Cement, a vital component of our global infrastructure, particularly in cities, faces a significant environmental challenge. Its production relies heavily on fossil fuels, contributing up to 8% of global greenhouse gas emissions, according to a 2023 study in Nature.
Traditionally, efforts to address this issue have focused on fuel efficiency and other improvements. However, some companies are exploring a more innovative solution: creating carbon-negative building materials by capturing and storing excess carbon dioxide in concrete.
Paebbl, for instance, captures carbon from the atmosphere and combines it with ground olivine rock to produce a rock powder or slurry. This material can be used as a filler or ingredient in building materials like concrete. The process, known as accelerated mineralization, can be completed within an hour, potentially reducing the carbon footprint of concrete by up to 70%, according to Paebbl’s co-CEO Andreas Saari. This is significantly faster than the natural mineralization process, which can take centuries.
“Not only are you storing carbon, but you are also substituting some of the [kiln-made] clinker, the primary carbon emitter in concrete,” Saari explains. “It doesn’t require high temperatures to produce; it generates heat, which we can recover and use as energy.”
Paebbl currently produces 200 kg to 300 kg of product daily at its pilot plant in Rotterdam, while also building a demonstration plant. By 2030, the company aims to have three commercial-scale plants operational across Europe and North America.
Other companies are focusing on storing carbon directly within concrete. CarbonCure injects carbon dioxide into fresh concrete during mixing. The injected gas undergoes mineralization, permanently bonding to the concrete. This approach allows companies to reduce their emissions by 3% to 5%. CarbonCure estimates that it has saved around 450,000 metric tons of CO2 to date.
One major challenge in scaling up these technologies is overcoming prescriptive specifications in codes and regulations. Building codes are being updated to accommodate newer forms of lower-emissions concrete. The Federal Buy Clean Initiative in the U.S. has spurred the specification of over $2 billion for the procurement of lower-carbon construction materials, including cement, for federally funded projects. Companies like Paebbl and CarbonCure also see economic incentives for their technology by selling credits for the carbon stored in their construction materials.
While these solutions offer a promising approach, Saari emphasizes that they represent a “bridge solution.” “We need to find a way to store billions of tons of CO2,” he says. “Construction materials offer a potential solution.”