Longaller Mill

The current owners had  been planning a hydropower scheme at this former mill for 20 years before the system was finally installed this year. Previous feasibility studies had considered various low turbine options but all were unsatisfactory from both a cost and a planning perspective. Plans to sympathetically update the mill with a new waterwheel system were proposed and permission was eventually granted to remove the existing listed wheel which was well beyond repair and unsuitable to adapt for electricity generation.

A layout was designed which enables as much of the historic infrastructure as possible to be preserved by positioning the new drive and generator on the opposite side of the wheel axle to where the old pit wheel is positioned. This now sits on a reinforced wall between the wheel pit and relief channel alongside.

The mill and surrounding area flood on occasion due to downstream flow restrictions. It is possible that future flood levels could reach the height of the wheel axle. With this in mind, the geabox unit has been designed with labyrinth seals which prevent water ingress if temporarily submerged.

Under the guidance of Pico Energy Ltd the scheme owners carried out the site preparation and building work themselves. The scheme has now been accredited under the MCS for the feed-in tariff and is earning 19.9 pence per kilowatt-hour from the FIT and a further 3 pence per kWh from the export-tariff.