Thursday, 24 July 2014
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Wirelessly charged, all-electric bus route is first for UK

Plans have been unveiled for the UK’s first wirelessly charged, all-electric bus route using vehicles that can match the capabilities of diesel models.

British engineering company Arup and Northern Irish manufacturer Wrightbus are among the organisations that today signed a five-year agreement to run the trial route in Milton Keynes, in anticipation of the end of a government bus fuel subsidy that will make electric vehicles more attractive.

The scheme, which is led by a partnership between Arup and Japanese conglomerate Mitsui, is designed to show that using wireless charging technology to recharge the electric buses throughout the day would allow them to fully replace diesel ones.

Prof John Miles of Cambridge University, who initiated the project and is Arup’s lead on it, told The Engineer that this would be the first time an established diesel bus route had been completely electrified.

‘People have been running electric buses on urban routes for quite a few years but they’ve always put a couple on a route that is already well served by diesel buses and when they run out of puff they simply get covered by more diesel buses,’ he said.

‘[We want to show that] you can put a fleet of electric buses on the ground and expect them to work the same hours and the same hardship routes you would expect a diesel bus to work.

‘[We also want to prove that] when you’ve done all that, it’s marginally cheaper to run electric buses than the diesels. If you can prove that then we believe that the transition afterwards to electric buses will be natural.’

The trial will involve installing wireless charging technology from German company Conductix-Wampfler at three points along a bus route in Milton Keynes from June 2013, allowing the new electric buses to recharge quickly during the timetabled 10-minute driver changeover time.

These 10-minute charges should replenish around two-thirds of the energy used on the bus’s route. By topping up the charge throughout the day, the bus should be able to complete an entire timetable, which could be up to 20 hours’ long in busy urban areas, without the need for a prohibitively expensive and heavy battery.

The partners say replacing the existing diesel buses should remove around 500 tonnes of tailpipe CO2 emissions a year, as well as 45 tonnes of other noxious tailpipe emissions. The route currently transports more than 775,000 passengers a year over a total of 450,000 miles.

Wireless technology is key to charging the battery in such short periods of time because it removes the need for a large, heavy cable that would slow the process down considerably, said Miles.

He added that while electric buses were generally twice as expensive to buy as diesel ones, the running and fuel costs should be much lower, saving around £12,000 to £15,000 a year.

‘At today’s prices, you cut the fuel costs to about a third. But the government is actually withdrawing an operating grant so bus operators face diesel prices that will become the same as the pump price. And when you get to that point in four or five years then you’re talking about a quarter of the costs.’

The trial will run until 2017 in order to collect enough to data to demonstrate the economic viability of low-carbon public transport, which the partners hope could kick-start electric bus projects in other towns and cities worldwide.

The scheme is run by Mitsui and Arup’s joint venture MBK Arup Sustainable Projects (MASP) and also involves Western Power Distribution, Chargemaster, Scottish and Southern Energy and Milton Keynes Council.


Readers' comments (15)

  • What precautions will be in place to prevent ill-intentioned persons causing problems with the power transfer system when the bus is present or absent?
    What is the efficiency of the power transfer system?
    Do the CO2 figures take into account the CO2 produced by the power station that makes the electricity used during charging.

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  • The transfer efficiency of this kind of technology is around 90 per cent. Take a look at our report on the topic for more info: http://www.theengineer.co.uk/in-depth/the-big-story/unplugged-inductive-charging-on-the-road/1006269.article

    The CO2 figures are related to tailpipe emissions only. Obviously as with any alternative propulsion technology, eliminating associated carbon emissions depends on the separate task of decarbonising the electricity supply. But emissions associated with electric vehicles are still lower than those of petrol engines even when the electricity is generated using coal. http://www.afdc.energy.gov/vehicles/electric_emissions.php

  • Fine - as long as _extra_ non-fossil fuel sources are available for the extra electrical energy required.
    Otherwise, "Coal by Wire", as Lord Robens once succinctly described it - (or perhaps nowadays, "Gas by Wire")...

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  • The article states that costs will be compared (and that is a major focus for service providers) but really it is relative efficiencies that matter to the public (costs are manipulated by taxation and subsidies, so are deceptive and can change on a whim). Accepting that much of our electricity will be generated from hydrocarbons for the forseeable future, is it more efficient and cleaner overall to have battery charging diesel engines on busses than to charge batteries as suggested?
    One clear advantage of the proposed system is that pollution local to the bus routes will be reduced.

