An Integrated System Dynamics Model and Life Cycle Assessment for Cement Production in South Africa

Abstract

Cement is one of the most produced materials globally. Population growth and urbanization cause an increased demand for the cement needed for expanding infrastructures. As a result of this circumstance, the cement industry must find the optimum compromise between increasing cement production and reducing the negative environmental impact of that production. Since cement production uses a lot of energy, resources and raw materials, it is essential to assess its environmental impact and determine methods for the sector to move forward in sustainable ways. This paper uses an integrated life cycle assessment (LCA) and a system dynamics (SDs) model to predict the long-term environmental impact and future dynamics of cement production in South Africa. The first step used the LCA midpoint method to investigate the environmental impact of 1 kg of Portland cement produced in South Africa. In the cement production process, carbon dioxide (CO2), nitrogen oxides (NOx), sulphur dioxide (SO2), methane (CH4) and particulate matter (PM) were the major gases emitted. Therefore, the LCA concentrated on the impact of these pollutants on global warming potential (GWP), ozone formation, human health, fine particulate matter formation and terrestrial acidification. The system dynamics model is used to predict the dynamics of cement production in South Africa. The LCA translates its results into input variables into a system dynamics model to predict the long-term environmental impact of cement production in South Africa. From our projections, the pollutant outputs of cement production in South Africa will each approximately double by the year 2040 with the associated long-term impact of an increase in global warming. These results are an important guide for South Africa’s future cement production and environmental impact because it is essential that regulations for cement production are maintained to achieve long-term environmental impact goals. The proposed LCA–SD model methodology used here 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, a number of policy changes are suggested for reducing emissions, such as introducing more eco-blended cement productions, carbon budgets and carbon tax.

Comparative Life Cycle Assessment of Different Portland Cement Types in South Africa

“…The cement industry has used a variety of alternative fuels around the world, including waste from wastewater treatment plants, industrial wastes (such as plastic waste and scrap tires) [51,52], wood residue [53][54][55], and biomass waste [56][57][58][59]. Moreover, innovative materials in cement production, such as blended Portland cement, might also be significant in producing sustainable cement [42,60]. Several studies have investigated the environmental impacts of cement production in the United States [29,61], Europe [48,[62][63][64][65], India [66], Africa [67][68][69][70], Canada [71], Japan [72][73][74], Hong Kong [54], and China [75][76][77][78][79].…”

“…Some cement plants in the country use only low-grade limestone as a raw material for clinker production [40]. Portland Cement (CEM I) is the most commonly produced cement product in South Africa, followed by blended cement products such as CEM II-CEM III, with 16 integrated cement plants within the country [41,42] using the dry process [18,43,44]. CEM I cement is Portland cement with more than 95% clinker content.…”

“…Gypsum, plus other pozzolanic components such as fly ash, blast furnace slag, micro silica and ground limestone, are present in CEM II cement. CEM III cement refers to Portland cement with clinker content between A (35-64% clinker ratio) and B (20-34% clinker) [40,42]. CEM III contains gypsum and GGBFS.…”

Evolution trend analysis of carbon emissions in light industrial parks: A system dynamics approach

“…Oluwafemi constructed an SD model for the cement production industry carbon emissions trend in South Africa and predicted that the carbon emissions of cement production in South Africa will double by 2040. 9 11 Onat used SD to study the impact of US green building-related policies on carbon emission trends and concluded that building renovation policies could improve carbon emission trends better than new net-zero buildings or high-performance green buildings. 12 Li et al constructed a SD model of Hebei Province including seven subsystems, such as population, economy, secondary industry, and policy.…”

“…Some scholars have adopted the SD method to research carbon emissions in countries or regions. Oluwafemi constructed an SD model for the cement production industry carbon emissions trend in South Africa and predicted that the carbon emissions of cement production in South Africa will double by 2040 9 . Mirzaei et al established an SD model of Iran's carbon emission trend from 2000 to 2025 and set up three scenarios considering energy policy factors to analyze Iran's carbon emissions under different energy intensity reduction scenarios 10 .…”