36 n MECHANICAL POWER TRANSMISSION June 2024 www.drivesncontrols.com Gearing up for Europe’s biggest waterwheel generator Europe’s largest electricitygenerating waterwheel has been built on a farm near Dorchester in Dorset. The 9m-diameter, 800mmwide wheel has snatched the title previously held by the 8.2m-diameter Aberdulais Wheel at a National Trust site in Port Talbot, Wales. The new wheel has been built by the Perrett family who own both the farm and a self-drive plant hire company, Buckland Newton Hire (BNH). To achieve the 9m head required for the project, BNH raised the water level of a lake on the farm by around 11m. The lake is supplied by a large spring and run-off rainwater from surrounding hills, and the wheel is expected to be able to generate an average of 150kWh per day for most of the year. The galvanised steel waterwheel, which has 92 buckets that carry a total of 6 tonnes of water at a time, is driven by an average flow of around 150 litres per second. It is delivering around one-third of the total electricity needed for the site, which includes more than 20 industrial units, many of which have substantial power demands, as well as five other properties and offices. The proportion of the farm’s electricity supplied by the wheel is expected to be even higher in the summer when the electricity consumption is lower. As well as its plant hire business, BNH also runs related operations, such as carrying out groundworks projects. It had previously been involved in installing renewable energy systems including wind turbines, solar installations and hydro schemes, and was inspired to install its own waterwheel to power its business and the farm. “As the lake is in front of his home on our family farm, my father wanted to watch a huge waterwheel from his window,” explains BNH manager and director, Brad Perrett. “We have made his dream come true, building the biggest wheel we can for him.” The wheel rotates at 4.5 rpm. A gearbox increases the speed to 450 rpm at the output shaft. A belt-and-pulley connection then delivers the required 1,500 rpm to the generator. Finding the correct shaft size was an important aspect of the project. The high torque from the waterwheel is accommodated by the 140mm-diameter input shaft of an Apex Dynamics NB series linear three-stage planetary gearbox that has been installed in line with the waterwheel shaft. The gearbox has a 48mm output shaft. A flexible grid coupler accommodates any misalignments, but this has proved unnecessary because the servo gearbox aligns perfectly with the input and output shafts. However, the coupler has been retained as a safety feature. Perret reports that he looked at gearboxes from other suppliers, but the precision Apex Dynamics box “was the only one to meet our specification, build and delivery time requirements, while easily achieving our 2530kNm maximum torque requirements”. The waterwheel, he adds, “has now been running perfectly, non-stop, 24 hours a day for more than three months, without a hitch. “We could easily have installed a crossflow turbine, but we wanted to do something a bit different that showcases our capabilities and our green credentials as a company,” Perrett continues. “We think we could replicate this project in the future to provide similar lake-based energy generation projects for clients.” BNH is landscaping the grounds around the waterwheel and plans to allow visitors to view the pioneering electricity generation project from the summer of 2025. n The biggest electricity-generating waterwheel in Europe has been built on a farm in Dorset. An inline planetary gearbox is used to control the wheel’s output, delivering accurate alignment, high efficiency and low transmission losses, thus maximising the electricity output. The 9m-diameter waterwheel is expected to generate an average of 150kWh per day
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