Thames hydro power15 January 2001
In an attempt to promote greater understanding and support for the successful development of hydro power on the river Thames, environmental regulators and industry members met recently in the UK. Lengthy but valuable discussion took place
The publication of an article in IWP&DC (Powering up the river Thames, November 2000, pp34-5) has helped to spearhead discussion between the regulators and developers of small hydro in the UK.
On 4 December 2000, five members from the Thames region of the Environment Agency (EA) gathered at Coaley Mill in Gloucestershire to discuss the development of small hydro in the UK. The EA team comprised Helen Phillips, area manager; Colin Candish, regional water manager; Ian Barker, head of the National Water Demand Manage-ment Centre; Sean Kent, Engineer-ing Services Office, and Alan Butterworth, fisheries and ecology manager. To provide a balanced discussion and exchange of views the following were also present: Osman Goring, owner of the 25kW Coaley Mill and Water Power Engineering; Richard and Marilyn Hodkin, hydro power and mill owners in the Stroud Valley; Julian Jones, director of Vision 21 for Gloucestershire; and Graham Haw, mill owner from Minehead.
A lengthy exchange of views followed when the two sides representing the UK hydro industry and its regulator agreed there were few good examples of modern small hydro power development in the UK. Goring explained that for the past 12 years he has had to stand back and observe poorly designed and manufactured schemes; constructed down to a price rather than up to a quality standard. He believes that industry regulators need a thorough understanding of small hydro to help improve the current situation. He suggested that river management and hydro power in the UK is a forgotten technology and art, both for inexperienced developers and ill-informed regulators.
Hodkin says it is apparent that the problems are with the rivers and the expertise needed to deal with them. The lack of such expertise allows specific valid interests, such as ecological considerations, to overrule the requirements of the basic functions of the river, such as the efficient flow of water without flooding. Hodkin believes hydro power is not in itself the problem; the same applies to any change to a river system which may not always be understood by the EA. However, at present hydro power does highlight the difficulties due to perceived changes to the river system associated with its introduction. But in most small installations this is minimal, which also highlights the lack of confidence that developers and the EA have in being able to predict a satisfactory outcome for a scheme.
Jones asked that the EA should recognise that it owns 45 weirs on the Thames and that, as a public body, should be accountable for not exploiting this valuable renewable energy worth millions of pounds. The EA’s failure to even mention this in any of the Thames local EA plans (known as LEAPS) is not only a waste of public resources but, Jones believes, raises the question about the EA’s seriousness in tackling global warming.
The function of weirs and the role hydro power can play in water management needs to be considered within a holistic view, Jones says. Small hydro power development is just one issue of public wealth here: the accumulation of algae and humus on trash racks shows that there is a potentially valuable soil conditioning and fertiliser material that can be recovered from the rivers – ideally at weirs. Jones says it is surprising that the EA does not seem to undertake any effective form of auditing of renewable public resources. He added that public health should be a consideration as weirs can distribute sewage-originated pathogens as aerosols to the atmosphere. The operations of combined storm and sewage overflow in proximity to weirs also needs to be reviewed, and small hydro power developments may have a beneficial role in river management to ameliorate health risks.
Other issues which were covered focused on fish. Alan Butterworth from the EA said that certain fish fry drifted naturally downstream and would be lost in hydro power turbines. He also was generally concerned about current fish pass design. He said further research is needed to be undertaken with regards to fish fry and fish pass operation. Goring pointed out that even without weirs, fish fry will always be lost at times of high river flow and floods. At times of very low flows, without weirs, sections of the river will tend to dry out and fish will be lost.
The EA was keen to discuss lessons from case studies but Goring explained few exemplary small hydro schemes have been developed in the UK over the past 60 years. Most sites, he says, have been built down to a price rather than up to a standard of best practice. He believes many of the shortcomings have been brought about by the former National Rivers Authority, and now the Environment Agency, insisting upon what the industry considers to be unsuitable concepts. For example, in several instances no tiltgates or inflatable weirs have been required to regulate water levels when water is taken away from the weirs to pass through turbines.
At the 700-year-old Coaley Mill site, on the river Cam in Gloucestershire’s Dursley Valley, the watercourse was widened above the mill by construction of a flood alleviation scheme 20 years ago. Goring says that this was stipulated by the river authority and designed with little consideration given to hydro power and how watercourses function. But it was given official approval with the result that water velocities have dropped and residence times increased, leading to more sediment settling above the mill.
As the meeting illustrated there is still a great need for further discussions between members of the UK small hydro industry and its regulators. But this meeting gave a positive outlook for the future. As Helen Phillips from the EA said, the Agency will be promoting debate and agreement within the Thames Region on how to forward hydro power proposals, with the EA as regulator and potentially promoter of such schemes.