The Anonymous Widower

First Passenger Journey In The UK With mtu Hybrid PowerPack

The title of this post, is the same as that of this press release from Rolls-Royce.

This is the first paragraph.

The mtu Hybrid-PowerPack has passed another milestone successfully: In the UK, a train with mtu hybrid drive carried passengers for the first time as part of a special journey.

So how did mtu, a German manufacturer of large diesel engines for trains and ships, end up in bed with Rolls-Royce?

Wikipedia says this.

MTU Friedrichshafen remained a subsidiary of DaimlerChrysler until 2006 when it was sold off to the EQT IV private equity fund, becoming a part of the Tognum Corporation.

Rolls-Royce Holdings and Daimler AG acquired Tognum in 2011. In 2014, Tognum was renamed Rolls-Royce Power Systems, having become a 100 per cent subsidiary of Rolls-Royce Holdings.

A bit tortuous, to say the least!

This paragraph from the press release describes the journey.

The journey of the train – called HybridFLEX – was part of celebrations to mark the 25th anniversary of UK rail operator Chiltern Railways, which will use the train on its routes. It is a converted Turbostar DMU, which was previously equipped with a conventional mtu drive system.

It doesn’t sound very special, but it’s the equivalent of taking your BMW, Jaguar or Mercedes from twenty years ago and converting it to a full hybrid car with batteries, to assist the diesel engine.

Fuel and emission savings of 25 per cent are claimed, with the additional benefit that the train will not use the diesel engines in stations or sensitive areas.

In HybridFLEX Battery-Diesel Train Continues Programme Of Testing, I said this.

In the UK, the following diesel multiple units are fitted with modern MTU engines and could be candidates from a replacement power pack.

That is a total of 990 diesel engines.

As some of the Class 196 and Class 197 trains have yet to be delivered, I do wonder, if it would be sensible to deliver them as diesel-battery hybrid trains.

That is a lot of diesel engines, that could be replaced by MTU Hybrid Power Packs.

Conversions of other trains are also ongoing in Germany and Ireland.

This article from Rolls-Royce, is entitled  Hybrid Train Trials and gives a lot more details.

This is a quote from the article on fuel savings.

A fuel saving of 15 per cent is a
fantastic result and means that under
optimum conditions, 20 to 25
per cent should be possible. 

The savings certainly fit with Chiltern’s findings.

I have a few questions.

Can Locomotive Size PowerPacks Be Built?

As an engineer, I don’t see why not!

And there is certainly a need for them to cut diesel usage and carbon emissions with locomotives.


These conversions could be a very good interim solution.


July 25, 2021 - Posted by | Transport/Travel | , , , , ,


  1. Diesel is part of the problem. In 2021 any investment in diesel is a diversion, and bad for the environment and for people.
    What is the UK doing about this –

    Comment by John Robin St.Clair | July 25, 2021 | Reply

    • I agree we need hydrogen solutions, especially as we have the ability to create masses of hydrogen. And bus companies are showing they can handle it safely.

      All of the trains similar to the Class 168 trains will have electric transmission after conversion and a 315 kW electrical generator based on an MTU diesel engine.

      There are two solutions to move to hydrogen.

      1. Replace the diesel with a small gas turbine of appropriate size from a cruise missile or an airliner APU, that runs on hydrogen.

      2. Convert the diesel to run on hydrogen.

      If Rolls-Royce and/or mtu can’t do one or the other or both, I’d be very surprised. Cummins; their great rival, have got a diesel engine, that will run on hydrogen.

      But first you need to convert the 168 trains from hydraulic to electric transmission.

      With all the clever electrical systems in these new transmissions, I suspect they wouldn’t need a generator as big as 315 kW.

      Imagine the surprise on passengers faces, when one Monday, they tuned up for their morning commute, only to find their outwardly similar train had lost its noise, vibration and exhaust pipes.

