Zurich, June 15-17 2016 Sustainable Built Environment (SBE) regional conference Expanding Boundaries: Systems Thinking for the Built Environment 1 ! LOW CARBON CEMENT: A SUSTAINABLE WAY TO MEET GROWING DEMAND IN CUBA S. Sanchez1*, Y. Cancio1, F. Martirena2, I.R. Sanchez1, K. Scrivener3, G. Habert4 1 Faculty of Economy, Central University “Marta Abreu”of Las Villas (UCLV), Carretera a Camajuanì km 5, Santa Clara, Villa Clara, Cuba 2 Center for Research and Development of Structures and Materials (CIDem), UCLV, Carretera a Camajuaní km 5, Santa Clara, Villa Clara, Cuba 3 Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Switzerland 4 Chair of sustainable construction, ETH Zurich, CH-8093 Switzerland *Corresponding author; e-mail: ssanchez@uclv.edu.cu Abstract Concrete is, after water, the most used material worldwide and its demand is projected to growth in the next 30 years. Among all concrete materials, cement presents the higher energy consumption and carbon emissions, that's why this industry has been developing several alternatives to gain sustainability. Reduction of clinker ratio by using Supplementary Cementicious Materials (SCM) allows a better use of existing capacities with low investment while a reduction in emissions, costs and energy per ton of cement is observed. The objective of this article is to assess the environmental and economic impact of a new cement with 50% of clinker: Low carbon cement (LC3). A procedure for evaluating sustainable and economic contribution of LC3, while projected demand is satisfied, is designed and applied in several scenarios. The results demonstrate that LC3 introduction is the best option to meet growing demand considering capital investment options in non-developed countries conditions with a reduction of ~30% in carbon emissions, of ~10% in costs and a faster return on investment related to OPC figures in Cuba. Keywords: Low Carbon Cement; cement demand; economic and environmental assessment 1 INTRODUCTION Cement is a key resource for economic progress and development. Consequently, global demand for cement and concrete has increased exponentially in the last twenty years as well as its related environmental impact. Due to this situation, the cement industry has applied several strategies to improve its production efficiency and to reduce both resources consumption and carbon emissions. One of the most effective solutions is the use of supplementary cementitious materials (SCM) [1-2]. Low Carbon Cement (LC3) has emerged as new alternative cement as a result of an international joint project funded by Swiss Agency for Development and Cooperation with the participation of scientists from Swiss, Cuba and India. In LC3 cement, it is replaced up to 50% of clinker in cement by using calcined clay and limestone. The Cuban economy is currently experiencing large structural changes. The Cuban government has declared an expected -and needed- annual Gross Domestic Product (GDP) growth from 3 to 5% [3]. To achieve this, the construction sector has to reach a level of production able to satisfy the development demands. In this paper, a method is designed and applied to assess the economic and environmental potential of the LC3 mailto:ssanchez@uclv.edu.cu Expanding Boundaries: Systems Thinking for the Built Environment 2 ! cement technology in several scenarios of the Cuban context, while projected demand is satisfied. 2 DATA AND METHODS 2.1 Methodology To assess the economic and environmental contribution of LC3 production the following methodologies are integrated and applied: I. Forecast of cement demand II. Life cycle assessment (LCA) III. Capital expenditures (CAPEX) and Operational expenditures (OPEX) analysis To forecast demand is a major issue in this study in order to estimate the investment needs to reach development. Demand for Cuba, cement demand was calculated using a model based on possible needs of cement according with social and economic infrastructure status and government plans for investments. The environmental evaluation is done through a Life Cycle Assessment (LCA). It is a method for evaluating the environmental load of processes and products during their life cycle, from cradle to grave [5]. The LCA method is divided into 3 main stages [5]. First the functional unit, and the system boundaries have to be defined. Secondly, the inventory phase includes all inputs to outputs from the considered system. Finally, the environmental impact categories are defined and assessed. These three stages are detailed in the following section. Capital and Operational Expenditures analysis are performed to assess and compare the economic impact of cements during their life cycle from investment process (CAPEX) until cement is produced. CAPEX were calculated based on literature and OPEX by using accounting norms established in Cuba. To a better understanding all costs were converted to US dollars. 