Micro-hydro power technology is increasingly popular in Peru and Nepal, where a one- kilowatt turbine can light a village. It has now arrived on the delta of the river Wandle in south London: here it will ring a bell at high tide and light the hall of a primary school.
The project is the brainchild of Platform, a group set up 10 years ago to combine art, science, ecology and earth magic. It cost pounds 25,000, from the Government's now-defunct urban programme, and is backed by the Department of the Environment, Wandsworth Council, the Arts Council and the London Arts Board.
The Wandle was chosen because it is one of the few rivers not to have been turned into a drain. Its delta was, in Bronze and Iron Age times, a site of votive water offerings: the Battersea Shield in the British Museum was found there. According to Platform, it was as sacred a river as the Ganges.
The group hopes the project will raise the average urban Briton's energy consciousness to nearer that of a rural Nepali, who knows the limits of the village hydropower plant and will switch off the lights when he or she starts to cook. Bikash Pandey, its programme manager in Nepal, watched yesterday's ceremony.
He said: 'What is exciting is that people are coming to the same conclusions, whether they are in London or in Nepal. It is easy in a big city to think nuclear power is the solution, but the best economics is using local resources intelligently, making a place beautiful and looking after the environment in the long-term.'
Platform describes the project as a celebration of ecological technology and sees it as part of the imaginative recreation of the city. The bell will 'reconnect' people with tidal rhythms. On a sculpted frieze are the names of species it seeks to lure back - salmon, otter, heron. St Joseph's school, which is taking energy from the turbine, is being rebuilt along green lines, with a bird-watching hide, an ecological garden, a log amphitheatre and nesting- boxes built into the school walls. Its children helped to plan these features.