Concrete is an integral part of modern construction, used in almost every structure, from bridges and office blocks to housing and stadiums. Whilst being incredibly important, its production has a big environmental impact.
"When making cement you start with limestone: that limestone is crushed and heated in a kiln well over 1,000 degrees," Robert Niven, CEO of CarbonCure, told CNBC's Sustainable Energy.
"Every molecule of limestone is actually broken in half," Niven added. "One half forms clinker, which is cement, and the other half is released into the air to cause climate change through the release of CO2."