Terms Of Global Warming Potential Research Articles

Thermodynamic Analysis of the Absorption of Common Refrigerants in Fluorinated Deep Eutectic Solvents

The potential to decrease the negative environmental impact of greenhouse gases in terms of global warming potential (GWP) is a current challenge. Apart from CO2, fluorinated greenhouse gases (F-gases), which are human-made chemicals used in refrigeration and other industrial applications, have a huge environmental impact due to their high GWPs. In this regard, the design of units to capture and recover these gases would contribute to their reuse, avoiding the negative impact of their final emission or incineration. Fluorinated Deep Eutectic Solvents (FDESs) have been considered as promising solvents for the absorption and the selective separation of F-gases. However, the complex and expensive experimental labour to fully characterize FDESs delays its study and development. In this work, a computational approach is applied to develop accurate thermodynamic models of the gas solubility of several F-refrigerants in DESs. The molecular-based equation of state (EoS) soft-SAFT is used to assess the absorption of three F-gases (1,1,1,2-tetrafluoroethane (R-134a), difluoromethane (R-32), and pentafluoroethane (R-125)) at different temperatures in five DESs derived from fluorinated salts and perfluorinated acids. New molecular models are developed through the soft-SAFT approach for FDESs in good agreement with experimental data, and the solubility of F-gases is also calculated at varying temperatures with high accuracy. Then, an in-depth analysis of the characteristics of the refrigerants, and of the FDESs affecting the F-gases absorption is performed, and the enthalpy and entropy of absorption and the selectivity are calculated. It has been encountered that the best FDESs for each particular F-gas separation can be obtained by modifying the composition of DES and the operating temperature. Finally, an assessment based on the selectivity obtained from the soft-SAFT model is carried out to choose the most adequate solvent to separate the studied F-gases.

Life Cycle Environmental Assessment of Three Excavated Soil and Rock (ESR) Treatment Methods: A Case Study in Shenzhen City

This study aimed to quantitatively assess the environmental impacts of different methods used for treating excavated soil and rock (ESR) in Shenzhen, namely landfilling, sintering, and non-sintering, using the life cycle assessment (LCA) method. The findings indicate that recycling ESR through sintering or non-sintering processes offers more sustainable alternatives than landfilling. The recycled products derived from ESR can effectively replace traditional building materials, thereby reducing their environmental impacts. However, when comparing the environmental impacts of sintering and non-sintering processes, the latter demonstrated more significant impacts, particularly in terms of global warming potential (GWP), acidification potential (AP), and eutrophication potential (EP). Furthermore, it is worth noting that the environmental impacts of the sintering processes are influenced by fuel type and exhaust gas emissions, with natural gas combustion yielding more substantial overall environmental benefits. Moreover, ESR landfilling poses constraints on sustainable development and land resource occupation. This study contributes to a better understanding of the environmental impacts associated with ESR landfilling and recycling, provides management departments with optimal ESR management suggestions, and alleviates environmental pressure from urban development.

Comparative life cycle assessment of light frame timber and reinforced concrete masonry structural systems for single-family houses in Luxembourg

The building sector's significant greenhouse gas emissions and energy consumption present added challenges to meeting European climate commitments amidst rapid population growth. In Luxembourg, single-family houses dominate the residential buildings, noticeably contributing to construction waste and CO2 emissions. This study compares the environmental impacts of a three-story reinforced concrete masonry single-family house and an identical timber building in Luxembourg, emphasizing greenhouse gas emissions and embodied energy. A cradle-to-grave life cycle assessment was conducted using Building Information Modelling (BIM) models to analyze the global warming potential and primary energy requirements. Environmental product declarations from the producers and the ÖKOBAUDAT German database were used to determine the environmental impacts of the materials. The results show that the timber building outperforms the concrete building with a 43.5% lower global warming potential, while the concrete building demonstrates a 15.6% reduction in primary energy demand. This aligns with the average outcomes of seven similar studies discussed in this paper, at 33.2% and 4.7%, respectively. Moreover, the timber building is 78.6% lighter than the concrete one. When evaluating benefits and loads beyond the system boundary, the timber building provides 3.6 and 4 times greater advantages in terms of global warming potential and primary energy, respectively, compared to the reinforced concrete masonry building. Additionally, the study explores the impact of reusing the floors in the timber building. The cradle-to-grave LCA reveals that reusing the timber slabs improves the building's global warming potential and primary energy by 2.4% and 1.2%, respectively. However, when considering the benefits and loads beyond the system boundary, floor system reuse exhibits a 38.9% surge in global warming advantages while reducing primary energy benefits by 28.1%. The findings advocate for a policy promoting timber construction and reuse in Luxembourg, aiming to achieve the net-zero emission target by 2050.

