About This Project
Direct air capture (DAC) is a promising pathway for atmospheric CO2 removal. Biocatalysts like carbonic anhydrases (CAs) rapidly absorb CO2 from air and reduce DAC costs, and are most effective when immobilised close to the gas-solvent interface so CO2 can reach them quickly. This project seeks to stably anchor CA onto cotton fabric using fused cellulose binding domain proteins (CBDs) under DAC-like conditions; while avoiding current immobilisation pitfalls, like loss of CA activity.
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What is the context of this research?
Atmospheric CO2 removal (CDR) and point-source capture (PSC) of CO2 are well-accepted as being necessary for successfully decarbonizing within climate goals (1). Direct air capture (DAC) is a CDR pathway with ideal verifiability and durability. Both DAC and PSC are cost constrained, primarily by the CapEx of the gas contactor and the energy required to drive large swings in temperature or pH to regenerate CO2 from the capture material (2).
Those high cost and energy requirements are driven by a thermodynamic trade-off between the rate of CO2 absorption and the CO2 regeneration energy: CO2 capture materials with high absorption rate, which reduce cost by reducing the gas contactor size, typically have high CO2 regeneration energy, and vice versa (3).
What is the significance of this project?
Carbonic anhydrases (CAs) catalyze fast CO2 absorption in solvents with low CO2 regeneration energy, resolving the tradeoff described above (4). CA could reduce DAC cost by reducing parameter swing or gas contactor size, if stable in DAC-like conditions e.g. high pH and temperature. Slow diffusion of CO2 through bulk solvent is also limiting to CA usage, so placing CA at <10 µm from the gas-solvent interface has been identified as a crucial performance factor (5).
Modelling is still needed to generate target properties for CA immobilisation and and quantify their effect on DAC cost. However, there are promising substrates for immobilisation at low-cost e.g. on cotton fabrics (6), where immobilisation that can be improved and characterised.
What are the goals of the project?
Modeling and technoeconomic analysis is required to provide quantitative targets for immobilisation of CAs in DAC. However, initial efforts should aim to increase in durability and density of immobilisation while retaining (or enhancing) high CA activity (kcat/kM ~108 M-1s-1). Durability and activity should be assessed in conditions and solvents relevant to DAC, such as 10-20% K2CO3.
Overall, a successful immobilisation approach should yield a many-fold improvement in overall DAC performance (e.g. see significant absorption enhancement in (6)). Moreover, the immobilisation method and the substrate should be manufacturable at large-scale and low-cost.
For a review of state-of-the art CA immobilisation techniques, see (7).
See solution statement for budget breakdown
The overall timeline of the project is 12 months
Mar 31, 2024
Immobilisation rig and documentation of characterisation protocols (Month 3)
Jun 30, 2024
CA-CBD fusion protein library and delivery of report on progress to date (Month 6)
Oct 31, 2024
CA-CBD screening dataset finalised (Month 10)
Dec 31, 2024
Final Report (Month 12)
Meet the Team
I am a Group Leader at the International Centre for Genetic Engineering and Biotechnology (ICGEB) and the University of Cambridge, building technologies for an open, globally inclusive and equitable bioeconomy.
My groups develop biomanufacturing tools and technologies that are sustainable by design and deployable in low-resource contexts. We also investigate the most effective ways that enzyme engineering and manufacturing can positively impact on health and sustainability, especially in developing and emerging economies.
We have a long-standing interest in protein functionalisation of sustainable and readily available materials (e.g. silica, cellulose, chitosan) and have worked on solid and hydrogel immobilisation of enzymes and peptides. We also have experience in high-throughput screening of proteins using cell-free protein expression systems. This seemed like a perfect opportunity to apply our experience to a real and impactful climate problem, as part of a community doing the same.
I am very interested in new approaches to funding and performing science and in scientific community building: I have co-founded four social enterprises and nonprofits supporting the development and deployment of open source tools for science through building communities, knowledge infrastructures and policy. So I would be excited to be part of the Homeworld Collective cohort and mentoring, to experience their forward-thinking mission to grow the field of climate biotech in a very intentional way. I think that in itself will be a great source of inspiration and ideas for my longer-term mission of equitable global access to biotechnology.
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