      The technology is there to do it. All it needs is the belief and the will

      Comment by AnonW | July 25, 2021 | Reply

      • Daimler AG would never have sold its stake in MAN to RR, if MAN was strategic to Daimler’s future.

        Did RR buy an asset with a short life expectancy? I rather think they did, unfortunately.

        Comment by John Robin St.Clair | July 25, 2021

      • according to the MAN Annual Report MAN SE is majority-owned by Traton, the heavy commercial vehicle subsidiary of automaker Volkswagen AG.
        Surely you were referring to MTU. MTU Friedrichshafen was a subsidiary of DaimlerChrysler until 2006 when it was sold off to the EQT IV private equity fund, becoming a part of the Tognum Corporation. Bought by Rolls-Royce in 2014 it was renamedRolls-Royce Power Systems AG and is owned by Rolls-Royce Holdings

        Comment by fammorris | July 25, 2021

      • In my previous post I referred to MAN when I should have written MTU. (mea culpa, generally MTU in much of my work is Maximum Transmission Unit, not the RR subsudiary)

        Comment by John Robin St.Clair | July 25, 2021

  2. How are they operating? Do they turn off the engines at stations to stop poison fumes reached lungs on the platforms? What?

    Comment by John | July 25, 2021 | Reply

    • It appears that the clever geo-located computerised fireman switches the train to electric in stations and where people are about.

      Some buses are able to do that!

      Comment by AnonW | July 25, 2021 | Reply

  3. That sounds good. Do the train accelerate faster using the batteries?
    If so trip times can be reduced.

    Comment by John | July 25, 2021 | Reply

  4. It is not just MTU diesel engine/hydromechanical power packages that can be replaced by hybrid diesel/battery electric drives but also earlier power packages that were supplied by Cummins/Perkins (formerly RRM) and Voith for the DMUs built between 1985 and 1993.
    AnonW I think you are mistaken, all DMUs like Class 168 will not solely have electric transmission after conversion whatever the source of the hybrid drive is. You can see in Rolls Royce MTU literature that there’s a combined starter/generator with an electrical motor drive motor interposed between the MTU diesel engine and the hydro-mechanical transmission which is made by ZF. As such the vehicle in effect has two sources of power; i.e. the engine that can in theory (maybe even in practice) be used in tandem to varying degrees, known as a parallel hybrid system to maximize the operating and environmental performance of the train.
    As far as hydrogen fuelled gas turbines go they’re only viable in a series hybrid arrangement where the electric motor is the only means of providing power to the wheels since load response characteristics are not as attractive as the internal combustion engine. What is more the volumetric energy density of hydrogen is about a third of that of natural gas or methane. I’d suggest we’d have problems storing it on many existing DMUs
    Having said that we are still a good 10 years from knowing whether we will be able to produce hydrogen cheaply enough by electrolysis (using renewably sourced electricity to split waters to extract hydrogen) since at present we produce most hydrogen from fossil fuels through the steam reforming process. Anyway who thinks using electricity to obtain hydrogen and then use that same hydrogen to generate electricity is an efficient process.
    As for hydrogen being burnt in reciprocating engines…………
    Can we exploit the same techniques of adapting existing diesel electric locomotives to incorporate a hybrid drive line, I suspect not owing to the lack of available space.
    For the future, and where it is practical, electrification of the network is the desirable route.

    Comment by fammorris | July 25, 2021 | Reply

    • The Wankel engine is 27% more efficient using hydrogen. The engines disadvantages dissolve when it is run at a constant speed and load – as a genny. At one third the size a weight of piston engine it ‘may’ have train applicactions. But the hydrogen fuel cell is more efficient.

      Quite frequently too much electricity is produced, that they pay companies to use it. At times of over production (e.g., high winds at night) hydrogen can be produced for transport or electricity generation to fill in for the fossil fuelled peakers.

      Comment by John | July 25, 2021 | Reply

      • These may solve one the Wankel’s big operating problems –
        Many years ago I contemplated buying a Wankel engined car (as a collectable), and was advised against it by the folk who built the original, because of the tip-seal issue.

