Cement Energy Environment

8 CARBON DIOXIDE MAKING A VIRTUE OUT OF NECESSITY It is an undisputed fact that CO 2 contributes to the greenhouse effect. The substance is generated when fossil fuels such as coal, crude oil and natural gas are combusted, primarily through the production of electricity and heat, in households, traffic and industrial production. With the Paris Agreement, 195 countries have set a clear objective for the first time: By the year 2050, the output of greenhouse gases must be reduced drastically in order for global warming to remain clearly below 2° Celsius by the end of the century. Cement, water and aggregates are the main components of concrete, the most popular construction material worldwide. It is therefore a great shame that the production of this cheap and versatile construction material is one of the largest sources of CO 2 emissions. For every ton of cement produced, up to one ton of CO 2 is produced. After all, the production of cement alone contributes between 7 and 8 percent of global CO 2 emissions! CO 2 is found naturally in limestone, which is the main component of cement. The limestone is heated in large rotary kilns at high temperatures to produce Portland clinker, an intermediate product. During this process, the limestone is broken down and the carbon dioxide escapes into the air. It is therefore possible to substitute the heated cement clinker in the cement or concrete with alternative materials, resulting in a significant decrease of potential greenhouse gases. For example, approximately 30 percent of CO 2 emissions can be reduced in each ton of cement by substituting calcium clays. Currently, there Cement with potential is no complete replacement for the raw material, as the clinker which is derived from the limestone is responsible for the strength of the concrete. The industry has begun developing solutions which could reduce this output to almost zero through the targeted deployment of concentration and separation procedures. Carbon capture and storage (CCS) and carbon capture and utilization (CCU) are two processes which separate the CO 2 produced during the manufacturing of cement, enabling it to be stored or used for subsequent chemical processes. By Martina Scherbel VDMA Germany