Going green: Towards more environmentally-friendly excavators.

The emphasis on reducing the impact construction equipment has on the environment is gathering momentum. Becca Wilkins reports on how excavator manufacturers are developing greener machines.

Investing in new technologies required to develop more environmentally friendly excavators comes at a high price - especially during an economic downturn. However, the global financial climate does not seem to be hindering machine development, rather it would appear to be advancing at a quicker pace because manufacturers are keen to prepare themselves for when market stability returns.

Excavator manufacturers are legally bound to comply with certain environmental projects, such as meeting the next stage of engine emissions regulations, which come into effect in 2011. Developing other technologies, such as hybrid systems, are also seen as a priority by manufacturers and this thinking can be seen in a number of new and prototype machines.

Hybrid brigade

According to Bill Seidel, Case's vice president for product portfolio and brand marketing, there are many ‘green' initiatives that the company is currently involved with - the most recent of which is a hybrid scrap handling excavator concept which was revealed at Intermat.

"This is an electric concept using a generator, an inverter, a converter and an electric swing motor and it takes the surplus energy and turns it, like any good hybrid, into useable power. Early tests that we have conducted on this machine show potential fuel savings of up to +40% through this hybrid technology - whether we'll see that on the final product we don't yet know," he told iC.

The machine retains a diesel engine to power the hydraulic system for the boom and track drive, but this motor also drives the electric generator, which in turn is used to power the lifting magnet and the electric slew motor.

When the engine is under low load conditions, surplus energy is converted to electricity and stored in high efficiency capacitors, Case explained. As the engine comes under higher load the electrical system provides power support, allowing for constant engine speed, hence reducing fuel consumption and lowering noise levels.

Working in a repetitive operation, such as scrap handling, the machine is continually turning from one side to the other but energy is saved by the use of the electric swing motor, which uses less energy than a hydraulic version, the company stated. When slowing down swing, the energy generated is again stored for later use by the capacitors. A third energy saving is achieved by integrating the magnet generator into the hybrid drive, rather than it being powered by the machine's hydraulic pumps. In this way the magnet makes use of the additional electrical energy stored in the system.

"By reducing fuel consumption there is an immediate reduction in gaseous exhaust emissions, resulting in a lower environmental impact and a significant cut in operating costs for the customer," Case said.

Other manufacturers are investigating the potential of hybrid technology, including Doosan, which plans to launch a hybrid excavator in the US in 2012, two years ahead of its previously announced 2014 development target. Doosan confirmed it will target the 22 tonne sector with its first hybrid model. It added the new machine will burn -35% less fuel than a standard DX225, equating to savings of US$ 10000 per year.

Doosan said it would be taking a similar approach to the one taken by Komatsu with the hybrid excavators launched in Japan last year. These use capacitors that act as a slewing brake and capture energy when the operator turns the upper structure of the machine.

Doosan said, "The innovative Doosan hybrid excavator will be equipped with a diesel engine, electric swing motor, electric converter and ultra-capacitor that will store excess energy during turning and light-duty work."

The reserve electricity will then be used to assist the power of the engine during heavier work allowing the engine to maintain low revolutions and high efficiency combustion during acceleration.

Meanwhile, compared with Komatsu's standard PC200-8 hydraulic excavator, the hybrid version achieves on average a -25% reduction in fuel consumption and in tests with customers, the company said it can achieve a maximum reduction of -41%.

A spokesman for Komatsu said, "We are determined to meet the needs of the time by proposing practical and innovative equipment designed to reduce environmental impact, which includes cutting down on CO² emissions."

Also currently only available in the Japanese market is Hitachi's 20 tonne hybrid Zaxis ZX200 crawler excavator. Speaking for Hitachi, Paul Burger said, "Custom-built hybrid models are already on sale in Japan, but no announcement has been made as to when they will be produced in Europe for the mass market."

Technology development

Mr Seidel said, "Our objective in green design is to offer the market machines that not only comply with emissions, which we are more or less by legislation forced to do, but we want to go beyond that legislation to improve our energy utilisation - consuming less fuel and again providing lower operating costs for the customer."

