Whisky distillery turning co-products into renewable energy

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Diageo’s on-site biogas plant is delivering a 25 percent reduction in fossil fuel energy demand

After just one year of operation, beverage company, Diageo’s on-site biogas plant at Glendullan, Scotland is turning 1,000 m3 of malt whisky distillery co-products per day into 16 MW hours of renewable heat.

The plant, commissioned one year ago by Clearfleau, a British provider of on-site anaerobic digestion plants, is helping lead the Scotch Whisky industry’s drive for environmental sustainability and carbon reduction at distillery sites.

“The UK’s food and beverage industry is becoming increasingly aware of the need to reduce its impact on the environment and limit its carbon emissions,” Richard Gueterbock, Marketing Director at Clearfleau, told The Source. “Effective management of process residues and their conversion into bio-energy is part of adapting to a more circular economy. Our plants are designed to optimise energy output from process residues such as pot ale and spent lees from whisky distillation.”

The plant is delivering a 25 percent reduction in fossil fuel energy demand at the distillery, saving Diageo significant costs and reducing its carbon footprint by 1,000 tonnes of carbon dioxide per year. The anaerobic digestion plants reduce the incoming chemical oxygen demand load by over 95 percent and minimise further treatment required for the discharge of cleansed water to the river Fiddich and then into the Spey.

Diageo and Clearfleau collaborated closely in developing the bio-energy plant at Glendullan and the initial plant at the nearby Dailuaine distillery that has been operational for over 3 years. Each on-site plant comprises a high-rate digester, specifically designed to handle liquid distillery co-products, followed by aerobic treatment for water clean-up.

“Only recently has on-site generation of bio-energy become a commercially viable proposition, helped by the development of suitable technology and government incentives,” added Gueterbock. “Other distillers are looking at options for on-site renewable solutions including digestion of residues. But industry also needs government to do more to support the transition to a more circular economy. It is particularly important to find ways of helping the smaller SME and family businesses that proliferate in the food and drink sector.”

Diageo also took the opportunity to invest in a new pipeline linking the nearby Mortlach and Dufftown Distilleries to the bioenergy plant at Glendullan, allowing co-products from all three distilleries to be processed and removing over 15 trucks a day from the local roads.

If the impact on the transport of co-products is included, the overall saving of carbon for the two sites increases to over 3,000 tonnes of carbon a year, for an expected 20-year period. If 10 additional, comparable on-site bio-energy plants were to be installed in the whisky sector in the next 3 years, the net annual saving could exceed 30,000 tonnes of carbon.