Bricks and mortar may never be the same, thanks to a group of scientists who have created a type of living concrete that may help reduce greenhouse gases.

The new bricks — green-toned during production — are manufactured using biology rather than traditional chemistry, according to the scientists at the University of Colorado, Boulder, who published their findings on Wednesday in the scientific journal Matter.

The process utilizes cyanobacteria, microbes that capture energy through photosynthesis. That means that carbon dioxide is consumed during manufacturing, in contrast to conventional concrete production, which spews the greenhouse gas. 

One of the key components of traditional concrete is cement, and the cement industry accounted for 8% of global CO2 emissions in 2015, according to Carbon Brief. The cement industry would be the third worst emitter behind the U.S. and China if it were a country, Carbon Brief reported.

The scientists hardened the bricks by dissolving gelatin in a solution with the cyanobacteria and pouring the mixture into molds that were then put in a refrigerator, “just like when you make Jell-O,” Wil Srubar, a structural engineer and the head of the research project, told The New York Times.

Because the bricks are biological, they’re also able to reproduce. The scientists were able to grow three generations of the material in the lab, according to the study.

That trait was of particular interest to the project’s funder — the Defense Advanced Research Projects Agency, or DARPA, an arm of the U.S. Department of Defense responsible for the development of emerging technologies for use by the military. Bricks that can grow or repair themselves could help with construction projects in places where trucking in lots of materials would be difficult, Srubar told the Times.

The research team still faces challenges, including how to make the material stronger, more practical, and more easy to assemble. The strongest of the living bricks only achieved “strength similar to the minimum acceptable strength” for ordinary cement bricks, according to the study.

  • Researchers at the Massachusetts Institute of Technology said in September that they were working on a process to make conventional concrete without emitting greenhouse gases.
  • A handful of startups are already working to develop cement alternatives as the International Energy Agency estimates that global use of concrete will rise as much as 23% by 2050.