Study of life cycle assessment: Transforming microalgae to biofuel through hydrothermal liquefaction and upgrading in organic or aqueous medium

Hydrothermal liquefaction (HTL) is a promising method for the utilization of low-lipid microalgae. For the upgrading of biocrude obtained from hydrothermal liquefaction of Dunaliella salina, two different catalysts for hydrodeoxygenation (HDO), which could function in organic solvents and aqueous phases respectively, were published in our previous work (Lin et al., 2023; Lin et al., 2022). Corresponding to quite different upgrading processes based on these catalysts, two systems for resource utilization of low-lipid microalgae were established, including microalgae growth & collection, HTL, HDO upgrading, and catalysts recovery, which were named case 1 and case 2, respectively. Through life cycle assessment (LCA), the product yield, energy consumption, and different environmental impact categories of the two systems were compared. It was found that both conversion processes of microalgae had significant environmental benefits for the reuse of wastewater in terms of global warming potential (GWP) and eutrophication (EP) by reducing up to a maximum value of 8.73 kg PO4-eq and 158.80 kg CO2-eq, respectively. In two systems, case 2 has more significant advantages in terms of low energy consumption, high product yield, and less hazardous substance emissions, which achieves 62 % total production yield and complete self-heating. The annual profits of case 2 increased by 41 % compared to case 1. Remarkably, the carbon-based catalysts contribute to the sustainability of the system due to the easy procedure of catalyst recovery. Through this work, the significance of technological innovation for environmental protection and economic development was emphasized.

Effect of Alternate Wetting and Drying on the Emission of Greenhouse Gases from Rice Fields on the Northern Coast of Peru

The cultivation of rice is one of the main sources of greenhouse gas (GHG) emissions due to continuously flooded irrigation (CF), which demands large volumes of water. As an alternative solution, alternate wetting and drying (AWD) irrigation has been developed as a water-saving strategy. This study was conducted at the Experimental Agricultural Station (EEA) in Vista, Florida, in the Lambayeque region located on the northern coast of Peru. Thus, it was analyzed the effect of AWD irrigation at different depths (5, 10, and less than 20 cm below the surface) compared to CF control on methane (CH4) and nitrous oxide (N2O) emissions and rice grain yield. AWD treatments reduced CH4 emissions by 84% to 99% but increased N2O emissions by 66% to 273%. In terms of Global Warming Potential (GWP), the AWD10 treatment demonstrated a 77% reduction and a Water Use Efficiency (WUE) of 0.96, affecting only a 2% decrease in rice grain yield, which ranged between 11.85 and 14.01 t ha−1. Likewise, this study provides sufficient evidence for the adoption of AWD irrigation as a strategy for the efficient use of water resources and the mitigation of GHG emissions in rice cultivation in the study area, compared to continuous flooded irrigation.

Gate-to-gate approach in life cycle assessment of steel pipe products

The iron and steel industry is of great strategic importance in Indonesia and is expected to continue its growth. One sector within this industry that is projected to see increased production is the steel pipe manufacturing sector. However, the significant emissions produced during steel pipe production have prompted many countries to seek ways to reduce these emissions. One such method is the implementation of the Life Cycle Assessment (LCA) technique, which assesses the environmental impact and serves as a valuable decision-making tool alongside other important methods. This approach aims to enhance sustainable production and consumption effectively and efficiently. In a specific case study, two types of steel pipe products were analyzed using LCA, focusing on various stages from material transportation to steel pipe production and delivery. The study assessed the environmental impact using the midpoint impact category, which includes factors like Global Warming Potential (GWP), Photochemical Ozone Creation Potential (POCP), Acidification Potential (AP), and Ecological Toxicity Potential (ETP) using the CML2001 characterization methods. The findings revealed that the production of SAWH pipes has a higher environmental impact in terms of GWP, AP, and POCP compared to HFW pipes, while HFW pipes had a greater ETP value. GWP was identified as the most significant potential impact for both products, with the pipeline production stage contributing the most to GWP. Overall, these results offer an initial understanding of the sustainability levels of steel pipe production, serving as a foundation for the development of pollution control measures to maintain the competitiveness of the industrial plant.

