Previous Life Cycle Assessment Research Articles

The ‘glass route’ for improving the sustainability of photovoltaic technology

The ‘glass route’ for improving the sustainability of photovoltaic technology Building upon previous life cycle assessments of photovoltaic technologies, the sustainability of photovoltaic modules will be increased by improving the mechanical and optical properties of the glass and plastics (PET and EVA) used to manufacture the modules. The reduction of ion migration towards the active solar cell will extend the lifetime of the modules and facilitate its recyclability at the end of life. Bismuth oxide has been tested as a material to improve the properties of the glass cover.

Exploring resource recovery from diverted organics: Life cycle assessment comparison of options for managing the organic fraction of municipal solid waste

Diversion of the organic fraction of municipal solid waste (OFMSW) from landfills is increasing. Previous life cycle assessment studies have evaluated subsets of OFMSW management options, but conclusions are inconsistent, and none have evaluated diverse applications of material by-products. The primary objective of this work was to identify sustainability-based improvements to the selection, design, implementation, and operation of organics waste diversion management technologies. Process modeling and life cycle assessment were used to compare OFMSW composting, anaerobic digestion, and pyrolysis, with biochar used as a landfill cover, leachate treatment sorbent, and land applicant. Material and energy flows, calculated by newly developed models for the defined functional unit (1 kg MSW over a 20-year timeframe), were translated to environmental performance using ecoinvent and USLCI databases and TRACI method. Additionally, uncertainty, sensitivity, and scenario analyses were conducted to evaluate the implications of model uncertainties, design decisions, and resource recovery tradeoffs. OFMSW pyrolysis usually (65 % of uncertainty assessment simulations) had the best global warming performance mostly due to energy recovery and biochar's carbon sequestration benefit, which was independent of fate. Pyrolyzing the biosolids from OFMSW anaerobic digestion recovered the most energy and had the best performance in 34 % of uncertainty simulations. Material recovery amounts were large (e.g., more biochar was produced than required for novel uses) and warrant feasibility considerations. Global warming performance was more sensitive to uncertainty in carbon sequestration and primary energy production than in fertilizer offset, energy conversion, or heat offset approach. Practical implications include the potential for biochar supply to outweigh demand, and inconsistent revenue from the sale of recovered energy and carbon credits; future research could focus on evaluating the relative social and economic sustainability of the OFMSW management technologies.

Assessment of climate change impact and resource-use efficiency of lettuce production in vertical farming and greenhouse production in Finland: a case study

PurposeOur aim in this study was to examine lettuce production in vertical farming or in conventional greenhouse production in Northern European conditions from the perspective of climate change impact and environmental sustainability. Further, the goal was to identify practices and choices that could mitigate adverse effects and increase resource-use efficiency, allowing the development of more sustainable production systems.MethodsThis article provides new information of the environmental impacts of lettuce production in greenhouses and vertical farming in Finland, compared using the life cycle assessment (LCA) methodology. The impact categories used were climate change impact, cumulative energy demand, resource use of fossil energy sources, resource use of minerals and metals, land use, and water scarcity. The system boundaries covered the production chains from cradle to farmgate, including inputs in production, as well as direct emissions caused by fertiliser use and the onsite composting of organic waste. The environmental impacts of the two production systems with different energy scenarios were assessed: (1) a greenhouse either with average or renewable energy; and (2) vertical farming either with average or renewable energy and with or without waste heat recovery. The data for vertical farming were based on one Finnish production site and supplementary data for the construction materials. The greenhouse data were based on a previous LCA investigation of average Finnish lettuce production.ResultsThe climate change and all other impact categories were lowest for lettuce produced in vertical farming with renewable energy and waste heat recovery. The climate change impact was largest for lettuce produced in greenhouse with average energy use. For energy use and energy resource use, the impacts of vertical farming were lower than greenhouse production, but for mineral and metal use and water scarcity, the impact of vertical farming was higher for average energy use without heat recovery. Direct land and irrigation water use on the production sites in Finnish circumstances represented only a small share of total land-use and water-use impacts on both production methods.ConclusionPaying attention to the energy source and heat recovery, the environmental sustainability can be advanced in both vertical and greenhouse production systems.

