Triple alliance

A triple Hybrid power system, combining a fuel cell, battery and supercapacitors has been developed by a German fuel cell system producer.

of Munich claims that its MH30 technology is made possible by an energy management system that controls the power distribution between the fuel cell, supercapacitors and battery.

The company unveiled the system on a forklift truck — claimed by the company to be the world's first to use it.

According to chief executive Felix Heidelberg, MH30 offers more than 50 per cent energy savings compared to diesel forklifts.

He explained that the energy management system ensures that all components are used in their 'optimal' operation range. The system draws on the strengths of the individual energy sources depending on the situation.

When a vehicle, such as a forklift, brakes, energy is recovered and stored in the supercapacitors and batteries. The fuel cells provide peak power during operations such as acceleration and lifting heavy loads.

The supercapacitors are used to provide sudden spurts of peak demand because unlike batteries they can be charged and discharged quickly. They also allow the recovery of energy from dynamic actions such as braking.

The total system can provide more than 30kW of peak power for seven to 10 seconds at a time.

'That amount of power is only necessary when a truck lifts large loads and possibly moves or goes up a ramp,' said Heidelberg. 'On average forklifts needs only six to seven kilowatts, and the fuel cell is designed to provide that amount constantly.'

Designed as a 'plug-and-drive' technology, Proton's system replaces the standard battery package for class 1 forklifts with an 80V 700Ah battery. There is no need for further adaptation.

The 10kW fuel cell can deliver sufficient energy for a three-tonne forklift to operate for eight hours. It can, said Proton, refuel with hydrogen in one minute.

The company was the first to develop and produce fuel-cell powered vehicles combining buffer energy storage devices such as batteries or supercapacitors seven years ago.

Heidelberg said the experience gained from those developments gave company engineers the knowledge to add an additional power source to their hybrid system.

Experience told them that neither batteries nor supercapacitors alone could completely cover storage demand, and these components were oversized in many applications.

Heidelberg said that by combining batteries and supercapacitors, the company was able to offer a solution to power storage and space constraint concerns.

'When we first developed a hybrid forklift with just a battery and fuel cell, the battery weighed 350kg,' he said. 'Now with the combination of three power sources it weighs only 30, and the supercapacitors are around the same weight.'

He added: 'The cost reduction potential for a triple hybrid is better than with a conventional hybrid.'

Proton is aiming its technology at manufacturers who use two to five tonne forklifts. 'It'll be very attractive to them because with normal hybrid technology, operators have to change the battery every eight hours or take the truck back to a charging station,' said Heidelberg.

While the technology was originally designed for forklifts, Proton plans to apply it elsewhere. It is currently looking at developing a triple-hybrid city bus.

But before moving on to other projects, Heidelberg said the company is seeking industry partners to help bring the technology to market.

'The market and the interest from OEM customers is there. Now it depends how fast we can make our product cheap enough to manufacture,' he said.