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Assay for CO2 mass transfer rates in small solvent volumes to enable enzyme-enhanced DAC and PSC

We invite proposals to Homeworld Garden Grants that address this Problem Statement.

Published onAug 26, 2023
Assay for CO2 mass transfer rates in small solvent volumes to enable enzyme-enhanced DAC and PSC
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This Problem Statement follows the Problem Statement structure for Homeworld Garden Grants. It is derived from the recommendations of Part 1 of our Roadmap for Biotechnology in Carbon Dioxide Removal.

We invite proposals to Homeworld Garden Grants Call 1: Protein Engineering that use a copied or modified version of this Problem Statement and present a novel Solution Statement.

Context

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).

Significance

Carbonic anhydrase (CA) enzymes catalyze CO2 exchange. CA can enable fast CO2 absorption in capture solvents with low CO2 regeneration energy, resolving the trade off discussed above (4). 

CA could enable efficient DAC and PSC with small temperature or pH swings, reducing cost, if protein engineering (PE) is used to stabilize it in DAC and PSC processes. However, testing CO2 exchange rates with engineered CA variants and solvent compositions is cost prohibitive: CA must be used at ~1-10 mg/mL, proteins at lab scale cost ~$100/mg (5), and current CO2 exchange rate testing platforms are designed to use 100-500 mL or more of solvent per replicate (6).

A novel experimental method to measure CO2 exchange rate in small solvent volumes would enable research to develop CA-enhanced DAC and PSC.

Goals

To enable flexible experimentation on CA-enhanced capture solvents, a method should be developed that enables measurement of CO2 exchange rate between gas and solvent in solvent volumes of <100 µL. A method that requires solvents volumes of 0.1-1 mL would also be substantially enabling.


Comments
2
Paul Reginato:

describing the resolution and precision of the measurement that is necessary to be useful for developing DAC would improve this Problem Statement

Paul Reginato:

describing the resolution and precision of the measurement that is necessary to be useful for developing DAC would improve this Problem Statement