From emissions to opportunities: harnessing bio-CO2 for sustainable industry applications

Carbon dioxide (CO2) emissions resulting from human activities have led to increased concentrations in the atmosphere, contributing to global climate change. The burning of fossil fuels and industrial processes release significant amounts of CO2, exacerbating global warming and ocean acidification. However, biogas production through the fermentation of biomass and waste generates a controllable and collectible form of CO2, known as bio-CO2. This chapter presents a comprehensive review of utilizing bio-CO2 in a sustainable and environmentally friendly way. Biogas generated by biogas plants is a mixture of methane (CH4) and CO2, but the presence of CO2 lowers the quality and calorific value of the biogas. To avoid this, researchers have focused on improving the quality of biogas as a fuel by removing other elements and lowering its CO2 content. Biogas upgrading includes the removal of CO2 and other negligible components in order to produce biomethane for use as pipeline natural gas or vehicle fuel. This not only increases the economic revenue of biogas facilities, but also decreases their greenhouse gas emissions. Methods for biogas enhancement and CO2 separation on an industrial scale include absorption, adsorption, membrane separation, and cryogenics. Utilizing separated and pure CO2, particularly bio-CO2, offers the possibility of mitigating the greenhouse effect by transforming it into high-quality products across multiple industries. It can be used as a raw material in commodity chemical synthesis, as a preservative and refrigerant in food and beverage production, in enhanced oil recovery, and in algae production, among other applications. Shifting the perception of CO2 from a greenhouse gas to a valuable commodity can generate revenue and contribute to a more sustainable and circular economy. The transformation of a problem into a resource and the paving of the way for a sustainable future through the efficient utilization of bio-CO2 are discussed in depth in this chapter.