How does a Kaplan turbine work?

The Mill Lane sluice site on the River Great Ouse lends itself to hydropower generation in terms of water head and flow rate, site access, space and grid connection options.

The difference in water level across the sluice will be able to generate up to 1,100MW hours per year of renewable energy.

The installation will have the potential to generate 860,000 KW hours per year equivalent to the energy required by over 300 homes in one year. This will save 257 tonnes of CO2 emissions per year.

How does a Kaplan turbine work?


The site at Mill Lane is suitable for a hydroelectric project. The difference in water level across the up to 1100 MW hours per year of renewable energy. This output will then be generated throughout the operational lifespan of the installation, expected to be a minimum of 50 years.

There is likely to be a limited impact from habitat loss due to the scheme’s construction but it is expected that this would be more than outweighed by benefits to the river ecology by the provision of a fish, eel and otter passage at the site. Waterside Green Energy Limited will ensure a Net Biodiversity Gain (NRG) of at least 10%. Benefits to the local community in the form of renewable energy generation, improved flood resilience, income generation and carbon off-setting would provide ample compensation for any short-term inconvenience during construction.

The land on which the site is based is owned by HDC and the EA both of whom have given their support to go ahead. They are negotiating the use of their land with Waterside Green Energy Limited.

The proposed hydro scheme would increase flow capacity past the weir by about 25%-30% which would help build community flood resilience.

The weir currently presents an obstacle to fish and eel migration and there is also an issue with otter fatalities caused when they try to cross Mill Lane. The proposed safe passage for these creatures would have a significant positive impact on the health of the river ecology of the immediate area and also benefit the wider river community.

Our preferred option of Kaplan turbine technology is based on installation costs, efficiency and suitability of the technology for this particular river profile. Kaplan turbines are more efficient and will generate more power for the flow and head we have here. They are also comparatively quiet in operation since the runner is fully submerged. However, Kaplan turbines are not fish-friendly so fine screening at the intake and provision for safe passage will be built in.

The amount of actual energy generated and available for distribution will depend on the capacity of the connection to the National Grid. A Kaplan unit with an output of 200KW is viable and will be expected to produce sufficient energy to power around 300 homes.

It is certain that a hydro scheme developed at Mill Lane, by and for the benefit of, the local community, will produce a sustainable energy solution helping to achieve government targets whilst bringing ecological and potential flood reduction benefits to the area.