Analysis of the Energy Efficiency of Gas Extraction from Lake Kivu

Lake Kivu, located on the border between the Democratic Republic of Congo (DRC) and Rwanda, contains vast amounts of dissolved methane and carbon dioxide, presenting a unique opportunity for power generation. The primary challenges are maintaining the lake's stability, minimizing environmental impacts, and optimizing methane recovery to ensure economic viability. Environmental concerns associated with the current production system include the release of large amounts of CO₂ and the impact of H₂S on oxygen depletion, prompting the search for alternative methods. This study investigates the energy efficiency of a new proposed method of gas extraction from Lake Kivu using a process simulation. We conducted a comparative analysis of two biogas upgrading techniques, water and amine scrubbing, under various scenarios. While water scrubbing achieves an optimal energy efficiency of ∼1.2 kWhe/m³ of extracted water, amine scrubbing, when integrated with cogeneration, offers similar energy efficiency with the added benefit of reducing impacts on the lake's biozone. However, amine scrubbing involves higher capital costs and higher on-shore facility requirements. Overall, the net energy efficiency of extraction ranges between 0.8 and 1 kWhe/m³ of extracted water. This study emphasizes that optimizing degassing pressure must account for lake stability and environmental considerations alongside energy efficiency. The proposed integrated workflow offers a balanced approach to sustainably harnessing Lake Kivu's gas resources.