The generation game: Hydropower pioneers

For half a century, Anthony Battersby has looked out over the same scene from his Somerset home. A delightful cottage garden leading down to the banks of the river Frome, overhung with weeping willows, the occasional otter playing in the fast-flowing waters, and, just yards from his front door, a dilapidated, ivy-strewn mill building.

This year he achieved his lifetime's ambition of restoring Tellisford Mill to its original purpose, harnessing the power of the water as millers have done for a thousand years – but this time meeting an urgent 21st-century need for clean, sustainable energy.

Anthony and his wife Rachel Feilden are at the vanguard of a growing environmental movement in Britain. As the climate warms and electricity prices soar, they are reinventing a long-neglected technology.

The hydropower pioneers have the official blessing of the Department of Trade and Industry. If small hydroelectric projects on all Britain's streams and rivers could be tapped it would be possible to produce 10,000 gigawatt hours of electricity – or 3 per cent of our total energy needs.

Since going live in January, Battersby and Feilden have sent 140,000 kilowatt (kW) hours to the National Grid. That's enough annually to power 60 homes and, thanks to a range of green energy premiums, the couple are in line to earn £25,000 a year from selling their electricity, not to mention saving 100 tons of carbon dioxide emissions. That should rise to an estimated 800 tons when six more residential mills on the River Frome, all part of the Mendip Power Group, come on line in the next couple of years.

Even with predicted income levels, it will take the couple the best part of 20 years to reclaim their outlay, chiefly because of the extent of dereliction – the mill was destroyed by fire in 1895 and finally closed in 1912.

After acquiring the mill in 2002, the pair spent the first summer clearing a century's worth of silt, rubbish and vegetation out of the mill leat and tailrace (the channels that take the water from and back to the river). They rebuilt and underpinned the banks, raised the height of the weir and stabilised the crumbling mill building before finally installing the turbine and generator.

At the other end of the scale, Peter and Lis Downs' turbine at Itteringham Mill, Norfolk, installed last November for £30,000, produces a peak output of 5kW. The mill, which is run as a bed and breakfast, is now self-sufficient in electricity. After installing an export meter in March, the couple are awaiting their first negative electricity bill.

Brian Shingler, secretary of the South Somerset Hydropower Group and owner of Gants Mill in Bruton, hooked his property up to the national grid three years ago in a ceremony attended by TV science presenter Adam Hart Davis.

Shingler now acts as an informal consultant to other hydro-pioneers. As well as the Mendip Power Group, mill owners are now joining forces on Dartmoor, Stour and Vale in Dorset and Hereford. He says there are two reasons for the emerging trend: "One is economic. The price of electricity is escalating and there are now grants available for this kind of project. The other is that people are altruistic and want to do their bit for the environment."

He says a typical scheme would pay for itself in six years, then generate income for the next 40 to 50 years. He stresses that purchasers of any mill site would need a feasibility study as a first step. This estimates how much energy could be generated, a complex equation involving the flow of water and distance it has to fall, the costs involved and how easy it would be to connect to the grid. "Purchasers would need professional advice, as every site is different," he says.

That first step has already been carried out at Weavers Mill, near Bradford on Avon in Wiltshire, on the market through Hamptons International for £900,000. The four-bedroom home with its own guest cottage occupies an idyllic spot on the banks of the River Avon. It was described as the "best hydro-potential site in the area" in a 2003 study by national environmental group Energy for Sustainable Development.

The group predicted that an outlay of £125,000 at Weavers would pay back in eight years without grant funding, or in four with 50 per cent funding under the Government's Clear Skies programme, which has now been replaced by the Low Carbon Buildings scheme.

Grants may be offered by local councils and power companies such as EDF Energy, which gave £55,000 to the Mendip Power Group, which includes Tellisford Mill. There are also tax breaks, with VAT on hydroelectric plant for domestic developers lowered to 5 per cent.

On the down side, new hydropower projects generate a lot of paperwork. Mill owners need planning permission from their district council, an abstraction licence from the Environment Agency, and must register with Ofgem.

At Tellisford, Battersby found the bureaucracy frustrating, even though as a health planner he was used to dealing with red tape. He said: "Ofgem has two classes – above and below 50kW – and as we are just above that, we have the same registration process as Hinkley Point nuclear power station. They call us 'the little big one'."

But it was all worth it last November, when, even before switch-on, the "Battersby Power Station" won an achievement award from British Renewable Energy. It was a good moment, but even winning that honour does not beat the quiet satisfaction the couple get today and every day, from knowing they are doing considerably more than their bit to help combat climate change.

Hamptons International: 01225 312 244; www.hamptons.co.uk. Useful websites: www.dti.gov.uk follow links to hydroelectric/what can I do; www.british-hydro.orghas information on all aspects of micro-hydro projects, including grants and approved manufacturers and installers; www.windmillworld.comlists mills for sale in the UK and Europe; www.gantsmill.co.uk gives the full story of Gants Mill

More mills for sale

Carlingcott Mill, Somerset

Mentioned in the Domesday book, this former flour mill is now a four-bedroom home occupying a tranquil spot on the Cam Brook six miles from Bath. The restored water wheel still turns at lower-ground level. Eleven acres of land include riverside gardens and parking for 15 cars. £1,250,000 (Hamptons International: 01225 312 244)

Warwick Bridge Corn Mill, near Carlisle, Cumbria

This Grade-II listed mill comes with planning permission for conversion into a three-bedroom home, plus a hydroelectric survey showing green energy potential. The early Victorian mill machinery, including a 14ft wheel, is largely intact. £445,000 (Phoenix Architects: 01228 539 537)

The Old Mill, Maesteg, South Wales

You can see the restored water wheel from the second sitting room of this four-bedroom former flour mill. Outside, two acres of grounds take in the millpond, formal gardens and extensive woodland. £485,000 (Watts and Morgan: 01656 644 288)

Rhyd Y Carw Mill, Trefeglwys, Powys

This four-bedroom converted mill on the river Trannon has original workings, including gears, drive shaft and mill stones. Outside there's an attached barn with potential for conversion, and an acre of grounds. £300,000 (McCartneys: 01686 623 123)