Total Global Warming Potential Research Articles

Biochar mitigates the mineralization of allochthonous organic matter and global warming potential of saltmarshes by influencing functional bacteria

Saltmarshes are suffering from severe degradation due to anthropogenic activities, leading to the loss of blue carbon and greenhouse gas (GHG) emissions. Given the significant potential of biochar in mitigating climate change, adding biochar to saltmarshes would alleviate this situation. This study investigated the effects of different biochar (made from Spartina alterniflora, corn straw, and Laminaria japonica) and their aged biochar on the carbon fraction contents, GHG emissions, and microbial community structure of saltmarsh soils with allochthonous organic matter (Enteromorpha prolifera) addition. After 60 days of incubation, total organic carbon (TOC) loss and global warming potential (GWP) of biochar-amended soils were reduced by 67.29–124.33% and 4.91–123.24%, respectively (p < 0.05). Biochar reduced the proportion of labile carbon (dissolved organic carbon (DOC) and microbial biomass carbon (MBC)) in organic carbon by 61.92–86.15% (p < 0.05). In addition, biochar reduced the relative abundance of specific functional bacteria (inc. cellulolysis, aromatic compound degradation, and xylanolysis) involved in organic carbon decomposition by 20.02–37.82% (p < 0.05). These results suggest that even in the presence of high levels of liable organic matter, the application of biochar to saltmarshes has a sustained effect in promoting carbon accumulation and reducing GHG emissions, and this effect is regulated by a decrease of functional bacteria associated with carbon metabolism. Therefore, the in situ study of biochar on restoring carbon sink function of saltmarshes is proposed for practical engineering in future.Graphical

A comparative life cycle assessment of recycling waste concrete powder into CO2-Capture products

Waste concrete powder (WCP), a byproduct of construction and demolition (C&D), currently has a low degree of recycling despite its potential for environmentally friendly applications. WCP can serve as a valuable substitute for cement, offering advantages for resource conservation and carbon sequestration. However, there are very few studies that quantitatively assess the environmental impact of incorporating WCP into the circular economy as a secondary material instead of disposing of it. The energy-intensive processing of WCP raises questions about the optimal carbonation time using available equipment. This study aims to fill this knowledge gap by employing carbon footprint and life cycle assessments (LCA) to optimize WCP recycling. Three recycling WCP scenarios are analyzed. The first scenario involved the conversion of WCP into compacts that absorb CO2 during the carbonation process. The results of the first scenario revealed that the optimal carbonation time for WCP compacts was 8 h, during which 42.7 kg CO2-e per tonne of WCP compacts was sequestered. The total global warming potential (GWP) was −4.22 kgCO2-e, indicating a carbon-negative recycling process. In the second and third scenarios, LCA was conducted to compare the use of carbonated and uncarbonated WCP as a partial replacement for cement in concrete. In these scenarios, it was found that uncarbonated WCP is a more effective solution for reducing the carbon footprint of traditional concrete mixes, achieving a significant 16% reduction of GWP when 20% of cement is replaced. Conversely, using carbonated WCP as a partial cement replacement in concrete mixtures shows limited potential for CO2 uptake. The sensitivity analysis reveals that the carbon footprint of the WCP compacts production process is strongly influenced by the electricity supplier used.

The external/internal sources and sinks of greenhouse gases (CO2, CH4, N2O) in the Pearl River Estuary and adjacent coastal waters in summer