2.2 Choice of the functional unit This study focusses on the production and transport of the cement raw materials and ends at an intermediate stage after concluding the production process at the cement plant (cradle to gate). The functional unit used in the study is 1 ton of cement. The study compares three cements production in Cuba: (1) The standard Ordinary Portland Cement (OPC). This cement in Cuba is made with 5% of Calcium Carbonate. (2) The current blended cement sold on the island (PPC). It is produced with 15% of Zeolite tuff considered as a Natural Pozzolan. (3) The new cement, called Limestone Calcined Clay cement (LC3) where 30% of Calcined Clay and 15% of Calcium Carbonate. Previous studies provided confidence in the fact that similar compressive strength can be achieved with these 3 cements [6] what was confirmed in the first industrial trial to produce LC3 [7]. The production system under study has been separated into five main processes: i) raw materials extraction; ii) extraction and refinement of fuels; iii) transport of raw materials and fuels; iv) clinkerization and calcination of clays; and v) grinding, packing and other processes. The final processes are gathered due to their low impact during the whole process of cement production [8]. The determination of same functional unit and system boundaries for economic and environmental assessment allows the integrated assessment after obtaining separately results. 2.3 Data collection In this study the data is organized according to the technological level to be implemented reflecting a gradation in the investment. 1. The first level (Pilot) considers no investment. The data used for energy and material consumption were measured during the first industrial trial [7]. The clinkerization as well as the clay calcination were carried out at existing facilities within an inefficient and non-optimized production processes (wet process). 2. The second technological level considers a low investment throughout retrofitting a wet cement kiln into a clay calciner, as a low CAPEX alternative to produce calcined clay. The clinker employed is produced by a more efficient technology (dry process). 3. The third technological level considers massive investment in Best Available Technology (BAT), with state of the art equipment for both the calcined clay and the clinker production. Clay would then be calcined through a flash calciner and clinker would be produced by a dry process with pre heater and pre calciner. Once these technological packages where established, the necessary data was collected. Data for emission factors and heating values of different types of fuels comes from different sources: a) the Cement Sustainability Initiative (CSI) of the World Business Council for Sustainable Development [9] and b) the Intergovernmental Panel for Climate Change (IPCC) [10]. Some processes linked with extraction of raw material and fuels, transport and electricity were modelled using Ecoinvent Expanding Boundaries: Systems Thinking for the Built Environment 3 ! database [11] and adapted when necessary to the Cuban conditions. The electricity mix, the fuel used for trucks and trains and lifetime of the current stock of Cuban transport infrastructure were adapted. Preliminary data was collected from Siguaney factory which has been selected by the Cuban Cement industry to introduce LC3 production. The main data is related to consumption indexes, distances to raw materials, technology type, transport means and extraction processes. To analyze CAPEX figures, data related with different investment scenarios was collected. The data is shown in Figure 1, where a simple comparison allows to prove the advantages of retrofitting over investing in a flash calciner. Figure 1: CAPEX (US dollars per ton of cement per year) and references 2.4 Impact assessment In this study, only one impact category is shown: Global Warming Potential for one hundred year period of time projection (GWP100) expressed in kg CO2 equivalent. It was calculated by the IPCC 2013 methodology [10]. This reduction is justified by the fact that CO2 emission is the main impact of concrete industry and it is difficult to look for the large number of background and foreground data required for the other impact categories in Cuban statistics reports. 3 RESULTS 3.1 Demand forecast for Cuban case Cuban cement industry reports production of 1.8million tons of cement in 2014 [16], this represents a 56% of utilization of the installed capacity. A higher utilization rate is not possible due to several periods of maintenance and reparation of equipment and facilities associated with the existing outdated technology. Then, a 68% of the available production capacity is determined. This proves the fact that present demand exceeds production and reflects the need for investment in this sector to increase manufacturing capacity. Official government figures forecast cement demand of 3.5Mt/year by 2019. Demand projection at peak demand phase (2016-2020) will grow 18% per year. This is linked to an expected booming construction activity that normally occurs in emerging economies. During the peak demand phase annual growth of 10% and 5% of demand are expected. Finally, authors estimate a capacity over 6.5 million tons/year to be reached in 2030. 