Engineered living photosynthetic biocomposites for intensified biological carbon capture

Carbon capture and storage is required to meet Paris Agreement targets. Photosynthesis is nature's carbon capture technology. Drawing inspiration from lichen, we engineered 3D photosynthetic cyanobacterial biocomposites (i.e., lichen mimics) using acrylic latex polymers applied to loofah sponge. Biocomposites had CO₂ uptake rates of 1.57 ± 0.08 g CO₂ g^-1_biomass d^-1. Uptake rates were based on the dry biomass at the start of the trial and incorporate the CO₂ used to grow new biomass as well as that contained in storage compounds such as carbohydrates. These uptake rates represent 14-20-fold improvements over suspension controls, potentially scaling to capture 570 tCO₂ t^-1_biomass yr^-1, with an equivalent land consumption of 5.5-8.17 × 10⁶ ha, delivering annualized CO₂ removal of 8-12 GtCO₂, compared with 0.4-1.2 × 10⁹ ha for forestry-based bioenergy with carbon capture and storage. The biocomposites remained functional for 12 weeks without additional nutrient or water supplementation, whereupon experiments were terminated. Engineered and optimized cyanobacteria biocomposites have potential for sustainable scalable deployment as part of humanity's multifaceted technological stand against climate change, offering enhanced CO₂ removal with low water, nutrient, and land use penalties.