But one Lamma resident, while initially amused at the irony of using a diesel-powered bus for green public relations, said the bus service on an island which has no cars runs contrary to the ethic underlying the use of a wind turbine to create alternative energy and could also constitute a safety hazard.

Liz Gower, a 16-year Lamma resident, said she noticed the bus seven months ago. 'They're running a diesel-engined minibus up to a renewable-resource wind turbine,' she said. 'First of all it had me in stitches, but then I thought it's silly and they shouldn't be allowed to do that on their cable path. ... they should go the whole hog and use an electric vehicle.

'I noticed it first when they drove a group of kids up there. It was in the middle of summer, so they let the engine run so that they could keep the air-conditioning on. They let the diesel engine churn out its gases, while the children were learning about renewable power sources. And then the children got back into the bus and were ferried back down again.'

Ms Gower also has concerns about safety. While Hongkong Electric denies that its bus trip will become a regular service, she says there are signs along the road, speed bumps and mirrors, and these do not exist anywhere else on Lamma where other forms of small vehicles run

'It's a path used by many pedestrians, cyclists and also children run freely and those buses come down the hill quickly,' she said. 'Putting up signs doesn't make it safer.'

Hongkong Electric spokeswoman Esme Lau said the bus was used only under special circumstances. 'We are applying for a temporary access between Lamma power station and the wind station. We don't have any plans to run a shuttle bus service to and from the wind station.

'If there are any absolutely necessary circumstances when we need to provide transportation for our visitors to visit the wind station, then we will use that. It will depend on the circumstances ... where transportation may be required for visitors who are physically challenged or from overseas when they have very tight schedules. But we won't be using it often.'

Ms Lau said she could not say whether an electric bus would be feasible for the trip without consulting her colleagues, but she had doubts that the vehicle would have the power to go up the steep hill.

Friends of the Earth Hong Kong director Edwin Lau Che-feng said if the bus was solely used as a service for people with disabilities, then its use was reasonable. Anyone else could walk. 'People who are in a rush? They should plan their trips better,' he said. 'We encourage people to have a leisure walk. It takes only 15 minutes.'

Lamma resident Oliver Armistead said he thought that after two years, the wind turbine project should be showing results. 'I'm slightly concerned that [the turbine] is turning into a tourist attraction rather than doing what it is supposed to, which is to generate clean energy,' he said.