Hybrid-power converted diesel buses bound for London

Posted: August 10, 2015 by oldbrew in innovation, Travel
London double-decker [image credit: buses world news]

London double-decker [image credit: buses world news]

The bad experience with batteries in London’s own-design hybrid buses hasn’t deterred further investment in the technology, reports E&T Magazine.

The first diesel buses converted to hybrid power will run on the streets of London early next year.

London is introducing an ultra low emission zone in 2020, so diesel buses will have to be replaced or converted to hybrid or all electric power.

While the price of fuel is rising, government subsidies are being cut. Vantage Power estimates that switching to hybrid power saves operators around £20,000 per bus per year and said retrofitting can convert four old buses for the price of one new one.

New hybrid electric buses cost more than regular diesel buses. Some of London’s hybrid Routemasters, which cost around £350,000 each, have suffered from prematurely failing batteries that will have to be replaced by batteries from another supplier under warranty.

Vantage strips the diesel bus’s engine bay back to the chassis and replaces the contents with its B320 system of a smaller diesel engine, drive motor, generator, battery, electronics and software to manage it. The engine is decoupled mechanically from the wheels.

Full report: Hybrid-power converted diesel buses bound for London – E & T Magazine.

  1. oldbrew says:

    ‘While the price of fuel is rising, government subsidies are being cut.’

    Not sure either of those statements is accurate. Crude oil prices are way below last year’s values.

  2. AlecM says:

    Paid 111 p per lit4re for diesel today. In 2000 it was 90 p.

  3. oldbrew says:

    AlecM: we had years of automatic fuel duty increases until recent ‘freezes’ – remember the fuel escalator?

    Fuel tax rises could start again as soon as next month.

  4. M Simon says:

    Well how could I resist:

  5. E.M.Smith says:

    In The Peoples Republic Of California, Diesel is $2.85 / gallon US (where a quart is just under a litre at about 946 ml?) while in Texas and the USA it is even cheaper (near $2).

    The Diesel engine is about as efficient as things get. Running it through a charger, battery, electric motor can only lose energy.

    A motor/generator set and battery can at most add a nice regenerative auxiliary brake, but only if the Diesel is direct mechanical drive will you avoid losses of the basic superior Diesel efficiency.

    Doing this as a Diesel electric generator and electric drive motor is a bit dumb, but does let you use constant speed Diesels. It can also make sense in a train where you need extended max torque at zero speed (slow or stall speeds) where a combustion engine gives little torque and is hard to couple to the rails (transmission hard to make).

  6. M Simon says:

    The Diesel engine is about as efficient as things get when running steady at full load. When idling at the curb it is very inefficient.

    Plus there are other mismatches. Electric motor torque is at maximum at zero speed. Not so for a diesel.

    Note that the gear box (no small thing for a diesel) is replaced by the electric system. We are in the early days of that – it is not a bad concept if the price can be brought down. It just looks like poor execution. If the rest is sound, getting a suitable battery shouldn’t be too difficult.

  7. Fanakapan says:

    Prematurely failing batteries 🙂

    Likely the company that’s offering a ‘Warranty’ wont be around when the claims come in ?

    With current technology, batteries aint going to make any economic sense, plus, the process of manufacture and recycling is probably many magnitudes dirtier than running diesel’s.

    So this bus malarkey is in no way ‘Green’ its merely some displacement exercise 🙂

  8. PeterMG says:

    M Simon, you are completely wrong about a diesels efficacy band. For a start it can be anywhere in the power band and different manufacturers tailor different engines to particular roles. With variable geometry turbo’s, infinitely variable fuel injection timing and variable valve timing available but seldom yet used the days of efficiency at one spot are over. The diesel beats all comers at all power settings at all points in the rev range. Plus idle fuel consumption is virtually nil. I have no idea where you got any other notion from.

    Besides all that this story has been done to death a couple of times lately but seems to get dragged up again and again. But here are a couple of important facts.

    The 6 cylinder diesel buses of about 250hp powered typically by a Euro 5 or Euro 6 certified Cummins ISB are burning less fuel than the exact same buses with hybrid drive and powered typically by the same companies 4 cylinder version of the same engine at 180hp or so. This become even more exaggerated when the batteries don’t work which is most of the time. I travel on these buses everyday and can tell when the batteries are working.

    It is impossible to get these engines any cleaner as they are zero emissions and there will be no further reduction in pollutants beyond Euro 6 or what in the US is EPA10 as the regulators have already admitted they are struggling to actually measure the current minute levels of NOx, HC, CO and Particulates.