Enhancing performance and sustainability: CRB600H high-strength reinforcement in recycled concrete

This paper addresses the urgent need for high-performance, eco-friendly construction materials due to increasing urbanization. It introduces CRB600H high-strength reinforcement to enhance recycled aggregate concrete (RAC) beam performance. Comparative analysis with conventional concrete (CC) beams demonstrates RAC's inferior shear performance, which CRB600H reinforcement effectively improves. A novel optimization method for high-strength reinforcement is established based on equal strength principles, demonstrating cost-efficiency. Economic analysis reveals that despite rising production costs with increased recycled aggregate replacement ratios, CRB600H reinforcement substantially reduces expenses, even when more expensive than HRB400 reinforcement. The environmental analysis reveals that the CRB600H reinforcement significantly influences the environmental performance of reinforced concrete beams. Utilizing 100% RAC beam with CRB600H as an illustrative example, the contribution rates of steel bars to Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), and Cumulative Energy Demand (CED) are determined as 39.30%, 56.85%, 51.87%, and 55.76%, respectively. In comparison to CC beam with HRB400, the 100% RAC beam with CRB600H exhibit reductions of 10.27%, 18.59%, 19.03%, and 16.93% in terms of GWP, AP, EP, and CED, respectively. In conclusion, CRB600H reinforcement offers cost-effective, eco-friendly solutions, promising significant advancements in RAC applications.

Prospective life cycle environmental impact assessment of renewable energy-based methanol production system: A case study in China

Integrating renewable electricity and green hydrogen with CO2 utilization to produce chemicals has drawn much attention due to its low carbon emission characteristics. The goal of this paper is to investigate the environmental sustainability of producing a steady hourly output of methanol by utilizing electricity and hydrogen produced via renewable energy resources, and CO2 captured from a coal-fired power plant located in Inner Mongolia, China. Six renewable energy-based electricity and hydrogen systems are considered based on photovoltaic, wind turbines and combinations thereof, including battery and grid technologies. The environmental impact indicators of these system are compared comprehensively through life cycle assessment approach, including not only global warming potential but also fossil fuel depletion, water & soil & air pollution indices and human health index. The results indicate that the most environmentally friendly system is Case B2 which uses photovoltaic to produce hydrogen and electricity, with battery for energy storage and excess electricity sold back to grid. It shows apparently the best sustainability performance in global warming potential, which is 0.105 kg CO2-eq per kg methanol. In general, the proposed six systems outperform conventional methanol production systems in terms of global warming potential and abiotic depletion potential, with reductions ranging from 74% to 92% and 51.1%–73.8% respectively, but they have high levels in other environmental sustainability indicators such as human toxicity, eutrophication potential, and ozone layer depletion potential due to the photovoltaic electricity generation unit. The findings highlight that it is essential to consider a comprehensive range of environmental sustainability indicators when developing renewable energy-based methanol systems on a large scale.

Comparison of the use of life cycle assessment and ecological footprint methods for evaluating environmental performances in dairy production

One popular methodology for assessing the environmental impact of livestock sector is Life Cycle Assessment (LCA), that quantifies the environmental impact of a product. Ecological Footprint (EF) performs an environmental sustainability assessment, by comparing the demand for natural capital by an economic activity with the offer of such capital within a certain territory. The aim of the study was the comparison between LCA and EF in assessing the environmental performances of milk production, assuming as case study three cattle farms with increasing levels of production intensity. Different metrics and functional units (FU) (i.e., fat and protein corrected milk, FPCM and hectare) were adopted for LCA analysis, considering some of the major impact categories. For greenhouse gases emissions, the Global Warming Potential (GWP) and the Global Temperature Potential (GTP) were considered. Both metrics were calculated assuming or not the distinction between biogenic and fossil methane. Adopting GWP as a metric, the results per kg of FPCM provided by the LCA highlighted a different trade off compared to the EF method: the farm with the highest productive intensity produced the least impactful milk in terms of GWP but had the most negative Ecological Balance (EB). The same occurred for the other impact categories. When GTP was adopted, or the hectare was considered as FU, the least intensive farm, characterized by greater feed self-sufficiency, became the one that produced the least impactful milk and had the least negative EB. The study highlighted the scientific significance of the integration between the two approaches for creating a comprehensive representation of the effects of human activities on the environment. The LCA method evaluates impacts intensity referred to a specific functional unit and its results are strongly influenced by productive efficiency; the EF method evaluates environmental sustainability of productions in relation to the territory that supports them.

