The Anonymous Widower

A Battery-Electric Class 99 Locomotive

In GB Railfreight Plans Order For Future-Proofed Bi-Mode Locomotives, I introduced the Class 99 locomotive, for which the first order was announced by Stadler and GB Railfreight today.

This was the start of that post, which I wrote in early March 2022.

The title of this post, is the same as that of this article on Railway Gazette.

This is the introductory paragraph.

GB Railfreight is planning to order a fleet of main line electro-diesel locomotives with a modular design which would facilitate future replacement of the diesel engine with a battery or hydrogen fuel cell module.

The rest of the article gives clues to the deal and the specification of the locomotives.

  • Negotiations appear to have started with Stadler for locomotives to be built at their Valencia plant.
  • Twenty locomotives could be ordered initially, with options for thirty.
  • The locomotive will be Co-Co bi-modes.
  • The diesel engine will be for heavy main line freight and not just last-mile operations.
  • They would be capable of hauling freight trains between Ipswich and Felixstowe, within two minutes of the times of a Class 66 locomotive.
  • They will be of a modular design, so that in the future, the diesel engine might be replaced by a battery or fuel cells as required and possible.

They have provisionally been called Class 99 locomotives.

Note the introductory paragraph of the Railway Gazette article.

GB Railfreight is planning to order a fleet of main line electro-diesel locomotives with a modular design which would facilitate future replacement of the diesel engine with a battery or hydrogen fuel cell module.

What sort of range and performance will this give to a Class 99 locomotive?

In Class 99 Electro-Diesel Locomotive Order Confirmed, I came to this conclusion.

It does appear that a design based around the latest version of a Caterpillar C175-16 diesel engine will be possible.

The easiest way to create a battery-electric Class 99 locomotive would be to replace the Caterpillar C175-16 diesel engine with the largest and most efficient batteries possible, add regenerative braking to battery and the best control system for the locomotive and the batteries, that engineers can devise.

These are my thoughts.

Range Of A Euro Dual On Diesel


  • A Euro Dual locomotive has a 3,500 litre fuel tank.
  • A Euro Dual locomotive has a fuel consumption of 1039.3 L/hr.

This should allow the locomotive to run for about three hours and twenty minutes or about 250 miles.

Obviously, any electrification on the route, will increase the range.

Weight Of The Diesel Engine

This data sheet for the Caterpillar C175-16 diesel engine gives a weight of over twenty tonnes, which is certainly a lot of weight.

You’ve also got the weight of the fuel tank, which could also contain in the Euro Dual hold nearly three tonnes of diesel.

I will assume that the weight of a Caterpillar C175-16 diesel engine and the associated gubbins could be as high as 25 tonnes.

How Much Energy Could A Twenty Tonne Battery Hold?

In Innolith Claims It’s On Path To 1,000 Wh/kg Battery Energy Density, which was written two years ago.

This was my conclusion of that post.

I am led to believe these statements are true.

  • Tesla already has an energy density of 250 Wh/Kg.
  • Tesla will increase this figure.
  • By 2025, the energy density of lithium-ion batteries will be much closer to 1 KWh/Kg.
  • Innolith might achieve this figure. But they are only one of several companies aiming to meet this magic figure.

These figures will revolutionise the use of lithium-ion batteries.

I feel it is reasonable to go along with Tesla’s figure of 250 Wh/Kg, which gives a 5 MWh battery could replace the C175-16 diesel engine, if it had a total weight of 20 tonnes.

If the battery could have a total weight of 25 tonnes, the battery would have a capacity of 6.25 MWh.

It does look like the Caterpillar C175-16 diesel engine and the associated gubbins could be replaced by a substantial battery.

As the years go by, the capacity of the batteries will only grow.

Will Battery-Electric Class 99 Locomotives Have Regenerative Braking?

According to Wikipedia, Stadler Euro Dual locomotives do have regenerative braking, so it would seem likely, that this could be used to recharge the batteries, in addition to 25 KVAC overhead electrification, where it is available.

I will assume that battery-electric Class 99 locomotives will have regenerative braking.

How Long Could A Battery-Electric Class 99 Locomotive Run On Batteries?


  • To have the performance of a Class 99 locomotive on diesel, the locomotive would need to output 2,800 kW.

Without regenerative braking this would give these figures.

  • A 5 MWh battery would run for at least one hours and 47 minutes.
  • A 6.25 MWh battery would run for at least two hours and 13 minutes.

Add in regenerative braking and short strategic lengths of electrification and large parts of the UK network would be opened up to electrified trains.


Stadler have probably done extensive simulations of the UK network with battery-electric Class 99 locomotives, so they would know the true potential of these locomotives.

April 29, 2022 - Posted by | Transport/Travel | , , , ,


  1. Stadler press release doesn’t state engine just that it will be stage 5 which im not sure the C175-16 is certified to.

    DfT should fund a couple equipped with hydrogen and batteries

    Comment by Nicholas Lewis | April 29, 2022 | Reply

    • I couldn’t find anything about a stage 5 C175-16, but the power quoted fits the Cat engine and I’d be very surprised if Cat didn’t go that way to conserve their market.

      I do think though, that Cat are on a hiding to nothing from Cummins, if they don’t provide something.

      It should be noted, that Cat, Cummins and mtu are all experimenting with hydrogen-powered ICEs, so Stadler will have something to create a powerful locomotive.

      Comment by AnonW | April 30, 2022 | Reply

  2. Toyota’s solid state battery is on the market. This charges about 5-6 time faster so improving brake regen. Batteries do not take all the energy the braking generates.

    In probably 5 years time, EV cars and EV trains may be quite the norm. The DfT is banking on these advances to preclude full electrification.

    We are still awaiting the Merseyrail 777s in battery/3rd rail form to be in service. No need not to have a firm plan with an announcement for these. Once these are in service the EV train rollout will accelerate aided by Toyota’s battery when available.

    I can see the Chiltern Line to be battery-electric trains.

    Comment by John | May 4, 2022 | Reply

    • I very much feel that batteries are the way to go, the low-life find overhead wires too valuable to leave in place. I suspect we’ll start to see some lines have their electrification removed in the next few years.

      I agree with you about Chiltern.

      Comment by AnonW | May 4, 2022 | Reply

  3. The thing about using battery trains is that it will make reopening old lines far cheaper as no electrification is needed.

    Comment by John | May 9, 2022 | Reply

  4. Absolutely. As Stadler appear to have agreed for it to be in the press release, I think that hydrogen power could also be used.

    We have several hundred large diesel locomotives, and I’m sure, if you shared a couple of bottles of the best Swiss rose with Stadler’s Chief Locomotive Engineer, they’d be happy to replace the lot of them, with a family of related locomotives.

    Comment by AnonW | May 9, 2022 | Reply

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