Whisky distillery slashes carbon costs with novel AD solution

North British Distillery, based in Edinburgh, turned to AD to help solve a bottleneck in the back-end of its manufacturing operations.

Instead of investing in additional evaporation capacity to process the liquid by-products from the distilling process, which would have been energy intensive, the company invested £6m in a by-products plant to produce distillers dark grain pellets for animal feed.

This incorporates AD technology utilising an external circulation sludge bed from HydroThane to process a third of the post distillation liquor.

The project, which was completed in two phases with help from biogas specialist ENER-G, is capable of treating 27,000kg of chemical oxygen demand per day, producing up to 24,000MWh of biogas.

The biogas is converted into steam and electrical energy for use on-site, significantly reducing the distillery’s reliance on the use of fossil fuel based energy inputs from the national gas and power grids.

The company is also able to flex between selecting either maize or wheat as the optimum raw material, dependent on cost and availability of the feedstock.

The latest phase of the project saw the construction of a water treatment plant to process the effluent stream from the AD facility. This has improved the quality of the post-treated water before being discharged to local sewer, enabling up to 40% of the total volume to be recycled within the distillery.

According to the distillery this represents a considerable saving as it uses an average of 20 million litres of water per week.

The company, which supplies brands such as Famous Grouse and Johnnie Walker Black Label, is now working with the Bio-Fertiliser Association to have the bio-solids produced from the aerobic process accredited under PAS110.

Commenting on progress made, North British Distillery managing director David Rae said: “Our sustainability business strategy is enabling us to make savings in terms of energy costs while at the same time reducing the environmental impact of our production process.

“By reducing our carbon footprint we are contributing significantly to the Scotch whisky industry’s global target of sourcing 80% of its energy needs from renewable sources by 2050.”

Maxine Perella