A comparative environmental Life Cycle Assessment study of hydrogen fuel, electricity and diesel fuel for public buses

Hydrogen fuel and electricity are energy carriers viewed as promising alternatives for the modernization and decarbonization of public bus transportation fleets. In order to choose development pathways that will lead transportation systems toward a sustainable future, the authors developed an environmental model based on the Life Cycle Assessment approach. The model tested the impact of energy carrier consumption during driving as well as the electricity origin employed to power electric buses and produce hydrogen. Energy sources such as wind, solar, waste and grid electricity were investigated. The scope of the study included the life cycles of the energy carrier and the necessary infrastructure. The results were presented from two perspectives: the total environmental impact and global warming potential. In order to create a roadmap, an original method for choosing sustainable development pathways was prepared. It was shown that the modernization of conventional bus fleets using hydrogen and electrical pathways can provide significant environmental benefits from both perspectives, but especially in terms of global warming potential. It was emphasized that attention should be paid to the use of low- and zero-emission energy sources, because their impact often strongly influenced the final environmental judgment. The energy carrier consumption also had a strong impact on the results obtained, and that is why efforts should be made to reduce it. In addition, it was confirmed that hydrogen and electricity production systems based on electricity generated by a waste-to-energy plant could be an environmentally reasonable dual solution for both sustainable waste management and meeting transport needs.

Innovative 100% RAP cold in-situ recycling of wearing course layers: laboratory and field characterisation and environmental impact assessment

ABSTRACT In the last decade, research is pushing forward the use of innovative techniques and environmentally friendly materials aiming at sustainable development in the road sector. In the present paper, a 100% RAP mixture is proposed through an innovative cold recycling in-situ technique for road pavement maintenance of small damaged sections and repairing distresses. The localized patching is developed through an innovative milling machine that is capable of directly and simultaneously milling and mixing the RAP produced. The innovative machine develops repairs that guarantee the safety and comfort of users. For obtaining the final mixture, RAP is combined with cement and a chemical additive. The experimental program was divided into a laboratory study of the milled material and a trial field campaign. After these phases, the environmental impacts that affect the repaired road sections are also evaluated through Life Cycle Assessment (LCA) tool. Tests from the laboratory and field phase highlighted positive results and downsides that need to be optimized to obtain a good quality intervention. The LCA analysis showed a positive impact in terms of global warming potential. Thanks to the use of this innovative machine, it is possible to mitigate the negative environmental impact associated with road pavement maintenance.

Assessing technological properties and environmental impact of fired bricks made by partially adding bottom ash from an industrial approach

Over the past few decades, the fired clay brick industry has searched for industrial wastes to substitute raw clay deposits and lessen their impact on the environment. Despite several investigations showing positive results, industrial applicability is still scarce, mainly due to differences between industrial and laboratory procedures and the usage of certain wastes that already have added value in other circular economy chains. In addition, the assessment of such proposals commonly misses the environmental impact issue which is merely assumed to be positive. For these reasons this study, for the first time, has assessed together technological properties and the environmental impact of bricks made by strictly following industrial procedures. Hence, biomass bottom ash (BBA) was added at 9 replacement ratios, ranging from 2.5 to wt. 20.0% for making extruded bricks subjected to industrial drying and firing curves. Physical, thermal and mechanical properties of fired products were properly assessed and compared with the requirements set forth by Chilean standards. In addition, a life cycle impact assessment was developed to compare the ecological footprint among series. Although mechanical and water-proof requirements may limit the replacement ratio for exposed bricks, the feasibility of using BBA at industrial scale has been successfully demonstrated. Regarding the environmental impact, the raw clay may be replaced without adversely causing toxicity levels to exceed mandatory limits. However, this study demonstrated that the incorporation of BBA increases CO2 emissions due to the decomposition of contained carbonates during the firing process which compromise the results in terms of global warming potential and water consumption which highly impact on human health and ecosystems quality.

