About This Project

Concrete, produced at 40 gigatons annually, can naturally soak up CO2 to form a scalable, durable and verifiable carbon sink. However, this process is limited by CO2 diffusion and hydration. We are engineering carbonic anhydrase enzymes to overcome this kinetic bottleneck. Through machine learning, metagenomics, and high-throughput testing, we will optimize enzymes to unlock additional gigaton-scale carbon sequestration within our built environment.

Ask the Scientists

What is the context of this research?

Concrete, produced at 40 gigatons annually, is the most consumed man-made substance. Concrete production presents both a challenge, accounting for ~8% of global emissions, but also an opportunity. Specifically, its alkaline, calcium-rich composition confers the ability to serve as an annual gigaton-sink for atmospheric carbon removal (ref1, ref2). However, natural carbonation of CO2 is too slow to meaningfully mitigate climate change. By leveraging carbonic anhydrase (CA), a highly efficient enzyme for hydration of CO2, the project aims to dramatically accelerate this process. Through a combination of natural enzyme discovery, machine learning-driven design, and directed evolution, we seek to create enzymes capable of surviving in cement and significantly boosting CO2 uptake.

What is the significance of this project?

We see multiple implications:

1. Increased concrete carbonation rates have the potential to form a gigaton-scale carbon sink (ref).

2. Compressive strength improvements due to carbonation (10-20%, ref1; ref2) can significantly reduce the required amounts of cement that account for 8% of global emissions.

3. With protein production being an established industry, adding carbonation catalysts could be adopted rapidly with minimal changes to existing concrete infrastructure and supply chains.

Finally, alkaline-stable CO2 hydration catalysts are expected to aid in other CO2 sequestration contexts, such as during enhanced rock weathering, liquid direct air capture and end-of-life concrete carbonation, as well as confer self-healing properties to concrete to reduce material replacement needs.

What are the goals of the project?

The project’s overarching goal is to develop biologically enhanced concrete capable of sequestering significant amounts of CO2. To achieve this, the team will engineer carbonic anhydrase enzymes that function optimally in the high-pH environment of cement.

The research plan manages risk with four key aims:

1. Building a comprehensive database, including sampling of natural extreme environments, to identify enzymes adapted to such harsh conditions.

2. Using machine learning to design novel carbonic anhydrases tailored for concrete.

3. Implementing a high-throughput screening platform to identify the most effective enzyme variants.

4. Testing the effect of enzyme addition in concrete to measure the impact on CO2 absorption and material properties.