Estuary acts as a hotspot of greenhouse gases (GHGs, including CO2, CH4 and N2O) to the atmosphere. However, the GHGs budgets, including input/output fluxes through interfaces and biogeochemical source/sink processes in water columns, of the estuarine systems are still not well constrained due to the lacking of comprehensive observational data. Here, we presented the spatial distributions of GHGs of surface/bottom water and sediment porewater along the Pearl River Estuary (PRE) and adjacent region during summertime. The incorporation of the monitoring for the sediment-water interface (SWI) with these of the water-air interface (WAI) allows us to close the budget revealing additional information of internal consumption/production processes of the three GHGs. The oversaturated CO2 (481–7573 μatm), CH4 (289–16,990 %) and N2O (108–649 %) in surface water suggested PRE is a significant GHGs source to the atmosphere, in which CO2 is the major contributor accounting for 90 % of total global warming potential (GWP), leaving 2.8 % from CH4, and 7.2 % from N2O. Addition to the river input, the SWI releases GHGs to the overlying water with fluxes of 3.5 × 107, 10.8 × 104 and 0.7 × 104 mol d−1 for CO2, CH4 and N2O, respectively. Although all three GHGs exhibited emission to the atmosphere, our mass balance calculation showed that 16.9× 107 mol d−1 of CO2 and 1.0 × 104 mol d−1 of N2O were consumed, respectively, inside the estuary water body, while extra-production (13.8 × 104 mol d−1) of CH4 was demanded in the water body to support its output flux. This is the first experiment quantitatively assessing the importance of internal carbon and nitrogen biogeochemical processes in the PRE. Our finding is of guiding significance to constrain the GHGs budget and draw up realistic pathways for modeling works of GHGs prediction.

On a new environment-friendly gas mixture for Resistive Plate Chambers

The standard gas mixture for the Resistive Plate Chambers (RPC), composed of C2H2F4/i-C4H10/SF6, allows the detector operation in avalanche mode, as required by the high-luminosity collider experiments. The gas density, the low total charge delivered inside the gas and the comfortable avalanche-streamer separation guarantee high detection efficiency, rate capability and slow detector aging. The standard RPC gas mixture is mostly based on Hydrofluorocarbons, HFCs, extensively used in the refrigeration industry. The Hydrofluorocarbons are now considered to be non-eco-friendly gases for their high Global Warming Potential (GWP). The SF6 has the largest GWP, 22900, but, due to its low concentration, it contributes only with few tens of units to the total value. The major contribution comes from the main standard gas mixture component, the C2H2F4 (GWP ≈ 1300). These gases are not recommended for industrial uses anymore, thus their availability will be increasingly difficult over time and the search for an alternative gas mixture with low-GWP is then of absolute priority within the RPC community. We report the performance of the RPC working with new environment-friendly gases which could replace the standard mixture. In this work the standard mixture main component, the C2H2F4, is replaced by a proper mixture of CO2 (GWP = 1) and Tetrafluoropropene (C3H2F4, GWP≈6). The other high-GWP component, the SF6, is replaced by a molecule, the Chloro-Trifluoropropene (C3H2ClF3, GWP ≈ 5) never tested in RPC detectors. The mixtures studied have a total GWP ≈ 10. We report, for several eco-gas mixtures, the detection efficiency, streamer probability, electronic and ionic charge as a function of the high voltage. Moreover, the timing properties are studied and the detector time resolution is measured. We also focus the attention on a new category of signals having intermediate properties between avalanche and streamer, called ”transition events”. This category is negligible for the standard gas mixture but relevant for HFO/CO2-based gas mixtures. We show a direct comparison between SF6 and C3H2ClF3 to study in depth the possibility to replace the SF6.

Costs, carbon footprint, and environmental impacts of lithium-ion batteries – From cathode active material synthesis to cell manufacturing and recycling

Strong growth in lithium-ion battery (LIB) demand requires a robust understanding of both costs and environmental impacts across the value-chain. Recent announcements of LIB manufacturers to venture into cathode active material (CAM) synthesis and recycling expands the process segments under their influence. However, little research has yet provided combined costs and environmental impact assessments across several segments of the LIB value-chain. To address this gap, we provide a combined cost assessment and life cycle assessment (LCA), covering CAM synthesis, cell manufacturing and hydrometallurgy recycling. 1 kWh cell capacity (NMC811-C) is chosen as functional unit. Results for cell manufacturing in the United States show total cell costs of $94.5 kWh−1, a global warming potential (GWP) of 64.5 kgCO2eq kWh−1, and combined environmental impacts (normalizing and weighing 16 impact categories) of 4.0 × 10−12 kWh−1. Material use contributes 69% to costs and 93% to combined environmental impacts. Energy demand, meanwhile, accounts for 35% of GWP. Initially, hydrometallurgy recycling adds 5 to 10% to total costs, GWP, and environmental impacts. Including recycling credits, as recycled material substitutes new virgin material, shows benefits for recycling. Combined environmental impacts benefit most from recycling (−75%), followed by costs (−44%) and GWP (−37%). Further, we present a comprehensive dashboard which reveals how different scenarios, such as, using wind power instead of grid electricity, influence costs, GWP, and environmental impacts across process segments. Switching to low-carbon energy, for example, reduces GWP more than recycling would. Also, our dashboard shows that recycling or low scrap are more suitable options if reduction of costs or combined environmental impacts is the objective.

