Closed-Loop Biomethane Technology Integrating CO₂ Recycling, Biogas Upgrading, and Organic Substrate Pretreatment

The development of green and sustainable engineering technologies is essential for improving the efficiency of renewable energy systems and reducing greenhouse gas emissions. This presentation introduces an innovative environmental technology for biomethane production based on the closed-loop integration of biogas upgrading, CO₂ recycling, and low-temperature pretreatment of organic substrates. The proposed concept, referred to as TeCH₄BiogasUp, uses solidified CO₂ recovered during biogas upgrading as a functional agent for substrate disintegration before anaerobic digestion.

The main advantage of this approach is the integration of several technological functions within one circular process. CO₂ separated from raw biogas is not treated as a waste stream but is converted into a useful material for improving substrate biodegradability. In this way, the system combines organic waste pretreatment, biomethane production, biogas purification, and CO₂ utilization. Such a configuration supports the principles of circular economy, resource efficiency, and sustainable carbon management. The technology was assessed in terms of its technical, technological, and economic fundamentals and compared with conventional substrate pretreatment methods and standard biogas upgrading solutions. Its hybrid and multifunctional character distinguishes it from existing technologies that usually perform only selected process stages. Although this creates challenges for direct market comparison, it also provides a significant innovation potential and competitive advantage.

The proposed closed-loop solution may reduce CO₂ emissions, improve biomethane production efficiency, and increase the profitability of biogas plant operation by transforming captured CO₂ into a process-relevant resource. TeCH₄BiogasUp therefore represents a promising environmental technology for renewable energy development, sustainable waste management, and the transition toward low-emission circular bioeconomy systems.