    Some of our regulators have however descended into fairy land where they are trying to regulate CO2, which due to chemistry is entirely dependent on fuel burn, and is at odds with trying to achieve zero NOx which makes engines less efficient.

    So to reduce CO2 we have to reduce fuel burn. Retrofitting hybrid systems to these older buses is a moronic brain dead political charade that will more than likely produce the opposite effect.

  9. catweazle666 says:

    “While the price of fuel is rising…”

    It would seem not.

    Currently our local filling station is selling diesel for 3p per litre less than petrol – I can’t remember the last time diesel was cheaper than petrol.

  10. M Simon says:

    Plus idle fuel consumption is virtually nil.

    The efficiency is still zero at zero speed. .

    But you present an interesting question. Do all those additions replace the electric motor system COST EFFECTIVELY? What about reliability?


    The electric transmission also has a few advantages.

    1. Controlability
    2. The displacement of shafts with wires gives you options in component placement.

  11. Many years ago most cities had all electric trolley buses. Maintenance costs were high and of course like trams limited to specific routes. Also, a bit embarrassing holding up traffic when they break down.

  12. oldbrew says:

    Fanakapan: it’s about reducing particulates and improving air quality in the centre of London. Not so much about supposed climate issues.

    cementafriend: trolleybuses are still going strong. Is a trolleybus breakdown worse than a ‘normal’ bus? Both need towing away.

    ‘As of 2012 there were around 300 cities or metropolitan areas where trolleybuses were operated’

  13. M Simon says:

    cementafriend says:
    August 11, 2015 at 9:03 am

    A lot of the trolly issues were caused by their very primitive controller. With modern controllers –> Power losses are down. MTBFs are up. The other trolly issue was contact with the overhead lines.That is still a problem. As are the overhead lines themselves (height limits on traffic).

  14. Ben Vorlich says:

    I read an assessment somewhere that said that due to unconventional oil and gas the price of crude was set to remain stable for the next 5 years, or perhaps longer. The Middle East states need a much higher price but every rise will make more marginal American/Canadian/etc sources viable which will come online to hold the price. Bankrupt suppliers can be bought and the infrastructure will be in place ready for the next opportunity.

    So the only above inflation price increases will be from taxation. The government of any country will have to tread carefully on the front.

    [reply] this assessment maybe: https://tallbloke.wordpress.com/2015/08/06/too-late-for-opec-to-stop-the-shale-revolution/

  15. PeterMG says:

    M Simon the steam Engine produces max torque at zero rpm as does the electric motor. We are not going back to steam on the basis of one parameter. Everything in engineering is a compromise. There is nothing wrong with electric drive. It has its place, we use it extensively in trains, but that is more because the mechanical transmission would be too complicated. Trains also make extensive use of hydraulic drives, which usually means the electric drive technology is too expensive and doesn’t give a commercial return vrs other alternatives.

    These buses we are discussing are hybrid drives, which mean they fit a smaller than normal diesel engine and rely on stored energy to make up the difference. The reality is the stored energy and energy recovery systems are not working as thought and the small engine works harder than has been programed and as a result burns more fuel than the std diesel power equivalent bus absolutely defeating the whole purpose of the hybrid which is to save fuel. Remember hybrids can’t pollute less as Euro 6 is zero emissions anyway. Even with my connections people are being very careful what they say to me. That tells me this technology is not working and is an embarrassment to someone very powerful.

  16. PeterMG says:

    I would just like to add as with all these press articles no one challenges any of the decision makers and asks simple questions like, which pollutant is the hybrid going to save? And just see what answer you get back. These Vantage Power people were students back in 2010 and so will understand none of the issues about running city buses. They talk about being able to run in certain zero emission areas on just battery power (dream on). Nothing of this is thought through and I bet your bottom dollar that the bus company they are teamed with is run by accountants with 20 20 hind vision and no sense.

    Another point is at low speeds rolling resistance is the major force to be overcome and aerodynamics plays almost no part in moving a city bus. Minimising rolling resistance requires removing weight, and hybrids are all heavier, which is partly why the Boris bus uses more fuel than the std diesel bus. If this mob think they will be able to move a 16 tonne bus on battery power at city speeds and for more than a few yards they will need not only a serious electric motor but some serious battery storage which is more weight, and more fuel to move it. All a waste of money if you ask me.

