Advertisement 2). Only a third of these CO 2 emissions result from the combustion of fossil fuels such as coal or petroleum coke, while the biggest share is released by the calcination of limestone. Depending on quality, limestone – the main component of cement – consists of 35% to 44% CO 2. .Luc Rudowski, Head of Innovation at thyssenkrupp Industrial Solutions, Business Unit Cement Technologies: “Reducing CO 2 emissions in cement production is one of the most important challenges facing the industry today. As part of our #grey2green journey we are developing technologies and solutions for sustainable cement production without losing sight of plant profitability and productivity. One example of this is the newly developed polysius