Development of a Municipal Solid Waste Management Life Cycle Assessment Tool for Banepa Municipality, Nepal

In this study, the life cycle assessment (LCA) method has been used to evaluate the environmental impacts of various municipal solid waste (MSW) management system scenarios in Banepa municipality, Nepal, in terms of global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), human toxicity potential (HTP), abiotic depletion potential (ADP), and photochemical ozone creation potential (POCP). There are at least six possible scenarios of MSW management in Banepa: the current or baseline scenario (Scenario 1); composting with landfilling (Scenario 2); material recovery facility (MRF) recycling, composting, and landfilling (Scenario 3); MRF and anaerobic digestion (AD); composting, and landfilling (Scenario 4); MRF, composting, AD, and landfilling (Scenario 5); and, finally, incineration with landfilling (Scenario 6). Using both information from Ecoinvent 3.6 (2019) and published research articles, a spreadsheet tool based on the LCA approach was created. The impact of the recycling rate on each of the six abovementioned scenarios was evaluated using sensitivity analysis, which showed that the recycling rate can considerably decrease the life-cycle emissions from the MSW management system. Scenario 3 was found to have the least overall environmental impact with a GWP of 974.82 kg CO2 eq. per metric ton (t), EP of 0.04 kg PO4 eq./t, AP of 0.15 kg SO2 eq./t, HTP of 4.55 kg 1,4 DB eq./t, ADP of −0.03 kg Sb eq./t, and POCP of 0.06 kg C2H4 eq./t. By adoption of MRF and biological treatments such as composting and AD, environmental impact categories such as AP, EP, HTP, ADP, POCP, and GWP can be significantly reduced. The findings of this study can potentially serve as a reference for cities in the developing world in order to aid in both the planning and the operation of environmentally friendly MSW management systems.

Fabricating Strong and Stiff Bioplastics from Whole Spirulina Cells

AbstractSince the 1950s, 8.3 billion tonnes (Bt) of virgin plastics have been produced, of which around 5 Bt have accumulated as waste in oceans and other natural environments, posing severe threats to entire ecosystems. The need for sustainable bio‐based alternatives to traditional petroleum‐derived plastics is evident. Bioplastics produced from unprocessed biological materials have thus far suffered from heterogeneous and non‐cohesive morphologies, which lead to weak mechanical properties and lack of processability, hindering their industrial integration. Here, a fast, simple, and scalable process is presented to transform raw microalgae into a self‐bonded, recyclable, and backyard‐compostable bioplastic with attractive mechanical properties surpassing those of other biobased plastics such as thermoplastic starch. Upon hot‐pressing, the abundant and photosynthetic algae spirulina forms cohesive bioplastics with flexural modulus and strength in the range 3–5 GPa and 25.5–57 MPa, respectively, depending on pre‐processing conditions and the addition of nanofillers. The machinability of these bioplastics, along with self‐extinguishing properties, make them promising candidates for consumer plastics. Mechanical recycling and fast biodegradation in soil are demonstrated as end‐of‐life options. Finally, the environmental impacts are discussed in terms of global warming potential, highlighting the benefits of using a carbon‐negative feedstock such as spirulina to fabricate plastics.

The environmental impact and development direction of grass carp, Ctenopharyngodon idella, aquaculture

AbstractGrass carp, Ctenopharyngodon idella, is the largest freshwater aquaculture fish species worldwide. However, its environmental impacts are increasingly controversial. In this paper, we considered the production of a 1500 g commercial grass carp as an example, analyzed through a life cycle assessment. The results showed that the indicators of global warming potential (GWP), acidification potential, eutrophication potential, freshwater eco‐toxicity potential (FAETP), land competition (LC), and fossil energy consumption of producing 1 kg of grass carp were equivalent to 5.7267 kg of CO2, 0.0648 kg of 1,4‐DCB0, 0.0010 kg of P, 0.0276 kg of SO2, 8.2951 m2, 0.3491 kg of oil, respectively, and were mainly from feed processing and water pollution. Compared with pig, beef, and sheep production, grass carp production has lower environmental impacts, but in terms of GWP, FAETP, and LC were significantly higher than chicken production, especially water pollution and discharge, which is an important consideration. This study clarifies the direction of grass carp production and key focus areas include producing low carbon and nitrogen emission feed, application of ecological engineering aquaculture system, intelligent mechanization technology and equipment.

