Environ. Sci. Technol. 2010, 44, 9143–9149
Identifying Improvement Potentials in Cement Production with Life Cycle Assessment MICHAEL ELIAS BOESCH AND STEFANIE HELLWEG* Institute of Environmental Engineering, Ecological Systems Design, ETH Zurich, CH-8093 Zurich, Switzerland
Received March 9, 2010. Revised manuscript received October 18, 2010. Accepted October 18, 2010.
Cement production is an environmentally relevant process responsible for 5% of total anthropogenic carbon dioxide emissions and 7% of industrial fuel use. In this study, life cycle assessment is used to evaluate improvement potentials in the cement production process in Europe and the USA. With a current fuel substitution rate of 18% in Europe and 11% in the USA, both regions have a substantial potential to reduce greenhouse gas emissions and save virgin resources by further increasing the coprocessing of waste fuels. Upgrading production technology would be particularly effective in the USA where many kiln systems with very low energy efficiency are still in operation. Using best available technology and a thermal substitution rate of 50% for fuels, greenhouse gas emissions could be reduced by 9% for Europe and 18% for the USA per tonne of cement. Since clinker production is the dominant pollution producing step in cement production, the substitution of clinker with mineral components such as ground granulated blast furnace slag or fly ash is an efficient measure to reduce the environmental impact. Blended cements exhibit substantially lower environmental footprints than Portland cement, even if the substitutes feature lower grindability and require additional drying and large transport distances. The highest savings in CO2 emissions and resource consumption are achieved with a combination of measures in clinker production and cement blending.
Introduction Cement production has received increased attention in sustainability research due to its high energy and resource intensity and the large volume of global cement consumption. Cement is the hydraulic binder in concrete and mortar, and concrete is the most abundant manufactured material globally (1). Concrete contains about 10-12% cement by volume, with the remaining concrete components being a mix of sand and gravel or other aggregates (65-80%), water (14-21%), air (0.5-8%), and admixtures (
