Using biogas to reduce natural gas consumption and greenhouse gas emissions at a large distillery

The need to reduce global greenhouse gas (GHG) emissions may require the use of renewable gaseous fuels in the food and beverage industry to decarbonise processes that are difficult to electrify such as whiskey distillation. Large companies report their GHG emissions according to the Greenhouse Gas Protocol in terms of direct and indirect GHG emissions. Anaerobic digestion (AD) of distillery by-products can replace up to 64% of the natural gas consumption of the distillery and could reduce direct GHG emissions by 54% and indirect GHG emissions by 11,389 tCO₂eq (41% of direct savings) if digestate replaces synthetic fertiliser used to cultivate barley consumed by the distillery. The replacement of animal feed produced by the distillery with imported animal feed (distillers’ grains from the USA and soybean meal from Argentina) could, in a worst-case scenario, negate a significant portion of direct and indirect GHG emission savings. The decision as to whether the GHG emissions associated with imported animal feed should be included in the calculation is not clear cut and can be subjective. Digestate management, particularly storage and transportation may pose a significant barrier to the implementation of an AD plant processing distillery by-products. Alternative methods of digestate transportation such as pipelines, and digestate treatment (separation, drying, and evaporation) should be assessed to mitigate logistical issues. To successfully integrate AD with a distillery future research should conduct multi criteria decision analysis to identify the most suitable share of distillery by-products to use in an AD plant to balance positive and negative attributes of such projects.