Development of an Integrated Energy Recovery System for Productive Biogas Applications in Uganda

Abstract

Today, biogas system deployments in Uganda face challenges related to sustainability of biogas production, which has led to massive dis-adoption in recent years. This could be linked to insufficient R&D in the biogas sector. This thesis presents a full account of a study to optimize biogas production and system long-life performance for productive applications. The aim was to develop and evaluate an optimal integrated system for energy recovery from organic wastes as an enabler to system sustainability. An assessment of performance of productive biogas systems was done, aiming to highlight key success factors for system sustainability that could influence policy for a better future of Uganda’s biogas sector. This was followed by characterization of selected feedstocks and mathematical modelling of their optimal substrate mixing ratios to augment digester organic loading for enhanced biogas and methane yield. Development and piloting of an integrated energy recovery system then followed, with intent to optimize, through monitoring and control, the key parameter that influence biogas and methane yield.

Results show that productive biogas has registered satisfactory performance despite it being a recent development in Uganda with meager deployments, while the characteristics of feedstocks for biogas generation were found to vary widely according to source and type with unmatched substrate mixing ratios. The developed integrated system is about 33% more efficient than the conventional one, allows alteration of feedstocks, and can be deployed to replace conventional energy usage for productive applications. For instance, a poultry farm with 10,000 commercial layers may have its energy needs met 100% by the system with a pay-back period of 4 years. Overall, the developed system revealed performance parameters desired for productive biogas applications, outmatching the relatively high initial investment required for its deployment due to system long lifespan. However, there is need to strengthen policy incentives in support for system acquisition due to its high initial investment cost. This, in addition to tradable renewable certificates, could go a long way in encouraging investment in biogas energy systems and thus contribute to energy transition for Uganda and beyond.

Keywords: Productive biogas; optimization; sustainability; integrated system; economic feasibility