Modelling performance and range of Hitachi 80x Trimode trains, and implications for future mainline electrification

[Elecman]

That's an average consumption of 33.7kWh/min = 2.025MW.


So 5kW per car. Thanks.



OK. So if you won't let me have diesel engines, let's try a 9-car all battery Hitachi IET, the 80x-B

• 2 x driving cars with 6MW transformer under the floor and three pantographs for use at stations with 25kV conductor bars sufficiently thick to deliver 6MW to each end car.
• 7 x Battery packs rated at 700kW / 550kWh. Each weighing the same as an 80x diesel GU.
• Hotel power = 5 x 9 = 45kW
• Maximum power output 4.9MW,
• Total battery capacity = 3.85MWh. At WCML record attempt consumption, that's 1.9h = 114 minutes endurance.

Assuming the MML north of Wigston and the Cross Country route both use power at the same 2MW average rate as a Pendolino to Glasgow:

• Wigston to Sheffield (67 mins) will use 59% of the battery. e.g. 90% to 31%. Ten minutes recharging at 12MW at Sheffield will put back 2MWh (52%). So the return journey will get back to Wigston with 24% charge left. If Sheffield grid supply fails, then the return journey will have to be in limp home mode (but wiring Derby station too would fix that).
  
  
• On the Cross Country route, Proof House Junction near New St to South Kirby Jn near Wakefield (89 mins) will consume 78% of the battery. e.g. 90% to 12%, without recharging at all. Five minutes dwell at Sheffield (or Derby if wired) would give a much bigger reserve. (Or you could wire Tamworth, fed from the WCML grid feeder point already there.)

In practice, I'd expect MML and XC consumption to be less than a Pendolino being driven to the limit, but that's the best I can do for now without more precise data.

Tamworth doesn’t have a grid feeder anymore, it does have a Sectioning Auto Transformer unit

 

[Zomboid]

I would be surprised if running batteries that close to the edge would be acceptable from a resilience standpoint. For example I believe a Voyager can generally keep time with one engine out, so a battery train may also need to keep time with one carriage worth of cells isolated.

And deep discharges and fast charging is a great way to reduce battery lifespan - these things are already going to be hammered much harder than in a typical EV with multiple fast charge discharge cycles in a day, and keeping them within an operating range to give a reasonable lifespan is going to be important.

So yes, if you go to the limits of performance and resilience then you can probably get away with fairly limited charging infrastructure, but (and I have no insider knowledge here) I suspect the people doing this stuff for a living are making much more conservative assumptions than this analysis.

 

[HSTEd]

I would be surprised if running batteries that close to the edge would be acceptable from a resilience standpoint. For example I believe a Voyager can generally keep time with one engine out, so a battery train may also need to keep time with one carriage worth of cells isolated.

And deep discharges and fast charging is a great way to reduce battery lifespan - these things are already going to be hammered much harder than in a typical EV with multiple fast charge discharge cycles in a day, and keeping them within an operating range to give a reasonable lifespan is going to be important.

So yes, if you go to the limits of performance and resilience then you can probably get away with fairly limited charging infrastructure, but (and I have no insider knowledge here) I suspect the people doing this stuff for a living are making much more conservative assumptions than this analysis.

Even if the batteries wear out quickly, and battery performance on that score keeps improving, you can buy an awful lot of cells for the price of 25kV railway electrification.

 

[andrewgs]

https://turntide.com/products/energy-storage/ has a graph of capacity vs cycles. It shows a capacity of 80% after 3300 cycles for a 1C rate (1C = charge in 1 hour)
3300 cycles / 3? cycles per day gives 1100 days before dropping to 80% capacity.

Your 80x-B proposal has a capacity of 3.85MWh and charge speed of 6 MW,
3.85MWh / 6 MW = 38.5 mins so a C rate of 1.6C. This is more intense than the 1C charging, so you'd expect faster degration than calculated above.

Using larger batteries gives lower C rates, so less degredation, and a smaller depth of discharge (eg 80% to 20% rather than 90% to 10%) so again less degredation.

 

[Trainbike46]

Even if the batteries wear out quickly, and battery performance on that score keeps improving, you can buy an awful lot of cells for the price of 25kV railway electrification.

While this is true, there are good reasons to not plan to run batteries empty in an operational railway; the main one is resilience, and battery longevity is very much secondary.

Planning to use the batteries between 20% and 80% state of charge gives a sizeable buffer in case of disruption, avoids the slower charging when a battery is almost full, and is better for battery longevity, so I would suspect that is what the railway will do.

Whether this is achieved with more cells per train or more charging infrastructure, remains to be seen

 

[Nottingham59]

Your 80x-B proposal has a capacity of 3.85MWh and charge speed of 6 MW,
3.85MWh / 6 MW = 38.5 mins so a C rate of 1.6C. This is more intense than the 1C charging, so you'd expect faster degration than calculated above.

Yeah, the 6MW (at each end, so 12MW overall) is to allow rapid recharge when operationally required. But 1C50 today had a 35 minute layover at Sheffield, which I assume is typical. Putting 2MWh back in (i.e. from 31% to 52%) in 30 minutes is a rate of 4MW, which would be much less damaging than 12MW.

Whether this is achieved with more cells per train or more charging infrastructure, remains to be seen

It would need modelling and optimising, of course. But it still looks to me that a 125-capable EMU with a battery that is feasible today, on trains already in service today, could get from the wires at Birmingham onto the wires at Doncaster without having to recharge. And from Wigston to Sheffield and back with only minimal new charging infrastructure.

And that result I have found really quite surprising, given some the comments on here about electrification.

 

[Class15]

Just feels like the latest excuse to not electrify doesn’t it. First bi-modes and now this, what a shame.

 

[Class 317]

Just feels like the latest excuse to not electrify doesn’t it. First bi-modes and now this, what a shame.

Why would this be a problem if BEMU'S allow most current diesel servicea to go electric at a fraction of the cost and on a much quicker timescale.

Going back to the ops question, I looked at this a few years back when I worked on a similar study for DB. I was surprised that a quick back of the envelope calculation suggested circa 250 miles of OHLE could in theory removed all intercity and local diesel operations. In real world conditions there were probably some operating constraints not included in this quick and dirty calculation but I'd be surprised if more than 300 miles away required. This could be done far quicker than a rolling programme at far lower upfront and lifetime costs.

In terms of the 80x fleet, I have been lead to believe that replacement of some diesel GU with battery packs is still under investigation but as mentioned up thread requires a contract variation with Hitachi.

 

[Bald Rick]

Just feels like the latest excuse to not electrify doesn’t it. First bi-modes and now this, what a shame.

It is electirifcation. Just not of the infrastructure.

 

[Class 317]

It is electirifcation. Just not of the infrastructure.

Exactly, I don't get the attitude that it's somehow not upgrading a diesel service to an electric one.