Recovering heat from water and by-products in distilleries
Distilleries are excellent locations to study the recovery of heat and the reuse of water as they have considerable heating requirements for mashing and distillations and use great volumes of water, e.g. for cooling.
Heat recovery options in a whisky distillery. Heat can be recovered after mashing (1.), at the two distillations (2.) and from the by-products pot ale and spent lees (3.). This can save up to 25% of heating fuel in the boiler, plus water for the boiler, for cooling or for cleaning. Dotted line: study boundaries.
In 2018, the UK counted over 450 distilleries [1], mostly micro-distilleries. In Scotland for instance, 80% of the water abstracted by distilleries is used for cooling [2]. Several process streams (at mashing and distillations) and the by-products (pot ale and spent lees) are suitable heat sources.
They can serve to save up to 25% of heating fuel, as could be shown in a case study on whisky production in a micro-distillery. However, as additional equipment has to be purchased and installed for heat recovery, it also comes with an environmental footprint, including a carbon footprint, and at a financial cost. The assessment showed that both environmental and economic burdens are by far outweighed through the savings, and that despite requiring additional equipment, it can be recommended to recover heat from all possible steps in the whisky making process. The capital investment costs can be paid back in less than 2 years. It could also be shown that the distillery has more recovered heat to offer than it can reuse itself. In order to maximise the use of the recovered heat, heat and water sinks outside the distillery should be integrated in a heat recovery project.
[1] O’Connor, A., 2018. Brewing and distilling in Scotland - economic facts and figures. Scottish Parliament Information Centre (SPICe).
[2] SEPA, 2019. CLAS Report 160119. Scottish Environment Protection Agency
Arbikie distillery served as a case study for heat recovery in micro-distilleries. Thanks to Arbikie distillery and Kirsty Black (right) for the collaboration with Isabel Schestak (left) from Bangor University.