Wellington Scoop

Electric bus, with 3 tonnes of batteries, tested in Ngauranga Gorge


by Roger Blakeley
Regional Councillors were yesterday taken on a bus tour with NZ Bus CE Zane Fulljames. It started with a smooth ride on a full battery electric bus, an 8 year-old bus converted with batteries weighing 3 tonnes, and being used to gather data on how a fully electric vehicle performs.

We were driven from the Council’s office at Shed 39 on the waterfront, up the Ngauranga Gorge to NZ Bus’ Newlands Depot.


We were then able to view one of the trolley bus fleet which has been converted to Wrightspeed technology and is undergoing prototype testing before being handed over to NZ Bus. The bus has an electric powertrain with a light-weight battery, regenerated by an on-board diesel micro turbine generator. When in use the battery would be fully charged overnight, the charge would be regenerated on down-hill sections of bus routes, and when necessary regenerated on-route by the on-board diesel micro turbine.

The batteries are at the back of the bus, and the micro turbine on the roof of the bus. We were told that the first bus could be received by NZ Bus after acceptance testing by November, and the fleet of 57 trolley buses could be converted to Wrightspeed technology in time for the new bus contracts which start on 1 July 2018.

I asked two questions:

Cr Blakeley’s Question One

If the batteries are fully charged at the start of the day and then recharged by the on-board gas-oil (diesel)-fired turbine during the working day, what fraction of the total energy input will be grid electricity and what fraction of the energy input will be gas-oil (diesel) fuel? (N.B. a fully-charged 40kWh battery would contain the same amount of energy as 4 litres of diesel fuel).

NZ Bus Response

Based on Wrightspeed mathematical modelling and assuming that the 40 kWh is fully charged overnight, and we run services in the day totalling 125 km (current average in Wellington) then the turbine will provide 89% of the energy input with 11% coming from overnight grid charging.

Cr Blakeley’s Question Two

How would the diesel consumption for the on-board Wrightspeed turbine over the working day compare with the diesel consumption of a new Euro-6 bus doing the same duty?

NZ Bus Response

Using the same assumptions as above then the effective fuel consumption of the Wrightspeed turbine over the course of the day would be 65.75% of the equivalent new Euro-6 bus.

My comment is that the response to Question One gives what appears to be a low figure of 11% of energy from the overnight grid. From talking to NZ Bus technical staff, this seems to be a worst case of no regenerating of the battery during downhill running, which could be the case for a flat terrain route. Technical staff said they were looking for a ‘sweet spot’, with slightly bigger batteries, and the capacity on Wellington’s hilly routes with down hill recharging to run for a whole day without the use of the micro turbine. That is, they would not need a micro turbine on the bus. In that event, the diesel fuel consumption would not be 65.75% of an equivalent new Euro-6 bus, but zero percent. I will continue to ask questions on progress towards this ‘sweet spot’.

by Daran Ponter
I travelled up Ngauranga Gorge in a BYD 100% electric battery bus yesterday.

The bus was brought into NZ by NZ Bus to provide baseline information for the the Wrightspeed conversion project.

Also yesterday, I travelled on a trolley bus converted to a Wrightspeed motor. Not fully completed but gave me confidence that this technology has a real chance of working in Wellington.

The bigger question is whether it will be cost effective to deploy. Time will tell.

Roger Blakeley and Daran Ponter are Wellington Regional Councillors.


  1. Chris Calvi-Freeman, 6. July 2017, 14:50

    Progress at last, but questions remain over battery range & vehicle weight. Hope these can be solved as our hills aren’t getting any less steep, nor are our roads getting stronger. And passengers, well let’s say they’re not getting any lighter either. [via twitter]

  2. Neil Douglas, 6. July 2017, 15:34

    Three tons of battery? That’s the equivalent to around 35 passengers (80kg as assumed by NZTA for an adult). I trust the batteries in the Wright Speed will be much lighter (say a ton). Surely they must know the weight?

