Prometheus Materials in Longmont, Colorado, is pioneering algae-based concrete bricks that offer a sustainable alternative to traditional cement. With cement responsible for roughly 8% of global CO2 emissions, these new bricks are poised to make a significant environmental impact. Using microalgae cultivated in bioreactors, Prometheus creates a cement-like substance that bonds with sand and gravel, mimicking the natural formation of coral reefs. This innovation emits just one-tenth of the CO2 compared to conventional concrete blocks. Developed in collaboration with U.S. architecture firm Skidmore, Owings & Merrill (SOM). Prometheus CEO Loren Burnett aims to make production carbon neutral by using solar panels and ultimately achieve carbon negativity within three years. The U.S. Department of Energy recently awarded Prometheus a grant to continue its work on net carbon storage technologies. SOM partner Brant Coletta highlights the bricks’ scalability and sees their potential to revolutionize the construction industry. Safety certification from the American Society for Testing and Materials is expected by the end of the year, and SOM plans to integrate the algae bricks into its projects immediately. This partnership marks a significant step towards reducing the construction industry’s environmental impact.
Cement, the essential binding ingredient in concrete, bricks, and mortar, is a significant contributor to climate change. Its production involves heating limestone and clay to extremely high temperatures using fossil fuels, triggering a chemical process that releases vast amounts of carbon dioxide into the atmosphere. Cement accounts for approximately 8% of global CO2 emissions due to its carbon-intensive nature and widespread use. As the global building stock is projected to double by 2060, the search for alternative materials is urgent.
Prometheus Materials, a company formed in 2021 from a University of Colorado research project, is offering a promising solution. Their factory in Longmont, Colorado, will soon produce concrete bricks made from algae instead of cement. By growing microalgae in bioreactors, they feed it carbon dioxide, seawater, and light from LED lamps, allowing it to produce a cement-like substance that binds sand with gravel or stone to create concrete. This method mimics the natural process through which organisms form coral reefs and seashells.
These algae-based bricks are set for commercial release in 2023. They were developed in partnership with U.S. architecture firm Skidmore, Owings & Merrill (SOM), known for projects like the Burj Khalifa in Dubai and One World Trade Center in New York. According to Prometheus Materials CEO Loren Burnett, their production emits only a tenth of the CO2 of conventional concrete blocks. Once solar panels power their manufacturing plant, the process will become carbon-neutral and, in three years, carbon-negative. “There’s virtually no CO2 emitted during the process, and we actually sequester CO2,” Burnett says, as the algae absorbs it through photosynthesis.
Prometheus’ algae bricks are among the leading innovations aimed at replacing carbon-intensive building materials like steel and concrete. The “bio-based” materials sector is still in its early stages, but advocates believe it could transform construction from a major emitter (responsible for 11% of CO2 emissions) to an absorber of carbon.
Using plants and organic matter in construction is not new; straw, bamboo, and timber have been used traditionally worldwide. However, building on a large scale with natural materials has proven challenging. To stimulate progress, the U.S. Department of Energy recently provided $39 million in grants for 18 projects developing carbon-neutral building technologies. The University of Colorado team working on algae bricks is one of the recipients.
Prometheus’ bricks face the same challenges as other climate-friendly technologies: scaling up from lab successes to commercial production at competitive costs. However, Brant Coletta, a partner at SOM, believes the technology’s “easy scalability” makes it attractive. Prometheus plans to expand by shipping lightweight, dried versions of their bio-cement to customers who can then create bricks locally.
Certification by the American Society for Testing and Materials is expected to be complete by the end of this year, allowing the manufacturing plant to start producing “tens of thousands” of bricks. Despite commercial sensitivities, Burnett assures that the final pricing aims to match conventional concrete blocks. Coletta believes architects and developers will gradually trust that these bio-based bricks will perform well and have a minimal cost impact. SOM, a leader in sustainable architecture, is eager to incorporate these bricks into projects once certified. “We’ve had clients see us working on this and say they want it in their project right away,” Coletta says.