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  • To recharge approx 2/3 capacity of a buses usage in 10 minutes pre-supposes a serious electrical energy supply, presumably powering coils under under the roadbed. I calculate that a bus over 2 hours and using an average of 20bhp will require 7 1/2 KwH to recover power usage so the charging density for 10 minutes will be 7 1/2 x 6 = 45 KW. If I've got the numbers right, this seems a lot to me.
    If this is an 'always on' system, will there be problems with eddy current generation in cars passing above the coils. Unless the system is only 'on' when a bus is stopped above it, or is in bays that cars are physically unable to enter, then I forsee problems.
    I'll also bet that some enterprising pirate will develop a way to use the charge point free for their own use.
    Also, what effect will these charging points have on nearby automobile or personal electronic equipment?

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  • According to John Miles at Arup, the charging system will actually supply 120kW of power.

    Wireless charging technology is designed to only activate when the receiving vehicle is parked in the correct position above it. The equipment is designed such that the electromagnetic field it creates is tightly shaped so as to only interact with the vehicle.

  • Cleaner cities and a decent hedge against future oil prices. Wireless charging teshnology has been around for decades but hopfully will now see its true potential.
    I'm sure pirates will be able to steal some electricity but it is easier to do today as the wireless tech talks to the device being charged (be it a laptop or bus) and only authorised devices can switch the charger on.
    As regards co2 from the grid v co2 from the tailpipe. People forget about all the co2 inbedded in petrol before it ever gets to the pump. There are plenty of studies that suggest petrol cars already consume vast amounts of electricity reflecting how much coal and gas you have to burn to refine petrol and deisel in the first place. and the grid gets cleaner everyday.

    win less subsidies
    win cleaner cities
    win less co2
    win reduced fuel imports
    win cheaper full lifecycle

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  • Seems like a excellent concept and well worth pursuing, however the one advantage of diesel buses is their flexibility and low infrastructure requirements.
    If the power coils charged the electric buses from the side and not from underneath then roads wouldn't need to be dug up and the power coils could be easily be relocated if routes changed. Maybe a small stretch of guided busway, like the one in Cambridge, could be utilised for recharging on the move.

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  • Glad my sums were more or less ok. 120Kw is a lot of power. If I recall my formal educative days, now long past, then Volts X Amps = Watts. Whichever way you slice and dice 120,000 watts it'll need some hefty power equipment installing and supplying from somewhere

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  • "it’s marginally cheaper to run electric buses than the diesels.", does that include the cost of replacing and recycling the batteries?

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  • This is a brilliant idea, don't knock it before it even starts. Surely the idea of a trial is to evaluate, modify and prove based on actual results not theory. Just a shame it will probably be sourced from overseas.

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  • The wireless charging technology is made by German firm Conductix-Wampfler but the buses are from Northern Ireland-based manufacturer Wrightbus.

  • The idea is sound.What is the effect of the ElectroMagnatic field on human body?
    Do other close to body devices like mobile, walkie-talkie, pacemaker, tablet pc expect signal deterioration?

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  • 120 kW is quite a substantial load but there are many industrial users that have far greater demands and l dont think the infrastructure would be ridiculous. The energy transfer rate might ramp up over a few seconds and such a "soft start" would help reduce costs.

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  • John MacKinnon.
    There is a distinct difference between 'knocking' and asking pertinent questions. That's what engineers do, and sometimes the answers to these questions may help develop yet better equipment.

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  • 120Kw = approx 3000 street lights. Seems to me heavy duty for a city road based charging point. I have visions of every electrical device and building within a mile going dark for 10 minutes while the charger is 'on'.

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  • Ref JohnK
    The proposal has been developed by engineers and scientists, not politicians or environmentalists with perhaps other agendas. By all means question but don't delay if, as I understand, locals are in agreement with the proposal. Let the trials begin, you never know, there could be an oportunity for electric cars and vans to be developed from this.

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  • JohnMac - I am one of those 'locals', which is why I am asking the questions regarding safety and electrical loading.
    I don't dispute this has been designed by engineers, but surely you cannot believe that politics, local and possibly national are not the final decision makers.
    As for locals being in agreement, whilst I am not a dedicated follower of local politics, I heard nothing about this trial before this article and I dare say this is probably true of the majority of 'locals'.

    I'm not against this in principle, but too many 'trials' go ahead without sufficient forethought being given to possible consequences.

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  • As far as we're aware, this is the first time the trial has been announced and the vehicles aren't due to be put on the roads until summer next year.

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