Life cycle assessment (LCA) analysis towards a sustainable cement industry for Sri Lanka : an analysis of three process pathways

Abstract

Cement has already become an essential commodity which contributes for global development which also contributes globally ~5% of man-made CO2 as an adverse environmental impact, during its production phase. Cement manufacturers have already implemented programs aiming to reduce their GHG footprint introducing clinker substituted cement types, utilizing alternative fuels and optimizing the cement manufacturing process. LCA is a tool which can be used to quantify & assess the environmental impacts for a selected scope. Study covers a detail LCA study on different cement manufacturing scenarios selecting GHG emission as the main impact category for a local integrated cement manufacturing facility. As the scope of the LCA ‘cradle to gate’ approach was selected and functional unit defined as ‘one tonne of cementitious material’ in order to compare with different clinker percentage cement types. Holcim (Lanka) Ltd – Puttalam Cement Works was selected for the study as the only operating integrated cement manufacturing facility in Sri Lanka. For the scope inland transportation GHG contributions were also included as an extended scope item. An author designed simple LCA tool ‘Cement LCA Calculator’ was introduced and used to life cycle inventorying and analyzing process. This tool is compatible with the cement CO2 protocol published by the WBCSD (World Business Council for Sustainable Development) aligned with GRI (Global Reporting Initiative) & International Panel for Climate Change (IPCC) guidelines. LCA analysis was categorized into two process units. More than 90% of GHG generated inside the facility due to calcination and kiln fuel combustion in the baseline scenario where no alternative fuels being used. In year 2007 the thermal substitution rate was 19.9% and average overall clinker factor was 76.5%. Also it has been shown the reduction from 913 to 764 net kgCO2e/tonne of cementitious material from the baseline year – 2001 to 2007. Reported neutral absolute CO2 volumes were 39,940 tonnes in year 2007. However a small increase shown in the local transporting area from 0.56 to 1.31 net kgCO2e/tonne of cementitious material due to increasing alternative fuel transporting activities. The net savings of CO2 by utilizing waste derived fuels were 3,464 tCO2e in year 2007 as per the ‘Cement LCA Calculator’. Research outcomes also opened a number of LCA based research options as future research areas. The LCA study has clearly shown the GHG benefits a reduction of 16% by using alternative fuels and clinker substituted products. Both these corporate initiatives are way forward actions towards sustainable cement manufacturing process, which Holcim (Lanka) Ltd is committed by its group strategies. Introduced Cement LCA Calculator can also be used on finding CO2 minimizing strategies in future cement industry focused ecological improvement studies.