Investigating the mitigation of greenhouse gas emissions from municipal solid waste management using ant colony algorithm, Monte Carlo simulation and LCA approach in terms of EU Green Deal

This study majorly aimed to determine the effect of optimization on transport routes on the reduction of greenhouse gas (GHG) emissions from municipal solid waste management (MSM) within the scope of European Union (EU) Green Deal. Optimization of collection and transportation routes has been regarded as an effective methodology in order to mitigate the GHG emissions of municipal waste management, recently. Optimization of routes has been obtained using ant colony algorithm (ACA) and Monte Carlo simulation, in this study. In this context, this study investigated to reduce GHG emissions from municipal waste management using optimization of transportation routes in Diyarbakir city in Turkey. Firstly, GHG emissions which are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions from waste collection and transport have been calculated using a new developed model based on Tier-I method. Then, Monte Carlo simulation has been used to figure out the GHG emissions. Finally, life cycle assessment (LCA) approach has been applied to determine the GHG emissions. According to the route optimization resulting ACA methodology, nearly 47.43% of reduction on each GHG emissions. Approximately, 58%, 38% and 51% of reduction on CO2, CH4 and N2O emissions respectively has been achieved, in the result of the route optimization using Monte Carlo simulation. The results of LCA methodology revealed that the reduction reached up 45.71% on GHG emissions in terms of Global Warming Potential (GWP). The reduction amounts have been overlapped with each other.

LCA approach for environmental impact assessment within the maritime industry: Re-design case study of yacht’s superstructure

Sustainable development, one of the main challenges of our time, is a policy focused on the perfect balance between three fundamental pillars: environmental, economic and social sustainability. As regards the environmental protection, the Life Cycle Assessment (LCA) methodology allows to evaluate the sustainability profile of the overall Life-Cycle (LC) of products, processes and services, based on an inventory (in terms of materials/energy consumption and emissions/waste production) referred to all LC stages. The paper describes an application of LCA in the maritime transportation field, after a careful analysis of the state of the art. In particular, the case study consists in the environmental comparison of two alternative design solutions for the superstructure of a Azimut-Benetti yacht, designed by Corporate R&D department and manufactured in one of Benetti botyards. The competing construction options are a Glass Fiber reinforced Vinylester-isophthalic Resin (GFVR) and a Carbon Fiber reinforced Epoxy Resin (CFER) component, and they are assessed in terms of Global Warming Potential through the CML2001 Life Cyle Impact Assessment (LCIA) method. The study takes into account the entire LC of the superstructure component, divided into production (including raw materials, manufacturing and transportations), use (including both fuel consumption and exhaust air emissions) and End-of-Life (EoL). The Life Cycle Inventory (LCI) is mainly based on primary data (materials and energy consumption for manufacturing) directly provided by the construction company; missing data are retrieved from secondary sources (literature and LCI database provided by the GaBi6 environmental software). Results show that, despite the higher impact in production stage, the innovative solution allows achieving a significant quota of GWP over the entire LC (more than 16%), which is mainly associated with decreased amount of fuel needed and lowered CO2 exhaust emissions during operation. The sensitivity analysis reveals that the environmental advantage provided by the CFER design becomes bigger as both component life-time and yacht consumption increase.

Steel Bridge-Coating Systems and Their Environmental Impacts: Current Practices and Future Trends

Coatings are essential for protecting structural steel bridges from corrosion in harsh environmental conditions. The selection of a suitable coating system can significantly impact the performance and longevity of a bridge as well as its environmental footprint. This study investigates the U.S. and Canada’s environmental ISO corrosivity map and the general environments to which bridges are exposed. Additionally, environmental data and road maintenance practices of transportation departments and the use of de-icing salts were investigated to examine the impact of micro-corrosive environments on bridge elements. The study reviews commonly examined coating systems and their expected service life in moderate and highly corrosive environments. This sheds light on factors influencing coating system selection, such as life-cycle cost analysis and maintenance practices for bridge elements. For the first time to our knowledge, an environmental life-cycle evaluation of one of the most commonly used coating systems with theoretical maintenance scheduling for a bridge project’s expected service life is presented to encourage the use of a quantitative tool for environmental impact assessment of coatings in terms of global warming potential (GWP). Additionally, perspectives on patented state-of-the-art and future steel-protective technologies and their potential role in bridge engineering are reviewed.