How will manufacturing capacity additions in China and North America affect the carbon footprint of silicon photovoltaics?

Global annual PV installation is expected to increase from 150 GW in 2021 to 820 GW in 2030 to reach net zero emissions by 2050. Electricity production from PV generates almost zero carbon emissions, but the emissions from the manufacturing phase are nonnegligible. While most installed PV modules in the US are imported from China, manufacturers are expanding the manufacturing capacity in North America to reduce reliance on Chinese PV modules. Although it has been commonly perceived that the North American modules would have a lower environmental footprint than Chinese ones, the effect of capacity expansions and regional impact considering where each component is produced has yet to be fully understood. This study aims to compare the carbon footprint and cumulative energy demand of PERC modules manufactured in China and North America based on the expected 2024 manufacturing capacity additions. We develop PV manufacturing scenarios to perform life cycle assessment (LCA) for the first time considering the regional manufacturing capacity, partnerships between suppliers and manufacturers, and regional electricity grids, while previous PV LCA studies evaluated the national average production. The carbon footprint of China's PERC modules for monofacial and bifacial designs, when using the national average grid, is 517 and 412 kg CO2eq/kWp, respectively. In comparison, the GWP of modules produced in North America is 22.0–22.2 % lower than in China, a difference attributed to the lower carbon footprint of electricity grids. When considering where each component is made, the GWP increases by 1.5 % in China compared to the national average. This difference arises because most of China's solar manufacturing facilities are in regions with higher carbon intensity grids than the national average. Solar manufacturers can reduce the carbon footprint of their products by changing manufacturing locations or increasing the share of renewable sources for manufacturing. We find that both China- and North America-made PERC modules meet the Electronic Product Environmental Assessment Tool (EPEAT) low carbon solar criteria (630 kg CO2eq/kWp). However, to meet the ultra-low carbon solar criteria (400 kg CO2eq/kWp), a significant share, approximately 60 % for China and 15 % for North America, of the total electricity supply must be sourced from renewable energy in addition to the existing grid. This study identifies the significant impact of manufacturing locations on the overall carbon footprint of PV modules. It is important to consider production locations by stage and the regional electricity supply when developing the carbon assessment methodology of PV modules. Otherwise, manufacturers may take advantage of assessing carbon footprint using the country's average grid while producing products in dirty grid regions.

Environmental life cycle assessment of reusable launch vehicle fleets: Large climate impact driven by rocket exhaust emissions

After the success of the reusable Falcon 9 rocket, space actors are pursuing competitive space access by developing Reusable Launch Vehicles (RLVs). While this initiative may enhance recycling rates, it may also trigger the Jevons’ paradox as it amplifies the overall environmental footprint due to increased launch frequencies. It is therefore essential to quantify RLVs’ impacts and identify key design drivers to enable efficient design choices while mitigating undesirable environmental effects.Consequently, this article uses a space specific Life Cycle assessment (LCA) approach to evaluate the environmental footprint, in terms of climate impact, water depletion and land use, of different RLV fleets designed to serve a forecasted European space market. The results show that the LH2 fleet options have 2–8 times lower carbon footprint when compared to the LCH4 fleet as a result of lower propellant consumption and lack of black carbon emissions, suggesting that the environmental burdens are mostly driven by propellant choice. Moreover, the analysis reveals a potential underestimation of climate impacts in previous LCA’s by 2–3 orders of magnitude due to the absence of high altitude characterisation of rocket exhaust emissions and demised aluminium oxides. This increased forcing could lead to fleet choices surpassing the Earth’s carrying capacity given by its planetary boundaries.The methodology and results within this study can support further integration of launch and reentry emissions within LCA by refining modelling techniques, improving impact characterisation and quantifying uncertainties. These advancements can ultimately enable robust eco-design strategies for launch vehicles.

