Human Toxicity Potential Research Articles

Production and recycling of blast furnace slag: A life cycle assessment approach in India

AbstractThis article investigated the cradle‐to‐gate environmental impact of granulated blast furnace slag (GBFS) produced in the steel industry and replacement of blast furnace (BF) slag (50%) in place of clinker in Portland slag cement using GaBi software (Indian extension database). In case of GBFS production, maximum burden on the environment is due to BF slag production and the amount of electricity consumed (161 MJ/ton) during the granulation process. The influence of electricity sources on GBFS production was studied via scenario analysis. For investigation, solar and thermal electricity mixes were considered in 50:50 and 75:25 ratios. For the 75:25 ratios, the abiotic depletion potential (fossil), acidification, eutrophication, global warming, and human toxicity potential show a decreasing trend of approximately 45%, 49%, 48%, 46%, and 41%, respectively. The scenario analysis of BF slag transportation (from 100 to 750 km) demonstrates a negative impact due to fuel. The results quantitatively confirm that the addition of GBFS can lower the overall impact for construction and steel industries.

Assimilatory sulphate reduction by acidogenesis: The key to prevent H2S formation during food and green waste composting for sustainable urbanization

Food and green waste composting is a nature-based process for sustainable management of municipal organic waste. Although widely used for these organic wastes, composting is hindered by rapid organic acidification and malodor emission, particularly hydrogen sulphide (H2S). Using genome-resolved metagenomics, this study aimed to decipher the underlying mechanisms of sulphate reduction to H2S by acidogenesis during food and green waste composting. Results showed that both volatile fatty acids (VFAs) and H2S were significantly produced within the first week of composting. Further analysis identified that bacteria (e.g. Lactobacillus) with acid-producing genes (ackA and LDH) were key accomplices to assimilatory sulphate reduction for producing H2S by providing VFAs, especially acetic and lactic acids, as a carbon source. Such sulphate reduction could be directly induced by bacteria (e.g. Bacillus, and Ureibacillus) with intact assimilatory sulphate-reducing genes (cysNC, cysH, and cysJ/I). Nevertheless, individual bacteria (e.g. Paenibacillus and Acetobacter) without any sulphate-reducing genes could collaborate with their partners carrying complemented genes to complete sulphate reduction toward H2S. Furthermore, VFAs production could acidify composting substrates to abiotically aggravate the conversion of sulphur ions (e.g. S2- and HS-) to H2S. Nevertheless, alkaline additives suppressed these mechanisms to prevent both acidogenesis and H2S production, thereby, reducing the global acidification and human toxicity potentials of food and green waste composting.

Assessing Carbon Capture and Carbonation in Recycled Concrete Aggregates: A Holistic Life Cycle Assessment Perspective with Simulation at Industrial Scale

This work explores a life cycle assessment (LCA) concerning carbon capture and carbonation of recycled concrete aggregates (RCA), addressing the growing challenges posed by increased carbon emissions in power generation and ecological concerns tied to construction waste. We propose an integrated solution involving the capture of low-concentration carbon dioxide (CO2) from natural gas combined cycle (NGCC) power plants through aqueous ammonia absorption and sequestration by mineralization of RCA. The cradle-to-gate LCA focuses on an industrial-scale scenario for capturing 200 kilotonnes of CO2 annually, with functional unit per tonne of carbonated RCA output. The findings reveal a net positive carbon abatement of 21.42 kg CO2 eq., with heat production and electricity consumption being the major contributors to global warming potential (GWP). Within the spectrum of environmental impact categories under study, Marine Aquatic Ecotoxicity Potential (MAETP) exhibits a significant impact, primarily influenced by sulfur production. Human Toxicity Potential (HTP) follows as the second-worst contributor, with 96.80% of its impact attributed to heat and sulfur production. Subsequently, Acidification Potential (AP) follows, arising from sulfur and sulfuric acid production. Sensitivity analysis and Monte Carlo simulation introduce a ±20% standard deviation to electricity and thermal energy consumption. Scenario analysis demonstrates a net carbon-positive abatement potential of 286.66 kg CO2 eq. per tonne of CO2 input. Employing carbon mineralization for CO2 capture not only reduces emissions but also repurposes waste materials, providing a comprehensive and sustainable solution for effective CO2 management, contributing to reduced sand mining, and offering cost advantages through the production of carbonated RCA.

