MEMBER’S PRESS RELEASE: Clearfleau completes commissioning of new AD plant for Diageo

New on-site bio-energy plant at Glendullan, on Speyside, coverts 1,000m3 of distillery co-products per day into 1 MW of heat, feeding biogas to dedicated biogas boiler to supply valuable renewable energy to distillery, reducing its carbon footprint

Award-winning British company Clearfleau, the leading UK-based provider of on-site anaerobic digestion (AD) solutions for food and beverage companies, today announces handover of its latest bio-energy plant at Diageo’s Glendullan distillery.

This innovative bioenergy facility, which was visited by Scotland Office Minister Lord Dunlop on 13 August, is an example of how the Whisky sector can embrace the circular economy.  By generating bioenergy from its co-products, Diageo is showing how one of Scotland’s most traditional industries can deliver carbon savings and wider environmental benefits. 

The Glendullan plant optimises energy output using co-products from the distillation process.  The project involved close collaboration between Clearfleau’s in-house design, installation and commissioning engineers, their counterparts from Diageo and an extended supply chain. 

Following the 2013 completion of an initial high-rate digestion facility at the Dailuaine malt distillery (also in Speyside), Diageo commissioned Clearfleau to build a second facility.  The Glendullan plant is very similar.  It receives feedstock from other distilleries in the Dufftown area, fed to the plant in a recently completed pipeline reducing local truck movements.

Initial results indicate the Glendullan bioenergy facility is generating 2 million m3 of biogas per year – producing about 8,000MW hours of thermal energy for the distillery, based on processing up to 1,000m3 of distillery co-products on a daily basis.  

Clearfleau’s on-site AD technology converts a range of co-products into valuable biogas that generates renewable heat for use in the distillation process while reducing a major overhead, its co-product disposal costs.  By reducing costs and benefiting the local environment, Diageo is setting an example to British food and beverage companies (including other distillery sites). 

Clearfleau’s unique liquid anaerobic digestion system can achieve a reduction in COD load of greater than 95%, minimising additional treatment required for discharge of cleansed water to the river Fiddich. The facility will also reduce the site’s fossil fuel based energy costs. 

Engineering challenges involved developing a plant able to handle higher strength materials such as pot ale, as well as the variability of strength and volume of feedstock being fed to it.  They also included the location of the plant on a sensitive location in a valley adjacent to the river Fiddich and achieving the complex water course discharge standards.

Clearfleau’s unique liquid digestion system delivers a reduction in COD load of greater than 95%, minimising additional treatment required for discharge of cleansed water to the river Fiddich.  The discharged water is carefully monitored in terms of COD removal, biogas output and microbial performance, protecting the regions’ important aquatic eco-system.  

Keith Miller, Diageo’s Distillation and Maturation Director, said:

We’re very proud of our record in investing in cutting-edge sustainable technology at our distilleries. The bioenergy plant at Glendullan is the most recent example of how we use innovative technology which harnesses the potential of the natural raw materials we use in the distillation process to generate renewable energy.

When visiting the Scottish Office Minister, Lord Dunlop added:

The commitment to powering distilleries like Glendullan with sustainable energy, recycled from the co-products of the whisky-making process , is also exactly the right thing to do. Good for the planet, good for the whisky industry and good for the Scottish economy.

Commenting on the second contract from Diageo, Craig Chapman of Clearfleau said:

This project, a result of close collaboration between Diageo and Clearfleau, shows how British technology can enable a traditional but energy intensive Scottish business sector to embrace the circular economy, reduce its costs and create a more sustainable basis for production. However, wider adoption of this technology requires on-going support for renewable energy.  The Scottish and British Government should be working together to support the development of indigenous renewables technologies and their adoption in a range of industry sectors, helping to deliver our long-term sustainability targets.

For further information and more high/low res images and diagrams please contact: Gaye Spencer, GSPR Environmental Tel:  01635 569992 Email:

Posted in: Members' press release

Tags: member's press release, Clearfleau, diageo, glendullan distillery, brewery, wastewater, lord dunlop, bioenergy, liquid digestion, biogas, keith miller, craig chapman, whiskey, Derek Sivyer