Turbines through Time: A short history of the Energy Research Unit’s wind turbines
22 Feb 2023







Wednesday 22nd February 2023 marks the fifth anniversary of the STFC Rutherford Appleton Laboratory (RAL)'s wind turbine and its installation on the Energy Research Unit (ERU) test site. 

​The test site​, which was founded in 1978, is available to energy researchers and students to investigate new and renewable energy exploitation. It is notable for its involvement in innovative wind energy research in the 1980s and 90s - in areas such as aeronautics, electrical engineering, meteorology and mechanical engineering. In 1978, ERU staff members were involved in the creation, and subsequent running, of the British Wind Energy Association, which later became the trade association RenewableUK. Over its lifetime, the ERU has been the home to several wind turbines, each of which added another facet to RAL's history in pioneering energy research.

The first wind turbine installed on the site was a Vertical-axis Wind Turbine (VAWT). It was originally built for a sustainable building in Cambridge but, after a change of heart, it came to RAL in 1978. The VAWT was one of the first post-1960s experimental wind turbines in the UK and provided vital input into the debate of whether turbines should have a vertical or horizontal axis. The turbine was removed in 1999 to make way for the Building Integrated Wind Turbine's (BUWT) concentrator.

The VAWT installed at RAL in 1978

In 1983, five years after the installation of the VAWT, a second wind turbine was added to the site - the American-built North Wind L-916 turbine. The new 14kW turbine was used in wind/diesel experiments and also provided data for projects modelling dynamically active turbines. It is interesting to note that the turbine's maintenance logs recorded a repeated issue of jackdaws making nests in the turbine cover! The equipment was finally dismantled in 2005 (having been rebuilt in 1996) and was taken to the University of Leicester for use in undergraduate projects.

The North Wind turbine in 1986

Fast forwarding to 1990, the Windharvester was installed. This 45kW turbine featured a 17m rotor diameter, three blades and a 15m high tower. It was designed for high wind speed locations – a similar machine provided power on Fair Isle in the Shetlands for many years. The turbine was refurbished in 2000-2001 and raised again in July 2002. In October 2016, the Windharvester was lowered for a final time to make room for two new ISIS buildings on site. While the turbine generated 549,305 kWh over 23 years, it had spent a significant amount of time being instrumented during various research campaigns. In its later years, the Windharvester's role was solely to generate power into the RAL grid and to be a large exhibit for Public Engagement purposes. It was lovingly maintained for many years by Technology Department staff members Peter Anthony and Alan Ruddell.

The Windharvester installation in 1990 (left) and the turbine seen in 1996 (right)

.The test site has also hosted two turbines designed by Imperial College. The first – a 5kW, 6.5m diameter, 2-bladed, upwind, variable pitch and speed device on a 10m tower - was erected in 1987. The turbine was used in various PhD projects until it was dismantled in 1997 and taken to Loughborough University. The second Imperial College turbine - the Sail Wing turbine - was much smaller. It was rated at 4kW and featured three cloth sail blades. The Sail Wing turbine was built to explore a modern replacement of the traditional turbines used on the Lasithi Plateau in Crete and developing countries. It was installed at RAL in 1994, tested for three years and then taken to Crete.

The Imperial College turbine in 1987 (left) and the Sail Wing turbine in 1994 (right)

In 1999 the Building Integrated Wind Turbine (BUWT) was hosted by the ERU for an EU-funded project led by Imperial College. The structure was made to accommodate very small vertical and horizontal axis wind turbines and was installed to evaluate the optimum design for integrating wind turbines into buildings. In 2016, when the ERU test site was moved, the BUWT was dismantled. This move occurred due to building work and provided the ERU team with a new control room and weather station but resulted in the loss of the Windharvester and the BUWT.

The BUWT hosted for Imperial College

On February 22nd 2018 the site's latest wind turbine was installed as a part of the Siemens-led £2M InnovateUK project involving Cardiff University, the University of Oxford and the Energy Research Unit. As part of the project, STFC had committed to providing the “Green Ammonia" demonstration plant with a supply of renewable electricity from a wind turbine.

The Green Ammonia Demonstrator

After some initial research, the ERU team realised it would be cheaper to install a new wind turbine than to install the foundations and ducts required by the existing Windharvester (which was later sold to a farmer in Scotland). A specification was drawn up for the purchase and installation of the new Britwind 12kW turbine, a three-bladed upwind turbine optimised for low wind speed.

Installing the new wind turbine in February 2018


During the five years the Britwind turbine has been at RAL it has generated over 100,000 kWh – it starts generating at low wind speeds (3 to 4 m/s) until the rated wind speed (about 12 m/s) when it generates its maximum power of 12kW. Above the cut-out wind speed (about 14 m/s) the wind turbine starts to be shut down ​​for safety and to avoid excessive stress – as happened last year during Storm Eunice.

The Britwind turbine in 2018

Today the UK has over 11,500 operational wind turbines (on land and offshore) with a capacity of 28,087 MW (roughly 14GW onshore and 14 GW offshore) - in 2022 about 25% of the UK's electricity was generated by wind power. The UK Government has committed to a major expansion of offshore capacity to 50 GW by 2030 with 5GW of this coming from floating wind turbines

If you are interested in finding out more about new and renewable energy research at RAL, please visit the Energy Research Unit's dedicated website and the briefing note about green ammonia.

Written by Cat Lewin-Williams and Dr Jim Halliday.​