted on the ‘802’ during these trials was capable of powering up to 75 houses for a day, and of generating a peak power of more than 700kW.

For passengers, and for the wider industry, these trials represented a test of how well a battery-electric inter-city train can enter, alight and leave non-electrified stations, as well as its ability to conserve energy.

But there is a much broader question that these trials could help answer. Can battery-electric inter-city trains with the potential to travel at up to 110kph (75mph) be a possible answer for inter-city rail travel in the future?

Given the investment (£17 million so far by Hitachi Rail and Turntide Technologies), as well as the time and energy that both Hitachi and Turntide have invested in the project since joining forces in 2020, the belief that it would work was clearly there.

The project began with the battery’s development at Turntide’s plant in Sunderland. The company had been developing the battery for two years before assembling it and sending it to Japan, where it was then tested by Hitachi’s battery train experts - many of whom had been instrumental in developing the world’s first passenger battery train (the DENCHA, which Hitachi launched in 2016).

One of those experts, and one of the most instrumental people involved in this project, is Koji Agatsuma, who is an Executive Director at Hitachi Rail, as well as Chief Technical Officer for Rail Vehicles.

“Conceptualisation for this has been done since the early design stages in 2015, although it is slightly different,” he tells RAIL.

It’s different because technology continues to move forwards. Creating the ideal conditions for this project to work is hard enough, without the technology keeping ahead of the design.

“The technology keeps moving forward, so we carefully need to check the weight, dimensions and final performance is OK,” he adds.

Degradation was one of the issues which required time for the team to understand it better, as well as to ensure compliance.

Agatsuma explains: “It’s all about ensuring compliance meets regulation. This could not be done from the beginning, because ten years before we didn’t know what the regulation would be in the UK.”

So, rather like a plant that needs the perfect conditions to grow, this project has needed the timing and the technology to align to get to where it is right now.

Part of those perfect conditions included securing a trainset for the trial. That opportunity arose when two Class 802s were involved in a shunting incident in March 2022.

To many, this would not be great news. But for Hitachi Rail and TPE, it was fortunate timing. So, while one of them re-entered traffic, TPE and Angel Trains allowed 802207 to be fitted with a battery testbed.

From there, the team fitted the six-metre-long and 2.2-metre-wide battery to the train and started the tests - gingerly at first - at Hitachi Rail’s Newton Aycliffe factory in County Durham. That involved low-speed testing and understanding the dynamics of the battery.

“The most important thing is not just fitting the battery, but its performance,” says Agatsuma.

“That’s why we have extensive testing. As well as functional testing, we check performance in many different environments.”

This is important. As Agatsuma points out, this project has a case to make so that when the government or potential customers look at greener options, one of their key focuses will be on faster performance.

Can journey times be improved? Can the battery withstand the strains that this performance will put on it?

It will also matter when it comes to train design, especially when it comes to retrofitting, altering or adjusting a train’s layout. This will add to costs that not many will want to bear.

Agatsuma explains that once low-speed and functional testing was completed, the most important next step was examining the battery’s performance against the original simulations - including, crucially, how it degrades. By all accounts, these tests went well.

The tests also had to guarantee that the battery has a sustainable lifecycle, as Agatsuma explains: “We need to provide a warranty that this battery can last for five, eight or ten years, so degradation and understanding it and matching it in reality against our simulations is very important.”

In the past, operators and rolling stock companies have been reluctant to choose battery-electric, with concerns over degradation, range and lifecycle weighing heavily on the minds of decision-makers.

There is also the lack of charging points past main terminus stations to consider.

Siemens Mobility recently unveiled its new fast-charging battery-mode train, which it believes could replace ageing diesel fleets.

It has had plenty of interest and potential orders, although its suburban rail option has not swayed one of those operators, Northern, as it looks to update its fleet.

However, charging the battery is one of the areas which can be most damaging to it. Agatsuma says this is because of the weight of the train: “The train itself weighs nearly 60 tonnes, which is a lot more than the two tonnes of a car.”

Given the weight of the train, the battery is also suitably powerful: “When charging, the power required is roughly the same as ten Tesla Model Y cars. That’s because our battery is 700kWh, so it is roughly the same battery power as 50 electric cars.”

At nearly six tonnes, the battery is also heavy.

For Hitachi Rail, it is fundamental to the project’s success that it can demonstrate that any damage to the battery by its scale can be minimised, if it is going to win the confidence of rolling stock companies and operators.

This is why it has poured plenty of resources during this battery’s development into understanding its charge state.

Given its size, it’s likely to be impracticable for widespread use, although Hitachi Rail is bullish about its potential in this area, seeking to reduce its weight and size (if possible) while still holding its power and efficiency.

Meanwhile, developing the technology is essential to determining the art of the possible and to establish a base on which to develop further.

But Hitachi Rail is not pinning its hopes on just this project, when it comes to battery power.