Modeling the impact of pesticide drift deposition on off-field non-target receptors

Pesticide application can result in residue drift deposition in off-field areas, which can be harmful to non-target organisms inhabiting adjacent off-field environments. In order to comprehend the impact of pesticide drift deposition on off-field non-target organisms, an integrated modeling approach was incorporated into the life cycle analysis perspective for the assessment of their exposure to pesticide residues and the characterization of their human toxicity and ecotoxicity potentials. The modeling assumption comprises four modeling scenarios: children & cattle & sensitive crops (tomatoes) based on exposure assessment, and the continent-scale human health toxicity & ecotoxicity under a life cycle analysis perspective. The simulation results for the nearby off-field exposure scenario revealed that pesticide dissipation kinetics in environments and drift deposition type were two important factors influencing non-target organisms' exposure to pesticide residues deposited in off-field environments. The continental scenario simulated via USEtox revealed that considering off-field drift deposition resulted in lower simulated human toxicity potentials of pesticides when compared to simulation results that did not consider drift deposition, given that pesticide residues remaining within the treated field contributed the most to overall human exposure. Taking drift deposition into account, on the other hand, could result in higher or lower simulated ecotoxicity potentials of pesticides than not taking drift deposition in off-field areas into account, depending on the physicochemical properties of pesticides. The proposed modeling approach, which is adaptable to drift deposition types and chemical species, can aid in investigating the off-field impacts of pesticide residues. Future research will incorporate spatiotemporal factors to characterize region-specific drift deposition functions and pesticide fate in off-field environments to conduct site-specific impact assessments.

Current and potential materials for the low-carbon cement production: Life cycle assessment perspective

Given the carbon-intensive nature of cement production, conducting a comprehensive environmental evaluation using life cycle assessment (LCA) modeling is paramount to achieving eco-friendly cement standards. This study meticulously compiles and evaluates LCA findings from diverse analyses of current and potential supplementary cementitious materials (SCMs) within the blended cement sector. It underscores the impact of the functional unit (FU) within the LCA approach, supply chain considerations, and technical and regulatory factors on the sustainability of blended cement mixtures. Most of LCAs studied herein show that integrating SCMs into the cement matrix typically reduces land use, energy consumption, and greenhouse gas (GHG) emissions, thereby lowering the global warming potential (GWP) of ordinary portland cement (OPC) samples from 831 to 980 kg of CO2-eq to 768-481 kg of CO2-eq per ton of cement. However, in some instances, environmental indicators like abiotic depletion potential-elements (ADP-E) and human toxicity potential (HTP) rise due to increased mining, electricity, and transportation demand for SCMs. Regarding the environmental potential of alkali-activated cementitious materials and low-carbon clinker formulations, we found that limitations arise in fully replacing OPC due to global raw material availability constraints, rendering them economically unfavorable and impeding their widespread adoption. Among the SCMs examined in this study, clays, which are more widely available compared to industrially sourced materials like fly ash, slag, and silica fume, exhibited a more favorable environmental profile when evaluated using a mass-based FU. Incorporating compressive strength into the FU resulted in greater environmental benefits from high-strength blendedcement composites. However, this approach might lead to inaccurate results because higher strength does not always correspond to a lower environmental impact. Thus, establishing a FU that accurately reflects the environmental impact of blended cement and its composites (e.g., concrete and mortar) is crucial. Despite the potential of various pozzolanic materials to reduce clinker content in cement mixtures, their wide utilization remains restricted due to the absence of widescale market-based initiatives, green procurement strategies, and effective policy measures, which hampers their industrial and public acceptance. Consequently, governmental support is essential for developing and integrating sustainable cement solutions.

