The Edinburgh Scotch whisky grain distillery, which supplies famous brands such as Famous Grouse and Johnnie Walker Black Label, won the AD & Biogas Award for Best integration of AD into a food and drink business.
The £6 million green technology project has reduced the distillery's carbon dioxide emissions by approximately 9,000 tonnes per year, which equates to the annual carbon saving benefits of a 7,377 acre forest, or removing 3,000 cars from the road.
The project introduced high rate anaerobic digestion to help the company provide a sustainable solution to a bottleneck in the back-end production process. This comprises a by-products plant producing Distillers Dark Grain pellets for animal feed.
Instead of investing in additional energy intensive evaporation capacity to process the liquid by-products from the distilling process, a decision was made to install an anaerobic digestion plant which, conversely, produces renewable energy in the form of biogas.
By using HydroThane's ECSB (External Circulation Sludge Bed) high rate anaerobic digestion technology to process a third of the post distillation liquor, the company has reduced the load on its existing energy intensive evaporation plant - increasing productivity while reducing energy demand.
As a result of increasing output, 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. Previously, wheat hadn't been a consideration because it reduced capacity.
The AD plant, which was completed in two phases, is capable of treating 27,000Kg of Chemical Oxygen Demand (COD) per day and produces up to 24 000 MW hours of renewable energy in the form of biogas.
A high efficiency 500kW ENER-G combined heat and power system and a 1 000kW steam boiler convert the biogas into steam and electrical energy for use on-site. These two energy streams dramatically reduce the distillery’s reliance on the use of fossil fuel based energy inputs from the national gas and power grids.
A third phase of the project, completed in 2012, consisted of the construction of a water treatment plant, designed and installed by MSE Systems. The plant uses two large aerobic bio reactors and micro-filtration membrane technology to process the effluent stream from the AD plant. This significantly improves 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. This represents a considerable saving, considering that the distillery uses an average 20 million litres of water per week. It has also obviated the significant recent increases in trade effluent charges affecting many processing industries.
The distillery is working with the Bio-Fertiliser Association to have the bio-solids produced from the aerobic process accredited under PAS110.
David Rae, Managing Director of North British Distillery, said: “Our sustainability business strategy is enabling North British Distillery 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 per cent of its energy needs from renewable sources by 2050.”
Michael Lyle, Managing Director of HydroThane UK said: “HydroThane technology is giving North British Distillery considerable improvements in their energy costs and reduction in environmental emissions. The ECSB technology, a third generation anaerobic digestion process, ensures that all anaerobic odours are contained within the process, which was an essential factor in the choice of the technology by the distillery, due to its central Edinburgh location and environmental licensing conditions.”
Scott Tamplin, Director of Anaerobic Digestion for ENER-G, said: "North British Distillery is leading the way in demonstrating how anaerobic digestion can reduce costs and improve sustainability in the food and drink and industry. We are proud to partner with them to ensure high efficiency in renewable energy production and biogas utilisation."