Valorization of CO2 generated in the BioVO membrane upgrading plant

The Consortium for Waste Management of Vallès Oriental and the Besòs Tordera Consortium have partnered to implement BioVO, a biogas upgrading plant designed to optimize waste treatment resources and generate renewable energy.

Biogas is a renewable gas produced from the anaerobic digestion of municipal, agricultural, and industrial waste streams. Its composition is typically 50–75% methane (CH₄), 25–50% carbon dioxide (CO₂), and trace amounts of other gases such as H₂O, N₂, O₂, and H₂S. While biogas is carbon-neutral, its high CO₂ content limits its calorific value. To increase its energy potential, biogas undergoes upgrading at BioVO, where membrane technology separates CH₄ from CO₂. The result is biomethane, a green gas with properties equivalent to natural gas, which can be directly injected into the grid as a sustainable substitute for fossil fuels.

This process delivers significant environmental and energy benefits:

• Injection of at least 5.2 GWh/year of biomethane into the natural gas network.

• An additional 178 MWhₜ/year of renewable thermal energy capacity.

• Annual CO₂ emissions reduction of 1,161.3 tons, equivalent to planting 2,322 native Mediterranean trees.

The BioVO facility, covering 620 m², processes 500 Nm³/h of raw biogas, producing 337 Nm³/h of biomethane. The residual stream contains 163 Nm³/h of CO₂ (≈322 kg/h), at 1.05 bar, with ~99% CO₂ and ~1% CH₄. This side stream, however, is currently vented into the atmosphere, representing both a lost opportunity and an environmental challenge.

The valorization of this high-purity CO₂ stream has the potential to significantly improve the circularity and techno-economic performance of the plant. Opportunities include:

• Direct utilization, such as in greenhouses, beverages, or industrial processes.

• Chemical transformation, producing e-fuels, methanol, polymers, or building materials.

• Biological routes, such as microalgae cultivation or microbial conversion into bio-based products.

• Energy pathways, including integration into Power-to-X systems (e.g., methanation or hydrogen-based storage).

By integrating a CO₂ valorization strategy, BioVO could become a benchmark in circular economy practices, maximizing the value extracted from waste, minimizing emissions, and positioning itself as a model for future biogas upgrading facilities.

Our challenge
We invite innovative solutions and collaborations to transform this concentrated CO₂ stream into valuable renewable products or energy. The aim is to turn what is today an emission into tomorrow’s resource—closing the loop of renewable gas production and contributing to a resilient, low-carbon economy.