Life cycle carbon emissions of China's passenger vehicle sector: a fleet-based study

The passenger vehicle sector has been identified as a major contributor to carbon emissions in China. Accurately estimating carbon emissions is crucial, particularly in light of China's ambitious goal to reach its carbon emissions peak by 2030. Previous life cycle assessment (LCA) studies on single-passenger vehicles rarely consider technological advancements to accurately predict future carbon emissions in the entire fleet. As such, a fleet-based life cycle approach that integrates input-output-based hybrid LCA (IOH-LCA) and system dynamics is proposed to simulate the evolution of carbon emissions in the passenger vehicle sector from 2016 to 2035. This method captures the complex changes in the sets of vehicles produced for sale, in use, and disposed of over time, as well as the multiple time-dependent technological advancements. A scenario analysis is constructed to analyze carbon emissions in alignment with the commitment to achieving the carbon emissions peak by 2030. The results indicate that, in a positive scenario with the combined advancement of multiple technologies, the passenger vehicle sector will be able to peak carbon emissions before 2030. This study could provide support for policymaking regarding carbon reduction in China's electrification of passenger vehicles.

Biodiversity burdens in Spanish conventional and low-impact single-family homes

Biodiversity loss caused by housing is not a well-defined sector of environmental impact. This research quantifies effects on biodiversity of an average Spanish Single-Family House (SFH) with 180 m2 of built surface. The current Spanish SFH stock GWP amounts to 1.16 Gt CO2eq in a 50-year life cycle, 40 % of which is embodied in the building materials and the 60 % are emissions due to the use of the building. This stock also impacts with 10.2 Gt 1,4-DCB the land, water and human health. SFHs also drive 6052 species extinct in a 50 year life cycle, and account for 3.03 M years of life lost due to premature death or lived with a disability. Divided by the 16 M people living in Spanish SFHs, each one lost 0.19 years of their lives (68.1 days) due to their home's impacts on human health.The article compares a reference conventional building against three low-impact cases, to understand how different building techniques and materials influence environmental outcomes that keep biodiversity loss the lowest possible. Scenarios include a standard brick and concrete house as Scenario 0 (SC0, Base), a timber Passivhaus as Scenario 1 (SC1), a straw-bale house with renewable energies as Scenario 2 (SC2), and an earth bioclimatic house as Scenario 3 (SC3). An initial Global Warming Potential (GWP) analysis was performed to relate previous building Life Cycle Assessment (LCA) studies with biodiversity metrics. Three main biodiversity metrics; ecotoxicity (as midpoint indicator), biodiversity loss and damage to human health (both as endpoint indicators) have been considered.Compared to SC0 with 1292 kgCO2-eq·m−2 (516 embodied) of GWP, we found that SC1 emitted −47.0 % of that, SC2–41.4 % and SC3–80.9 %. Concerning ecotoxicity, where SC0 has 11,399 kg 1,4 DCB, the results are −27.9 % in SC1, −19.2 % in SC2, and −45.6 % in SC3. Regarding biodiversity loss, where SC0 has 7.54 E−06 species.yr·m−2, the impacts are −30.9 % in SC1, −32.6 % in SC2, and −58.6 % in SC3.Human health damage in SC0 being 3.37 E−03 DALY, has been reduced in the timber home (SC1) is −44.2 %, of the Straw SFH (SC2) −39.2 %, and of the earth house (SC3) −67.1 %.This article shows that with current existing technological solutions GWP could be reduced in −80.9 %, ecotoxicity in −45.6 %, biodiversity loss in −58.6 % and human health in −67.1 %. Spanish Single-Family Houses built in timber, earth or straw-bale are real alternatives to current cement traditional building.