        Comment by John Robin St.Clair | July 25, 2021

      • I can’t say I’d recently given much thought to the Wankel engine despite in my youth having been part of a research department that was investigating the use of the Wankel engine in armoured vehicles. I did however find this research paper on comparatively recent investigations into the use of hydrogen in the engine
        As someone who has invested his own money in companies engaged in hydrogen production and the High-temperature Solid Oxide Fuel Cell I can hardly be accused of rejecting the technology, yet I am aware that it’s not a case of battery-electric Vs the fuel cell more it’s a case of horses for courses. I am for example inclined towards the view that batteries at the moment do little to offer a solution as the means of transport becomes heavier while the fuel cell will more likely be part of that solution for heavy road and rail.
        You haven’t mentioned the Super or Ultracapacitor. While discussion has seemingly gone out of fashion it too shouldn’t be overlooked.
        As for the overproduction of electricity is concerned, isn’t that why we are building more interconnects and developing our smart network. If all that doesn’t work then the market will ultimately decide, corporations are not there to take on the role of charities.

        Comment by fammorris | July 25, 2021

  5. The electricity system is production must match demand. At time difficult to do. That is why storage is needed.

    Supercapacitors are superb at brake regen in clawing back most of the kinetic energy.

    The sealing tip problem was solved many years ago. Revving a Wankel up and down as in direct drive, they are inefficient. At a constant speed they start to shine, with their other attributes of smoothness and low size & weight, shining forth. Mazda are to introduce a Wankel battery-electric hybrid early next year. There have been many patents awarded to improve the Wankel over recent years. Whether it can compete with a hydrogen fuel cells needs some simple R&D. If a hydrogen Wankel can near match a fuel cell being cheaper to make, then it make have a place.

    Mazda made a dual fuel hydrogen Wankel car, in production.

    In my opinion, a Wankel in a hybrid has come too late as full EVs will dominate the market. Also the solid state battery is game changer here. But maybe using hydrogen in other applications: trains, ships, etc.

    Comment by John | July 25, 2021 | Reply

  6. @fammorris
    Why was the Wankle rejected for military applications? On the US Abrams tank they use e small Wankle as generator. The US also us the Liquid Piston rotary as a genny for a artillary gun. The Liquid Piston engine is a Wankel inside out.

    Comment by John | July 25, 2021 | Reply

    • Not being at the heart of the problem in the early mid 1970s, apart from the inherent problems associated with compression ignition combustion chamber in a Wankel and the then seemingly insuperable problems with tip sealing I don’t really know.
      In the book “Wankel Rotary Engine: A History”
      by John B. Hege he speculates that the MOD cancelled the project in 1974 as a result of the Yom Kippur which caused the British Army to lose the interest in a compact tank powerplant.
      Why does/did the Abrams Tank employ a Wankel auxiliary power unit, could it be that the following answers your question. In 2010 Army G-4, Research, Development and Engineering Command (RDECOM) released a paper initiating research to supplant the original Abrams M1A2 Wankel JP-8 APU with an alternative. This involved 3 modified versions of the JP-8 engine, a fuel cell solution and a reciprocating diesel engine. In 2020 the US military announced the introduction of a modified version of the Hatz 1D90 single cylinder diesel engine. This fits in the same space envelope as the original. It seems that problems with oil consumption, rotor side seals, intolerance to the sulfur content in the fuel and the need for glow plugs finally laid low the future for the Wankel in the Abrams Tank.

      Comment by fammorris | July 26, 2021 | Reply

  7. The Class 168 sound like the a Vivarail configuration. These trains are bought and ready to use on the Bidston-Wrexham line. They have been waiting a while. Reports are confusing as many imply Merseyrail 777s made do this line. If so, I suppose they can go to Sth Wales.