Rigorous environmental and energy life cycle assessment of blast furnace pig iron in Brazil: The role of carbon and iron sources, and co-product utilization

Iron and steel are valuable commodities worldwide. Pig iron is produced mainly by blast furnaces, being the primary raw material used in steel manufacturing. The ironmaking sector is intensive in energy use and greenhouse gas emission; however, detailed information on further environmental impacts concerning the blend of material sources and co-product utilization as well as a rigorous application of the life cycle assessment (LCA) method are scarce. This study aimed to assess the environmental and energy performance of the production of 1.0 t of pig iron from cradle-to-gate via LCA. Global warming potential (GWP), renewable and non-renewable cumulative energy demand (CEDR and CEDNR), fossil resource scarcity (FRS), mineral resource scarcity (MRS), blue water footprint (WF), and land use (LU) were assessed in five scenarios in the Brazilian context, being S0: the baseline scenario with coke as a carbon source; S1: partial utilization of by-/co-products (top gas and slag), representing the current industry practice; S2: carbon and iron input blends proportional to the current industry practice; S3: current industry mix (S1 and S2 combined); and S4: ex-ante (forecast) scenario with an enhanced blend of inputs and maximum utilization of co-products. Results show that, when evaluated against an unrefined but realistic fossil-based state of the technology (S0), the existing practice in co-product utilization (S1) provided more gains in terms of GWP, CEDNR, FRS, and MRS (11 % on average) than the current iron and carbon input blends (S2, 9 % on average) if compared side-by-side. The current industry mix (S3) showed further improvement in environmental and energy performance (22 % on average) compared with the baseline scenario (S0), while the forecasted scenario (S4) indicated additional gains, reducing GWP by 47 % (down to ~1 t CO2 eq), CEDNR by 69 %, FRS by 70 %, MRS by 12 %, and WF by 5 %. The GWP, CEDNR, and FRS presented the greatest improvements with a significant statistical difference, and using charcoal as a carbon source was key in that regard, despite the great increase in CEDR (3× for biomass) and LU (2×) indicators suggesting that a robust sustainable wood supply chain will be decisive for the sector strategy. The sensitivity analysis (SA) and benchmarking of the ex-ante scenario (S4) showed notable competitiveness of such pig iron in the global market, especially for carbon and energy footprints, reaching 0.69 t CO2 eq t−1 pig iron and 4.6 GJNR t−1 pig iron from 100 % sustainable charcoal and including rail logistics (SAiv), which are from 2× to 5× smaller than those of any conventional blast furnace pig iron reported in the consulted literature.

Valorization of biogas from the anaerobic co-treatment of sewage sludge and organic waste: Life cycle assessment and life cycle costing of different recovery strategies

Nowadays, biogas produced from the anaerobic digestion of biowaste is considered a valuable renewable energy source to implement the transition to a climate-neutral society. Recently, biogas upgrading to biomethane, instead of the usual co-generation of heat and electricity (CHP), has been an attractive option, as biomethane can be used for different purposes. This study performed the life cycle assessment (LCA) and life cycle costing (LCC) of different scenarios for the valorization of the biogas produced from the anaerobic co-digestion (AcoD) of secondary sewage sludge (SS) and organic fraction of municipal solid waste (OFMSW), pre-treated by an anaerobic dark co-fermentation (DF) process. Four configurations were compared, exploring the recovery of one or more of the following: heat, electricity and biomethane. Furthermore, two sensitivity analyses were performed on LCA analysis, considering the use of the produced biomethane as a fuel for transport and the European electricity mix expected by 2050, respectively. The use of biogas for CHP was the most environmentally friendly solutions in 8 out of 11 impact categories provided by the CML-IA baseline method; however, biogas upgrading-based scenarios showed less impacts in relevant categories, such as global warming potential (up to −1.14E+05 kg CO2 eq. y−1) and ozone layer depletion potential (up to −4.73E-01 kg CFC-11 eq. y−1). Sensitivity analyses confirmed that the biogas upgrading processes should have generally a lower impact on climate change than CHP systems. Furthermore, the use of biomethane to replace petrol resulted to be the best option in terms of global warming potential (up to −5.67E+05 kg CO2 eq. y−1). All the proposed configurations represented economically sustainable projects, as they reported positive net present values (NPV) in 20 years (up to 10,518,291 €). Biogas upgrading-based scenarios showed the highest NPVs; nevertheless, the combined production of heat, electricity and biomethane was the most cost-effective option, thanks to biomethane revenues and electricity sales, despite the latter being modest. In conclusion, contrary to most of the previous studies in the literature, we found that CHP should not be neglected, as the optimal configuration may lie in the combined recovery of biomethane, electricity and heat.