Cement, Energy and Environment

According to the World Resources Institute, 37 countries already face extremely high levels of water stress, using more than 80% of water supply every year, thereby hurting businesses, farms and communities (Water Footprint Network). Cement industry consumes 10% of coal and 6% of electricity demanded by the Indian industrial sector. While thermal energy required for clinker formation is about 726 kcal/kg of clinker, the electrical energy demand is about 78 kWh/t of cement. However, continuous upgradation of technologies has resulted in a decrease of thermal and electrical energy consumption at 670 kcal/kg clinker and 68 kWh/t of cement respectively (Good Practices Manual, 2017). On an average, energy costs, whether in the form of fuel or electricity, represent about 40-45% of the total production cost of 1 tonne of cement (IL&FS Ecosmart Limited, 2009). While the Indian cement industry is expected to increase this demand threefold by 2040 (TERI, 2017), simultaneously, population expansion and economic development will push consumption of India's primary energy by 1.2 billion tonnes of oil equivalent or 156% by 2040 (BP Energy Outlook, 2019), thus making energy security a critical issue for all industries including cement. CO emission intensity of 2 cement industry in India is approximately 0.7 t CO /t 2 cement, further targeted to reduce to 0.58 t CO /t cement 2 by 2020 and 0.50 t CO /t 2 cement by 2050 (Concrete Update, 2018). Its break-up is as follows: about 30-40% from burning fossil fuels to reach the required high temperature for the kiln process, 10% from transportation and generation of electricity needed for other plant processes and remaining 50-60% from decomposition of limestone and other calcareous material to produce clinker. Calcination, the process of producing clinker, releases 525 kg CO /t clinker. 2 A contribution of 7% to global CO emissions places India the 2 th 4 largest emitter of CO in the 2 world (Business Line, 2018). Simultaneously, a study published by Carbon Brief suggests India's CO 2 emissions from energy will grow to 3.8-3.9 giga tonnes or 91-98% by 2030 above 2012 levels (Carbon Brief, 2018). Production capacity of the Indian cement industry is projected to equal demand for cement at 600 million tonnes by 2025. However, in a business-as-usual scenario, actual production may be only 67% of the production capacity, rendering a supply of 402 million tonnes in 2025. Reasons for a sub-optimal production (<70% of production capacity) may be disproportionate capacity addition for grinding rather than clinker production (Cement production may grow at 6-7% in FY19: Report: The Economic Times, 2018), low demand, government regulations to cap carbon dioxide emissions, and lack of natural resources, among others. For instance, Indian Bureau of Mines estimates that the total cement grade limestone available for cement industry is 89,862 million tonnes, expected to last only 35-41 years for the projected growth and consumption pattern (Conserving Limestone: Indian Cement Review, 2014). All the above facts clearly indicate that the critical challenges posing major risks to the sustenance of cement sector are availability of water, energy, and raw materials, and release of emissions and waste. Drivers of circular economy in the cement industry Current resource utilization by the industries indicates that if proper steps are not taken immediately, then the world might run out of several valuable and essential resources. Transition towards 7