The goal is theoretically possible thanks to the remote southern Japanese island's inexhaustible water resources.

As a major step towards the ecological grail, in April a joint industrial-academic team set up a hydrogen filling station to allow for the test driving of fuel-cell cars on the sub-tropical island.

As part of the project, Honda Motor's prototype 'FCX' car cruises along a winding coastline road surrounding the circular island, also famed for its millennia-old cedars and registered as a UNESCO nature World Heritage site.

"The project is unique because we use hydroelectric power to produce hydrogen, which means all we need is water," said Takami Kai, an associate professor from Kagoshima University, which is heading the project.

In hydrogen production, electricity is needed to separate hydrogen from water, but carbon dioxide (CO2) is produced if a fossil fuel is burned as an electricity source.

"Here, electricity is produced using only water. So, our hydrogen is 100 percent greenhouse gas free," Kai told AFP at the station on the northern edge of the rocky Pacific island 1,100 kilometers (682 miles) southwest of Tokyo.

The facility looks just like an ordinary gas station -- with a filling pump, hose and nozzle -- except there is no smell of petrol.

The driver of the FCX, which can run at 150 kilometers (93 miles) per hour, pulls in for more fuel, driving around a lawn in the shape of a large H for hydrogen.

"There's nowhere else we can aim at an ultimate zero (greenhouse gas) emission but here," said Hirokazu Takanashi, another associate professor at the university.

"We know it's ambitious, but zero emission is our final goal."

On the island, which has a population of 14,000, hydroelectric power already accounts for all electricity generation, compared with the national average of 3.3 percent reliance, according to Japan's environment ministry.

Rainfall here reaches 10,000 millimeters (400 inches) a year, which in theory can produce 1,130 billion watts per hour of which the islanders use only 32 percent.

Analysts and experts, however, say the project is still a long way from achieving its goal.

"Theoretically Yakushima is able to achieve zero CO2 emission, but there are a lot of hurdles to clear," said Tadahiro Mitsuhashi, professor of environmental studies at Chiba University of Commerce.

"A major hurdle is the islanders' awareness and understanding of the project," Mitsuhashi said. "To achieve success, people on the island have to accept some extra burden," including higher energy supply costs, he said.

Local government official Koji Kihara concedes the islanders still have some way to go.

"Although people's awareness of environmental conservation improved after Yakushima was registered as a World Heritage site, it's too early to seek their full support," said Kihara, who works for the island's environment policies bureau.

Mariko Kawaguchi, chief analyst at Daiwa Institute of Research Ltd., also stressed a clear conception of the advantages the project will bring is indispensable if the private sector is to participate.

"If private companies want to take part in an environmental project, they've got to be told what the benefit is from it. The Yakushima project is no exception," Kawaguchi said.

While Japanese carmakers have spent millions of dollars on developing fuel-cell cars, the day when they will make economic sense for consumers and be profitable for the manufacturers is still far off.

Analysts say high production costs and an insufficient number of hydrogen stations are major obstacles to wide use of the next-generation vehicle. Last year Toyota officials estimated the production cost of a fuel-cell car at more than 100 million yen (913,000 dollars).

"Fuel cell vehicles are expected to be what will supersede gasoline cars," said Sachito Fujimoto, a senior Honda researcher working on the development of the FCX.

"We expect (fuel-cell vehicles) will become widespread between 2015 and 2020, but there is a problem with infrastructure. It is necessary for the industry and society in general to tackle the problem together."

For Japan, a leader in the fight against global warming under the Kyoto Protocol on climate change, a reduction in greenhouse gas is an urgent priority as it spewed out a record amount of CO2 in the year to March 2003.

"We regard the Yakushima project as an ideal model in the bid to realise a recycling society," said an environment ministry official who declined to be identified.

"Although the project may not help reduce Japan's overall greenhouse emissions markedly, it's a symbolic campaign to achieve the goal of the Kyoto Protocol," the official said.

The nation's CO2 emissions rose 2.8 percent to an all-time high of 1.25 billion tonnes for the year to March 2003, or 11.2 percent above the fiscal 1990 levels which provide the benchmark for the Kyoto Protocol on global warming.

CO2 accounts for more than 90 percent of Japan's emissions of greenhouse gases.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.