Life cycle assessment of wind turbine blade recycling approaches in the United States

Most wind turbine blades reaching end-of-life are sent to landfill where embedded cost, energy, and materials are lost. To avoid landfilling future blades, a broad range of recycling and material recovery approaches have been proposed as solutions in the U.S., each with benefits, challenges, and varying levels of technical maturity. The approaches include 1) cement co-processing, 2) mechanical recycling, 3) pyrolysis, 4) microwave pyrolysis and 5) solvolysis. While these approaches are all capable of recovering various forms of materials for use in secondary markets, there are trade-offs between material circularity, reducing harmful environmental emissions, and cost-effectiveness for the U.S. market. Life cycle assessment (LCA) is a critical step needed to compare these trade-offs and determine where future research and development should be focused. As a result, some previous LCA has been performed on recycling approaches. However, attempts to quantify and compare greenhouse gas emissions across a broad range of technologies have been limited, particularly within the U.S. market where landfill availability and costs do not hinder disposing of wind blades. This work addresses this limitation by presenting a detailed comparison of LCA greenhouse gas emissions and material yields from a range of wind turbine blade recycling approaches in the U.S. The LCA presented in this work includes baseline results, as well as a variety of sensitivity and scenario analyses that look at the impact of process modelling uncertainty, future energy mixes, and other critical input parameters. Overall, results show that mechanical recycling and microwave pyrolysis have the lowest net greenhouse gas emissions. However, the value of mechanically recycled materials is highly uncertain, as mechanical recycling generates a mixed feedstock that may underperform compared to virgin materials. Cement co-processing has higher net emissions than mechanical recycling or microwave pyrolysis but does generate a value-added feedstock that offsets virgin material from mining for cement production. Other advanced thermal and chemical recycling methods such as pyrolysis and solvolysis have higher net emissions due to increased energy consumption but are also highly sensitive to thermal energy sources within the model.

Life cycle assessment of a decoupled biofloc aquaponics facility across seasons

Aquaponics promises a more sustainable approach to food production by repurposing waste from aquaculture for the production of crop plants. Previous life cycle assessments have been published on the environmental impacts of coupled aquaponics using recirculating aquaculture systems, however, impacts from decoupled biofloc aquaponics systems remain unknown. Decoupled systems offer many operational advantages over coupled systems, and the objective of this study was to use life cycle assessment to quantify their environmental impacts. Data from a multi-greenhouse aquaponics system was collected over a one-year period to generate a life cycle inventory. A previously published mass balance model was also used to analyze alterative operational scenarios. Both avoided burden and mass allocation approaches were considered given the high sensitivity of the model toward the former. Results showed that electricity, heating fuel, and feed made up 40%, 22%, and 24% of global warming potential (GWP), similar to other aquaponics studies. These inputs similarly dominated cumulative energy demand. A switch to renewable electricity sources could reduce GWP by over 40% in scenario analysis. Eutrophication impacts of the decoupled biofloc aquaponics system ranged from 8.93 × 10−3 to 5.27 × 10−2 kg N-eq per kg fish depending on the scenario. While at least 10% lower than aquaculture alone, these rates were over four times higher than coupled aquaponics due to discharge of nutrient-containing waters after plant production. Efforts to balance fish and plant production are especially critical in decoupled systems, as is re-use of post-plant effluent. These results show that careful consideration of operational decisions is important when trying to minimize the environmental footprint of decoupled aquaponics systems.