    Comment by John | July 25, 2021 | Reply

    • Reading this link
      and comparing it with the Rolls Royce literature it’s clear that they are not the same, the Vivarail concept being a Series Hybrid, while the Rolls-Royce (MTU) solution seems, without the benefit of being able to understand the control logic, to be a form of Parallel Hybrid. That said they both have their pros and cons much in the way that respectively Honda hybrid cars are to Toyota hybrids.

      Comment by fammorris | July 26, 2021 | Reply

  8. Also what about Cummins QSK 500 powered trains like Siemens Desiro class 185,Alstom Coradia Class 180 and its Class 175 sibling also Cummins powered.All of these diesel mechanical or hydraulic transmissions.Do not forget either the Networker class 165/166 precursors of the Turbostar classes and also the class 158/159 fleets and even classes 150,153,155 and 156.Some of this technology could also surely work with the Bombardier class 220/221/222 diesel electric trains as well?

    Comment by Hugh | July 26, 2021 | Reply

    • Cummins are one to watch. They have recently developed a diesel engine, that can run on hydrogen, as they can see a lot of business disappearing up the Suwannee.

      I have done consultancy work for Cummins and I wouldn’t be surprised to some hydrogen conversions. But a lot of the old BR DMUs will probably be scrapped.

      Comment by AnonW | July 26, 2021 | Reply

    • Hugh, the Class 175, 180, and 185 all have Voith hydraulic transmissions incorporating supplementary hydrodynamic brakes which despite their success in DB’s typ 610 and 611 I believe have ended up not being used here in the UK , the T312bre for the 180/185 and the T211bre for the Class 175.
      Although hybridisation is not impossible replicating the Rolls-Royce battery/diesel/hydro-mechanical automatic transmission arrangement in the QSK powered vehicles would be problematical/expensive since no transmission manufacturer has adapted an automotive automatic transmission for rail application in a higher power range than the current ZF EcoWorld unit which forms part of the hybrid Class 168 package.
      As for the Voyagers and Meridian DEMUs, yes hyridisation could be possible although I’m inclined to think it would be more along the lines of the Vivarail, series hybrid concept.
      Some of the Class 15X vehicles are pretty much age expired, but then again Vivarail have proven what can be done with time-expired LUL rolling stock.

      Comment by fammorris | July 27, 2021 | Reply

  9. Well Cummins are riding four horses at the same time, advanced convention ICEs, hydrogen combustion, fuel cells and battery packages. I don’t think they know which one, or combination of the technologies is going to be good for their future – and who can blame them I wouldn’t get too attached to hydrogen combustion engines yet.

    Comment by fammorris | July 26, 2021 | Reply

    • I think that hydrogen combustion will certainly emerge. There’s at least five companies that I know off, experimenting with the technology using diesel engines. Start with Cummins, Clean Air Power, JCB, ULEMco and Anglo-Belge. Add in gas turbine manufacturers and Rolls-Royce and Honeywell have shown their hands.

      There must be space for a disruptive technology.

      Comment by AnonW | July 26, 2021 | Reply

  10. […] One of their products recently made its debut in the UK and I wrote about it in First Passenger Journey In The UK With mtu Hybrid PowerPack. […]

    Pingback by Distributed Power Supplies Key To Rolls’ Earnings « The Anonymous Widower | August 7, 2021 | Reply

  11. I see Chiltern have just been awarded a new 7-year contract which commits to all their trains being converted to hybrid.

    Personally, I agree with the first comment here: diesel hybrids are a distraction that don’t solve the problem. Other countries are moving ahead with replacing diesel with battery and in some cases hydrogen. So why isn’t GB?

    Comment by Peter Robins | December 10, 2021 | Reply

    • sorry – 6-year contract

      Comment by Peter Robins | December 10, 2021 | Reply

    • I think Chiltern could be waiting to see how Hitachi’s various trials with battery trains and discontinuous electrification work out. The alternative is to go for hydrogen, which could be easy on their Birmingham route and hydrogen Aventras could handle the Southern services.

      Comment by AnonW | December 10, 2021 | Reply

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