High-efficiency utilization of biomass and seawater resources based on a distributed system with SOFC-assisted CO2 capture: Feasibility analysis and optimization

This paper develops a distributed system with SOFC-assisted carbon capture (SACC) by integrating the Rankine cycle, double-effect absorption chiller and multi-effect distillation unit to produce electricity, cooling and freshwater. To study the feasibility of the developed system, thermodynamic, economic and carbon footprint analyses and optimization are conducted on six different cases for the system. The results reveal that regardless of the biomass sources used as fuel, the developed SACC system requires 5%-9% less power consumption for CO2 capture compared to traditional methods. Moreover, the system fueled by switch grass exhibits superior efficiencies, and the system thermal efficiency (ηth) with SACC achieves 56.35% with corresponding levelized cost of products (cp) and total global warming potential (GWPt) of 54.94 $/GJ and −0.129 kg/kWh. Exergy analysis demonstrates that the prime mover unit (PMU) deserves the greatest irreversibility for all cases with a relative exergy destruction rate (y*k) of over 65% of the whole system. Within the PMU, the gasifier and SOFC are responsible for the highest irreversibility, and the y*k of the gasifier is over 50% and the SOFC’s is close to 9%. The parameter study indicates that an increase in the gasification temperature is unfavorable to ηth, however, it is conducive to the improvement of net power output (Wnet) when the temperature exceeds a certain value (e.g., 914.3℃ and 885.7℃ for Case-5 and Case-6). An appropriate increase in current density improves ηth and Wnet, and reduces cp, albeit slightly detrimental to environment. The optimization results demonstrate that Case-2 and Case-6 have superior thermodynamics and economics but are detrimental to the environment. In contrast, Case-1 and Case-5 are the most environmentally friendly, but their economics and thermodynamics are degraded to some extent.

The combined effects of nitrogen fertilizer and biochar on soil aggregation, N2O emission, and yield from a vegetable field in southeastern China.

Biochar amendment is a recently promoted agricultural management strategy that can exert distinct impacts on reducing greenhouse gas (GHG) emissions and improving soil fertility and crop productivity. This study aims to evaluate the combined effects of biochar and nitrogen (N) fertilizer on soil aggregation, nitrous oxide (N2O) emission, global warming potential (GWP), vegetable yield, and greenhouse gas intensity (GHGI). The experiments were conducted in a vegetable field with two consecutive vegetable crops in 2019 and 2020 in southeastern China. There were four treatments: control (CK), conventional N fertilizer (U), biochar applied at 15 t ha-1 with N fertilizer (UB1), and biochar applied at 30 t ha-1 with N fertilizer (UB2). The results indicate that while N application significantly increased N2O emission of the vegetable field, both UB1 and UB2 led to significant reductions of the total N2O emission, GWP, and yield-scaled GHGI as well as significant growth of the total vegetable crop yield compared with U. However, no significant differences have been found in N2O emission, GWP, crop yield, and yield-scaled GHGI between UB1 and UB2. Meanwhile, biochar application in addition to N fertilizer did not result in any significant change in the soil water-stable aggregate size distribution and stability compared with U. Soil water-stable aggregates smaller than 0.25 mm and those larger than 5 mm have been found to significantly impact N2O emission and vegetable yield.

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.

