Colorado-based Prometheus Materials and other emerging companies are developing new biocements that could help meet the world’s growing concrete demands and avert climate catastrophe.

Innovation thrives when we pause to observe, question, and reimagine the world around us, turning challenges into opportunities for progress. Nature, in particular, serves as a rich source of inspiration. By observing it, studying its daily challenges, and contemplating its processes, we can discover valuable insights that inspire innovative solutions.

One of these current challenges is the production of concrete, an ancient and extremely popular material that is now accountable for a significant portion of global CO₂ emissions, due to the energy-intensive process of cement production and the chemical reactions involved. It is estimated to be responsible for approximately 8% of the world’s annual CO₂ emissions, pumping 11 million tons of CO₂ into the atmosphere every day and consuming 9% of the world’s annual industrial water usage. In addition, the world’s building stock is expected to double by 2060—the equivalent of building an entire New York City every month for the next 36 years, which means an incredible increase in demand for cement and concrete. Faced with this daunting situation, is there anything we can do? In this article, we speak with Loren Burnett, CEO of Prometheus Materials, which has developed a material that mimics nature’s processes to recreate concrete as we know it.

The journey to create the material began with an initiative by the US Department of Defense to find sustainable and readily available raw materials for construction in resource-deprived environments. Four professors from the University of Boulder in Colorado developed –over a period of five years– a new process that uses microalgae as a building material. In other words, instead of creating a new raw material, they cultivated one. These professors, together with Loren Burnett, co-founded Prometheus Materials in 2021, and continue to play active advisory roles in the company.

Burnett explains that the process takes its inspiration from nature, specifically harnessing the remarkable capabilities of naturally occurring microalgae – the same microorganisms that are found in lakes, rivers, oceans, and fish ponds. Inside water-filled bioreactors, these microalgae are stimulated to produce chlorophyll, aided by strategically placed light-emitting diodes. Infused with nutrients and natural ingredients, the water facilitates the formation of calcium carbonate through a process known as biomineralization. In essence, this is similar to the natural creation of shells and coral reefs, but they were able to harness and accelerate it to a level where it becomes the raw material for a highly efficient zero-carbon bio-cement production. “When mixed with aggregate, the bio-cement forms a zero-carbon bio-concrete with mechanical, physical, and thermal properties that are comparable or superior to Portland cement-based concrete. Our process both avoids the carbon-intensive operations involved in manufacturing and transporting traditional cement and sequesters embodied carbon from the microalgae and biomineralization. Another essential feature of our solution is that virtually all of the water used in production is returned to the earth.”

The aggregate used in bio-concrete is locally sourced, with an emphasis on incorporating recycled materials wherever possible. Prometheus concrete demonstrates impressive performance in several parameters compared to traditional concrete. Loren Burnett points out that “Our zero-carbon bio-concrete is around 15% to 20% lighter, which provides economic and environmental advantages, and its compressive strength rivals that of traditional concrete, while its flexural strength being 3 to 4 times greater… The bond strength of our material has a modulus of rupture (MOR) of 660-990 PSI, compared to 200-325 PSI for traditional concrete – so we are 3 times better in this category. The strength of our material reduces the need for steel reinforcement in some applications.”

In addition to its structural prowess, Prometheus concrete exceeds ASTM performance requirements and exhibits greater blast resistance. When it comes to acoustic properties, it outperforms traditional concrete with a noise ratio coefficient (NRC) of 0.60 compared to 0.05, and additional sound transmission testing is underway. The material also excels in thermal insulation, reducing thermal transmission by 90% compared to traditional concrete, thus reducing operating carbon, as well as eliminating embodied carbon.

Prometheus has received funding rounds that have allowed it to build pilot manufacturing and biotech production facilities and expand its team. Currently, the company is refining its zero-carbon bio-cement and bio-concrete products, while introducing innovative offerings such as zero-carbon bioclock masonry units. Looking to the future, the company looks forward to significant growth, as well as diversifying its product line by exploring bio-cement and bio-concrete variations and licensing its technology to existing manufacturers, with a strong commitment to making a substantial global impact on carbon reduction.

At theopening of the Chicago Architecture Biennial, traditional architecture firm Skidmore, Owings & Merrill (SOM) unveiled Bio-Block ™ Spiral, in collaboration with Prometheus Materials. SOM has designed a spiral installation of bio-blocks that invites visitors to explore Fulton Market. With building blocks rotated to create openings and pleated ends to enhance the structure, the installation highlights the simplicity of block and mortar construction while demonstrating the versatility of the bio-block form. It holds the potential to reduce global CO₂ emissions by up to 8% when deployed at scale. While it goes through further performance testing, it is already available for selected projects, offering a sustainable replacement for the concrete masonry units commonly used in contemporary construction. The spiral marks a significant milestone in advancing the adoption of this eco-friendly material and addressing the climate crisis.

Essentially, Prometheus’ emphasis is on combating climate change while meeting the growing demands of the construction sector. In a world where global CO₂ emissions continue to rise, their commitment to achieving a significant reduction by targeting a carbon-negative status exemplifies their dedication to a more sustainable future. To conclude, Burnett calculates that “There are currently ~53 gigatons of CO₂ emitted globally on an annual basis – and that number is increasing, not decreasing. Our overall goal at Prometheus Materials is, in time, to reduce CO₂ emissions by a gigaton or more per year.”