Recycling of Tire Waste Using Pyrolysis: An Environmental Perspective

End-of-life tires are a common and hazardous type of waste. According to estimates, over 2 billion tires are produced each year, and all of these tires will eventually be discarded as waste. Landfilling waste tires is strictly prohibited by the regulations of the European Union and the Environmental Protection Agency; they should be retreated and reused in an alternative scenario. As a waste-to-energy technology, pyrolysis can emerge as a useful technique to thermally degrade waste tires and produce useful byproducts in the form of liquid, gas, and char. The derived products can be filtered and used in further industries as biofuel substances. Pyrolytic oil has a high calorific value of 35–45 MJ/kg and can be used as an alternative to diesel to fuel specific vehicles. However, the environmental footprint of the technology has been widely neglected when using waste tires as feedstock. Made from synthetic and natural rubbers, tires contain a high amount of sulfur and styrene, which can cause toxic emissions and negatively affect the environmental sustainability of pyrolysis. This concept paper aims to elaborate the parameters of an operating rotary kiln reactor by reviewing previous life cycle assessment studies and applying the methodology to an industrial-scale pyrolysis plant in Northern Cyprus. Results found a maximum production yield of 45.6% oil at an optimal temperature of 500 °C. Influential parameters such as temperature, residence time, and heating rate are reviewed based on their overall contribution to the production yield and the environment. The outcome of this paper emphasizes the need in the literature to apply environmental analyses to industrial and commercial-scale reactors to test the sustainability of using pyrolysis as a tire waste management strategy. In addition, complex engineering concepts and tasks in waste recycling will be discussed in a broad and accessible manner, with the implications and future work discussed.

Life cycle assessment of a large volume parenteral for hospital use

The growing demand for pharmaceutical products is increasing concern about their environmental impacts. Large Volume Parenteral (LVP) is used to administer intravenous solutions and drugs for treating patients, being one of the most globally used pharmaceutical products. There was not previous environmental life cycle assessment of LPVs and this article investigates the life cycle impacts of an LVP and identifies opportunities for improvement. A cradle-to-grave LCA was performed, addressing distribution distances, energy scenarios and alternative end-of-life for LVP with different approaches to consider avoided burdens. The results show that LVP packaging production presents the largest environmental impacts due to electricity and natural gas requirements. The use of renewable electricity and energy improvement in LVP manufacturing can significantly reduce impacts. Regarding end-of-life, credits from avoided burdens significantly reduces the impacts of LVP end-of-life. This article highlights the importance of assessing the entire life cycle of products used in hospitals.

Increasing the sustainability of photovoltaic technologies

Increasing the sustainability of photovoltaic technologies Building upon previous life cycle assessment of photovoltaic technologies, the sustainability of photovoltaic modules will be increased by improving the mechanical and optical properties of the glass and plastics (PET and EVA) used for the manufacture of the modules. The reduction of ion migration towards the active solar cell will extend the lifetime of the modules and facilitate their recyclability at the end of life.

Characterization factors for the impact of climate change on freshwater fish species

Human activities increasingly threaten the highly biodiverse freshwater ecosystems. Life Cycle Assessment (LCA) is a useful tool to quantify the impacts of products and services on freshwater biodiversity. Current methodologies in LCA address the impact of climate change on freshwater fish diversity by changes in average river discharge only. Given the ectothermic nature of fish, previous studies have highlighted the importance of including water temperature changes as a driver of species loss. Moreover, the impact of climate extremes might be more important than changes in average conditions. In this study, we derived new characterization factors for 207 individual greenhouse gas (GHG) emissions that quantify the impact of an emission change on freshwater fish, accounting for climate-driven changes in both streamflow and water temperature extremes. We combined a novel dataset of fish range climate threats with a newly developed species-area relationship to quantify global freshwater fish extinction risks at various global warming levels. The global characterization factors range from 0.00 to 4.56·10−10 Potentially Disappeared Fraction (PDF)·yr·kg−1. Our results imply that freshwater fish diversity impacts per kg of GHG emission have been underestimated in previous LCA methods that excluded the impact of water temperature and climate extremes, as the newly developed effect factor is higher by 172%. Future contributions should focus on increasing taxonomic coverage (e.g., by including lentic fish species and macro-invertebrates) and developing complementary models to reflect other aspects of biodiversity in LCA.