Environmental impact assessment of the manufacture and use of N- type and P-type photovoltaic modules in China

For a long time, solar power has been considered a clean and non-polluting energy source because it absorbs sunlight without consuming other energy or materials and does not emit pollutants. Nevertheless, the manufacturing and end-of-life stages of solar power systems leave an environmental footprint and produce pollutants. Hence, a global perspective on photovoltaic (PV) systems using life cycle assessment methodology is necessary. Here, we investigated the life cycle impacts of P- and N-type PV modules in terms of their energy consumption, carbon emissions, and human toxicity potential. In addition, the energy payback durations of P- and N-type PV modules were computed. In this study, we used the Life Cycle Assessment Basic Database from the National Engineering Laboratory of Industrial Big Data Application Technology at Beijing University of Technology to create a life cycle assessment model for N-type PV modules. Subsequently, we performed a life cycle assessment of Chinese silicon N-type- and P-type PV modules. The research system encompassed the production processes for metallic silicon materials, solar-grade silicon materials, silicon wafers, cells and modules, utilization, recycling, and other interrelated processes. We found that the production and processing of silicon-to-solar-grade polysilicon feedstock were crucial stages that significantly affected the energy consumption and environment of P- and N-type PV modules in China. The high electricity consumption of this process, combined with the dominance of coal power in China's electricity structure, contributed to the substantial energy consumption and environmental impacts of the PV modules. Therefore, this stage is critical for the low-carbon and environmentally sustainable manufacturing of N-type PV modules in China. Carbon emissions for both the P-type and N-type PV modules were lower only during the cell production phase but higher during the other stages when compared to the P-type and N-type PV modules. The n-type bifacial PV modules yielded the highest return on investment in terms of energy. Different regions and installation types have a substantial impact on the carbon emissions of P-type and N-type PV modules. Projections indicate that the potential to lower carbon emissions from n-type PV modules will increase by 2060.

Life Cycle Assessment of Abandonment of Onshore Wind Power for Hydrogen Production in China

The development of clean energy is a crucial strategy for combating climate change. However, the widespread adoption of wind power has led to significant challenges such as wind curtailment and power restrictions. A potential solution is the abandonment of onshore wind power for hydrogen production (AOWPHP). To ensure the sustainable development of clean energy, it is essential to assess the environmental impact of the AOWPHP. This study employs a life cycle assessment (LCA) methodology to evaluate the environmental impacts of the AOWPHP using QDQ2-1 alkaline electrolyzer technology in China. Furthermore, a scenario analysis is conducted to project these environmental impacts over the next 30 years. The findings indicate the following: (1) The global warming potential (GWP) over the life cycle is 5614 kg CO2-eq, the acidification potential (AP) is 26 kg SO2-eq, the human toxicity potential (HTP) is 12 kg DCB-eq, and the photochemical ozone creation potential (POCP) is 3.77 × 10−6 kg C2H4-eq. (2) Carbon emissions during the production stage significantly contribute to the environmental impact, with steel and concrete being notably polluting materials. The POCP shows high sensitivity at 0.97%, followed by the GWP and AP. (3) The scenario analysis indicates an upward trend in environmental impacts across low-speed, baseline, and high-speed development scenarios, with impacts peaking by 2050. For instance, under the high-development scenario in 2050, the GWP for each material reaches 41,808 kg CO2-eq. To mitigate these impacts effectively, recommendations include reducing reliance on steel and concrete, developing green logistics, enhancing operational efficiency in wind farms and hydrogen production plants, and exploring new epoxy resin materials. These insights are crucial for promoting sustainable growth within the AOWPHP in China while reducing global carbon emissions.

