Optimizing biogas upgrading containing high carbon dioxide content for enhanced biomethane quality and energy efficiency using blended amine absorption

There is a significant obstacle to the widespread adoption of the present solvent-based CO₂ capture technology in industrial biogas upgrading due to the corrosive nature of the solvent and high energy demand required for regenerating it. This research embarks on the use of MDEA activated with Piperazine (PZ) as a promising alternative solvent to address the sustainability issue of the absorption process. Our findings experimenting with the proposed solvent demonstrate that MDEA/PZ solvent blend enhances both methane purity and reboiler duty to a significant extent. For instance, the proposed system achieves CO₂ content in the upgraded biogas of less than 1% and a reboiler duty of around 18 kW with a feed biogas containing 40% CO₂. While conventional MEA typically achieves methane purity levels around 97–98% and requires a reboiler duty exceeding 25 kW, the MDEA/PZ blend improves methane purity to 99.99% and reduces reboiler duty to 9 kW under optimized conditions of biogas flow rate at 29 kg/h, amine flow rate at 0.1 m³/h, and CO₂ content of 25%. This approach not only improves the efficiency of the biogas upgrading process but also reduces the environmental footprint, offering a sustainable and viable alternative for the industry. Considering the favorable environmental impact and life cycle of the proposed solvent system, there is a potential avenue for further research and promising application in the field. This analysis is beneficial for assessing the sustainability and potential widespread adoption of the innovative approach in the biogas industry.