Environmental and Economic Life Cycle Assessment of low-tech digesters coupled with gasification technology implemented in a small-scale dairy farm

Improving organic waste management while strengthening the circular bioeconomy and providing clean energy remains a key challenge for small-scale farms in low- and middle-income countries. This study assessed the potential environmental and economic impacts of low-tech digesters coupled with gasification technology in a small-scale farm producing dairy products in Colombia, using the Life Cycle Assessment and the Life Cycle Costing tools. Three scenarios were considered: i) a baseline scenario based on conventional waste management and fossil energy use, ii) a scenario with a low-tech digester, and iii) a scenario with a digester coupled with a gasifier. The selected functional unit was 1 kg of produced cheese. The system boundaries (i.e. cradle to grave) included the emissions associated with waste management, the construction and operation of the low-tech digester and gasifier, and the use of fuels, synthetic fertilisers and/or digestate in agriculture. The results showed that adopting low-tech digesters to co-digest cattle manure with waste generated from dairy processing (i.e. cheese whey) reduced the environmental impacts associated with eutrophication, climate change and fossil resource scarcity (up to 17% reduction compared to the baseline scenario). Moreover, coupling the digester with gasification further increased bioenergy production and completely replaced fossil fuel consumption. From an economic point of view, the synergies between low-tech digesters and gasification technology reduced the total costs associated with cheese production by 56% compared to the baseline scenario. Overall, the study demonstrated the potential of decentralised, low-tech bioenergy solutions to support circular bioeconomy and sustainability in small-scale dairy farms in low-income countries.