Colorado-based Prometheus Materials has developed masonry blocks from a low-carbon, cement-like material grown from micro-algae. The blocks meet the American Society for Testing and Materials (ASTM) standards and were made using an organic cement-like material grown in bioreactors, which reproduces itself in ways like coral.
Using nature to re-invent
“Coral reefs, shells and even the limestone we use to produce cement today show us that nature has already figured out how to bind minerals together in a strong, clever and efficient way,” said Prometheus Materials co-founder, Wil V Srubar III.
“By working with nature to use existing microalgae to bind minerals and other materials together, to create new types of sustainable bio-composite building materials, we can eliminate most, if not all, of the carbon emissions associated with traditional concrete-based building materials.”
Prometheus Materials combines microalgae with water, sunlight and CO₂ to create a bio-cement. This bio-cement was made from biomineralizing cyanobacteria that are grown using sunlight, seawater and CO₂. The blocks were created by mixing this bio-cement with aggregate to create a low-carbon building material with mechanical, physical and thermal properties comparable to Portland cement-based concrete.
Possibility of mass production
The bio-cement could be mass produced as an alternative to Portland cement, which is a huge source of carbon emissions as it relies on clinker made from crushed and burned limestone. The process separates the calcium, which is a key ingredient in cement, from the carbon, which is released into the atmosphere.
“You can’t just simply decarbonise fossil fuels and change it,” said Prometheus Materials chief executive officer, Loren Burnett. “You’ve got to decarbonise building materials,” he told Dezeen. “Building materials are a huge problem from a CO₂ perspective.”
Existing facilities used for harvesting
The company is using existing facilities to harvest the biomaterials necessary to create the blocks. “There are some major facilities, which were already in place, that were put in place for the biofuels industry several years ago, which are at this point dormant but available,” said Burnett.
The material was first developed at the University of Colorado by Boulder (CU) professors in response to a call from the United States Department of Defence to envision sustainable materials. Prometheus Materials was established in 2021 to make the material available for public use, with masonry blocks being the first application. Since it was established, it has received funding from the Microsoft Climate Innovation Fund, European venture capital firm Sofinnova Partners and global architecture studio SOM.
Low-carbon materials for skyscrapers
SOM’s involvement came on the heels of a prior relationship with co-founder Srubar, who won a fellowship from the SOM Foundation in 2006. The studio that designed the Burj Khalifa, which has a concrete structure and is the world’s tallest building, has previously invested in research about low-carbon materials. “SOM uses a lot of concrete and cement, and they are very aware of the need to decarbonise the process,” said Burnett.
When asked if some of the advances in concrete that have allowed for taller skyscrapers to be built could be repeatable, Burnett said that the bio-composite masonry will match and exceed the capabilities of Portland cement-based concrete.
“Because we use a different material, we actually enable new products to be developed and used that would not be available using traditional concrete,” he said. “We offer an alternative material that has additional capabilities”
Testing and materials protocols
The material is going through testing in the Colorado city of Boulder and will go through the American Society for Testing and Materials (ASTM) protocols later in 2022. The company has plans to create a precast material for roofing tiles, wall panels, sound barriers and other concrete elements in the next two years. Algae and other biomaterials have been proposed for a variety of uses in the design industry.
Earlier this year, Natural Material Studio and Frama presented terracotta materials made from algae. Other research into sustainable replacements for modern building materials includes an MIT initiative to make tree forks stand in for loadbearing steel.