Environmental and economic implications of applying augmented reality in express parcel delivery in China

State-of-the-art information and communication technologies (ICTs), such as augmented reality (AR), have been increasingly adopted in express delivery. However, their environmental and economic impacts remain underexamined. We pioneer to assess the environmental and economic performances of applying AR in a parcel distribution center for express delivery, using a perspective life cycle assessment (LCA) approach and a traditional life cycle costing (LCC) method. On the basis of our field investigation and literature analysis, three scenarios, namely Baseline Scenario, AR Scenario, and AR+ Scenario, are developed consistent with current and potential AR applications in parcel delivery. Our findings indicate that AR and AR+ Scenarios are more environmentally sustainable than Baseline Scenario, exhibiting a decrease in global warming potential (GWP) by 13.44 % and 13.06 %, respectively. With the introduction of AR, the values of most selected impact categories show notable declines, except for human toxicity potential and marine ecotoxicity potential. The total endpoint scores decreased by 13.39 % and 12.86 % in the AR Scenario and AR+ Scenario, respectively. Moreover, the AR Scenario and AR+ Scenario are economically advantageous, demonstrating cost reductions of 38.59 % and 49.31 %, respectively, compared with the Baseline Scenario. Most substantial benefits associated with AR occur in the picking & sorting process, exhibiting improved accuracy and efficiency. Our sensitivity analysis underscores the substantial benefit associated with applying AR in routing improvement; 1 % routing improvement leads to a reduction of 0.27 kg CO2-Eq. Moreover, the sensitivity analysis also shows that labor cost is the most influential factor in the overall economic performance; its 1 % fluctuation leads to a change of 1.37 USD in the total cost. Our uncertainty analysis suggests that using more advanced processing units in AR devices leads to superior economic performance, but at greater environmental costs due to increased metallic contents. Based on these assessments, we provide managerial and theoretical implications on adopting smart ICTs in logistics.

Life cycle assessment of post-combustion carbon capture and storage for the ultra-supercritical pulverized coal power plant

In this paper, different emerging post-combustion technologies, i.e., monoethanolamine (MEA), aqueous ammonia, pressure swing adsorption (PSA), temperature swing adsorption (TSA), membrane and calcium looping, were applied to an ultra-supercritical coal-fired power plant for carbon capture. A ‘cradle-to-grave’ life cycle assessment (LCA) was conducted to evaluate the technical performance and environmental impacts of the power plant with six emerging carbon capture technologies. Carbon capture significantly influences the impact categories directly associated with flue gas emission. The application of carbon capture reduced the GWP in the range of 49–75 %. TAP also reduced in the range of 18–51 %. However, the human toxicity potential, eutrophication potential, ecotoxicity potential and particulate matter formation potential increased due to energy and resource consumption in the upstream and downstream processes. For the life cycle water consumption potential, it decreased by 8 % with calcium looping, whereas it increased in the range of 36–75 % with other post-combustion technologies. The highest reduction in GWP and the least reduction in power efficiency was observed in calcium looping because of the high-temperature heat recovery from flue gas and elimination of complex solvent manufacturing. The plant with aqueous ammonia and membrane separation had the second and third highest reductions in GWP. In addition, the lowest values for TAP, FEP, and MEP were obtained in the membrane system. With MEA for CO2 capture, the total GWP value of the plant is slightly higher than these three technologies mentioned above, and the highest HTPc, FETP, and METP can be observed in this case. TSA and PSA have the most significant environmental impacts in most categories due to higher energy requirements.

Evaluating the environmental and economic performance of biological and advanced biological wastewater treatment plants by life cycle assessment and life cycle costing.

The primary objective of this study is to assess and establish benchmarks for environmental and economic sustainability of biological and advanced biological wastewater treatment plants (WWTPs) with different treatment technologies and characteristics. Furthermore, the study aims to determine the beneficial role of WWTPs to reduction of eutrophication potential. Environmental and economic sustainability of ten municipal WWTPs was assessed using life cycle assessment (LCA) and life cycle costing (LCC). In the first section of the study, LCA was performed to determine the environmental performance of the WWTPs. Furthermore, net environmental benefit (NEB) approach was implemented to reveal the beneficial role of WWTPs to eutrophication potential. In the subsequent section, LCA-based LCC was conducted by integrating the results of LCA. The most significant environmental impact was determined as marine aquatic ecotoxicity, which is highly affected from the generation and transmission of electricity consumed in the WWTPs. Wastewater recovery and co-incineration of sewage sludge in cement kiln ensure significant environmental savings on ozone layer depletion, human toxicity, acidification, photochemical oxidation, and abiotic depletion (fossil fuel) potential. Considering NEB approach, the highest NEB values were found for the WWTPs with the higher organic load and nutrient concentration in the influent. The results of LCC in WWTPs varied between 0.21 and 0.53 €/m3. External (environmental) costs were evaluated higher than internal (operational) costs for all selected WWTPs. While eutrophication was the highest among environmental costs, electricity cost was the highest among operational costs for almost all WWTPs.

