Globally, the cement industry is acknowledged as a contributor to greenhouse gas emissions. Worldwide the cement industry contributes about 5% of man-made CO₂ emissions. (Ref. World Business Council on Sustainable Development)  In the manufacture of cement, CO₂ is generated through two process-related sources. In these processes 40% of the total CO₂ generation emanates from burning coal while 60% is associated with the chemical process involved in the calcination of limestone in the clinker production process.