Life cycle assessment of bioethanol production from sugarcane bagasse using a gasification conversion Process: Bibliometric analysis, systematic literature review and a case study

• A coupling of LCA with process simulation was used for the environmental evaluation of bioethanol production. • A yield of 0.42 L bioethanol (97% pure) per kg of bagasse was obtained for producing 1,000 L/h. • A cradle-to-grave LCA scope quantified a GWP impact of ∼26.7 kg CO 2-eq/L. • Biofuel use in vehicles (70%) and biofuel production (25%) were major contributors for the GWP category. • A cradle-to-gate LCA scope quantified a lower GWP impact of ∼8.4 kg CO 2-eq/L. • For other CML impacts, biofuel production (ADP, MAETP, EP, ODP, and POP), and material extraction (LC, HTP, FAETP and TETP) were major contributors. A new integrated methodology to estimate environmental impacts of bioethanol production from sugarcane bagasse was developed for Mexico. The methodology included five modelling phases: (i) a bibliometric analysis and systematic literature review using peer-review journals, and world citation databases; (ii) a simulation of the gasification process to produce bioethanol; (iii) a life cycle inventory gathered from simulation, literature and Ecoinvent data sources; (iv) a life cycle assessment (LCA) of the bioethanol production stages (raw material extraction, transportation, sub-product extraction, biofuel production, biofuel use in vehicles, and refinery construction and decommissioning), the cumulative energy demand, and water footprint; and (v) the analysis of the major environmental burdens. After a comprehensive searching in Web of Science and Scopus, 55 articles dealing with the state-of-art of the main research subjects for the time period 2008 – 2021 were compiled. The bioethanol production was simulated by using the Aspen Plus v11 software, where a yield of 0.42 L bioethanol per kg of bagasse was estimated for a production of 1,000 L/h and a purity of 98.6%. In response to the limitations observed in previous environmental evaluations conducted for the bioethanol production, the present LCA work was carried out from a robust cradle-to-grave perspective to quantify the major environmental burdens, and the cumulative energy demand and water footprints. Biofuel use in vehicles (70%) and biofuel production (25%) stages present the highest contributions for the GWP impact category, which was totally quantified as ∼26.7 kg CO 2 -eq/L. When a cradle-to-gate perspective was modelled, this amount was significantly reduced (∼8.4 kg CO 2 -eq/L). For other impact categories evaluated, the highest contributions corresponded to the biofuel production (55% - 95% for ADP, MAETP, EP, ODP, and POP), and raw material extraction stages (70% - 100%: LC, HTP, FAETP and TETP). A comparison among previous LCA studies reported for gasification was discussed. This investigation constitutes the first study applied for bioenergy in Mexico from a successful coupling of LCA with process simulation as strategic tools for the evaluation of the environmental sustainability of bioethanol production.

Evaluation of environmental impact and GHG emission with energy system modeling combined with LCA in building sector: A review

Entering the 21st century, building energy consumption ranks first in total energy consumption, environmental pollution is increasing, and the construction sector has become the main energy source. The ability to reduce greenhouse gas emissions by replacing fossil fuels such as oil, gas and coal with fuels from renewable sources is a key factor in the development of net zero energy buildings. Therefore, it is important to analyze and organize previous and current research in this area to get an overview of the importance of built environmental assessment and net zero energy buildings. This review therefore summarizes the literature of previous life cycle assessment (LCA) and energy modeling studies conducted for environmental assessment of construction and construction-related industry sectors, considering construction products and entire building systems, buildings and civil structures. Bibliographic methods and scientometric analyzes have been adopted and proposed to tentatively explore research themes in this field. This observation indicates that BIM-LCA (Building Information Management Life Cycle Assessment) optimization is currently an important and inevitable research focus in the building-related energy field. Finally, there was a qualitative discussion on the achievement of key goals. We provided an up-to-date literature review on LCA construction, used energy system models to assess environmental impacts, and discussed key challenges in LCA construction, ongoing research, and possible solutions to solve the identified problems. The results also provide a comprehensive knowledge framework linking previous and current research areas with future research trends. The results provide researchers with an interdisciplinary focus on insights and solid engineering knowledge from the latest research on BIM-LCA.