Research on Life Cycle Assessment and Performance Comparison of Bioethanol Production from Various Biomass Feedstocks

Bioethanol, as a renewable energy source, has been widely used in the energy sector, particularly in replacing traditional petroleum energy, and holds great potential. This study involves a whole life cycle assessment of bioethanol production and the co-production of high-value by-products—xylose, lignin, and steam—using three types of waste biomass: corn cobs, corn straw, and wheat straw as feedstocks by chopping, pretreatment, hydrolysis, fermentation, and distillation methods. Secondly, the benefits of three raw materials are compared for preparing bioethanol, and their impact on the environment and energy production is analyzed. The comparison indicates that corn cobs offer the best overall benefits, with a net energy balance (NEB) of 6902 MJ/Mg of ethanol and a net energy ratio (NER) of 1.30. The global warming potential (GWP) is 1.75 × 10−2, acidification potential (AP) is 1.02 × 10−2, eutrophication potential (EP) is 2.63 × 10−4, photochemical ozone creation potential (POCP) is 3.19 × 10−8, and human toxicity potential (HTP) is 1.52 × 10−4. This paper can provide a theoretical reference and data supporting the green refining of bioethanol and the high-value utilization of by-products, and broaden its application prospects.

TiO2 recovered from spent selective catalytic reduction catalysts as anode material for lithium-ion batteries

Environmental protection and sustainable development are among the most severe problems in the world today. Spent selective catalytic reduction (SCR) catalysts are recognized as hazardous waste. Here, the TiO2, which accounts for nearly 80% of spent SCR catalysts, is recovered by the alkaline leaching method, and performed higher electrochemical performances than commercial TiO2 products for anode materials of Lithium-ion batteries. W, V, Si, and Al leaching rates are 40.04%, 89.59%, 61.64%, and 11.57%, respectively. A combination of density functional theory (DFT)--based calculations and experiments revealed that trace doping of Al is beneficial to the electrochemical performance of the cell, which helps us tune the Al content in the obtained materials. On this basis, the regenerated TiO2 anode materials with graphene (GR) materials are synthesized to improve the electrochemical performance, and the specific capacity of the recycled TiO2 is 188.5 mAh·g−1 after 500 cycles, and that of the regenerated TiO2/GR is the highest at 275.2 mAh·g−1. Finally, an environmental assessment of this recycling process is also carried out, human toxicity potential, CO2 gas emissions, NMVOC gas emissions, and SO2 gas emissions in this work are reduced by nearly 86.9%, 87.0%, 92.5%, and 87.0% compared with commercial sol-gel synthetic method. This work highlights the significance of recovery for preparing new energy storage materials from secondary resources.

Environmental impact assessment of battery boxes based on lightweight material substitution

Power battery is one of the core components of electric vehicles (EVs) and a major contributor to the environmental impact of EVs, and reducing their environmental emissions can help enhance the sustainability of electric vehicles. Based on the principle of stiffness equivalence, the steel case of the power cell is replaced with lightweight materials, a life cycle model is established with the help of GaBi software, and its environmental impact is evaluated using the CML2001 method. The results can be summarized as follows: (1) Based on the four environmental impact categories of GWP, AP, ADP (f), and HTP, which are the global warming potential (GWP), acidification potential (AP), abiotic depletion potential (ADP (f)) and human toxicity potential (HTP), the environmental impact of lightweight materials is lower than that of the steel box. Among them, the aluminum alloy box has the largest reduction, and the Carbon Fiber Sheet Molding Compound (CF-SMC) box is the second. (2) In the sensitivity analysis of electric structure, an aluminum alloy box is still the most preferable choice for environmental impact. (3) In the sensitivity analysis of driving mileage, the aluminum alloy box body is also the best choice for vehicle life. (4) Quantitative assessment using substitution factors measures the decrease in greenhouse gas emissions following the substitution of steel battery box with lightweight materials. The adoption of aluminum alloy battery box can lead to a reduction of 1.55 tons of greenhouse gas emissions, with a substitution factor of 1.55 tC sb−1. In the case that composite materials have not been recycled commercially on a large scale, aluminum alloy is still one of the best materials for the integrated environmental impact of the whole life cycle of the battery boxes.

