The water wheel at Trebandy Farm, near Ross on Wye, will generate enough electricity to supply the farm and holiday lets, and save over 20 tonnes of CO2 per year. Landowner Geoff Jordan (right) admires the results of the 3-year project with contractor Ben Living (centre) and project manager Greg McCormick (left).
The flow of water in streams and rivers has long been harnessed as a source of energy, and water power played a key role in the early Industrial Revolution, for corn milling, textile manufacture, and diverse other applications. Many of the old waterwheels now lie abandoned and overgrown, but there is growing interest in the potential of such sites for generating electricity using modern hydro power generators. Indeed, it is estimated that small-scale hydro schemes could generate an additional 1 to 2% of the UK's energy needs.
According to the British Hydropower Association, there are as yet no micro-hydro schemes in Staffordshire - these are plants with a generating capacity of less than 50 kilowatts - although JCB at Rocester are hoping to operate an Archimedes screw turbine at Tutbury Mill. So when I was invited to the opening of a scheme at Trebandy Weir near Ross on Wye, I took the opportunity to see first hand what micro hydro can deliver.
The site at Trebandy
Trebandy is a mixed farm of some 70 acres in a picturesque setting above the Wye Valley. The land features a false owbow lake fed by a tributary of the Garren Brook, following diversion of the brook in the 1920s and the creation of a weir. The oxbow lake and Brook now form a rich and diverse wildlife habitat, with otters, kingfishers, and even white-clawed crayfish, Britain's rare native crayfish.
Owner Geoffrey Jordan has restored the old farm buildings, some of which are now holiday cottages. He was looking for a source of clean and renewable energy that would power the farm and other buildings, but also harmonize with the surroundings and local wildlife. The solution was a water wheel installed below the existing weir, alongside a new fish ladder and eel pass. This will help salmon, trout and other species to overcome the long-standing barrier posed by the weir, and travel upstream to spawn. The waterwheel is hoped to produce over 30,000 kilowatt hours of electricity per year, depending on water flow.
The installation at Trebandy
- Water wheel of stainless steel construction, made in Derby. Projected operating life 50-100 years
- Fish pass and eel pass
- Metering and control shed
- Head of water: ~1.5 metres
- Generating capacity: 1 to 7.5 kilowatts
- Annual output: est. 30,000+ kilowatt hours
- Feed-in tariff: 21 pence per kilowatt hour
- Return on investment over 20 year tariff lifetime: at least 7.5%
The generation meter and ancillary equipment are housed in a shed on the riverbank.
Benefits of micro-hydro
Small-scale hydro has several advantages over other renewable technologies:
- High energy conversion efficiency: typically 70-90%
- High load factor: typically >50% (meaning it actually delivers over 50% of maximum output on average, compared with 10% for solar PV and 30% for wind energy).
- Works day and night, and operating life span is long
- Output is predictable according to rainfall paterns
- Maximum output in winter when power most needed
- Output varies only gradually as flow varies, not rapidly as with solar PV.
The scheme makes use of an existing weir giving roughly 1.5 metres 'head' of water to turn the wheel. Power generated depends on the head and flow rate of the Garren Brook.
Upfront costs are high, and depend greatly on the nature of the particular site. Also, a range of permissions and agreements must be obtained, including planning permission. Expert help is required from the outset to ensure that all aspects are covered, and would-be developers are advised to contact their local authority at the earliest stage. In the case of Trebandy, the following were required:
- Planning permission
- Impoundment Licence
- Ecology Survey
- Flood Defence agreement
- Grid connection agreement
- Ofgem accreditation for FiT payments