As we deal with the climate crisis, architects and builders need to decarbonize more than ever. After all, we’ve heard again and again that the construction industry contributes up to 40% of carbon release. Now, Skidmore, Owings & Merrill has partnered with Boulder, Colo.–based Prometheus Materials, an innovator in zero-carbon building materials, to design and produce microalgae-based bricks and bio-concrete. Their bio-concrete prototype is an alternative to traditional carbon-heavy concrete. “Replacing this carbon-heavy material with a zero-carbon bio-concrete could rapidly accelerate the transformation of building construction into a carbon-free industry,” says Brant Coletta, AIA, SOM managing partner. “As the need to decarbonize buildings becomes more urgent, the materials offer a promising, immediate, zero-carbon alternative to traditional, concrete-based building materials.”
How is this done? The process relies on photosynthesis to create bio-concrete, whereby nontoxic blue-green algae, or microalgae, is grown using only sunlight, water, and CO2 to create a material similar to the calcium carbonate generated in coral reefs and oyster shells. “These algae are cultivated in controlled conditions and, thus, do not display any characteristics that would impose negative effects on the environment—only positive,” explains Loren Burnett, Prometheus Materials CEO and co-founder. The result is promising and I’m curious to see how this plays out.
The seeds for this idea were planted more than 15 years ago, when the SOM Foundation awarded then-university student Wil Srubar an academic fellowship. Later, SOM reconnected with him through his research on material science at University of Colorado Boulder, and when he co-founded Prometheus Materials, the firm jumped at the opportunity to collaborate. According to Coletta, SOM is constantly searching for materials that can help decarbonize the built environment, and through their work with Prometheus Materials, the team hopes to make great strides in achieving that goal. SOM is experimenting with the material, implementing bio-concrete into research. The firm also incorporated early versions of this biomaterial into Urban Sequoia, the design concept for a decarbonized building that it debuted at the COP26 conference in Glasgow in 2021. Clients have already expressed interest in applying these materials to their projects. Safety certification of the biomaterials by ASTM International is underway, and according to Burnett, Prometheus Materials is currently building an expanded manufacturing plant, which when completed will immediately begin producing thousands of bricks, with the ability to quickly scale up to a higher volume as demand grows.
How does bio-concrete compare to traditional concrete? The prototype is currently not as strong as traditional concrete, but the company is optimistic that it will improve with continued development. Prometheus’ goal is to not have any green premium attached to the material, and once they complete the ASTM certification, the team will confirm its strength and performance.
Coletta believes that bio-based materials have incredible potential to decarbonize the built environment. “We know that carbon offsets are no longer enough—the future needs to be carbon negative,” he says. “This material enables us to do that immediately without fundamentally changing the way buildings are designed, which is essential to ensuring its utility and ultimate viability on the market.”
Already states like California and Washington have passed regulations favoring reduced-carbon concrete. We all have to act fast because time is running out.
This article first appeared in the January/February 2023 issue of ARCHITECT.