Capture and liquefication of CO2 from biogas plants

Until recently, the emphasis in most biogas projects has been on utilising methane, its primary energy component, writes Tobias Eckhof, project engineer at Krieg & Fischer Ingenieure GmbH. With the increased use of biogas in the form of biomethane, carbon dioxide can now be effectively harnessed as a by-product of biogas upgrading.
Instead of being viewed as a waste product, the carbon dioxide stream from the biogas plant can be valourised in different sectors. CO2 is traditionally used in various industries, such as food and beverages (for cooling and carbonisation), agriculture, fire suppression, medicine and so on. Most of the commonly used production technologies rely on fossil fuels and contribute to the release of CO2 into the atmosphere.
Biogas plants are a source of biogenic (biomass based) CO2 and are part of the natural short carbon cycle, which starts with extraction of atmospheric CO2 through photosynthesis. As companies seek to reduce their carbon footprint and demonstrate their commitment to sustainability, the demand for biogenic CO2 is rising, as well as new applications in production of fuels, chemicals and building materials.
The...