Hydro scheme development

The UK has a long tradition of harnessing the power of water in rivers to generate energy. These schemes are known as ‘run-of-river’ and are very site specific. Eligible schemes require the river to have a sufficient ‘flow rate’ of water and an adequate ‘head’ or the vertical fall of the water from upstream to downstream. With this data the annual energy capture of the scheme can be estimated and its feasibility can be assessed.

Sites are classified according to whether they have a high head, above 10m, or a low head, below 10m, and differing turbines will be chosen according to these site characteristics.

A high head scheme generally has a weir at a high point of the river. This weir feeds a canal or leat which runs horizontally to a deeper forebay which acts as a settling tank where debris is blocked by a trash rack. The water then travels down the penstock, which is a pipe from the highest point to the lowest point, with the turbine at the bottom. The water then returns, via a tailrace, to the river.

A low head scheme operates using the same principal, with the exception of the penstock. 

Low head hydro schemes typically have a capital cost of £8-12,000/kW - the cost is very site specific. Variables include:

  • Grid connection
  • Civil works
  • Cost for fish-passage
  • Any historic monuments
  • Weir repair or strengthening
  • Associated risks

Developing a site with a good flow rate and head can be become cost prohibitive, if there are a combination of these factors: See Hexham Hydro

High head hydro schemes can potentially be cheaper to develop, with costs ranging from £3-8,000/kW

Despite the relatively high capital costs, if turbines and generators are serviced and maintained they can continue to generate well beyond their design life of 25-50 years providing good long term renewable energy generation and investment opportunity.

Industry bodies:

Micro Hydro Association: www.microhydroassociation.org/

British Hydro Association: www.british-hydro.org

Feasibility and Development

There are a number of stages involved in assessing the feasibility of installing a hydro-power scheme, See:

BHA guide to mini hydro development

Power from the landscape  hydro guide


European guide and funding

Siting and design considerations

  • Siting – A lease should be agreed with the land owner of the proposed site. Consideration should be given to whether the site is in a designated area, for example an SSSI or a spawning ground for aquatic life, access to the site for the necessary construction vehicles is required.
  • Grid connection – proximity to the grid is paramount, as the cost of connection to an isolated site could be prohibitive.
  • Consultations – Consultation with the environment agency, the local communities, local anglers and angler's trust should be undertaken.
  • Planning – advice should be sought from the local planning authority. 

Technical information: From the Micro Hydro Association

River flow data: Centre for Ecology and Hydrology website.  

Where data is not yet verified, CEH will provide what is available and will answer email queries free of charge. Note that the facilities on this website work with Internet Explorer and Google Chrome (March 2012) but not all do with Mozilla Firefox.  Further useful links below for main UK rivers (even though some are accessed via the EA):

Flow duration curves - use this to select the watercourse/gauging station anywhere in the UK;

Real time river levels (EA) - you have to navigate through maps or regions to get to a specific gauging station

Real time River levels (SEPA) - use the above links to select your watercourse and then view EA or SEPA recent river level (not available on-line for Northern Ireland);

Formulae for converting river level to flow - having selected the river and found the current level, then use this link to access the EA-maintained "Hi Flows" data site, select the watercourse again, and follow the link to "Ratings" where the conversion formula  from river level to flow is shown.  CAUTION: some gauging stations show equations only for high flows - check the Max Stage column for applicability - if not available contact the agency (SEPA is This email address is being protected from spambots. You need JavaScript enabled to view it. ).

Joe Hartvigsen's site (Turgo turbine components and design)

Ask the Renewable Energy Guru (from the USA)

Hydro potential map

 Community schemes