Abstract

     Bioenergy with carbon capture and storage (BECCS) is a carbon dioxide removal (CDR) solution necessary to achieve net-zero-carbon-emissions goals. While the BECCS potential from large industrial emitters has been quantified, the BECCS potential of small emitters, such as biogas facilities, has not been investigated. Moreover, most BECCS solutions rely on the expected availability of large geological storage capacity for future CDR implementation, although the deployment of CO2 transport and storage supply chains is still a barrier for geological carbon storage ambitions. An alternative opportunity for permanent sequestration of CO2 is concrete, in which captured CO2 can be permanently fixed through carbon dioxide mineralization technologies. We describe and discuss this solution by quantifying the potential of a European bioenergy with carbon capture, utilization, and storage (BECCUS) supply chain, which relies on biogenic CO2 from biogas facilities as a CO2 source, and on carbon dioxide mineralization in concrete as a permanent CO2 sink. This solution is available today, can be adopted seamlessly, and does not need economies of scale for its deployment. We find that European biogas facilities produce 24 Mtons of biogenic CO2 per year, of which 4 Mtons of CO2 per year are emitted from facilities already upgrading biogas into bio-methane.

Introduction

     Reaching net-zero greenhouse gas (GHG) emissions by 2050 requires a rapid decarbonization of European economies (European Commission, 2018), as well as the deployment of carbon dioxide removal (CDR) solutions to offset unavoidable emissions (European Commission, 2021). About 10% (500 Mton CO2eq per year) of current European GHG emissions are estimated to be hard-to-decarbonize and will likely need some degree of CDR (European Commission, 2021). Many net-zero-GHG emissions (hereafter simply net-zero) scenarios rely on CDR using bioenergy with carbon capture and storage (BECCS) (Scott and Geden, 2018; Rogelj et al., 2019). BECCS consists in deploying biomass to produce bioenergy, capturing, and transporting the resulting CO2, and permanently storing it in underground geological formations (Bui et al., 2018; Fuss et al., 2018). Because sustainable biomass is a limited resource (Rosa et al., 2021b), there is a growing consensus that the societal value of using biomass for CDR (i.e., BECCS) will exceed the value of using biomass for bio-energy production only (Sandalow et al., 2021a; Fajardy et al., 2021).

Conclusions

     A portfolio of solutions will be required to mitigate climate change. We introduce biogas-concrete BECCUS supply chains that permanently store biogenic CO2 in recycled concrete aggregates through carbon dioxide mineralization technologies. Biogas-concrete BECCUS supply chains combine carbon utilization with permanent sequestration and have the potential to permanently remove CO2 from the atmosphere while generating a marketable product, namely concrete, thus implementing a circular economy model. BECCUS supply chains represent a CDR solution available for small enterprises, such as biogas facilities, to mitigate their carbon emissions without the need of economies of scale and complex supply chains to transport and store CO2. We find that biogas-concrete BECCUS supply chains can permanently store 8 Mtons of CO2 per year in recycled concrete aggregates in Europe. On the one hand, this is a relatively small fraction of the CO2 that will likely need to be removed in Europe to reach net-zero GHG emissions (500 Mtons of CO2eq per year); in other words, the limited CO2 storage potential in recycled concrete aggregates is the bottleneck of BECCUS supply chains. On the other hand, short CO2 source-sink transportation distances represent a promising and efficient CDR opportunity for small emitters. This suggests that BECCUS supply chains should be deployed whenever possible and will have to be complemented with geological CO2 storage (or BECCS) to achieve European ambitious climate targets.