Putting electric buses to the test
The service will operate between Bletchley and Wolverton via Milton Keynes city centre with charging points located at either end of the route that are designed to top-up the bus’ batteries during a ten-minute layover.
The 15-mile route, currently served by seven diesel buses, operates seven days a week for up to 17 hours a day, and carries more than three quarters of a million passengers annually with each bus required to cover more than 56,000 miles a year. It is estimated that the use of electric buses on the route will reduce CO2 emissions by at least 269 tonnes a year.
A prelude to the demands of the route was evident on the launch day when one of the three buses - it was bound to be the one carrying all the media - refused to start after demonstrating the charging point at Wolverton. Wrightbus product director Mark Mitchell explained that there had been a fault with the sensor which incorrectly believed the charging plate was still down. However it was only a brief cessation as Arriva’s engineer was rushed to the scene to get the vehicle going again. A difficult moment for the organisers but, to be fair to them, the problem could well have been exacerbated by the fact that the TV crews repeatedly demanded to see the charging plate lowered to get shots from different angles. Indeed a slightly chastened BBC reporter admitted to me that he did feel somewhat uncomfortable as he had to use the fact of the breakdown in his story, whilst possibly being partly responsible. We will find out whether regular customers will be as demanding as the TV camera crews once the vehicles go into service.
Arriva is taking no chances however. Area MD Paul Adcock says that he plans to phase in the electric buses from 19 January and only switch to 100 per cent electric once everyone is satisfied that everything is working satisfactorily.
The attraction of the induction charging method is that it requires very little in the way of urban space. A plate set into the road at the terminus stops uses a technology that can be traced back to 19th century scientists Faraday and Tesla who demonstrated that magnetic fields can be used to ‘induce’ current in a wire. The buses stop above a primary coil set into the road and the bus’ charging plate containing the secondary coil is lowered enabling high-efficiency transfer of 90 per cent. It is claimed that a ten-minute charge will replace two-thirds of the energy used during the 15-mile route.
There is also a plug-in option at the rear for a slower overnight charge, which might not be necessary to keep the vehicles fully charged according to some of those involved in the project, but it does have the benefit of balancing the battery cells and thereby extending battery life.
The StreetLite EVs are 9.6m long with 37 seats and nine standees. This is fewer passengers than an equivalent diesel StreetLite of course due to the weight of the batteries, but the ‘opportunity charging’ offered by the induction system means that it compares very favourably with the weight of the BYD buses recently launched in London, albeit that the latter are full-size buses. The unladen weight of these StreetLite EVs is 9,720kg with a 13,000kg GVW, whereas the BYD buses’ unladen weight is 14,000kg.
The launch of the Milton Keynes StreetLite EVs was attended by transport minister Baroness Susan Kramer who pointed to the fact that the UK is being seen as a world leader in this type of technology. “These ultra low emission buses will offer the travelling public a quieter, smoother journey as well as cutting carbon and improving air quality,” said Kramer. “This project represents a fantastic opportunity to learn more about extending the future capability and rollout of electric buses.”
An impressive partnership has been developed to deliver the project with Arriva and Wrightbus being joined by Mitsui, Arup, Milton Keynes council and Cambridge University. An enabling company, eFleet Integrated Service, has been established by Mitsui and Arup to lead the project and has acquired the buses from Wrightbus, with support from the Green Bus Fund, and is subsequently leasing them to Arriva. The induction charging system is supplied by Conductix-Wampfler, the company which has provided the infrastructure for around 30 electric buses operating in Turin and Genoa for nearly a decade.
The Milton Keynes programme director is Arup consultant, professor John Miles, Cambridge University who believes that the scheme is a prime example of an enterprise-led initiative that is enabled by central and local government. “Electric buses’ physical and economic potential has historically been sidelined because no one could see around the range problem associated with the batteries,” said Miles. “Wireless charging can bring electric buses in from the cold, and potentially put them neck-and-neck with their diesel counterparts. If we can demonstrate true parity with diesel buses during this trial, we’ll have reached a tipping point for low-carbon transport - we’ll have proved it can be cost-effective as well as green.”
There is a real sense that electric buses without wires really could be a game-changer.
We look forward to reporting the results from Milton Keynes as the five-year trial progresses.