Effective Carbon Emission Reductions from Using Upgraded Fly Ash in the Cement Industry

Utilisation of supplementary cementitious materials (SCM) has been found as a suitable alternative to reduce CO emissions from cement production. Fly ash (FA) is the most well-known of these materials and has been used for decades in cement applications. Amongst these applications, the most significant is the replacement of clinker in cement blends, which reduces the consumption of resources and energy and at the same time, avoids the environmental burden associated with clinker production. Despite the existence of these opportunities, a large fraction of the FA produced worldwide is still unused and disposed as waste or stored in landfills. This occurs mostly because FA is unable to meet the quality requirements for replacing clinker in cement blends. Upgrading of FA to a suitable material that can effectively replace clinker is possible via upgrading processes (UP). These processes carry their own environmental impacts because in most of the cases, thermal and electric energy are used in them. Due to this fact, the use and implementation of upgraded fly ash involves additional environmental impacts to the life-cycle of the product. The most relevant of these impacts during the upgrading stage, is the generation of additional direct and indirect CO emissions from energy consumption. From a life-cycle perspective, the generation of these additional CO emissions decreases the net abatement achieved by using fly ash as a SCM. Therefore, it is necessary to account these emissions and calculate the net abatement achieved by replacing clinker and fossil fuel consumption. A system dynamics model is presented by simulating five different cement life-cycle scenarios in order to quantify the net CO reductions when using upgrading processes of fly ash. Ultra-fine grinding for the mechanical activation of FA is the UP modelled using published and direct data from the equipment manufacturer. A material flow analysis (MFA) was carried out to describe the scenarios and to simplify the life-cycle approach. It was found that the upgrading process modelled can have maximum value of 3.98 GJ/tonne of fly ash and still be able to produce net reductions. The same model also estimated that an 80% of the total reductions are avoided when ultra-fine grinding consumes 0.75 GJ/tonneFA of energy, compared to emissions from the baseline cement. The model is also complemented by reviewing the current use of FA as a SCM in the cement industry and by presenting a holistic systems thinking analysis. The model can also be further expanded to simulate other life-cycle scenarios which can include multiple upgrading processes and other materials

Framework for the Development of Thai Normalisation Factors for Life Cycle Assessment in Thailand

Life cycle assessment (LCA) has become a widely recognized method for evaluating the environmental performance of a product or system along its supply chain. Nowadays, site-dependent Life Cycle Impact Assessment (LCIA) methods have been developed and LCA results could therefore potentially reflect the local, national, and/or regional environmental conditions. In Thailand, site-dependent normalisation factors (NFs) which could support the local decision context have not been developed yet. The objectives of this study are to review underlying methodologies of the NFs in existing LCIA methods; and to establish a framework for the development of Thai NFs. Depending upon the spatial scales, four LCIA methods (ReCiPe2016, EF 3.0, CML-IA baseline, and TRACI 2.1) were selected to be reviewed and considered when designing a framework. The theoretical approach for the NFs of the four selected LCIA methods is similar but the considered impact categories are different depending upon the spatial distribution and targeted environmental impacts. NFs from each LCIA method apply different reference inventory and year depending upon its spatial scale and data availability, and apply different approaches for data source selection. The selection of an appropriate reference system and representative year for the inventory, and data gap filling are essential criteria to develop NFs for life cycle assessment in Thailand. After the reference inventory is developed for the NFs of desired spatial scale (regional or national), the robustness of the inventory should be evaluated to reflect the actual impacts from each category. The developed framework could provide the required information for the future development of NFs and satisfy the required gap specific for Thailand. Besides, this framework is potentially applicable for other regions

Exploring future scenarios of ethanol demand in Brazil and their land-use implications

Ethanol biofuel demand in Brazil is highly dependent on macroeconomic and policy drivers, making it difficult to anticipate future production and associated environmental implications. Here we develop scenarios of ethanol demand in Brazil towards 2030, based on a thorough examination of key influencing drivers, i.e. GDP and population growth, fleet composition, blending policies, fuel prices and energy efficiency. We then estimate their land-use implications using a detailed partial equilibrium model, GLOBIOM-Brazil. We find that ethanol demand is highly sensitive to the drivers considered and could increase between 37.4 and 70.7 billion litres in 2030 depending on the scenario. Such increase is 13% and 114% above the 2018 production. This represents an expansion in sugarcane area between 1.2 and 5 million hectares (14%–58% above the land-use in 2018). Compared to the low demand scenario, a high demand for ethanol in 2030 would drive sugarcane expansion mostly into pastureland (72%) and natural vegetation mosaics (19%). Our results suggest that future ethanol demand in Brazil should not substantially affect food production nor native forest. This outcome will however depend on the compliance with the sugarcane agro-ecological zoning (AEZ) by the ethanol sector in Brazil, a key assumption of our projections

Assessment of electric vehicle battery technologies using fuzzy linguistic and promethee-gaia multicriteria approaches

Introduction of zero emission concepts has opened the way for possible commercial markets for battery-powered electric vehicles (EV). In comparison to gasoline-powered cars, these vehicles produce CO emission half of that gasoline-powered and almost similar amount in comparison to hybrid electric vehicles over their useful lives. Since most of the emissions in electric vehicles are most likely attributable to production of their very large batteries, environmental consequences of producing and disposing of EV batteries may be significant. This study aims to analyze environmental impacts associated with recycling and waste management of four electric battery technologies likely to be used in the near future. Secondly, it aims to select the most environmentally benign battery technology by considering their manufacturing, political and social viability, environmental impacts and exposure and toxicity potential issues. The EVs' battery technologies considered here are lead acid (PbA), nickel-cadmium (NiCd), nickel metal hydride (NiMH) and sodium-sulfur (NaS). In this study, we compared potential health and environmental impacts of four battery technologies and focused on recycling and waste disposal life stages, with an emphasis on design factors that could prevent or increase impacts. With regard to the evaluation of battery technologies, since the data used are often contradictory, variable, uncertain and sometimes impossible to validate independently, fuzzy linguistic approach (FLA) is explored here to address this data ambiguity and its results are also being compared to the ranking obtained using a known Promethee-Gaia (PG) approach. Based on PG evaluation, the recycling assessment ranks the batteries studied in the following preferential order: NiMH>NaS>NiCd>PbA. In terms of disposal, NiMH and NaS batteries are of greater concern because of landfill impacts while both NiCd and PbA batteries are considered the most favorable. Almost similar results were also obtained using fuzzy linguistic approach. But due to the toxic characteristics of cadmium and lead metals, it is still recommended that NiCd and PbA batteries should be recycled instead

Modelling Uncertainties in Assessing Waste Gasification Technology

The inability of existing process design and life-cycle analysis (LCA) methods to account for variability and uncertainty may contribute to misleading estimates of pollution prevention, performance, and cost of potentially promising new environmentally conscious technologies. The objectives of this research are to develop a novel assessment methodology for evaluation of the risks and potential pay-offs of new technologies that avoid pollutant production; and demonstrate the methodology via case study of solid waste gasification technology. A methodology for simultaneous characterization of both variability and uncertainty based upon previous work in emissions estimation, exposure assessment, and risk assessment is developed. To represent uncertainties in any process technology, a probabilistic modeling is applied to the case of solid waste gasification