PARIS. When Renault Trucks brings diesel hybrids to the world, they won’t run on electricity alone, even though customers would like them to.

“We propose a hybrid that will never be purely electric,” said Robert Desportes, director of alternative fuel projects for the company. “The best answer is to have the electric motor boosting the acceleration.”

One client has asked Renault to develop a hybrid that would have an electric-only range of 50 km, but for that, said Desportes, “you need an electric truck or a bi-mode.”

There were examples of both at the Michelin Challenge Bibendum in France June 8-11. Renault Trucks displayed its 10-ton electric Midlum delivery truck with a range of 60 km on lead acid batteries that it makes with a partner for L’Oreal, the luxury goods company. A small Italian company, Micro-Vett, presented its converted 3.5-ton Iveco Daily that can switch between the normal 2.4-liter diesel and a lead-acid battery pack that gives a silent running range of 25-30 km.

Customer interest in alternative powertrains is based mainly on silence. L’Oreal, which makes perfumes, wants to distinguish its delivery fleet in Paris with quiet delivery, even though the trucks cost twice as much with their 3 tons of batteries and electric motor. Micro-Vett has sold 10 trucks in Milan as ambulances that pick up their patients on diesel power but deliver them into the hospital quiet zone running on electricity.

The problem for Renault Trucks, and its sister brands Mack and Volvo, is a hybrid running on pure electricity would require two sets of controls for the steering and brakes--and if it were to have 50 km of range, would need 3 tons of battery. All that adds cost, said Desportes, and in the truck business “it is good to have it not too costly.”

Aside from L’Oreal, only government units are supporting the cost of developing cleaner powertrains.

“We live because Italy gives money to the regions that wish to have zero-emission vehicles,” said Marco Ravagli, gm of Micro-Vett. His Bi-Mode Dailys cost 43,000 euros. “We are a little firm, but the first in Italy.”

Firemen near Bologna, Italy, are using a Micro-Vett Daily powered with a lithium-ion battery pack. If tests succeed, the all-electric range will be extended to 100 km, said Ravagli, and the battery pack could be in production in 5-6 years. He favors developing a bi-mode rather than a hybrid powertrain because hybrid power control is far more complicated, and because the constant recharging of the hybrid model may reduce the battery life. The lead-acid batteries can be recharged nightly from the grid 1,000 times, but in a hybrid they might recharge only 700-800 times, said Ravagli.

The real future for electric power, he said, will be fuel cells.

Renault Trucks, AB Volvo and Mack Trucks will get a boost in their diesel hybrid development from Nissan Diesel, said Dany Boulanger, head of global marketing for Renault Trucks. Nissan Diesel has agreed to furnish trucks in the 7.5-18 ton Midlum class, including diesel hybrid powertrains. AB Volvo and Mack Trucks have shown prototypes of heavy trucks using a hybrid system called I-SAM consisting of a combined starter, drive motor and alternator. Boulanger provided no details on how the Japanese technology might differ.

Besides L’Oreal, the French post office has purchased some all-electric Renault Midlum trucks for city delivery use prepared by Ponticelli VI. Ponticelli also makes an electric version of a 20-ton Renault that it calls Puncher, and it makes natural gas conversions.

The City of Paris is behind another Renault Trucks project – a garbage truck powered by natural gas, which adds 30,000 euros to the cost. Renault Trucks has delivered 200 of the gas-powered trucks, and will deliver 200 more.

However, Renault Trucks believes neither has a future. Packaging the gas containers required for a garbage truck is difficult, and range is a problem. “It takes 800 liters of gas to provide the same range as 160 liters of diesel,” said Desportes. In addition, there are so many rules regarding gas-powered vehicles in France that companies are reluctant to get involved.

None of the vehicles on display at Challenge Bibendum were being presented for the first time.

Jan Verhaeghe of CompositTrailer showed his 3,950 kg flatbed trailer, being marketed in North America by Martin Marietta. He has about 100 on the road in Europe; North American sales are smaller. Later this year he will lighten the trailer by switching to composite springs from LiteFlex LLC, of Englewood, OH.

Valeo displayed the HyTrans, a Ford Transit van with a stop-start system tied to a 42-volt battery. Higher voltage makes it easier to crank the diesel engine for restarts, said Joseph Guertler, the engineer in charge of Valeo’s belt-driven start-stop systems. While the only ones now in production are in the small Citroen C2 and C3 hatchbacks, stop-start systems are sold into other passenger cars beginning in 2007-2008, and in 2009 they will show up in light delivery vans like the Transit, he said. While stop-start gains only about 6% in the urban driving cycle, it saves 15% of fuel in real-life driving in dense cities like Paris or London.

Michelin started its Challenge Bibendum in 1998 as a way to promote sustainable road transportation, gathering green cars and trucks from large and small manufacturers to call attention to future energy challenges. Some 73% of European freight movements and 84% of passenger displacements use roads.