Reduce the embodied carbon in the built environment.

Engineering Biology for Climate & Sustainability

Materials Production & Industrial Processes Goal:

Reduce the embodied carbon in the built environment.

Current State-of-the-Art

The manufacturing of building materials is energy and carbon intensive – steel and cement productions already account for roughly 13% of global GHG emissions and are projected to grow in the coming decades.¹ Engineering biology could enable the production of sustainable building materials to significantly reduce the amount of energy and emissions required of the built environment. By engineering biocementing bacteria to grow faster and at-scale, it may be possible to eventually replace building materials like bricks and concrete with biobased alternatives, which would consume much less energy and lower emissions. To achieve this, more research is needed to increase the growth rate and ‘curing’ time of the primary biomass-generating microbe in microbial concretes and to improve the structural, load-bearing properties of biocement by enabling the engineering of crystalline structure of biocement. Bacteria capable of biocementation have already been used to repair cracks in concrete structures.² To increase the efficiency and scale of biocementation, we need to develop a more advanced understanding on biodeposition of calcium carbonate, advance genetic toolbox of naturally occurring calcium carbonate depositors, and engineer and optimize biosynthetic carbonate deposition pathways. Similarly, microbes that secrete other compounds like iron could be used to make self-repairing surface coatings.

Biomaterials can also be engineered to attain physical and structural properties that enable them to replace existing carbon-intensive materials. For example, engineering biology could be used to make wood stronger, enabling its use in more structures as an alternative to materials that embody more carbon.³ For example, trees could be engineered to produce denser wood for construction. Additionally, microbes could be engineered to produce cellulose and be used to repair and strengthen rotten wood. Mycelium-based products also have been successfully produced with desirable morphology and mechanical properties.⁴^, ⁵ Mycelium biomaterials could be programmed to grow to sizes specified by boundaries in the built environment (e.g., building walls or ceilings).

Biobased coatings that capture CO₂ can be applied to built surfaces to enhance carbon capture from the atmosphere (e.g., biofilms functionalized with CO₂ capturing particles such as metal-organic frameworks). Smart materials that can regulate moisture and temperature will help buildings and building residents adapt better to the changing climate. Potential technologies include phase change materials from organic fatty acid esters or protein-based materials that can store and release heat reversibly helping to keep indoor temperatures more consistent.⁶ Buildings could even be outfitted with radiation-resistant biomaterials, such as materials that have incorporated Deinococcus radiodurans.⁷ Regardless of the biobased or bio-enabled material, biodegradability and recyclability should be considered; materials need to be designed for persistence during their functional period, but also with sustainable and climate-friendly reuse/recycling or degradation for end-of-life circumstances.

Breakthrough Capabilities & Milestones

Enable the production of biocement and bioconcrete.

Enable scale-up of microbially-induced calcium carbonate precipitation (MICP) (Castro-Alonso et al., 2019*) for biocement production and self-repair.

Bottleneck/Challenge: If incorporated into the built environment, the harsh conditions (e.g., high pH, pressure, temperature, and nutrient deficiency) that microbes would be exposed to limits the scalability of MICP.

Potential Solution: Isolate or engineer new microbes capable of performing MICP and growing under harsh environmental conditions.

Bottleneck/Challenge: Production of toxic byproducts from MICP (e.g., ammonium, nitrous oxide) and the potential of uncontrolled microbial growth pose threats to the environment and human health.

Potential Solution: Engineer metabolic pathways to ensure the completion of biochemical reactions to limit the production of toxic byproducts.

Potential Solution: Engineer metabolic pathways to conditionally limit or stop microbial growth.

Bottleneck/Challenge: Urea, a primary feedstock for ureolytic MICP, is synthesized through energy- and carbon-intensive processes.

Potential Solution: Engineer microbes or consortia that can make urea from atmospheric nitrogen for use in ureolytic MICP.

Improve curing time of biodeposited calcium carbonate for biocement production and/or crack healing.

Engineer a greater number of environmentally-robust microbial species or consortia to biomineralize and deposit calcium carbonate.

Enable the production of robust bioconcrete from biocement that can withstand environmental stress.

Bottleneck/Challenge: Bioconcrete needs to meet construction standards (e.g., bioconcrete with compressive strength greater than 2500 psi).

Potential Solution: Characterize the materials properties of biocement and bioconcrete, including their durability, compressive strength, and fire resistance.

Bottleneck/Challenge: Biocement must be easily packaged, transported, and mixed (i.e., just add water).

Potential Solution: Develop biocement containing sporulating microbes and nutrients.

Engineer self-repairing biocement that can be used at scale.