Integrated biorefinery for bioethanol and succinic acid co-production from bread waste: Techno-economic feasibility and life cycle assessment

In this study, an advanced decarbonization approach is presented for an integrated biorefinery that co-produces bioethanol and succinic acid (SA) from bread waste (BW). The economic viability and the environmental performance of the proposed BW processing biorefinery is evaluated. Four distinctive scenarios were designed and analysed, focusing on a plant capacity that processes 100 metric tons (MT) of BW daily. These scenarios encompass: (1) the fermentation of BW into bioethanol, paired with heat and electricity co-generation from stillage, (2) an energy-optimized integration of Scenario 1 using pinch technology, (3) the co-production of bioethanol and SA by exclusively utilizing fermentative CO2, and (4) an advanced version of Scenario 3 that incorporates carbon capture (CC) from flue gas, amplifying SA production. Scenarios 3 and 4 were found to be economically more attractive with better environmental performance due to the co-production of SA. Particularly, Scenario 4 emerged as superior, showcasing a payback period of 2.2 years, a robust internal rate of return (33% after tax), a return on investment of 32%, and a remarkable net present value of 163 M$. Sensitivity analysis underscored the decisive influence of fixed capital investment and product pricing on economic outcomes. In terms of environmental impact, Scenario 4 outperformed other scenarios across all impact categories, where global warming potential, abiotic depletion (fossil fuels), and human toxicity potential were the most influential impact categories (−0.344 kg CO2-eq, −16.2 MJ, and −0.3 kg 1,4-dichlorobenzene (DB)-eq, respectively). Evidently, the integration of CC unit to flue gas in Scenario 4 substantially enhances both economic returns and environmental sustainability of the biorefinery.

Evaluation of environmental impact on cocoa production and processing under life cycle assessment method: From beans to liquor

This study aimed to identify the environmental impact on cocoa production and processing based on the life cycle assessment method (LCA). The major contribution of this study is to evaluate the environmental performance of a chocolate liquor in order to reveal the significant environmental hotspots along the entire supply chain. This is achieved through two main steps. First, the LCA method is applied to identify the environmental implications of managing the production and processing cocoa to become chocolate liquor. The LCA is performed based on the international ISO 14040–14043 series. Secondly, a sensitivity analysis was carried out to evaluate the impact of five proposed improvement options to discover whether any occurring potential environmental impacts will be reduced. The kind of scenarios are: reducing pesticides by 50 % (option 1); using compost instead of fertilizer (option 2); avoid burning stubble (option 3), conserving soil water (option 4) and applying alternative energy sources (option 5). As a result, the most significant environmental impact for the upstream and core processing was human toxicity potential (HTP) and cumulative energy demand (CED), 89 % and 59 %, respectively. In addition, the impact of the proposed improvement has significantly reduced environmental impacts (HTP, 68 %) and achieved savings (IDR 18800, 17.7 %). Survey data includes the entire supply chain, with a detailed focus on production and processing stages for an Indonesian chocolate company. This study only dealt with cocoa beans that generated 1 kg of chocolate liquor.