It recently announced a further partnership with German consultancy DB ESG, Innovate UK and the University of Birmingham’s Centre for Railway Research and Education (BCRRE). This partnership will feature the development of a new smaller battery which could potentially sit under the lower floors of suburban and commuter trains. That could potentially mean they could be suitable for level boarding.

As well as possibly opening its solution to the market, Hitachi Rail believes that this solution will bring down maintenance costs and simplify the process of retrofitting it to trains.

That project has huge potential - not only for Hitachi Rail, but also for the industry’s export opportunities. In a time when pivoting towards green solutions is needed more than ever, the project partners’ commitment to it is key.

Back with the Class 802, and Hitachi Rail seems acutely aware then that all eyes are on these tests to ensure that it will work.

Currently, 802207 has been put through its paces between York and Manchester Airport, as well as between Leeds and Liverpool Lime Street. It has also carried out runs to Scarborough, using drivers borrowed from GB Railfreight. In these tests, it charged its battery while running under the catenary wires.

Charging under the wires, however, is not straightforward.

Agatsuma explains: “We can program when we need to charge the battery. This means that understanding when best to do so is crucial. Energy demand on the network increases in the morning and during evening peak time. That is also when the demand for power is at its highest for the train, so programming for energy optimisation is essential.”

That also means understanding seasonal changes and demands, and the effect that this has on the battery’s performance.

When this conversation took place, it was a bright sunny day. For Agatsuma, this was an opportunity to highlight that surplus solar energy during the height of the day would be the ideal time to charge the battery under wires. Scaling this solution, so that energy demand isn’t altered too much if more battery trains come onto the network, also forms part of Hitachi’s thinking.

Optimisation has been constantly at the forefront of this trial. It was partly why the trans-Pennine route was chosen, although rolling stock availability also played a role. The challenging terrain and the gaps in electrification played nicely into what Hitachi Rail and TPE were trying to get out of these tests.

“It is one of the toughest routes, and therefore in technical terms one of the best,” says Agatsuma.

But TPE’s flexibility and support was also key in choosing this particular route.

The overall goal is to help resolve rail’s decarbonisation problem. It is an issue which acutely affects the UK rail network, with electrification of the network currently sitting stubbornly just under 40%.

And while projects are currently under development to advance the nation’s electrification programme, such as the Transpennine Route Upgrade and East West Rail, electrification is simply not moving fast enough.

For Agatsuma, there is no reason why this technology could not be utilised on Class 805s or ‘807s’ in the future, given that the weight, size and dimensions of these trains are very similar.

Meanwhile, where Hitachi Rail is keen to keep things ‘in-house’ is with the battery’s software. This is because of its experience in maintaining and managing a battery safely through its software.

This will help when Hitachi Rail gets to the point where it needs to scale this possible solution.

It also helps with its development of 24/7 monitoring software, to ensure the battery can have a second life after its use and to understand its behaviours in certain environments.

All of which is important because, of course, cost is an issue.

Says Agatsuma: “There is no doubt that developing a battery is expensive. Very expensive. But total cost ownership is very important for us to consider, and that is because we are wasting kinetic energy when a 300-tonne train is breaking. But, of course, we can recover kinetic energy when a battery is fitted.”

What that means is that energy consumption is reduced. When you also factor in energy price fluctuation, and even smaller elements such as controlling energy output when an engine is idle at stations, and it begins to make sense that there is definitely a future for such projects.

That future - and this project - is the exciting part for Agatsuma, in terms of moving the idea from simulation to real life, and a tangible product which could potentially have a shelf life of 80 years.

At the end of the trials in November, as a gaggle of expectant and proud Hitachi Rail employees listened to the results at an event to mark the occasion, it was clear that the company was excited… and with good reason.

The results considerably exceeded expectations in many areas.

It demonstrated fuel cost savings of up to 50%. At the start of the trials, the team had conservatively thought 30% was at the upper end of what was possible.

It also topped speeds of 75mph on just one battery in eco mode (the battery has two modes – eco and fast modes). Again, this was higher than what the team had originally thought, with 62mph the original target.

And it powered the train a mile either side of the station, when entering and exiting it, before switching back to diesel.

All these stats have vindicated Hitachi Rail’s faith in this developing technology, and it will now be looking at ways to improve its performance and secure orders for more retrofitting in the future.

While new orders are important (and Jim Brewin, Chief Director of Hitachi Rail UK & Ireland, is still buoyed by conversations it is having with government in that regard), it still has a little way to go in convincing the industry that this trial has answered all the questions.

There are still questions over infrastructure, electricity usage, cost and safety. But now the technology has been proven, Hitachi Rail is looking to answer those.

802207 will now have its battery removed and re-enter passenger service. But Hitachi Rail could conceivably have shifted the dial forwards in this developing technology.