Rethinking efficiency: Growth curves as a proxy for inputs and impacts in finishing beef systems

Quantifying and improving efficiency within beef systems is essential for economic and environmental sustainability. The industry standard for assessing efficiency is liveweight gain per day, however, this metric is limited in that it values each day of a growing animal's life as equally costly, despite the increasing maintenance requirements, inputs, and emissions associated with increasing liveweight. Quantifying the area under the growth curve (AUC) considers both time and liveweight as a cost and therefore may hold potential as a better estimate of cost, impact, and efficiency in beef systems. Liveweight data was taken from 439 finishing beef cattle split across three herds grazing on different pastures, known as ‘farmlets’. Analysis was conducted in three parts: [1] Validation of AUC as a proxy for costs using data from a sub-set of 87 animals that had been part of a previous life cycle assessment (LCA) study in which dry matter intake (DMI), methane emissions (CH4), and nitrous oxide emissions (N2O) were calculated. [2] Calculation of AUC relative to liveweight gain (LWG AUC−1) and comparison of that metric against the industry standard of liveweight gain per day (LWG day−1). [3] Assessment of how LWG AUC−1 varied with breed, sex, and management. When comparing to LCA results, AUC correlated significantly with DMI (r = 0.886), CH4 (r = 0.788) and N2O (r = 0.575) emissions. Over the full dataset, there was a negative non-linear relationship between LWG AUC−1 and slaughter age (r = −0.809). There was a significant difference in LWG AUC−1 between breeds (p = 0.046) and farmlets (p = 0.028), but not sex (p = 0.388). LWG AUC−1 has the potential to act as a proxy for feed intake and emissions. In that regard it is superior to LWG day−1, whilst requiring no additional data. Results highlighted the decreasing efficiency of beef cattle over time and the potential benefits of earlier slaughter. The use of LWG AUC−1 could allow farmers to improve their understanding of efficiency within their herds, aiding informed management decision making.

An overview of LCA applied to various membrane technologies: Progress, challenges, and harmonization

Life cycle assessment (LCA) has been developed to assess the possible environmental impact of a system over its life cycle. As LCA provides information on how to create a more sustainable infrastructure while also recognizing environmental hotspots, there is a growing interest in the sustainability of membrane treatment systems, especially for wastewater treatment (WWT). As a result, it is critical to revisit previous research to identify the challenges and accomplishments in implementing LCA for membrane systems. This paper provides a thorough review of 57 previous studies on the LCA of membrane systems for WWT. The collection of previous LCA studies was based on articles published between 2000 and 2020, where the progress, trends, challenges, and potential harmonization were explored using content analysis. Membrane bioreactor (MBR) and reverse osmosis (RO) membranes are the frequently studied systems concerning environmental impact. The review of articles was bound by the main frameworks of ISO norms and revealed differences in defining the functional unit, system boundaries, impact evaluation categories, and method of testing LCA, making comparisons difficult. The inconsistencies in defining the impact evaluation and methods used for certain papers, in addition to the lack of LCA studies in some geographical areas, are some of the difficulties addressed and illustrated in this paper. To ensure reliability and reproducibility, a more standardized implementation of LCA should be considered, allowing its adoption on new and existing membrane systems. • A total of 57 LCA studies on the LCA of membrane systems for WWT were reviewed. • Various aspects of LCA studies on membrane systems for WWT were evaluated. • Content analysis was used to explore the LCA studies of membrane systems for WWT. • The progress, trends, challenges and potential harmonization were discussed.