Exergy-efficient sustainable production of diesel additive in infrared energized continuous flow rotating real reactor: Optimization, heterogeneous kinetics, and life cycle analyses

An exploratory expedited synthesis of a diesel additive viz., glycerol monooleate (GMO) was investigated for the first time in a novel energy-efficient infrared-energized continuous flow rotating catalytic fixed bed real reactor (IR-RFBR). Under statistically derived optimum condition maximum 98 ± 0.5 % per pass GMO selectivity was obtained. Using kinetic data from a rotating batch reactor under equivalent conditions, an inclusive non-catalytic and heterogeneous-catalytic kinetic model (R2=0.99) was developed. The IR-RFBR’s performance was evaluated using the derived kinetic model and accounting for axial dispersion (Pećlet Number: 70.15).Comparative exergy and exergo-economic analyses were performed on rotating and non-rotating IR-fixed bed reactors. In terms of lower product exergy cost (4.69 $/kJ), the IR-RFBR outperformed its non-rotating counterpart (11.85$/kJ) due to a 22 % higher GMO yield at reduced residence time (3.2 min). Furthermore, IR-RFBR manifested greater exergoeconomic efficiency (91 %) than conventionally heated RFBR (CRFBR, 69 %, 7.67 $/kJ). Life cycle analyses for IR-RFBR confirmed significant reductions in environmental impact categories such as global warming, fossil depletion, and human toxicity potentials by ∼ 88 %, ∼84.3 %, and ∼ 83 %, respectively, when compared to IR-non-rotating and CRFBR. Thus, the developed process for glycerol based diesel additive synthesis ensures more glycerol utilization in a sustainable and economic pathway.

Demonstrating circular life cycle sustainability assessment – a case study of recycled carbon concrete

To counter the high consumption of resources and environmental emissions in the construction sector, innovative materials such as carbon-reinforced concrete (CRC) are needed. CRC has the potential to lower the resource use and emissions of the construction sector and lead to a circular economy (CE). To understand the overall circularity and sustainability performance of such materials, holistic assessments are needed. This study demonstrated the application of the newly developed circular life cycle sustainability assessment (C-LCSA) framework that is based on CE indicators and life cycle sustainability assessment (LCSA). The framework was applied to an industrial floor that was made from recycled CRC scrap (R–CRC industrial floor) in its development phase – using both the concrete faction and the carbon fiber fraction. The material circularity indicator (MCI) was used for the circularity assessment. It was applied in parallel to a life cycle assessment (LCA), life cycle costing (LCC), and a social hotspot assessment, using the same functional unit and system boundaries. The cut-off approach used was in line with the technical system boundaries. The results showed that the contribution to the circularity of the R–CRC industrial floor was high (0.8184) due to the use of recycled material and the potential of being recycled again. The global warming potential (GWP, 167 kg CO2 eq.) was lower while the human toxicity potential (HTP) was higher compared to similar products. The production costs far exceeded the current price of a comparable product which might be related to the inefficiencies in the production at the laboratory scale in the development phase of the R–CRC industrial floor. Social risks were found for health and safety, as well as for the social acceptance of the floor due to technical uncertainties. Increasing the circularity further by only using recycled aggregates mostly showed positive effects on the environmental impacts. However, HTP and costs increased. General statements on the interlinkages between a higher circularity and positive impacts on sustainability performance cannot necessarily be made. Instead, a robust and holistic assessment of new products is needed. C-LCSA has demonstrated its effectiveness as a reliable framework for identifying interlinkages and trade-offs between the different sustainability dimensions and circularity. Further studies should be conducted to validate and demonstrate the C-LCSA framework on different products.

A study on comparative environmental impact assessment of thermochemical cycles and steam methane reforming processes for hydrogen production processes

