AN enthusiastic supporter of sustainable energy says that the Forest's flooded underground mine workings could provide an inexhaustible amount of renewable energy.

The flooded shafts and galleries at Buckshaft and similar extensive voids left by coal and iron ore extraction – there are three such in the Dean – could be serving up virtually free hot water for commercial and domestic uses.

And the ideas of Nick Bull, who lives in Awre, are backed up by the Centre for Alternative Technology in Machynlleth, West Wales, Britain's leading promoters of renewable, non-polluting energy.

"All it would take is a little seed money to start exploiting this energy," said Mr Bull, who said the potential became apparent after he attended a seminar on energy production held at Coleford recently.

"Basically the water from the Buckshaft workings, which is at a constant 10 degrees centigrade, is already being pumped for drinking water in the Forest. By using a heat pump – the same technology used in refrigerators to 'extract' heat and move it outside the cabinet – this heat could be recovered by using it to heat water."

The Machynlleth centre told the Review: "Heat pumps are mechanical refrigeration devices which may be used to upgrade low temperature heat to a useful and usable temperature.

"Possible heat sources include ambient air, surface or ground water and the ground itself."

While cautioning that the system Mr Bull suggested would take more electrical energy than was at present used for pumping drinking water, it would still return as much as three times the energy put in.

Ideally that electricity would itself come from a renewable source such as the hydroelectric scheme suggested for the mines overflow culvert at Norchard.