    With heavy batteries MoT may insist on reducing the max passenger load which could translate into more passengers being left behind at bus stops in the peak period compared to a trolley.

    Also what safety checks are made on the batteries as there have been examples of exploding lithium batteries.

    Given the Wright speed efficiency stated above we can expect an increase in carbon monoxide of 6.1 tons a year plus half a ton of hydro carbons, 1.6 tons of NOx and 38 kg of PM10 as a result of converting our 60 existing trolley buses to Wright speed (based on two thirds the emissions of Euro 6, 125 kms a year and 250 days a year operation).

    What is the GWRC calculation for local emissions of a Wright speed compared to our zero local emission trolley bus?

  3. Mark Shanks, 7. July 2017, 8:31

    @ Cr Ponter – Why will time tell? Hasn’t the accounting been done? This entire conversion has revealed a lack of clearheaded planning from our council. It’s public transport on a wing and a prayer.

  4. greenwelly, 7. July 2017, 9:57

    @Neil ,the BYD has a 324Kwh battery (LFP),

    They are talking about a 40Kwh battery for the wrightseed so its equivalent weight would be ~400 kg

  5. Ramsey Eldib, 7. July 2017, 11:33

    Take a look at the Proterra BEV bus. Seems like a more fully thought out bus. Much lighter as it has a composite body. It was designed from ground up as a Battery Electric Bus.

  6. Elaine Hampton, 7. July 2017, 11:41

    Seems we are determined to retain a diesel component of bus transport. 11% on mains charge, not good enough, the technology can do better. Otherwise we should retain trolleys, really a no brainer.

  7. Daran Ponter, 7. July 2017, 13:01

    @ Mark Shanks The conversion of existing buses to Wrightpeed technology is wholly a decision for NZ Bus. No ratepayer funds have been invested into this trial.

    Once NZ Bus have worked through the final technological issues, fully tested the technology and crunched the numbers on the costs of conversion, they will be in a better position to determine whether the cost-benefit of deploying this technology stacks up. That time, I suspect, is at least another six months. In the meantime, NZBus will continue to provide bus services as per their contract with GWRC

  8. Daran Ponter, 7. July 2017, 13:11

    An issue that was raised at the presentation by NZ Bus is `geo-fencing’. This is the ability to specify areas of the city in which the the Wrightspeed buses will be 100% electric and the turbine engine will not operate. This specification could be quite fine (e.g. 100% EV when passing a school at particular times of the day), or quite broad (Willis St or Golden Mile).

    This then begs the question, for both Wrightspeed and other hybrid buses, about a policy for geo-fencing (i.e. where would the community prioritise for 100% electric mode), as well as the question of how this is enforced.

    I am looking to get this work onto GWRC / WCC agendas. Discussions will also be required with the Ministry of Transport.

  9. Alan Wickens, 7. July 2017, 16:05

    Daran. Did you actually ride on the Wrightspeed (former trolleybus 362) or were you referring to your ride as the one up to Newlands on the BYD battery bus? I understood councillors were only observing the Wrightspeed prototype as it is yet to be released for acceptance trials. I thought there was just the one prototype (362) but reading your Facebook post it seemed to suggest there was more than one. Could you clarify, thanks.

  10. Daran Ponter, 7. July 2017, 18:21

    @ Alan. We rode on the BYD from Centreport to Newlands, where we were given a presentation on the Wrightspeed prototype. We were then given a ride on the prototype inside the shed (backwards and forwards about 20 metres each way). It is awaiting some modifications. The turbine engine was not operational so didn’t get a sense of noise – through we were told that it is quieter than a diesel engine.

    From the photo above you can see a cowling on the roof that houses the turbine engine – this is only for the prototype.

  11. Daran Ponter, 7. July 2017, 18:35

    @ Ramsey I agree, fully built up electric buses might be a better option. But that’s not the objective here. Bus companies around the country, around the world for that matter, are facing some huge investment choices about the type of EV technology they adopt.