*Castro-Alonso, M. J., Montañez-Hernandez, L. E., Sanchez-Muñoz, M. A., Macias Franco, M. R., Narayanasamy, R., & Balagurusamy, N. (2019). Microbially Induced Calcium Carbonate Precipitation (MICP) and Its Potential in Bioconcrete: Microbiological and Molecular Concepts. Frontiers in Materials, 6. https://doi.org/10.3389/fmats.2019.00126

Enable the production of sustainable, non-concrete building materials.

Develop biopolymers and bio-derived polymers to function as construction binders (such as glues, sealants).

Design and engineer mycelium materials for construction, such as insulation materials.

Bottleneck/Challenge: Further study is needed to improve the physicochemical properties of mycelium composites, such as their compressive strength, density, and hydrophobicity.

Potential Solution: Engineer high-density and high-performance composites by incorporating biomineralizing microbes into mycelium-based materials.

Potential Solution: Experiment with genetic modification and changing growth conditions to improve hyphal density.

Engineer biofilms, biomaterials, or biocoatings for built surfaces to capture CO₂, such as by functionalizing these materials with metal-organic framework compounds.

Develop sustainable, biobased phase-change materials (PCM) for temperature regulation to reduce energy consumption in buildings (Nazari et al., 2020; Naresh et al., 2020)*.

Bottleneck/Challenge: Currently available biobased PCM could undermine food security, as they are mainly sourced from food-grade fats and oils.

Potential Solution: Enable the manufacturing of biobased PCM from biowaste (e.g., discarded cooking oil).

Potential Solution: Design and engineer bioreactions to produce fats and oils with suitable chemical and thermal properties to make biobased PCM.

Engineer microbial consortia or other organisms to produce cellulose and similar polymers that could be used to repair woody materials.

Engineer trees to produce denser and fire resistant lumber for constructing high-rise buildings.

Engineer paintable biocoatings with tunable albedo to optimize solar gain of buildings, or with radiation-resistant organisms, such as Deinococcus radiodurans.

Enable the wide-spread construction and adoption of living-architecture, for urban air and water filtration and purification (see for example Living Architecture, 2020**).

*Nazari, M., Jebrane, M., & Terziev, N. (2020). Bio-Based Phase Change Materials Incorporated in Lignocellulose Matrix for Energy Storage in Buildings—A Review. Energies, 13(12), 3065. https://doi.org/10.3390/en13123065; Naresh, R., Parameshwaran, R., & Vinayaka Ram, V. (2020). 11—Bio-based phase-change materials. In F. Pacheco-Torgal, V. Ivanov, & D. C. W. Tsang (Eds.), Bio-Based Materials and Biotechnologies for Eco-Efficient Construction (pp. 203–242). Woodhead Publishing. https://doi.org/10.1016/B978-0-12-819481-2.00011-8

**Living Architecture. (2020). LIAR Project – Living Architecture. https://livingarchitecture-h2020.eu/objective/

Footnotes

Fennell, P., Driver, J., Bataille, C., & Davis, S. J. (2022). Cement and steel—Nine steps to net zero. Nature, 603(7902), 574–577. https://doi.org/10.1038/d41586-022-00758-4
Zhang, J., Zhou, A., Liu, Y., Zhao, B., Luan, Y., Wang, S., Yue, X., & Li, Z. (2017a). Microbial network of the carbonate precipitation process induced by microbial consortia and the potential application to crack healing in concrete. Scientific Reports, 7(1), 14600. https://doi.org/10.1038/s41598-017-15177-z
Strain, L. & FAIA. (2022). 10 steps to reducing embodied carbon—AIA. Retrieved August 2, 2022, from https://www.aia.org/articles/70446-ten-steps-to-reducing-embodied-carbon
Haneef, M., Ceseracciu, L., Canale, C., Bayer, I. S., Heredia-Guerrero, J. A., & Athanassiou, A. (2017). Advanced Materials From Fungal Mycelium: Fabrication and Tuning of Physical Properties. Scientific Reports, 7(1), 41292. https://doi.org/10.1038/srep41292
Ecovative. (2022). Why Mycelium. Ecovative. Retrieved June 28, 2022, from https://www.ecovative.com/pages/why-mycelium
Nazari, M., Jebrane, M., & Terziev, N. (2020). Bio-Based Phase Change Materials Incorporated in Lignocellulose Matrix for Energy Storage in Buildings—A Review. Energies, 13(12), 3065. https://doi.org/10.3390/en13123065
Daly, M. J., Gaidamakova, E. K., Matrosova, V. Y., Vasilenko, A., Zhai, M., Leapman, R. D., Lai, B., Ravel, B., Li, S.-M. W., Kemner, K. M., & Fredrickson, J. K. (2007). Protein Oxidation Implicated as the Primary Determinant of Bacterial Radioresistance. PLOS Biology, 5(4), e92. https://doi.org/10.1371/journal.pbio.0050092