BUS AND ENGINEERING

Two 12-metre BYD ebuses are in service in central London with Go-Ahead

quiet revolution is slowly unfolding in Britain’s city centres as electric buses Astart helping to reduce urban air pollution and background noise. Already a supporter of battery power as a means of making mass transit cleaner and more efficient, Nottingham City Council, for example, has ordered 13 single-decker electric 12- metre ebuses, constructed by Chinese manufacturer BYD. They will join 45 electric buses already operating there. Buses and coaches are seeing greater uptake of advanced engine Two 12m BYD ebuses are also in service and transmission technologies, thanks largely to the incentives in central London, with Go-Ahead. Nottingham’s ebuses have a claimed available. Steve Banner looks at some of the latest systems range of just over 155 miles, so seem unlikely to run out of juice between 190 miles earlier this year, although there charge after 10 years, so can thereafter stops. However, costing one-third more are no plans to market it in the UK. be switched to static applications. than their diesel equivalents, ebuses do But BYD is by no means the only Also equipped with batteries, diesel- not come cheap. In Nottingham’s case, electric bus manufacturer. Rivals include electric hybrid buses can make use of an their purchase was part-funded by a and . Last year saw induction charging system. Last autumn’s £1.4m grant from the DfT’s (Department eight electric Wrightbus StreetLite 9.6m Euro Bus Expo, held at Birmingham’s for Transport) Green Bus Fund. The single-deckers go into service with NEC, saw and £2.1m balance comes from the city’s on a 15-mile route through the centre of extolling the virtues of a system that workplace parking levy. Milton Keynes. In this case, an induction employs roof-mounted rails rather than a charging point was installed in the road plate in the road. This allows Lothian’s RAPID CHARGING at both ends of the route, and now a 10- Volvo 7900H 12m hybrid single-deckers Recharge times? Go-Ahead’s ebuses minute layover replaces two-thirds of the to run for almost five miles on battery have to be plugged in for five hours, but energy consumed during each run. power. can then tackle a 17-hour shift, says BYD. One issue: traction batteries Meanwhile, battery disposal is not an Technology is continuing to develop, it eventually have to be disposed of, which issue with some other packages adds, with two hours now a realistic raises environmental concerns. However, becoming available. Last November, figure. Also, BYD unveiled a 47-seater BYD contends that the iron-phosphate ADL committed to acquiring 250 electric coach with a claimed range of batteries it installs still hold 75% of their Gyrodrive electric flywheel systems from

June 2015 www.transportengineer.org.uk 41 BUS AND COACH ENGINEERING

Technology is continuing to develop, with two-hour charging now a realistic figure. Also, BYD unveiled a 47-seater electric coach with a claimed range of 190 miles earlier this year, although there are no plans yet to market it in the UK

Heading down a similar path is Top gear Wrightbus with the Flybrid KERS (kinetic Braking systems energy recovery system) developed in a Fuel economy on gas and diesel engines is collaborative project with Torotrak, Voith Safety is of paramount importance, particularly heavily influenced by gearbox programming Turbo, Productiv and Arriva (see page on passenger vehicles. AEBS (advanced and, specifically, the timing of gear changes. In 12). This, too, uses a flywheel but in this emergency braking system) has been Allison’s case, its new FuelSense package – case linked to the rear diff by its own mandatory for all new type approvals on which is suitable for use on its automatic bus prop shaft, transferring energy directly. coaches since 1 November 2013. Stage 1 AEBS transmissions – is said to be capable of However, this should not be confused will be compulsory on all new coaches from 1 improving economy by up to 20% compared with the Micro Hybrid package offered November this year, while Stage II, which with the its earlier generation transmissions. on both StreetLite and the new imposes more demanding deceleration, will be It does so by taking into account factors StreetDeck double-decker. This also introduced on 1 November 2018. such as how steep an incline is and how recovers braking energy, but then uses it Both stages mandate equipment that can heavily the vehicle is laden and optimises the to power the bus’s pneumatic, hydraulic detect moving, decelerating and stationary shift pattern accordingly. It draws the data it and electrical systems. vehicles ahead, and alert the driver. If there is needs from sensors attached to the engine and no response, emergency brakes are applied transmission, and from a built-in inclinometer. COOKING ON GAS automatically. What about gas? Most believe it has a significant role to play. Biomethane GKN Hybrid Power. Designed to last the produced by a local sewage treatment Government funding for the purchase life of the vehicle, Gyrodrive employs a works, for example, is being used to fuel of low-emission buses – and the high-speed carbon fibre flywheel to one bus operated by Bath Bus Company infrastructure to support them – has store energy generated by the bus as it on a shuttle service between been given a fresh boost with the launch slows. That energy is then used to power Airport and Bath city centre. The new of a £30m package by OLEV (the Office a GKN EVO electric motor, which helps vehicle produces up to 30% less CO2 for Low Emission Vehicles). It will be accelerate the vehicle. than equivalent diesel buses. available from April 2016 to March 2019. One Euro 6 Enviro400 double-decker Then, at the other end of the UK, All that said, one of the best ways of fitted with Gyrodrive has already Aberdeen saw the opening of a reducing fuel usage – and hence achieved Low Carbon Emission Bus hydrogen production and bus refuelling emissions – is to cut the vehicle’s weight. Certification, says ADL. This signifies a station this year that will be used to fuel ADL has slimmed both its Enviro400 and 30% cut in CO2, which gives an 10 fuel cell buses built by Van Hool. Six the single-decker Enviro200, and the indication of the fuel saving and entitles will be operated by Stagecoach while latest Euro 6 versions are lighter than operators to enhanced fuel rebates. four are set to join FirstGroup. their predecessors to the tune of 400kg and 200kg respectively. Meanwhile, Optare’s MetroDecker double-decker (unveiled in 2014) boasts an unladen weight of under 10 tonnes, thanks to its integral construction and composite panels. Powered by a 5.1-litre twin-turbo Mercedes-Benz diesel, this vehicle highlights another trend – the drift to smaller, lighter engines at Euro 6. And an all-electric model is set to break cover later this year. So which way is the wind blowing? “Electric buses represent the future,” suggests Optare chief executive officer Lothian Buses uses an induction Enrico Vassallo. “I do not see hybrid charging system, in roof-mounted rails technology as a long-term solution.”

42 www.transportengineer.org.uk June 2015