Scientists meeting in Germany this summer have pointed to ways of making money from some of the carbon dioxide emissions that are fuelling climate change. It’s seen as an alternative to the costly process of storing CO2 underground.

Some companies are already using CO2 captured from power plants or factories to make useful products such as fuels, polymers, fertilizers, proteins and construction materials.

Carbon 8 Aggregates, for instance, is using waste-incinerator ash destined for landfill, mixing it with water and CO2 to form artificial limestone for building blocks.

Katy Armstrong of the Carbon Utilisation Centre at Sheffield University in the U.K. says, “We need to manufacture products without increasing CO2 emissions, and if we can use waste CO2 to help make them, so much the better.”