The hybrid revolution - years of research and development

In June 2011, Volvo Trucks delivered its first hybrid truck to a customer. Now there are over 50 Volvo FE Hybrids in operation. Years of R&D have gone into the making of these trucks and Volvo Trucks’ hybrid technologies show a promising future.
Volvo Trucks hybrid engine.
The Volvo Group first began investigating hybrid drivelines as far back as 1985, but it was not until 2005 that it really took off.

To fully appreciate the significance of the Volvo FE Hybrid, one needs to understand the level of research and development that has gone into the project. Contrary to popular perception, using electric machines is not a new concept, and the Volvo Group first began investigating hybrid drivelines as far back as 1985. However, these projects never progressed beyond prototypes and demonstration models.

Anders Kroon, Vice President Energy Efficiency & Environment, Volvo Trucks.

“Back then, these projects were more of an insurance in case we did not fully succeed in overcoming emission regulations,” says Anders Kroon, Vice President Energy Efficiency & Environment, at Volvo Trucks, who has been deeply involved in the hybrid project for over a decade. “They were not at all focused on the market financial aspect and making a commercially viable product.” 

This all changed in 2001, when Kroon was asked to initiate a study on future fuels, and the findings were startling.

“It was clear that not only would there be an end to the era of easy oil, but it was coming soon,” he recalls. “We realized pretty soon that we would need alternatives to fossil fuels, and we had to do something now if we were to be ready.” 

From 2002, having decided that electricity was the most viable alternative energy source given the high efficient conversion to mechanical energy, Anders Kroon and his team began investigating different combinations of electric and combustion machinery, which drove them towards parallel hybrid development. With financing from both the Swedish government and the US Department of Defense, along with funds from the Volvo Group, the development team was able to build a hybrid parallel system ready for demonstration by the end of 2005. 

We basically have the technology already - we are just working on perfecting it.

Then came the big turning point: after seeing the hybrid displayed internally, Leif Johansson, the CEO of the Volvo Group at the time, made a public announcement, promising the Volvo Group would launch a hybrid driveline within three years.

Miguel Hallgren, Product Requirement Manager, Volvo Trucks.

“We had only been working on this for three years, and had no formal organisation,” says Kroon. “We were in a hurry, hunting for competence. But in two and half years we realised a driveline ready for production.”

For Volvo Trucks, the result of their efforts is the Volvo FE Hybrid, which was officially unveiled in 2009. By June 2011 the first vehicle was delivered to a customer, and at the time of writing, over 50 hybrids are currently in operation. 

“This is the largest series produced hybrid truck available for commercial purposes,” says Miguel Hallgren, Product Requirement Manager, Volvo Trucks. “Before Volvo Trucks, no other manufacturer in the world had produced a 26-tonne truck with a hybrid driveline.”

The Volvo FE Hybrid travels silently using only its electric motor. Once the vehicle accelerates beyond 20 km/h, the diesel engine is activated, while the automated gearbox ensures an optimal balance between the two, which helps avoid low efficiency operations. The battery is recharged using recuperated energy generated during braking, which minimises energy wastage.

Since it doesn’t consume fuel at low speeds, and relies on recuperated brake energy, the Volvo FE Hybrid is best-suited for stop-start drive cycles. Consequently, refuse trucks have achieved the highest savings, using up to 20 percent less fuel. If used in combination with an electrified compactor, savings for the complete vehicle can be as high as 30 percent. Urban distribution trucks can also save up to 15 percent.

Before Volvo Trucks, no other manufacturer in the world had produced a 26-tonne truck with a hybrid driveline.

To date, customer feedback on the Volvo FE Hybrid is overwhelmingly positive. Not only does it deliver the promised fuel savings and noise reductions, but also high uptime and productivity.

“The big difference with the Volvo FE Hybrid and other hybrid trucks is that it’s a Volvo optimized system,” adds Hallgren. “We have integrated the whole system from the beginning and optimized all the components so that they work together, which ensures a high level of quality and added performance.”

Mats Alaküla, Global Advanced Engineering, Volvo Trucks.

Even the development team is surprised at how well the Volvo FE Hybrid has performed.

“The outcome is a very reliable vehicle,” says Mats Alaküla, Global Advanced Engineering, Volvo Trucks. “In the bus implementation in London, it’s had higher uptime than the non-hybrid versions of the same type of vehicle, which I think is remarkable. It is very good evidence of the quality of the work done.” 

“Engineering is like athletics – if you are first, you’re heard and seen,” adds Anders Kroon. “If you were to look at the market in two or three years, you will see more or less copies of what we have now.”

So what next? Is the Volvo FE Hybrid the end point or just the beginning? “Hybridisation is a good first step because it reduces fuel consumption, but we’re still using fuel so it’s not solving the problem,” says Alaküla. “The next step is to move from diesel to an alternative source, in this case electricity as the main energy supply.”

In the short term, the focus is on improving the hybrid by increasing battery capacity so that the hybrid driveline can be applied to more applications and truck models. But energy recuperation through braking will only go so far. To make the transition to full electric mode, it will become necessary to implement plug-in solutions. Therefore the future priority is to find ways of connecting to an electric grid, without altering a vehicle’s drive cycle, for example charging while a vehicle is stationary anyway. If fast, convenient methods of connecting can be found, buses offer the greatest potential due to the fact that they have regular, predictable stops in set locations, however urban distribution trucks could also benefit.

We basically have the technology already - we are just working on perfecting it.

“If a distribution truck stops ten times a day, for 5-10 minutes a time, and can access a reasonably powerful electric outlet, in many cases that will be enough,” explains Alaküla, “Those trucks will be able to run most of the day’s work in electric mode, which is good for the environment and the economy. We basically have the technology already - we are just working on perfecting it.”

As exciting as this sounds, it still has its limits as it relies on the vehicle stopping frequently, which is completely unpractical for applications like long-haul distribution. But what if it were possible to charge the battery while driving? The concept of electric roads, where vehicles are continuously connected to an electric grid, sounds fanciful, but it is an idea being given serious consideration. “We see test tracks being built right now in the US, Asia and Europe,” says Anders Kroon. 

“Charging is the key,” concludes Mats Alaküla. “If we could provide cheap electric energy, in a robust, safe and convenient way, that would completely change everything. If we can get that down, there are no limits.”

Volvo’s hybrid driveline has proven so reliable in buses that in London, it had higher uptime than non-hybrid versions of the same vehicle.

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