Case's hybrid machine is still "work in progress" he added and at this stage the company continues to investigate many different technologies around hybrids. Technologies currently being worked on by Case - many of which are in their infancy, but should available in the next couple of years, include electronic power management (EPM), "state-of-the-art" hydraulic systems, on-board energy recovery systems (that turn wasted energy into productivity) and alternative fuels (bio-diesels).

Case said most of its construction equipment can be used with a B20 blend of 20% biodiesel.

"As we develop our engines and emissions plans we are going to make sure that we don't compromise the ability to have even higher combinations of bio-diesel fuels," Mr Seidel added.

However, Case is currently focused on meeting Tier 4 engine emissions regulations. "Meeting Tier 4 is not rocket science but it's definitely a challenge because we have 15 product lines that between now and 2014 we have to make sure comply not only in Europe but also in North America," he said.

Mr Burger agrees the priority for Hitachi is compliance with the next stage of emissions regulations. He added, "Stage IIIB (interim Tier 4) engine regulations are aimed at reducing emissions rather than fuel consumption. Brussels focuses on green, environmentally friendly issues, but not everyone realises that you need more fuel to get cleaner exhausts.

"Hitachi develops new models with the aim of achieving higher productivity with similar levels of fuel consumption to the previous model," he said.

Electronic control

The integration of electronic controls in order to ease the operator's labour, simplify machine control and increase productivity is a growing trend in the excavator sector.

Case is currently developing its "electronic power management" (EPM), which, according to Mr Seidel allows inter-related systems, such as the engine, the transmission, the hydraulics and the axles to communicate with each other - thus improving the efficiency and productivity of the machine.

Mr Seidel said the EPM is available on every Case excavator to some degree and will develop as the company continues to manufacture greener machines.

He explained the EPM acts as the command centre of the vehicle to balance workload demands - like power, torque and speed. "It orchestrates the machine's systems to work in harmony - to produce the most work with the least amount of wasted energy," he said.

As well as achieving increased work, using less fuel, the EPM also means less machine wear and tear "because everything within the machine has been optimised for the best performance. Therefore operating costs are reduced," Mr Seidel added.

According to Mr Burger electronics are increasingly being installed into excavators due to the increased number of electronic components and secondary equipment in the cab, such as satellite communication systems.

"However, the main operation of an excavator is still powered hydraulically. You can work with greater precision and it is more comfortable for operators," he added.

Eastern opportunities

Excavator manufacturers who are developing new machines, particularly those with integrated green technologies, will be in a strong position once the construction market stabilises.

Mr Seidel told iC, Case is not compromising its R & D investment during the difficult times. Traditionally solid markets for Case including North America and Europe are now struggling but there are other opportunities for growth, he said.

"Although China is probably not a traditional market yet, it is soon to become one," he added. "We introduced our products there in 2007 and we have been very successful competing against the domestic Chinese producers. Our share of this market has grown steadily during the last two years."

Case is also expanding its product line in Latin America and other territories which show potential for growth include Asia, the CIS countries, the Middle East and Africa, he stated.

He added the Chinese excavator manufacturers, who still have quality and distribution issues, do not yet pose a threat to other global manufacturers.

However, Mr Seidel said, "Once China gets their quality in line with world expectations and they get a distribution network they are going to be a contender - it's just inevitable. We as a manufacturer have to make sure we are on top of it - to ensure we‘ve got the right distribution network, strong dealers, strong service and support."

Future

Although the market has not been as strong in recent months, according to Mr Seidel excavators remain the keystone of the earthmoving equipment sector and the "kings" of construction equipment business.

He added products will continue to evolve and global competition will strengthen, with the emergence of manufacturers from countries such as China.

Meanwhile, Mr Burger said once manufacturers have completed work on Tier 4 final machines there will be more of a focus on issues of sustainability, hybrid technology and other fuel-saving methods, such as solar power.

"It's all about going green - that's the future," he added.