3.2 Comparative Life cycle assessment of LC3 and other products in Cuban case Energy consumption Results of a detailed analysis of the improvement potential of LC3 production in relation to energy use show that the best improvement is observed in clinkerization and fuels extraction processes when compare with OPC production. An increase in energy consumption related to transport and raw materials extraction is also observed but this impact is clearly negligible when it is compared with savings achieved by the other processes. A reduction of ~20% in energy demand is achieved when compare with OPC, except using the BAT (which includes the use of renewable fuels) where 8% of energy is saved if LC3 is produced. Table 1 presents the final results in energy analysis. Table 1: Energy consumption (MJ) per ton of cement produced Cement MJ/t % OPC 5292 100 PPC 4626 87 LC3_retrofitted 4158 79 LC3_flash 3692 70 Environmental impact (GHG emissions) The comparison of the environmental impact for OPC, blended cement PPC and LC3 for the three different technical levels: Pilot, Industrial and BAT– is shown in the figure 3. It is interesting to note that whatever the technological level, the LC3 cement always produces around 30% savings of CO2 eq emissions. Furthermore, it is noticed that the worse LC3 cement made in the pilot industrial trial is better than the best OPC that can be produced with the BAT scenario. Major emission reductions are related to energy savings and clinker substitution, although there is reported a significant decrease in electricity consumption during grinding process due to LC3 softness in comparison with OPC. Expanding Boundaries: Systems Thinking for the Built Environment 4 ! Figure 3. Relative Global Warming Potential impact of cement production in Cuba. All scenarios 3.3 CAPEX and OPEX analysis Operational expenditures were calculated in collaboration with economic team of Siguaney cement plant. Results confirm that with LC3 production we can save 14-30% of costs in comparison with PPC and OPC respectively as shown in Figure 2. Figure 2. OPEX of cement production: comparison OPC and PPC vs. LC3 Is notable that OPEX between flash and retrofitted are quite similar (flash is only 1% lower). This can be supported by 2 reasons: i) CAPEX for flash is much higher; ii) the other processes of cement production process are carried out in similar facilities, thus, costs for grinding, clinker production, packing, etc. are the same. CAPEX figures show that the construction and installation of a clinker kiln (+ pre heater + pre calciner and cooling facilities) will always be more expensive than a clay calciner. Retrofitting is the best alternative thinking also in the lack of capital of non-developed countries like Cuba and the availability of old wet clinker kilns that can be retrofitted with low investment cost. 4 DISCUSSION This assessment shows that promoting the use of LC3 in Cuba is a long term efficient strategy from an environmental as well as from an economic point of view. Results show that LC3 technology, if implemented in Cuba will definitively provide an environmental advantage compared to the OPC and PPC produced on the island. The cost analysis shows also a smaller difference in comparison with PPC. Finally more detailed research needs to be done in the area of investment costs. The study shows the predominant contribution of investment costs (CAPEX) compared to operation costs (OPEX) in the production of cement from an economic and political point of view, but also from the availability of existing infrastructure. Then, the installation of a complete production line, will considerably increase the investment price for the LC3 technology. Savings from an OPC modernization strategy will still be achieved but the difference will be smaller. 5 CONCLUSIONS This study has assessed, from both an economic and environmental point of view, three cements that can be produced in Cuba. The study shows that the LC3 technology, which involves the combination of 50% of clinker, 15% of unburned limestone and 30% of calcined clay (and 5% Gypsum), is an energy and cost efficient technology. Savings in term of greenhouse gases emissions as well as production and investment costs are significant. The results presented have taken into account a number of variables and have shown to be robust. LC3 has therefore a great potential to provide a viable opportunity to meet an increase in cement demand with low CO2 released and low cost investment. 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