The first of a batch of six Volvo Hybrid Double Deckers, takes centre stage on the Volvo stand at the Euro Bus Expo at the NEC. The advanced parallel hybrid technology on this vehicle, unique to the Volvo Group, offers potential fuel savings, air quality improvements and significant whole-life cost reductions in operation.
The six Volvo B5L Hybrid buses are due to enter service with Arriva London during the period December 2008 to January 2009 and will operate on Route 141, being based at Wood Green.
This new Volvo Hybrid will enter series production in the fourth Quarter of 2009 and deliveries of complete production double deck vehicles will commence early in 2010. There will be some early production vehicles on the road in 2009.
The chassis layout follows the same principles as the Volvo 7700 Hybrid, which was recently launched at the IAA in Hanover, with a rear offset driveline. The battery energy storage unit is installed under two of the seats in the lower saloon, just behind the front axle, to achieve the minimum intrusion into the gangway and to optimise the weight distribution.
The show vehicle features Gemini bodywork, from Wrightbus in Ballymena, which is already a familiar sight in double deck fleets across London. With an overall length of 10.4 metres, the vehicle offers 66 seats (45 upper saloon, 21 lower saloon) and space for up to 20 further passengers.
A Long Experience in Hybrid Development
The new Volvo B5L Double Deck is a testament to Volvo Buses long experience in hybrid development, which dates back to the early 1980’s, a timescale which also underlines Volvo’s commitment to its core value of Environmental Care. That long experience has been distilled into the refinements seen in this new concept, which has prioritised commercial viability.
Ever tougher environmental standards for buses, be it emissions or noise, combined with the uncertainties over fuel prices in the long term, mean that the time is now right for hybrids to enter the market in quantity. However, that can only happen if the product is a commercially viable proposition for the operator.
To ensure this, the Volvo Hybrid technology and components are shared across several Business Areas in the Volvo Group, in to order to achieve higher volumes: Volvo Trucks have recently announced a hybrid development and plans are well advanced at Volvo Construction Equipment.
“Irrespective of the environmental benefits, it is vital that hybrid technology is quickly seen to be a good investment for the operator, with savings in fuel and other costs paying for the additional costs of the driveline” says Steve Dewhurst, Managing Director of Volvo Bus UK & Ireland.
“Our development builds on the strengths of the Volvo Group and means that service support and parts availability will be to the standard of any Volvo product. That support will include leasing and contract maintenance packages as a matter of course”.
The Driveline Elements
The key elements of the Volvo Hybrid are:
• D5E 4 cylinder 5 litre Volvo diesel engine to Euro 5 emissions level with SCR exhaust aftertreatment
• Volvo ISAM Integrated Starter Alternator Motor electric machine to provide parallel operation of diesel and electric power
• Volvo I-Shift 12 speed automatic transmission
• Lithium-Ion Battery Energy Storage System, rated at 600 Volts, water cooled
• Electrically-driven Air Compressor, Hydraulic Pumps and AC/Air Chill compressor
The chassis module is very similar to that of the existing Volvo B9TL Double Deck. Many proven Volvo components can be identified from the front end through to the drive axle, driveline and rear suspension for maximum service commonality.
The Hybrid Vehicle Management System includes the software “brain” of the vehicle and this interfaces with the regular Volvo diagnostic functions.
The ISAM unit is integrated in the clutch housing between the diesel engine and the gearbox, this allows for combining the power inputs of both motors in the simplest way. In a parallel hybrid, the vehicle can be driven by both the diesel engine or the electric motor or any combination of the two.
This means that the diesel engine can be downsized from that of a conventional bus, and at the same time the electric motor can also be smaller, because it does not have to provide the maximum power level on its own. Combining the two sources provides the power needed to climb steeper hills or for maximum acceleration.
The strategy for managing the hybrid system prioritises fuel efficiency and therefore reduced emissions of carbon dioxide. At the same time, the range of gear ratios in the transmission means that the diesel engine can operate in its most efficient range more of the time.
It is also possible to operate in purely electric mode - at bus stops for example – to minimise local air quality emissions in sensitive areas: the bus can pull away from the bus stop in quiet electric mode and engage diesel power as the system requires for maintaining battery charge. Normal braking can drive the ISAM unit in alternator mode to achieve regenerative braking/energy recovery to charge the battery and this is another key step to reduce fuel consumption.
Driving the auxiliary systems with electric motors also saves energy because the load can be delivered when needed most – as with power steering where the most power is needed at low speeds so matching the demand avoids wasteful operation.
Thorough Development and Support
The Volvo parallel hybrid system has been under development for some years, as can be seen in the presentation of a development vehicle at Euro Bus Expo in 2006. During that period, single deck and double deck test buses have been undergoing a comprehensive development programme centred on Volvo’s Hällered test complex in Sweden.
The next step will be the in-service operation of six Double Deckers in London and a Single Deck bus in Sweden. As well as defining the best control strategies for the vehicles to deliver the best results, this operation will also give operators, drivers and maintenance staff the practical experience needed ahead of volume introduction.
The Arriva London vehicles will be taken care of through the Volvo Truck and Bus Centre at Enfield, as the hybrid package and much of the chassis will be on a Contract Maintenance agreement. In addition, Transport for London are supporting the programme.
The Potential Benefits
The Volvo Hybrid Concept should deliver significant savings in fuel consumption – potentially up to 30% - and corresponding reductions in emissions of carbon dioxide, the principal greenhouse gas contributing to man-made global warming.The more effective use of the diesel engine will result in reduced emissions of NOx and Particulates, two key pollutants in urban areas.
The Hybrid bus will be quieter in operation because of the reduced use of the diesel engine. Passengers will also experience a smoother ride because of the characteristics of the electric motor and, in turn, service and mechanical maintenance demands should also be reduced because of the smoother operation.
Volvo Buses will be following the introduction of the hybrid system in Single and Double Deck buses with an articulated vehicle in the future.
Looking longer term, a parallel hybrid has the potential to also deliver fuel savings on intercity and express routes - although savings may not be as significant as on a citybus, the longer distances travelled in express services still result in significant fuel savings. There is therefore considerable potential for greater sales volumes in the future.
Speaking at the show, Steve Dewhurst said, “We see the new Volvo B5L Hybrid Double Deck as one of the most important developments in recent years. Whilst diesel-only powered buses are likely to continue to be the bedrock of bus fleets for many years to come, hybrid vehicle projects which can prove their commercial viability will be watched with great interest by operators in cities throughout the British Isles.”
4 November 2008
Photographs: A selection of images to accompany this and other show press releases is available for download at the media centre section of www.whenproductivitycounts.com