  17. M Simon says:

    The real question to ask is why they didn’t let the design out for bids? Get some one wit experience to do the design. This sort of thing has been done before.

  18. catweazle666 says:

    My recollection of the trolley buses in 1960s Bradford is that they were reliable, smooth, had excellent acceleration and were ideally suited to the hilly terrain.

    I certainly didn’t notice any improvement when they were replaced by diesels.

  19. oldbrew says:

    PeterMG: the London ULEV comes in during 2020. Vehicles in this inner zone must be Euro 6 compliant (with a few ifs and buts) or pay a charge. That’s why a batch of diesel hybrid conversions is coming in.

    ‘We are working with manufacturers to develop a retrofit system for its Euro V hybrid buses, to ensure they meet the Euro VI standard.’

  20. PeterMG says:

    Hi oldbrew nowhere in those regulations does it state the buses need to be hybrids. It seems to me to be a ludicrously expensive exercise As I have tried to illustrate the hybrid can not save on any of the pollutants listed over a std Diesel powered bus. As the article states it is only NO2 that London needs to reduce and that could be done now if cars had to comply. There is not a gnats whisker of a practical difference between Euro 5 and 6 so this is window dressing. Take a std bus and transplant its Euro 4 or 5 Cummins ISB for a new Euro6 isb and bobs your Uncle you have compliance. The ISB is a medium duty engine of 6.7 litres so replacing it make sense by 2020.

    In the 80’s the engines were either the 10.5 litre Gardner 6LXB of 180hp, an old tech naturally aspirated engine or 10 litre turbocharged LT10 Cummins. Both engines were heavy duty and I once did a factory test on a 5 and a half year old LT10 out of one of Lothian’s Buses double decker’s as they were nervous about a new order. The engine passed all new engine test parameter except for a head gasket water leak. When stripped down the engine had no warn parts requiring replacement and could have run a further 2 to 3 years. We gave Lothian a new engine and they ordered 50 new Leyland Olympians with Cummins power. In todays world you often can’t deliver something designed to last forever, or this instance 7 or 8 years plus second life recon of 5 years as some moron of a regulator will come along and put it off the road.

  21. JohnR says:

    Vehicles are not barred from the ULEZ, just charged to pass thro’ it. If they were barred when not compliant, there would be very few vehicles within the zone. I note that practically all vehicles are included. No diesel vehicle produced prior to September 2015 will be compliant (TfL)

  22. oldbrew says:

    Peter MG and others may be interested in this if they haven’t seen it already.

    ‘What are the implications of the New Routemaster’s technical problems?’

    The report says: ‘It’s useful to grasp in simple terms how the buses work. They are powered by an electric motor, which is, in turn, powered by the battery. The battery is charged in transit by a small diesel engine, which switches on when the battery needs topping up and switches off again when not required. In this “series hybrid system”, the diesel engine never directly powers the bus, which simply isn’t built that way. It is there to generate battery charge, and nothing else.

    The hitch with the batteries has been that some of the individual cells clustered inside them have been eroding or packing up. All such cells erode and pack up eventually but those in the batteries of the earliest buses to come off the production line have been doing so sooner than they should have (which is why they’re being replaced for free under warranty). The consequence has been that the diesel-run generator-engine has been switching on more frequently to maintain the battery’s charge and generally having to work harder.’ [as PeterMG mentioned]

    Also: ‘As TfL itself has said, newer forms of hybrid bus will soon produce fewer toxic emissions than the “Boris bus”.’

    A driver complains: ‘The driver offers this summary: “I don’t feel in control of the bus. The bus is in control of me.” One result, he or she says, has been “silly minor accidents”.’ Oops :/

    ‘All such cells erode and pack up eventually’ – electric car fans take note.

  23. PeterMG says:

    Thanks oldbrew Its plainly obvious that none of these commentators has the slightest idea about any of the facts surrounding pollution. I ride on these buses every day and although I don’t ride a route with a Boris bus, my route uses Dennis Alexander Enviro 400 Hybrids with the same Cummins 4.5 litre 4 cylinder ISB 185hp Euro 5 or 6 engine . Those engines work hard and are seldom off. Near to where I work is the end of a route serviced by Boris Buses and I often see them parked with the engine running to charge the battery whilst the driver is on break. It is nonsense to think of these buses as being less polluting than a diesel only bus. The reality is for all practical purposes there is no difference, except you waste a lot more money and have higher operating costs for the Hybrid.