Integrated life cycle assessment and system dynamics model for prediction of cement production and environmental impact of cement industry

Abstract

Cement is one of the most produced materials globally. The cement industry faces significant environmental challenges due to high raw materials usage and energy consumption, resulting in emissions that are global and local environmental concerns. The industry faces challenges globally in reducing its carbon dioxide (CO2) emissions while saving material and energy resources. The cement industry contributes to high global greenhouse gas (GHG) emissions due to the calcination of raw materials and fuel burning. Globally, cement plants are among the sectors with the highest energy consumption and the highest release of potentially harmful health-threatening carbon dioxide (CO2), nitrogen oxides (NOx), sulphur dioxide (SO2), and dust particles. This study focused on Portland cement production and environmental impact-related problems and found the best ways to discuss the potential policies and scenarios to reduce CO2 emissions and ensure sustainable cement production while maintaining the strength of the equipment and the quality of the plant production requirement. Since the cement industry's environmental impacts are expected to increase, assessing the cement production and carbon emissions produced at each stage of the cement life cycle is compulsory to mitigate these environmental impacts. Life cycle assessment (LCA) has been used in many studies to assess the environmental impact of cement production and investigate ways to improve environmental performance. In this thesis, the first step uses life cycle impact assessment (LCIA) based on the Recipe 2016 v 1.04 midpoint and endpoint methods to investigate the environmental impact of 1 kg of Portland cement produced in South Africa using Ecoinvent database v3.7.1, integrated with SimaPro 9.1.1. software to assess the impact categories. The study was conducted using data modelled from South African cement plants and uses a cradle-to-gate system boundary. The integration method includes data collected between 2000 and 2017 on cement production and real GDP. Data on cement production were obtained from the South African greenhouse gas inventory report of 2017. The data on South Africa’s real GDP in US dollars were obtained from World Economics. The LCA-SD framework of cement production in South Africa involves three main stages, (i) gathering data for key LCA processes, (ii) assessing the impacts of production processes using LCA SimaPro 9.1.1 software and (iii) integrating the results of the LCIA as input variables with system dynamics (SD) to predict the possible future dynamic and long-term environmental impact of cement production in South Africa. An integrated LCA-SD methodology is used to assess and predict the environmental impacts of the cement industry. This research uses the LCA method together with the system dynamics framework in the form of a mathematical model to study how to reduce GHGs in cement production. The possible dynamics of cement production and the long-term environmental impact of cement production in South Africa were investigated using these methods. According to the results, clinker production and electricity usage stages contribute the most to atmospheric impact (global warming, which causes climatic change due to high CO2 emissions), followed by raw materials and fuel consumption, contributing to the toxicity and resource depletion impact category. These stages contribute more than 76% of CO2 eq. and 93% of CFC-11 eq. In the midpoint method, CO2 is the most significant pollutant released. Among the three main damage categories in the endpoint method, human health is the most affected by releasing substances into the air during Portland cement production. The clinkering stage is the most harmful production stage for human health and the ecosystem since it produces the highest amounts of CO2 gas. From our projections, the pollutant outputs of cement production in South Africa will approximately double by the year 2040, with the associated long-term impact of an increase in global warming. The proposed LCA-SD model methodology enables us to predict the future dynamics of cement production and its long-term environmental impact, which is the primary research objective. Using these results, several policy changes are suggested for reducing emissions, such as introducing more eco-blended cement production, carbon budgets and carbon tax.