Europe’s largest electricity-generating waterwheel is operating in Dorset

The BNH waterwheel under construction.

Technology from servo gearbox specialist Apex Dynamics is driving the largest diameter electricity-generating waterwheel in Europe. Here, the firm details the background to the project, and some of its technical highlights.

The groundbreaking new hydro project from family-owned self-drive plant hire company Buckland Newton Hire (BNH) saw Apex Dynamics UK supply the inline planetary gearbox used to control the waterwheel. It has provided the wheel with near-perfect alignment, high efficiency and minimal power loss through transmission to ensure as much electricity as possible is generated.

Based near Dorchester, Dorset, it is the largest waterwheel generating electrical power in Europe at 9.0m in diameter, overtaking one at a National Trust site in Port Talbot, Wales. To achieve the required head for the project, BNH raised one of the lakes on the family farm by around 11m. The lake is supplied from a large spring and run-off rainwater from the valley slopes.

The galvanised steel waterwheel, which has 92 individual buckets carrying a total of 6 tonnes of water at a time, now delivers an average flow of approximately 150 litres per second 24/7 nearly all year round, supplying an average of 150 kWh per day. This contributes around one-third of the total electricity needed for the site – which includes more than 20 industrial units, many with large power demands, 5 properties, and offices – and even more in summer when daily consumption is lower.

An Apex Dynamics NB series linear 3 stage planetary gearbox is in line with the waterwheel shaft and is connected to the generator via a pulley and belt system. The waterwheel rotates at 4.5 rpm and the Apex gearbox provides additional flexibility to fine tune the speed up to 450 rpm at the 48 mm gearbox output shaft. The high torque from the waterwheel is accommodated at the 140 mm diameter input shaft of the gearbox. Getting the shaft size to match was very important to the project. Having incorporated a flexible grid coupler into the system design to accommodate any misalignment, this has proven unnecessary because the NB servo gearbox perfectly aligned with the input and output shafts but has been retained as a safety feature. The pulley and belt connection delivers the required 1500 rpm to the generator.

In addition to plant hire, BNH also runs a number of related operations, including carrying out specialist groundworks projects. It has previously installed renewable energy – such as wind turbine, solar installations and hydro schemes – for some customers and was inspired to install its own waterwheel to power its business operations, nearby houses and family farm. The company is now open to repeating the success of the waterwheel project if requested.

Brad Perrett, BNH Manager and Director, explains, “As the lake is in front of his home on our family farm, my father wanted to watch a huge waterwheel from his window and we have made his dream come true, building the biggest wheel we can for him! Apex Dynamics UK has been an excellent partner for this project.

“We could easily have installed a cross-flow turbine, but we wanted to do something a bit different that showcases our capabilities and our green credentials as a company. We think we could replicate this project in the future to provide similar lake-based energy generation projects for clients.”

The grounds around the waterwheel will be landscaped by BNH so that visitors can come and view the pioneering electricity generation project from summer 2025.

Apex Dynamics patented gearbox designs come with a 5-year warranty, 2-3 week lead times, guaranteed delivery and ATEX as standard.