Kirkthorpe hydro is a hydroelectric generating plant located on the River Calder at Kirkthorpe Weir, 4 miles (6.4 km) east of the City of Wakefield in West Yorkshire, England.[1] Kirkthorpe Weir, which is a grade II listed structure, has been an obstruction for fish passing up the River Calder since it was built in 1827.[2] It is a 13 feet (4 m) drop weir which is the highest in Yorkshire,[3] and was built to maintain a steady flow of water into the Aire and Calder Navigation which branches off just upstream of Kirkthorpe Weir on the left bank.The eel pass has a constant flow of water and is protected by overhead screens to prevent predation.[10] As the turbine is generating constantly with water running through the power station, the unused electricity is stored in the battery which can be released at a time when supplies are lower.