Leftovers from Chivas Brothers whisky distilling process are being successfully converted into green energy in a trial at Nigg wastewater treatment works in Aberdeen, Scotland.
The Scottish Water treatment plant already uses a process called anaerobic digestion to turn wastewater sludge - the semi-solid substance left from sewage treatment - into biogas. This is a renewable energy that can be used to run the boilers and combined heat and power (CHP) engines onsite instead of oil or diesel.
Energy-rich residues from brewing and distilling can be used in the same way and resources brought in from Chivas Brothers’ facilities have been added alongside the sewage sludge in a trial that started in October 2021. According to Scottish Water, co-digestion of the sewage and brewing waste has noticeably increased the amount of biogas being produced.
"We ... benefit from a boost in production of green energy at our site, which reduces our reliance on fossil fuels and helps our journey to net zero.”
Chief scientist Elise Cartmell said, “The team at Chivas Brothers approached us because the various residues created as part of the distillery process are often rich in energy, and they were keen to find alternative outlets to capture and use it. Fortunately this aligned very well with Scottish Water’s existing ambitions to investigate co-digestion, extending work we had already begun with SEPA, so we decided this would be the perfect opportunity to try out this process.
“It’s turning out to be a win-win for both parties: the distilleries are provided with an outlet for treatment which helps this key regional industry become more sustainable, while we at Scottish Water benefit from a boost in production of green energy at our site, which reduces our reliance on fossil fuels and helps our journey to net zero.”
With the addition of the distillery and brewery residues, the plant saw a saving of 58 tonnes of carbon over the 12-week trial period, which equates to 250 tonnes per year – the same as 250 passenger return flights from Paris to New York.
Cartmell said, “We’re very pleased with the findings which show that the trial boosted biogas production and significantly reduced the site’s need for oil to power its onsite boiler. Just as importantly, there was no adverse impact on the operation of the site or on the quality of the biosolids that are also produced for recycling to land.
“We believe there is excellent potential for this approach to be used at Nigg in the future and for it to be rolled out to other sites across Scottish Water.”
Chivas Brothers’ environmental sustainability manager Ronald Daalmans said, “The trial with Scottish Water has shown that residues from our effluent treatment process still have an energy value that can contribute to a more circular and sustainable economy and provide an alternative outlet for distillery residues when other routes are full. We hope the trial will open up further opportunities for collaboration between the Scotch Whisky sector and utility operators.”
"Residues from our effluent treatment process still have an energy value that can contribute to a more circular and sustainable economy."
The trial was made possible by close collaboration between the industry, the Scottish Environment Protection Agency (SEPA) and Scottish Water. It was led by the publicly owned water company’s commercial subsidiary, Scottish Water Horizons.
David Harley, SEPA’s Interim chief officer, circular economy, said, “Against a backdrop of climate and nature emergencies, there’s a real environmental imperative for us all to act. But more than that, innovative partnerships like this between SEPA, Chivas Brothers and Scottish Water are real economic and social opportunities.
“The Nigg trial is an excellent example of that collaboration in action, driving sustainability in Scotland’s food and drink sector, and making a tangible contribution to a circular economy and a net zero society.”