Techno-economic analysis of living biocomposites for carbon capture from breweries

The brewing sector is investigating the use of algae for CO2 capture and wastewater treatment. Loofah-based biocomposites (composite materials comprising living algae or cyanobacteria immobilised to a loofah sponge support by a latex polymer binder) were developed to intensify biological CO2 capture as a direct replacement for conventional suspension cultures. This study presents a simplified techno-economic analysis for experimental biocomposites exposed to low light intensity (30.5 μmol m−2 s−1) (the experimental scenario) compared to the predicted performance of biocomposites (the predicted scenario) and three well-known algal cultivation systems; open raceways, flat panel photobioreactors (PBR) and biofilm PBRs, exposed to natural solar light intensity (467.6 μmol m−2 s−1). The biocomposites and algal cultivation systems were applied to the capture of CO2 emitted from beer fermentation. The techno-economic analysis consisted of: 1) sizing algal cultivation systems to achieve 90 % CO2 removal; 2) estimating annual water and energy consumption; and, 3) calculating the overall capital and operating costs. The CO2 avoidance costs were estimated using an annualisation method to evaluate biocomposites against other algae carbon capture and storage technologies. The biocomposites significantly decreased the water and energy required per unit culture volume compared to other algae systems. The biocomposite CO2 avoidance costs were estimated to be between 120 and 140 US$ t−1CO2 avoided t−1biomass yr−1 for the experimental scenario and 90–110 US$ t−1CO2 avoided t−1biomass yr−1 for the predicted scenario, which compares favourably with the best performing established algae culture system (80–100 US$ t−1CO2 avoided t−1biomass yr−1 for the biofilm PBR). The CO2 avoidance costs of the biocomposites in the experimental scenario were higher due to lower light exposure resulting in less CO2 captured.