Next stop, hybrid: Volvo's sustainable bus fleet

30 August 2012



A new fleet of 25 Volvo hybrid buses is fresh on the streets of Gothenburg and another cutting-edge model is currently rolling off the assembly line as the firm continues leading the charge towards making diesel obsolete. Volvo Buses’ area director north Uri Peleg and environment director Edward Jobson discuss the project.


Urban Transport Agenda: What are the key issues involved in transitioning to more sustainable bus models?

Edward Jobson: Our EU 20/20/20 target is to decrease climate gases by 20%, increase use of renewables by 20% and decrease energy used by 20%. You can't just do one part - you have to do all three to be successful.

Uri Peleg: No matter what fuel you're coming with, you will need to work hard on your energy decrease because it doesn't matter if it's a renewable or a gas, a diesel or a bio-diesel - whatever alternative you choose, you will have to substantially decrease your energy consumption.

EJ: That's the major focus for us. But we also feel it's very important to increase the attractiveness of public transport. You can't forget you need to get the noise down, and that you want to arrive at and leave a clean bus stop so that people don't have clouds of gases in their faces.

Is maintaining and increasing passenger satisfaction one of the main challenges?

UP: We need to look at how we keep meeting passenger needs and supporting our customers. Our customers need to meet the demands of passengers, but also of the Public Transport Authority (PTA), which is tendering the main part of public transport where it is deregulated.

When we looked into the challenges, one of them is the requirement of what we call 'up time', or how we keep the buses running at peak hours. So for us, as the bus producer, we have to see that the quality is right and the service programme efficient - that it doesn't spend too long in the workshop. On top of that, we have developed systems and services for vehicle and fleet management to optimise this.

What country or urban city is a prime example of the progression to hybrid bus technology?

EJ: When it comes to being early out, we have four regions. London has really been pushing this development. When [former] mayor Ken Livingstone said in 2005 that by 2012 London will only buy hybrids, we took that very seriously, and that has been one of the cornerstones in this development. Luxembourg has also been very early out, as well as Switzerland and Norway.

It's mainly for environmental reasons that they've been forthright in renewable fuels, energy efficiency and greenhouse gases going hand in hand. And the low-noise issue in cities - not having exhaust gases at bus stops - is also a key driver. In the early dialogue, for instance, the electrical start was something we wanted to get rid of due to technological challenges, but Luxembourg was adamant.

Can you talk about advances in your braking mechanisms?

EJ: We apply two energy management functions: torque blending, which mixes energy from the combustion engine and the electric motor; and brake blending, which mixes the braking from the electric motor, engine brake and wheel brakes.

In reality, a mixture of the different torque or brake functions is used more or less constantly. Depending on the speeds, the energy management system decides what is most favourable and prioritises drivability and energy management without involving the driver.

With regard to the brake pads, we've found that the hybrid has roughly 20% longer maintenance intervals than diesel buses for wheel brakes. And using only the electrical brakes has two advantages: energy recuperation and fewer particulates from the brake pads, which is a direct positive environmental impact.

"If you get a reasonable 12–18 hours of use a day out of a hybrid bus, then you will receive a return on your investment in five to seven years."

UP: We have also learned from our customers that, due to smoother braking and starting, you see less wear and tear of the tyres, which are another substantial cost to the operators.

How are you saving on space and weight, and how do these advancements translate into the bus interior and the passenger experience?

UP: We've been trying to improve on the logistics of passengers coming in, being on the bus and coming out. Better weight distribution between the axles means our hybrid bus - because we have the battery in the front - can carry seven additional passengers compared with a similar diesel bus.

EJ: When comparing passenger capacity for the hybrid buses relatively with the diesel buses, we have about 5% higher capacity for the hybrid bus, due to weight distribution. In addition, we've cut the weight of both the brand new 7900-model diesel and hybrid buses by 500kg to increase the capacity of each by another seven people.

What were the unique challenges or nuances to address in the Göteborgs Spårvägar public transport contract?

EJ: There are some similarities and differences in every market. In Gothenburg, there was a lot of focus on reducing noise levels; that was one thing they initially wanted to secure, with a view to improving the environment subjectively.

We underwent a short survey and found that 86% of travellers and people living around the buses find them less noisy than the diesel buses. The remaining 14% did not notice any difference. Gothenburg was also requesting bio-diesel compatibility, which is quite a typical request of the Swedish market.

This is a very competitive market. How are you ensuring that you remain at the very top of the field?

UP: We are in the lead and providing the benchmark for hybrids, and the feedback we're getting from Gothenburg and other customers is very positive.

EJ: Of course it's a very complex product and in the beginning there was an attitude among customers that it could lead to less availability of spare parts, but there have been no complaints about deliveries or performance. The more people discover the hybrid, the more they enter into the competitive spirit.

UP: It's always a challenge to maintain a long-term perspective in the short-term, particularly in challenging times. And you have to look at the whole of public transport, and how it looks in countries where it was deregulated not too long ago, and where it's on track to be deregulated. That's a challenge for the whole industry.

In such a fragmented framework, we have to manage different demands from customers and their customers - passengers and public transport authorities - from country to country, and even within countries. And it's not like all bus transport will suddenly move simultaneously to hybrid technology; it's going bit by bit and you still have to have a lot of offers at the same time. If the transfer takes a long time then you need to have a wide range of options. And meeting these demands is a major challenge.

How do the environmental and fuel-saving advantages stack up against performance and costs?

EJ: We don't usually use only economical calculations when we look at the cost of ownership. We also, from society's standpoint, consider the benefit of health issues. You can typically say that, if you compare the life hybrid bus with that of a diesel model in terms of the cost of environmental damage, it will be about €100,000 less for the hybrid than the diesel.

"At first, customers believed the hybrid could lead to less availability of spare parts, but there have been no complaints. The more people discover it, the more they enter into the competitive spirit."

UP: That said, we developed our hybrid as a commercially viable alternative, not only on the basis of its environmental benefits. And the PTA and governmental authorities are supporting all new technologies and alternatives that contribute positively to environmental and other causes. In general, however, we have a payback time on those innovations, which varies according to variables such as the number of kilometres you're travelling, the fuel price and how you operate the bus.

EJ: When you look at the purchase price of the hybrid buses, they are more expensive. When you examine the total cost of ownership, however, it's lower because they're using much less fuel. So it's about distributing the cost over time, which, for some operators, can be an issue if they don't have good liquidity in the company - the capital can be expensive -but for the many operators that have the possibility to look long-term, this is an extremely attractive offer.

So the return on investment timeframe is attractive?

EJ: If you get reasonable working hours, then yes. If you have a school bus and use it two hours a day, then it's not good business to buy a hybrid bus. But if you get 12-18 hours of use a day, then you will have payback in five to seven years.

The 7900 hybrid is now travelling the streets of Gothenburg.


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