A tribute to the past and an eye on the future

Carbon free and fit for the future, Cromford Mills in Cromford, Derbyshire is harnessing sustainable energy generation to produce energy for the site and provide heat to its buildings – providing a perfect example of how modern heat pumps can help breathe new life into much-loved older and historical structures.

Cromford Mills has a proud industrial past. It is the site of the world’s first water-powered cotton spinning mill created by industrialist Sir Richard Arkwright in 1771, which sparked the beginning of the Industrial Revolution and the creation of the factory system.

Today, Cromford Mill is a key part of the UNESCO Derwent Valley Mills World Heritage Site; the highest heritage designation, celebrating Britain’s industrialised history and influence. Every year, thousands of visitors descend to take a peek into the past, enjoy the events, cafes and artisan shops on site, experience expert-led tours and attend historical exhibitions. It is a living, breathing place.

Ongoing restoration and preservation work continues under the guidance of The Arkwright Society and the heritage site’s team, to ensure Cromford Mills remains relevant and accessible to all.

Arkwright’s water wheel powered the cotton spinning machines in the second mill he built at Cromford Mills. Although that mill is no longer standing, amongst its ruined foundations is the historic structure of Arkwright’s wheel pit.

With an eye on a more environmentally friendly future, the wheel pit is being used again to bring waterpower back to Cromford Mills – brought into the modern age with the design and installation of two low carbon Vaillant flexoTHERM water source heat pumps, which form the centre of a new heating system that is providing sustainably generated heat to its buildings.

Clean energy ambition

Simon Gill is the former Operations Director at Cromford Mills and led the ambitious waterpower project. He says: “We have an original water supply (Bonsall Brook) that fed Arkwright's Mills with natural power, still running right through the site. Our goal has been to try to harness such a powerful resource and use it for the benefit of the mill. Today’s sustainable technologies allow us to do this in a responsible way so that we maximise the energy we can obtain from the water flow.”

Architect James Boon has also been instrumental in pulling the proposals together for the project. Reflecting on the potential he saw in bringing together the old and the new, he said: “I appreciated the historic connection of once more using water to create energy just as Richard Arkwright first did nearly 250 years ago. He was able to use the lead mines and Bonsall Book to support his pioneering cotton spinning mill and it is entirely appropriate that we, once again, follow his inspirational lead.”

Arkwright's invention of the world’s first successful water-powered cotton spinning mill created a system for factory production that spread throughout the world. However, when society became more reliant on fossil fuels, waterpower as an energy source was abandoned.

This all changed in 2023 when, with a team of experts, the original wheel site was cleared and repaired, and the water wheel reinstated with a reconditioned (Gilkes) 17kW hydro-turbine installed by Derwent Hydroelectric Power.

This new water wheel became the ideal energy-generating asset to underpin the ambition that lay behind the water source heat pump installation.

Installing the heat pump system

Also located along the Derwent Valley – in Belper – Vaillant has close ties with Cromford Mills and began engaging with the waterpower project team early on. Alongside his colleagues, Richard Burley, Systems and Future Portfolio Engineer at Vaillant, quickly established that water source heat pumps would be key to harnessing the energy generated by the water wheel and turbine, to provide an efficient, modern heating system for the historical site.

Richard comments: “Given our ties to the local community here in Derbyshire and the long-standing relationship we had with Cromford Mills, our initial discussions with Simon started at the very early, ideas stage of the project. We discussed the aims and feasibility of bringing waterpower back to Cromford over several weeks. It was established that our heat pump technology would be a fantastic, low carbon way to capture the energy generated by the new water wheel and turbine and wanted to donate two of Vaillant’s flexoTHERM water source heat pumps to the project to support the charity and local heritage site.

“We established a new plant room, in what was previously part of the Cheese Shop, and supported with a system that utilised the water course and the water wheel to provide the electrical power to run the heat pump system.”

Installer Paul Leedham from Matrix Energy Systems says the system design delivers environmental benefit, adding: “Working with Vaillant, we designed the heat pump solution to consume less power than the level generated by the water flow. In effect, the site has a carbon negative system as we can generate more electricity than is needed.

“We capture energy via the restored water wheel and turbine, transfer it into the plant building, use the heat pump technology to raise the temperature and then use the heat for the buildings.

“This project sets a real precedent about what can be achieved, and it is a great example of how older buildings can be perfectly serviced by renewable technologies such as heat pumps.”

An exciting and sustainable future

Through many years of fundraising, the new system was finally able to launch in June 2024. Eilis Scott, CEO at Cromford Mills, who proudly opened the launch event says: “It is fantastic to see that the ambition of the waterpower project team has been realised. Our site is an integral part of the Derwent Valley Mills Heritage Site that we are all entrusted with preserving. Being able to combine the natural on-site waterpower with today’s sustainable technology, generating clean, low carbon energy to meet the needs of the site, is highly satisfying.”

She concludes: “In many ways the project’s success is a fitting tribute to the genius of Richard Arkwright and his original vision over two centuries ago. We are so grateful to Vaillant for its generous donation of their highly effective flexoTHERM heat pumps and the company’s assistance with bringing the project to a successful conclusion.”

As the nation’s decarbonisation journey continues, Cromford Mills is well placed to benefit from its newly created sustainable energy source. And, with the water wheel and turbine providing a free source of energy to power the new heat pumps, running costs are expected to significantly reduce – a real advantage for Cromford Mills – which is a registered charity – in the current economic climate.

The clean power emanating from Cromford Mill’s significant water resource and transformed by Vaillant’s heat pump technology into reliable energy, will be used to provide heating and hot water to ‘Building 1’ at the site, with the goal of transforming it into vibrant, accessible spaces including a restaurant and events area, that will generate income for the continued preservation of the site.

To bring this vision to life, the Arkwright Society needs ongoing support through funding, donations, and business partnerships. This support is crucial to advancing the regeneration of this nationally significant heritage site, ensuring that its mill gates remain open for future generations to enjoy.

This will be the foundation on which historic Cromford Mills can continue to enjoy an exciting, preserved and carbon free future.