Betchworth Estate hydro, Surrey
The weir was fitted with two identical hydro turbines by NHT Engineering Ltd, giving a total capacity of 55 kilowatts. Such small hydropower technologies usually allow part of the river to pass through the submerged turbine at speed due to the drop in height at the weir (metres at Betchworth), guiding the water optimally onto the internal rotor blades that are fixed to an electrical generator. The power thereby generated is fed into the regional electricity network; some of this covers the estate's own power demand, but about 90% is surplus and the purchasing electricity company provides revenue according to this net amount supplied. First estimates of annual income have been put at £18,000. Due to legislative and technical requirements and delays, the entire project's consultancy fees were around £150,000 before work even started, although this includes the weir restoration and therefore would not be a typical figure for a pure hydropower project. Betchworth House lies in attached parkland near Dorking in Surrey. On the River Mole which flows through the park there is a late 18th century weir, which in 1999 the estate owner determined to restore.