Hamburg goes hybrid

21 October 2013

As part of its plan to be a leader on the road to fully electric public transport, the city of Hamburg has taken delivery of a new fleet of Volvo hybrid buses. Jim Banks talks to Edward Jobson and Thomas Hartmann of Volvo Buses about the benefits of their technology and how hybrids bring a fully electric future one step closer.

Hamburger Hochbahn, the operator of Hamburg's underground transportation system and large parts of the city's bus network, has been bold in setting its environmental agenda. The company has taken a long-term view toward a future where fully electric public transportation reduces carbon emissions, fuel consumption and noise pollution. Its plan recently took a big step forward with the help of Volvo Buses.

A new fleet of 15 buses - the environmentally friendly, low-floor, parallel hybrid Volvo 7900 Hybrid model - was commissioned at subsidiary Friedrich. They will operate mainly in the south of the city, where they will be fully integrated into regular scheduled services. The move is validation of Volvo's belief that the environmental agenda, driven in part by changing European regulations, will be the biggest influence on bus technology in the years ahead.

"Sustainability is a big priority and there are many different drivers," says Edward Jobson, environmental director at Volvo Buses. "The main focus is on improving cost-efficiency and reducing price without sacrificing performance. The progress on environmental regulation is also rapid, and we have to keep pace with that. Euro 6 will be much improved on the Euro 5 version."

Euro 6 is the latest incarnation of the EU's regulatory regime for passenger vehicles. When it comes into effect next year, it will further define emissions output thresholds for light commercial vehicles.

"The hybrid model is very efficient, providing carbon emissions reductions of up to 25%," says Thomas Hartmann, commercial director of Volvo Buses Germany. "That is a mighty impact, though it could be even more efficient. We have delivered two lots, so the customer must be satisfied. Also, Euro 6 is defining other negative effects of the internal combustion engine, so it is also important that hybrids reduce noise pollution, for instance."

"The 25% figure comes from the operator in Hamburg, but the reduction could be even greater depending on the circumstances," says Jobson. "But in Hamburg, this is the benchmark compared with the original reference point."

Pushing boundaries

The Volvo 7900 Hybrid could, against some benchmarks, save up to 39% of fuel costs. It is the company's second series-produced hybrid bus model and its development has been informed to a large degree by the operation of its predecessor, which has been on the market for some years, and has proven its ability to successfully deliver both fuel savings and reliability.

The extensive experience Volvo has gained from the operation of the first model has allowed it to further develop its versatile drive-train solution to combine the key benefits of emissions reduction, high performance, economy and reliability. The new model features a lighter body design, higher passenger capacity, better fuel economy, up to 50% lower exhaust emissions, and the versatility to adapt to both inner city and suburban traffic conditions.

These improvements were key to Hamburg's choice when the city decided on how to make its next step towards the ambitious goal of buying only emission-free buses from 2020. The city envisages a future built on electric transport and Hamburger Hochbahn, as one of the largest public transport operators in Germany, is aware that it must be a front-runner in the introduction of alternative drive technologies.

"The 'Green Efficiency' strategy of Volvo Buses includes more than simply environmentally friendly vehicle concepts – it must provide complete system solutions."

"A promise was made by the lord mayor of Hamburg that the city will buy only emission-free vehicles from 2020, so they are starting with hybrids, but not as a compromise," explains Hartmann. "Every decision on hardware must make economic sense. It has to deliver on a real business case.

"We are already in discussion with other cities interested in hybrids as a stepping stone to fully electric public transport, such as Munich and Cologne, and we are very strong in the north of Germany. In Munich, where we came into the picture late in the day, our vehicle is competing well among hybrid models and has shown fuel economy greater than 28%," he adds.

For Volvo, Germany is a good place to make inroads. One reason is that - as in Hamburg - there is often a willingness to cooperate between vehicle manufacturers, politicians and the operator of the transport network. A second reason is that passengers are often used to alternative public transport options.

"In Germany, 59 cities have a tram system, so electrically powered travel is already accepted," says Hartmann. "In those cities there is the least resistance to other forms of electric transport."

Of course, Volvo's plans extend far beyond Germany, but cities like Hamburg give the company valuable opportunities to evaluate their technology and the support systems that accompany it.

The 'Green Efficiency' strategy of Volvo Buses includes more than simply environmentally friendly vehicle concepts - the company understands that it must provide complete system solutions.

This entails the installation of infrastructure and charging stations as well as supplemental service offerings such as battery and maintenance contracts, telematic services and an extensive fleet management portfolio.

"This is a very competitive market and there are a lot of big cities investigating how to reduce carbon emissions, often backing up their measure with fines," notes Hartmann. "The issue is complex because it is not only about the efficiency of the vehicles, but also whether workshops can accommodate another model of vehicle. We have to educate and manage the training of specialists as well.

"Volvo has many differentiators when it comes to hybrid vehicles," adds Jobson. "We have proven technology and our buses have been in operation since 2010. They provide higher fuel savings than competing models, thus reducing costs, and they have very good reliability. We have versatile in-house technology so the vehicles suit all kinds of road that a bus would run on."

No standing still

The process of development that led to the 7900 Hybrid entering operation in Hamburg has not stood still, with Volvo already testing new technologies that will drive hybrid technologies further towards the goal of fully electric transport. Eying a full roll-out of commercial production in 2015, the company is in the research and testing phase for the Volvo 7900 Plug-in Hybrid, which it believes could save operators up to 80% of their fuel costs and emissions.

The Plug-In Hybrid model, three of which are being trialled in Gothenburg, is different in that with just a few small changes to the original hybrid technology, the vehicle can connect to the electricity grids through a collector installed on its roof. It also has a bigger battery, so that it can operate in fully electric mode in the city centre by charging at bus stops. When the vehicle is idling at a red light or bus stop, the diesel engine can be shut off, reducing emissions to zero. In electric mode, the noise reduction is in the range of 20dB.

"We are optimising the system for the average user, not just for a very specialised application."

In the Plug-in model and the version of the 7900 Hybrid that is hitting the streets in Hamburg, the battery is recharged when the bus is using the diesel engine to achieve higher speeds. Both models feature active temperature-controlled lithium-ion battery cells, with individual cell charge control, which results in more reliable and efficient energy storage.

Alongside the trial of the Plug-in hybrid in Gothenburg, the company is planning a further demonstration project in 2014 in Stockholm. As in Hamburg, the buy-in of politicians, operators and vehicle manufacturers will be crucial.

The other key factor in determining how successful such hybrid technologies are in moving public transport to a fully electric future will be the speed of passenger acceptance. This, however, does not seem to be a big problem in countries like Germany and Sweden, where the travelling public seems willing to embrace the change. Volvo has made that transition easier by looking closely at passenger needs and designing buses that improve environmental performance without any negative impact on how the transport network services the community.

"We are optimising the system for the average user, not just for a very specialised application," says Jobson. "Although, to get the right cost-efficiency, there needs to be a certain frequency of buses, around ten an hour. So, the plug-in technology would not be used on countryside or regional buses. Some roads and routes support fully electric travel, some hybrid and others the plug-in technology. There is no one single technology for maximum cost efficiency.

"Hybrid and fully electric travel is becoming very familiar to passengers in Europe, though it takes a few years for people to get used to the technology. But times are changing."

Volvo is committed to designing buses that combine environmental performance with practicality.
The environmentally friendly, low-floor, parallel hybrid Volvo 7900 Hybrid.
In the version of the 7900 Hybrid, the battery is recharged when the bus is using the diesel engine to achieve higher speeds.
The Hamburg handover (© Marc-Oliver Schulz)

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