Recommendations

The best economical option for Balmenach identified in this study was an anaerobic digestion plant producing biogas from liquid co-products combined with co-generation plant with steam regeneration.

Main features of this solution were:

1. Liquid co-products (Pot Ale & Spent Lees) mixed and processed in Anaerobic Digestion (AD) plant with short retention time to minimise capital cost to produce biogas.
2. Feeding liquid co-products to AD plant before their temperature drops below 38°C will remove the need to pre-heat.
3. Biogas used to fuel an internal combustion engine generator with waste heat boiler recovering heat from exhaust to provide low grade heat and steam.
4. FIT’s, electricity Export Tariffs and RHI earned for electricity and heat produced.
5. Payback period of 4.6 years could be achieved for a plant with capital cost of £770,000 based on 2010 energy prices.
6. Annual net benefit assuming maintenance and operating costs at 5% of capital cost was £178,449.
7. Annual CO2 emissions reduction of 139 tonnes.