Alternative energy sources are extensively studied to meet the increasing energy demand. To address rising energy demand, hydrogen generation through environmentally friendly sources are explored, and new technologies are now needed badly. Hydrogen can be generated using fossil fuels, nuclear energy and renewable energy. Most of the hydrogen is still produced using fossil-based fuels, which increases the amount of greenhouse gases. This study examines the life-cycle impact of three alternative hydrogen-generating processes. The solar-based hybrid sulfur (HyS) thermochemical cycle, the nuclear-based HyS thermochemical cycle, and steam methane reforming (SMR) are all considered, and the environmental consequences of the SMR and thermochemical facilities are evaluated. The CML-IA impact categories are used to analyze environmental impacts. The SimaPro 9.2, a modeling software package developed for the detailed descriptions and simulations of complex products, services and processes, is used to perform the life cycle impact assessment (LCIA). This study aims to determine the best environmentally friendly option for hydrogen production by analyzing and comparing its environmental implications. Different impact categories namely global warming potential (GWP), human toxicity potential (HTP), ozone layer depletion (ODP), abiotic depletion factor (ADF), and acidification potential (AP), are examined based on the CML-IA impact classifications. The results show that the solar-based HyS cycle options yield the lowest global warming potential, abiotic depletion, acidification potential, ozone layer depletion, and human toxicity potential values were 1.04 kg CO2 eq/kg H2, 0.013 kg Sb eq/kg H2, 0.0027 kg SO2 eq/kg H2, 0.0007 kg CFC-11 eq/kg H2, and 0.27 kg 1,4-DB-eq/kg H2, respectively. The environmental impact results further show that the solar-powered hydrogen generation is a promising approach for cleaner hydrogen generation.

Life cycle assessment of municipal solid waste generated from hilly cities in India – A case study

Improper disposal of waste poses a grave environmental threat, contributing to pollution of air, water, and soil. It is necessary to address this issue in order to mitigate the adverse effects of solid waste on both the environment and public health. In many developing nations, municipal authorities of bigger cities are enduring significant challenges in proper management of waste. The present study evaluates the impacts of various waste management alternative scenarios for environmental impacts for the selected study locations using Life Cycle Assessment (LCA) methodology. The methodology comprised of five different scenarios of waste management including an existing baseline scenario. In this context, the environmental impact categories analyzed were Global Warming potential (GWP), Acidification potential (AP), Eutrophication potential (EP) and Human Toxicity potential (HTP). The results indicated that amongst all the proposed scenarios, Scenario 1 and 4 exhibited the maximum and minimum environmental impacts respectively. The study revealed that least greenhouse gas emissions, acidification potential, eutrophication potential and human toxicity potential were comparatively lesser for scenario 4 varying from 5.65 to 11.36 kg CO2eq t−1; 1.24–3.345 kg SO2eq t−1, EP 0.19–0.68 kg PO4eq t−1, and 0.35–4.22 kg 1,4-DBeq t−1 respectively. Further, a sensitivity analysis was also performed to evaluate the influence of recycling rate of valuable resources in all the considered scenarios. The sensitivity analysis indicated an inversely proportional relation between change in recycling rate and total environmental burdens.

Life cycle assessment of SBS modified bitumen waterproofing membrane

Building waterproofing membranes constitute essential components of construction materials. This study utilizes the life cycle assessment (LCA) methodology to develop a comprehensive life cycle inventory and conduct an environmental impact assessment of typical styrene-butadiene-styrene (SBS) modified bitumen waterproofing membrane products. The main research objective of this paper is to identify the key factors influencing the environmental impact of products and to provide data for the selection of green materials in the construction industry. The results reveal that the production of raw materials for SBS-modified bitumen waterproofing membranes contributes the most to all environmental impact categories, followed by the transportation and energy production stages, while the production stage of the membranes exhibits a relatively smaller contribution. Within the raw material production stage, the bitumen production process exhibits the highest contribution to fossil fuel depletion (FFP) environmental impact, surpassing 50%. The production process of polyester tire cloth demonstrates the greatest influence on human toxicity potential (HTPc), global warming potential (GWP), freshwater eutrophication (FEP), marine eutrophication potential (MEP), and mineral resource scarcity potential (SOP), accounting for 54.63%, 32.86%, 68.55%, 72.41%, and 61.69%, respectively. Additionally, the production process of base oil exhibits the most significant contribution to fine particulate matter formation (PMFP) and terrestrial acidification potential (AP) among the environmental impact indicators. Variations in the quantities of polyester tire cloth and base oil exhibit the most notable influence on the environmental indicators of the product. Specifically, the sensitivity analysis reveals that polyester tire cloth has the greatest impact on mineral resource scarcity potential (SOP); base oil exhibits the highest sensitivity to fossil fuel depletion (FFP).