Introduction to the Energy from Whisky Co-products tool
A key outcome of this project is a spreadsheet-based tool, designed to assist malt distillery operators examine the potential costs and benefits of generating energy through anaerobic digestion of their liquid co-products. This tool is intended to give an indication of the financial viability of generating energy from whisky co-products, but should not be used in place of a detailed feasibility study.
The key input required by the tool is the amount of liquid co-products produced annually by a distillery. From this, the tool calculates the volume of biogas which could be produced by anaerobic digestion. It then calculates the capital costs, annual benefits and payback periods associated with four different options for using the biogas. It also enables the sensitivity of these results to changes in biogas production rates, energy costs and other factors to be explored.
The four generation options evaluated by the tool have been selected as they are likely to provide the largest benefits. They are:
- Biogas Boiler: Distilleries require large amounts of steam. Currently this is provided by oil or natural gas fired boilers. A separate biogas boiler could be installed to meet a proportion of this steam demand, reducing fossil fuel requirements. The volume of biogas produced would not be enough to supply all of a distillery’s steam demand however.
- Electricity Generation: The biogas could be used to fuel a generator unit. The tool calculates the electricity that could be generated by a unit operating at constant load throughout the year, and assumes that surplus electricity can be exported to the grid.
- CHP Producing Hot Water: This is effectively an extension of the electricity generation option. Packaged biogas CHP units producing hot water at 90°C as well as electricity are readily available. Malt distilleries generally have little demand for low grade heat however, and this option may only be attractive if heat can be exported to a district heating scheme or nearby commercial site.
- CHP Producing Steam again this is an extension of the electricity generation option. It involves running the hot exhaust gas from a generation unit through a waste heat boiler to produce steam, reducing the amount of fossil fuel used by a distillery’s current boiler. The amount of steam which can be generated by this method would only be a small fraction of a distillery’s total steam demand.
Structure of Tool
The tool spreadsheet contains seven pages. Key inputs and results are set out in the first two pages. The remaining five pages contain calculations based on default values. The default values on each page can be adjusted by the user to improve the accuracy of the results. The tool is initially setup with default values on the Primary Input page for an average malt distillery with an annual production volume of 2,300,000 litres.
Spreadsheet pages:
- Primary Input
- Results
- Biogas Production
- Biogas Boiler
- Electricity Generation
- CHP
- Climate Data