    Many bus companies face the prospect of “stranded assets” – assets that still have life in them, but which they can’t use. In the case of Wellington, the GWRC has made a decision to remove trolley buses (not a decision I agree with mind you). This means that come November this year, NZ Bus will have 60 buses that they can’t do anything with. In addition, the GWRC has said that from 1 July 2018 all current buses must be Euro IV or better. This again means that operators like NZ Bus will have stranded assets – a fleet of diesel buses that they can’t deploy in Wellington.

    If Wrightspeed stacks up financially it will be a very clever way to re-power buses which still have a lot of life in them. And it’s not just about the engine – it’s an opportunity to replace driving gear, electrics and improve the passenger experience. As battery technology improves the buses will have longer range and their reliance on the turbine will decrease. NZ Bus envisage that at some point they will be able to remove the turbine altogether = 100% EV vehicle.

  12. Neil Douglas, 8. July 2017, 19:01

    Darran P: Come July 2018, NZ Bus will have 250 buses it can’t use in Wellington, given it lost 75% of its contracts with GWRC. Presumably it will sell them. So why not sell the 60 trolley buses too? There should be an enlightened overseas northern hemisphere city willing to consider them. It would be good for Planet Earth to have Wellington’s trolley buses running somewhere 100% electric.

  13. Daran Ponter, 8. July 2017, 23:16

    Hi Neil. Of course, if they can find a buyer for the older diesels and the trolleys. Other regional councils have also started imposing more stringent emission standards so I suspect there will be a glut of older diesel buses.

    The buses are owned by the bus companies so they are free to do what they like with them.

  14. TrevorH, 9. July 2017, 8:41

    There is a fallacy at the bottom of all this gushing over “electric” buses. Batteries are incredibly energy intensive to manufacture and eventually dispose of. The carbon-footprint of three tonnes of batteries will be immense. Trollies or biodiesel are greener options.

  15. Keith Flinders, 9. July 2017, 20:17

    From NZ Bus we now learn that 89% of the energy required to propel a Wrightspeed bus will be from using a fossil fueled micro turbine. The other 11% coming from the overnight charging of the woefully inadequate 40 kW/hr battery being installed. At least 15 times that capacity is required if the micro turbines are not going to be deployed. A Nissan Leaf electric car has a 30 kW/hr battery and weighs about an 8th of a passenger bus. Energy required is related to work to be done.

    By this stage in the process the converted trolley bus should have been used to collect GWRC councillors from CentrePort, and take them to Newlands. Instead they are taken in a battery bus which has totally different characteristics to a Wrightspeed, so can’t be compared.

    We know that battery buses work; we should replace the trolley buses with them eventually, not Wrightspeed hybrids which offer so little in the way of fossil fuel savings compared to a diesel ones.

    The converted trolley bus can currently get from one end of a bus stop to the other, hmm. Pity that the noise level from the micro turbine was not demonstrated also, as these turbines will be in operation most of the running time of the Wrightspeed conversions, day and night.

    TrevorH’s point about the carbon footprint of the batteries gets worse as when in public transport applications they need replacing every 3 years. By way of contrast, Wellington trolley buses are still using some components recycled from buses of 40 years ago and the buses are 100% pollution free.

  16. KB, 10. July 2017, 10:39

    @trevorH: the ecological friendliness of battery production is dependant on the manufacturer. Yes they require a lot of energy to make, but if the energy used to manufacture them is 100% renewable then its Carbon footprint is far less than one made in a factory powered by coal. For instance the Tesla battery manufacturing plant is 100% solar powered. So saying that “the carbon footprint of 3 tonnes of batteries will be immense” is something that cannot be stated as fact unless you know where, how, and by whom the battery was made.

  17. Kerry, 10. July 2017, 14:44

    A gas turbine bus should have much lower pollutant emissions than a diesel, but does it have lower carbon emissions?
    How noisy is it? There is no way that a hybrid bus can come anywhere near a Wellington trolley bus for carbon emissions, or noise.

