This roadmap was prepared with funding from Additional Ventures, in partnership with Innovative Genomics Institute at UC Berkeley.
In Part 1 of our Roadmap for biotechnology in carbon dioxide removal (CDR), we identified substantial opportunity for applying biocatalysts to reduce energy usage and cost of Direct Air Capture (DAC), Direct Ocean Capture (DOC), and the point-source capture (PSC) component of bioenergy carbon capture and storage (BECCS). In particular, the enzyme carbonic anhydrase (CA) has evolved to catalyze CO2 exchange in organisms, and can be used accelerate the rate-limiting chemical step in DAC, DOC, and PSC. We anticipate that cost and energy savings could exceed 30%.
Despite that potential, there is no publicly-available research that explores the use of CA in DAC or DOC. While applications of CA in PSC have been developed, several of the most powerful tools of contemporary biotechnology have yet to be applied for CA in PSC, and there is substantial room for further technology development.
The actionable research questions surfaced and explained by the roadmap are described below.
1. Techno-Economic Analysis (TEA): Modeling studies are needed to provide clear engineering targets and quantitatively estimate the benefits for the most promising applications of biocatalyst-enhanced CDR. Specific research questions include:
Target biocatalyst properties: What are the ideal catalyst properties and process parameters for cost and energy reduction in DAC, DOC, and PSC?
Process design: What solvent properties and modalities (e.g., pH swing, temperature swing) are favored for DAC and PSC, and when is it advantageous to immobilize CA?
Replacing pH swing in DOC: What are the requirements for fully replacing pH swing with catalysis in DOC? Are there benefits to using higher-permeability membranes in combination with a catalyst?
2. Protein Engineering of CA: This involves optimization of CA for the process conditions of CDR technologies. Key research areas include:
AI-Driven Protein Design: How might we use to produce a hyper-stable CA that can function optimally under the process conditions of DAC, DOC and PSC?
CA Variant Screening Platforms: How might we develop platforms that can efficiently screen large numbers of CA variants for stability and efficiency?
Metagenomic Data from Extremophiles: How might we better leverage data from organisms that thrive in extreme conditions to find robust CA variants?
3. Catalytic composite materials: This involves engineering composite materials containing CA that offer improved cost and/or energy savings compared to free CA. Key research areas include:
Immobilization Techniques: How might we durably immobilize CA without damaging its activity? Further, can we durably immobilize CA at a density that exceeds the catalytic efficiency of free CA? Can we avoid the cost of protein purification by immobilizing CA directly from cell lysate?
Immobilization Substrates: How might we develop low-cost immobilization substrates that durably retain CA and enable CO2 absorption rates equal or better than free CA? Can we position immobilized CA directly at the gas-solvent interface?
Biocatalytic membranes for DOC: How might we make hollow fiber membranes containing immobilized CA or CA mimic that are stable or replaceable over the life of the membrane (~5 yr)?
4. Biofouling Mitigation: This involves understanding and addressing the risk of biofouling, a potential challenge in long-term industrial processes. Key questions to be addressed include:
Biofouling Risk Assessment: What is the expected impact of biofouling on DAC, DOC, and PSC processes?
Mitigation Strategies: How might biofouling be mitigated, and how would mitigation strategies impact CA performance and the overall CDR process?
5. Community Enablement: This involves ensuring researchers have access to CA for R&D and understand the existing Intellectual Property (IP) landscape. Key questions are:
CA Supply: How might we provide the research community with necessary quantities of CA variants with a range of pH, temperature, and alkalinity robustness to support bench-scale research?
IP Landscape Characterization: How might we characterize how the IP landscape of CA in PSC technologies affects opportunities in DAC, DOC, and novel PSC applications, to help newcomers identify commercializable solutions?
If you would like to learn more, either as a practitioner, funder or partner, please email [email protected].