Carbon footprint of self-healing geopolymer concrete with variable mix model

Carbon footprint analysis of geopolymer concrete can be used to determine its advantages over conventional Portland cement concrete. However, the influence of allocation assumptions has been neglected in previous geopolymer life cycle assessment studies. This research gap is addressed here through an analysis of the effect of allocation scenarios in the assessment of self-healing geopolymer concrete made from coal fly ash and ground granulated blast furnace slag feedstocks. In addition, an empirical, variable-mix “gray box” model was integrated into the life cycle assessment to allow different blends that meet product property specifications to be considered. The cradle-to-gate life cycle assessment was done using OpenLCA and MS Excel, using inventory data from databases and literature. The allocation assumptions are found to significantly affect the results, with carbon footprints ranging from 208.72 kg eq. CO2 to 395.72 kg eq. CO2 per cubic meter of concrete. Using allocation based on economic value, the price of coal fly ash has a greater effect than that of ground granulated blast furnace slag. The implications of this result on the commercial use of geopolymer concrete are discussed, as well as the potential application of the “gray box” approach as a generic methodology in life cycle assessment.

Life Cycle Assessment of the Polyvinylidene Fluoride Polymer with Applications in Various Emerging Technologies

Polyvinylidene fluoride (PVDF) is one of the most popular fluoropolymers in the market. It is commonly used as pipes and cables, binder materials, and membrane materials. Lately, PVDF is being examined for applications in batteries, biomedical research, chemical engineering, and wastewater management. These PVDF applications cover most emerging technologies, which can be attributed to its outstanding physicochemical properties. With the global demand for PVDF in diverse technologies increasing significantly, it is imperative to quantify the environmental impacts associated with its production. Life cycle assessment (LCA) methodology is a standardized approach for evaluating the environmental impacts of novel materials. However, most previous LCA studies have not accounted for PVDF in a scientifically rigorous manner. While compiling the life cycle inventory (LCI) on PVDF, several kinds of surrogates were chosen to bridge the data gap, rather than establishing the new dataset for PVDF. When we investigate the similarities and differences between PVDF and popular surrogates regarding the synthesis pathways, adopting surrogates to replace PVDF becomes difficult. Due to the use of these surrogates, the global warming potential (GWP) calculated in the literature varies significantly, with a difference of 60.7 kg CO2 equiv between the highest and lowest estimates. After evaluating the life cycle environmental profiles of those commonly used surrogates, we find that the application of surrogates is hardly reliable; besides, the PVDF inventory dataset is underestimated. For this reason, we model the PVDF production process according to the commercialized synthesis approach and assess the cradle-to-gate impacts, which lowers uncertainty. The impact assessment on the PVDF inventory dataset results in an acceptable GWP value (55.8 kg CO2 equiv/kg PVDF), but a high cumulative energy demand (CED, 756 MJ equiv/kg PVDF), due to the large demand for chlorine during the production of vinylidene fluoride (VDF). In terms of uncertainty analysis, the upper and lower bounds for the newly developed LCI dataset for PVDF are 801 and 714 MJ equiv for CED values and 59.1 and 52.8 kg CO2 equiv for GWP values, respectively. Notably, this is the first study to develop a detailed LCI for PVDF involved in emerging technologies.

Maintenance and End-of-Life Analysis in LCA for Barge-Type Floating Wind Turbine

This paper is aimed at improving the maintenance and end-of-life steps in the associated Life Cycle Assessment (LCA) of barge-type floating wind turbines to reduce their environmental impact. Maintenance and end-of-life steps are given special attention since these phases have received only cursory focus in previous LCA studies. Different maintenance and end-of-life scenarios have been considered in the analysis. From the LCA results, it has been found that by applying on-site and onshore maintenance strategies, the lifetime of the turbine can be extended. Four alternative scenarios for the end-of-life step have been examined: mechanical recycling, mechanical-incineration, incineration processes, and landfill. The environmental impacts of these scenarios are evaluated using the LCA methodology. The investigation showed that the lowest environmental impacts correspond to the onshore maintenance and the mechanical recycling scenarios. These CO2 emissions of these scenarios are 13.68 g CO2 eq/kWh and 0.107 g CO2 eq/kWh, respectively.