Heat recovery and water reuse in micro-distilleries improves eco-efficiency of alcohol production.

The number of micro-scale spirit distilleries worldwide has grown considerably over the past decade. With an onus on the distillery sector to reduce its environmental impact, such as carbon emissions, opportunities for increasing energy efficiency need to be implemented. This study explores the potential environmental benefits and financial gains achievable through heat recovery from different process and by-product streams, exemplified for a Scotch whisky distillery, but transferrable to micro-distilleries worldwide. The eco-efficiency methodology is applied, taking into account both climate change and water scarcity impacts as well as economic performance of alcohol production with and without heat recovery. A Life Cycle Assessment, focusing on climate change and water scarcity, is combined with a financial assessment considering investment costs and the present value of the savings over the 20-year service life of the heat recovery system. The proposed heat recovery systems allow carbon emission reductions of 8-23% and water scarcity savings of 13-55% for energy and water provision for 1 L of pure alcohol (LPA). Financial savings are comparatively smaller, at 5-13%, due to discounting of the future savings - but offer a simple payback of the investment costs in under two years. The eco-efficiency of the distillery operations can be improved through all proposed heat recovery configurations, but best results are obtained when heat is recovered from mashing, distillations and by-products altogether. A sensitivity analysis confirmed that the methodology applied here delivers robust results and can help guide other micro-distilleries on whether to invest in heat recovery systems, and/or the heat recovery configuration. Uptake should be enhanced through increased information and planning support, and in cases where the distillery offers insufficient heat and water sinks to use all pre-warmed water, opportunities to link with a heat sink outside the distillery are encouraged. A 10% reduction in heating fuel use through heat recovery has the potential to save 47 kt of CO eq. or £7.4 M per annum in United Kingdom malt whisky production alone, based on current fuel types used and current prices (2021).