Investigating the biogas potential from organic waste flows in Santiago de Chile – A study of the Metropolitan Region.

Sammanfattning: In the Metropolitan Region in Chile the population is growing as the inhabitants are relocating towards the capital of Santiago de Chile. The capital, located in a valley, is now home to over 40% of the population, and faces challenges with sufficient air-quality and waste disposal. 58% of all waste in Chile today is of organic matter, and with economical limitations in the municipalities, change towards a circular economy happens slowly. At the same time the country faces the global challenge of lowering greenhouse gas emissions to sustainable levels. This study thus aims to investigate flows of organic waste in municipalities of the Metropolitan Region in Chile, to estimate the biogas potential and its possible contribution to lowering the national greenhouse gas emission levels. The methods that are used for data collection are literature and interview studies, and the data is further processed through case studies. The resulting biogas potential is presented in Nm3 and GWh per year. The substrate composition in the flows is investigated and discussed, as well as the convertibility of the substrate in anaerobic digestion and its contribution to the energy content of the biogas. Average values of the biogas potential on municipal and regional scale are calculated for and are put to context through presented data from the Chilean waste and energy market. Two Chilean municipalities (El Monte and Providencia) and their pure flows of organic waste were studied, as well as an average fictive municipality that was created and used to represent typical municipal values in the region. The result of the study showed that there is variation in terms of amount as well as substrate type in the municipal waste flows. The average municipality in the Metropolitan Region in Chile had a biogas potential of 86 GWh per year, and the region 4 500 GWh per year. The regional biogas potential could be enough to run 67% of the regional buses in public transport, or 78% of the trucks in the region. The biogas potential could also contribute to lowering Chile’s total annual greenhouse gas emissions with 2 million tons of CO2-eq, corresponding to 2%. The conclusion of the study shows that anaerobic digestion of organic waste in Chile would be a step in the right direction of several of the national guidelines. Additional studies of the market, process technology availability and substrate mixture models are recommended, to optimize the direction of a future implementation.