We are currently facing a new energy scenario, in which it is necessary to implement new negative emission technologies to eliminate CO₂ from the atmosphere. These technologies include the BECCUS processes (bioenergy with carbon capture, utilization, and storage). Due to their relevance in the context of bioenergy, both biogas and biomethane are postulated as important renewable energy sources. The use of biomethane contained in biogas, as a substitute for methane of fossil origin (natural gas), necessarily requires a purification, or upgrading, which is a process that separates the CO₂. In order to evaluate the environmental benefit of this technology, a Life Cycle Assessment (LCA) of the biogas purification process is proposed. This process integrates a PSA (pressure swing adsorption) unit, which is a fundamental part of the CO₂/CH₄ separation process. Whether considering the recovered CO₂ as a waste or as a product, the results obtained showed that, regardless of the energy source used (renewable or fossil), biogas purification with CO₂ capture results in a negative environmental impact value, since, firstly, carbon dioxide emissions are reduced (which is not emitted into the atmosphere), and also the captured CO₂ could have a second useful life. It is, therefore, a clear example of a circular economy.

Peer reviewed