The project in detail
We have built a 49 kW hydro scheme on the small island adjacent to Osney Lock in Oxford.
At its heart is an Archimedean screw hydropower system, suggested to us by the Environment Agency for its efficiency, robust design and ‘fish friendliness’. You can read more about this technology at www.mannpower-hydro.co.uk.
Our initial lease from the Environment Agency is for 40 years. With a 25-40 year lifespan, the screw within the concrete hydro casing should only need to be replaced once during this time.
The amount of electricity generated at any one time will depend on the flow of the river. The performance figures quoted are an average estimate based on five years of flow data, and take into account restrictions imposed by the Environment Agency’s Abstraction Licence.
The civil engineering needed to be scheduled to coincide with work the Environment Agency has planned to improve the buck gates at the site starting in the summer of 2013.
Solar panels to boost generation
The generating capacity of the project has been maximised by the inclusion of 7.75 kWp solar photovoltaic array panels on the roof of the building, generating an additional 6,665 kWh of green electricity annually.
As well as aiming to maximise the environmental benefits we have taken great care to minimise possible negative impacts of the scheme, and commissioned a number of independent expert assessments to study the potential impact on biodiversity, noise and flooding. This information formed a key part of the rigorous process we followed in order to be granted planning permission and for our application to be supported by the Environment Agency. You can download the impact assessment reports here.
The following reports are also available on request by email. We are currently unable to display them on line due to the size of the files, but we hope to be able to resolve this shortly.
- Flood risk assessment
- Macroinvertebrate and protected species survey
Measures to minimise negative impact:
- The hydro site has been designed to minimise noise through sound proofing.
- It incorporates a fish pass to allow fish to travel freely.
- Landscaping at the site will include native planting to enhance local biodiversity and, with input from the Environment Agency, to ensure it poses no extra risk to this flood-prone area of the city (see below).
We were disappointed that the Oxford City Council Tree Officer did not accept our proposal to retain all the trees on site. You can read our original survey and the Tree Officer’s rationale in full here.
The conditions of our Abstraction Licence have been designed to allow careful flow management in the area.
In particular, there will be no additional flow as a result of the scheme. There may be a very localised effect in that less water will flow over the main weir when operating, as it will be diverted down the Archimedean screw which will be directly adjacent to the buck gate.
Impact on fish
As part of the process to secure planning permission an Environment Agency support for the scheme, we commissioned an independent environmental study to investigate any potential negative impact on local biodiversity, including impact on fish. The study concludes ‘Currently the weir represents an impassable barrier to all fish species and therefore it is not anticipated that the proposed scheme will have any adverse impacts on the river from a fish upstream migration perspective. Installation of the fish pass associated with the proposed scheme is likely to significantly improve fish migration opportunities past the barrier.’
You can read more about the fish-friendliness of archimedean screws and the studies to support this in this paper by New England Hydro.
Find out more about community owned hydro schemes
Settle Hydro is another community owned hydro scheme, featuring an Archimedean screw. You can learn more about their scheme, in this short video on YouTube.