    The only options for emission improvements on the existing trolleybuses are new trolleybuses or light rail.

  18. Keith Flinders, 10. July 2017, 21:27

    Kerry: Not my words, but the following comments are from an engineer involved in this field. Others with knowledge in the field may wish to voice their opinions.

    “The turbine’s efficiency is no doubt appallingly low (certainly much less than 30%) when using automotive turbocharger technology and no word on how they manage to run the hot end turbine at the 1400C needed to get decent efficiency. Take into account the stop/start operation of a public transport bus and its low average speed. Wright appears busy solving the wrong problem as he starts with the answer is a turbine, and his benchmark is a less than a 30% thermally efficient 1940s aircraft petrol engine with a 600 hours between overhauls, not a modern 45% thermal efficiency turbo intercooler and after cooled twin turbo diesel with a 20,000 hours between overhauls. His rubbish truck running a small modern diesel range extender would cost less and be more fuel efficient. He appears to be trying to find answers for micro turbines, but efficiency wise they are not the answer. Hence the Wrightspeed buses will be expensive and inefficient failures. Just like rotary engined cars, they worked but they were intrinsically expensive gas guzzlers.”

    No one yet knows how noisy the converted buses will be, what battery protection there will be if a bus gets rear ended, and if will they get certification to be on the road. Issues that ought to have been addressed 12 months ago by the GWRC. Lithium ion batteries present thermal runaway dangers when punctured, and there have been many battery fires on buses. .

  19. Paul Clutterbuck, 13. July 2017, 13:14

    GoWellington would have been better to convert the trolleys and its Euro III-IV-V diesels with the Siemens ELFA 2 system, which has been used on buses throughout Europe. Another option would be the Ziehl-Abegg electric axle, used successfully by VDL Bus & Coach and others. The Wrightspeed solution is likely to fail just like Designline’s gas turbine hybrids did in the late 90s and early 2000s.

    I wouldn’t recommend BAE HybriDrive, not because it’s not a successful and proven system, but because British Aerospace Engineering is a nuclear weapons manufacturer and defence-sector supplier which it would be immoral and possibly illegal for New Zealand companies and councils to support.

  20. Jack Davis, 30. July 2017, 7:50

    Paul Clutterbuck: the DesignLine buses were running in Christchurch successfully and with popularity up until the earthquake. They did not have so successful a run in Auckland. They had the advantage of a microturbine which has been developed and successfully deployed, mainly in stationary applications, for over twenty years.
    It’s been claimed that the Wrightspeed system has been running successfully overseas, but to my knowledge that is not quite correct. FedEx trialled two Wrightspeed delivery vans which were powered by the same brand of turbine as the Christchurch buses. On the basis of that trial, FedEx placed a further trial order of, I think, twenty vans. Then Wright pulled his ‘Fulcrum’ turbine out of his hat blindsiding the previous turbine supplier. At that point, I think, FedEx interest diminished and there seems to be no longer a connection.
    With much fanfare, Wrightspeed delivered one converted rubbish truck to Ratto Group after long delays similar to the GoBus saga. Ratto has since met regulatory and financial troubles and been taken over by a bigger outfit. Nothing more has been heard of the Wrightspeed truck.
    It is interesting that the turbine was ‘not operational’ during the Councillor’s visit.

  21. steve, 2. October 2017, 17:37

    We should never be replacing an electric system with diesel, which is what we’re doing here. Replace the diesel buses with Wrightspeed and leave the electric trolleybuses as they are until we are able to run a 100% battery operated system.

  22. Mary Daynes, 9. October 2017, 19:14

    Thanks for the information. My question is: when is an electric bus not an electric bus? Well that would be when it needs diesel. Tonight the news says Wellington has done an amazing thing – dumped the trolley buses for diesel. Well done Wellington.