Digging the dirt: hybrid technology in the earthmoving equipment sector

Manufacturers of earthmoving equipment are more aware than ever of the importance of producing environmentally friendly machines. Developing hybrid technology is one way of helping to achieve this.

Unstable economic conditions are not deterring earthmoving equipment manufacturers from investing in expensive new technologies to help reduce machine fuel consumption.

According to Komatsu, this issue is the most important current product driver in the earthmoving sector and with increasing environmental awareness, the company believes hybrid machines will become commonplace in the future.

In June this year Komatsu introduced the PC200-8 hybrid excavator, which is powered by a newly developed electric motor. This turns the upper structure, power generation motor, capacitor and diesel engine. Compared with the standard PC200-8 hydraulic excavator, the hybrid model achieves on average a -25% and up to -41% reduction in fuel consumption while on test with customers.

Initially available in the Japanese market it will be sold in the Chinese market in the near future a company spokesman said.

Also looking at developing hybrid technology is Hitachi, with the launch in Japan earlier this year of its 20 tonne hybrid Zaxis ZX200 crawler excavator.

Speaking to iC, Hitachi's Paul Burger said, "It's not going into mass production yet. It's being produced and built to order for the Japanese domestic market only in the beginning."

Challenges

The biggest problem with developing Hitachi's hybrid excavator according to Mr Burger was finding storage space for the batteries.

"We are following the car manufacturers and looking at the new generation of smaller batteries with bigger capacities. I think once we have cleared that stage there could be massive developments in hybrid technology for excavators."

Mr Burger said Hitachi supports new engineering ideas with particular focus on fuel consumption in periods of economic instability. He explained, "Everyone knows fuel consumption is the way to move forward within the next 10 to 20 years."

Hitachi's hybrid engineering takes place in Japan and it is this country that will lead the company's development in this technology Mr Burger said.

"If there is market demand in Japan for a higher number of hybrid excavators and the percentage for them increases year on year there then it will certainly come to Europe," he stated.

However, the downside is that hybrid technology will increase machine prices.

"The price of hybrid excavators will be, certainly in the beginning, about +20% to +25% if not +30% more expensive than a standard excavator. So that needs to come down to about the same level or just a little bit higher to convince our industry that investing in hybrid technology is an investment which is better for everybody," Mr Burger said.

The flipside of hybrid technology is that earthmoving equipment typically ends its life in the developing world where this kind of technology is not so readily accepted. Mr Burger said this has led Hitachi to think about manufacturing different products for different parts of the world.

"So will hybrid technology change the face of construction sites? In Western Europe yes, but globally it will take a long long time," Mr Burger concluded.

Research

Meanwhile, according to Volvo, the construction equipment industry could reduce its carbon footprint by millions of tonnes a year and radically cut fuel consumption by a wholesale adoption of hybrid technology.

Speaking for Volvo, Arvid Rinaldo said that continuing research into diesel-electric hybrids shows significantly larger (than previously stated) benefits in fuel reduction, CO² emissions and performance.

"Hybrids are not a gimmick - construction equipment responds extremely well to the technology," Mr Rinaldo said. "We are facing the very real prospect of fuel savings up to +50%, significant performance increases and a reduction in CO² emissions in the order of millions of tonnes a year if adopted industry-wide."

Volvo officially unveiled its L220F hybrid wheel loader in the US this year, offering fuel reductions of -10% (depending on application). It will be available at the end of next year.

The heart of the hybrid system is the Integrated Starter Generator (ISG), which allows the diesel engine to be turned off when stationary and then almost instantly restarted by rapidly spinning the engine up to optimum working speed using a burst of energy from the high power battery, the company said.

"As up to 40% of a wheel loader's time can be spent with the engine idling this will be a major benefit," a spokesman for Volvo added.

Elsewhere, New Holland, in association with excavator partner Kobelco, previewed its prototype hybrid excavator at the 2006 Intermat show.

"The goal of the hybrid project is to obtain a +40% reduction in fuel consumption and C0² emissions over our existing product line," a company spokesman said.

Hybrid potential

Some manufacturers, who have not yet introduced hybrid machines, are still interested in the technology.

Speaking to iC, Hidromek's Bora Kocar said although the company does not have any plans to use the technology in the near future, there are many benefits to be had from hybrid machines.

"As our company does not produce its engines or power-trains, we will have to wait and see the developments brought by the producers in this area," he added.

"When the technology becomes viable and reliable, we will definitely prefer to use hybrid technology because we, as everyone else, believe that all means should be used in order to protect the environment," he explained.

Meanwhile, Keith Heiar, Caterpillar's senior project engineer for tractor products (dozers), said the company is researching different options including hybrid technology. He said although the company currently doesn't use hybrid technology it sees its potential.

"We want to keep an open mind about what's out there because it's very easy to hear the hype about hybrids, but we want to see what really makes sense for us," Mr Heiar added.

Caterpillar's AC electric drive system, on its D7E dozer, uses similar technology to a hybrid system Mr Heiar said and although it can achieve similar results, it is not classified as a hybrid machine.

"The D7E is not a hybrid because we don't have extra battery storage on it to store energy. However, we do store energy on it in the form of kinetic energy when you drive power back through the engine," Mr Heiar explained.

Future

Despite being in the early stages of development, hybrid technology looks set to be an integral part of the future of earthmoving construction equipment.

Mr Burger said, in future, Hitachi would extend hybrid technology to most of its earthmoving equipment and other manufacturers too see potential for their product lines.

Mr Rinaldo stated, "What we are looking at here is a true case of disruptive technology. Our ongoing research shows that such are the benefits of hybrid systems that we could well see a paradigm shift in the power train of modern construction equipment."

He added significant performance improvements and radical fuel and CO₂ reductions have the potential to fundamentally alter the structure of the construction equipment industry.