Biomethane-powered Energy-as-a-Service innovation for improved access to off-grid cooling for dairy processing in Uganda (BioCool project)

Abstract

As dairy farms expand in Uganda, farmers and processors struggle to safely store and process milk and dairy products due to a grossly limited cold chain. The BioCool project piloted a biomethane-powered off-grid cooling innovation, leveraging the local application of digesters in Uganda. A stepwise approach to optimising the energy output from traditional dome-type digesters in Uganda was implemented, including (i) installing a mechanical stirrer and external gas storage bag to improve the digestibility of and biomethane recovered from cow dung (ii) modifying a refrigerator originally designed to run on liquefied petroleum gas (LPG) to directly run on biomethane to enable off-grid cooling and (iii) developing an Energy-as-a-Service (EaaS) tool to provide efficient energy costing. Installing the stirrer and storage bag increased biomethane yield by 28.3% and enabled 35% volatile solids destruction compared to 4% without modifications. Cooling down to -6°C was achieved, and only 7.7% of biomethane produced would be required to deliver the 4°C temperature required for milk cooling. The EaaS tool demonstrated opportunities to scale biomethane energy solutions across the entire agricultural sector. Therefore, BioCool innovation can be the game-changer technology for sustainable off-grid cooling to boost productivity in the dairy industry and the agricultural sector at large.