Evaluating carbon payback time by optimizing insulation materials for different orientations: A cradle-to-gate life cycle assessment

The European Union aims to reduce greenhouse gases emissions by 80–95% compared to 1990 levels by 2050. Therefore the life cycle concept has gained widespread acceptance as a model for evaluating the environmental impact of goods and services. In this study, the optimal thickness of various insulation materials for external walls, roofs, and floors using a Mediterranean climate zone's hot summers and mild winters for a hypothetical residential building for four cardinal orientations was determined. The criteria for determining the optimum thickness represent a turning point in terms of cooling energy consumption (electricity). The optimum thickness of nine different types of insulation materials was defined using the aforementioned approach. These materials included aerogel, polyisocyanurate, polyurethane, extruded polystyrene, expanded polystyrene, phenolic foam, cellulose fiber (cellulose), mineral wool, and glass wool (GW). The purpose of this paper is to calculate the carbon payback time (CPBT) using the cradle-to-gate life cycle assessment method by considering the global warming potential (GWP) of insulation materials at their optimum thickness. The CPBT is calculated as the ratio of the total building's GWP to the GWP of savings from cooling and heating (electricity and natural gas). The results indicated that when evaluating the average CPBT for four cardinal orientations (FCO), aerogel has the longest CPBT of 2.34 years, and GW has the shortest CPBT of just 0.09 years. Aside from cost payback time, the findings of this study provide a new perspective on selecting appropriate thermal insulation.

Sulfur-aided aerobic biostabilization of swine manure and sawdust mixture: Humification and carbon loss

To investigate how sulfur addition affects humification and carbon loss during swine manure (SM) biostabilisation, various proportions of sulfur, i.e., 0 (CK), 0.2%-0.8% (S1-S4) were added to SM in a 70-day pilot-scale test. Compared to CK (16.07%), sulfur addition resulted in the mineralization of 17.05%-24.27% of the total organic carbon. Sulfur addition also reduced CH4 emissions, which were 3.7%-29.3% lower than that of CK. The total global warming potential values were in the range of 913.1–968.2 g CO2 eq kg−1 for all treatments. Although the sulfur-added treatments showed lower HA/FA ratios than CK after 70 days, no significant impact on the maturity of the final products was observed. Sulfur addition impacted the microbial community, CH4, CO2, N2O emissions, and affected the variation of temperature in biowaste biostabilization. These discoveries provided an important basis for understanding the function of sulfur in regulating the aerobic bio-decomposition of organic waste.

Poster 147: Identifying Opportunities to Improve the Environmental Sustainability of ACL Reconstruction: A Life Cycle Analysis

Objectives: Environmental sustainability is a topic of increasing recognition within the field of orthopaedic surgery. To decrease the carbon footprint of orthopaedic procedures, the baseline carbon footprint of said procedures must be calculated. Life cycle assessment (LCA) is the most rigorous means of establishing the overall carbon footprint of a system and also identifies the carbon contribution of each step of the process. The latter allows for a targeted carbon reduction approach to address the steps with the greatest potential impact. Methods: An LCA was employed to analyze the environmental impacts of an anterior cruciate ligament reconstruction (ACL-R). The environmental impacts were estimated using TRACI 2.1 (Tool for Reduction and Assessment of Chemicals and Other Environmental Impacts), which was developed by the Environmental Protection Agency. The system boundary of this study included production of single-use items, production of reusable items, waste management, and energy consumed in an operating room (OR) (e.g., monitors, lighting fixtures). Required data regarding type and quantity of materials utilized in an ACL-R were collected via material audit. The material audit encompassed measuring and documenting the mass of surgical items and instruments, as well as identifying material composition of different items. During the audit, surgical materials or instruments were disassembled to measure mass of specific materials. To measure the impacts of different gases produced, such as carbon dioxide (CO2) and methane, values were converted to the Global Warming Potential (GWP), a metric that indicates how different gases warm the earth relative to carbon dioxide (CO2) equivalents. Results: The preliminary results, which represented the impacts from manufacturing single-use materials, showed that plastics followed by cotton were the major contributors of ACL-R to global warming by being responsible for 47% and 44% of the total GWP, respectively. Initial results also showed that plastics (64%) and cotton (32%) had the highest ozone depletion potential compared to other materials. Among the six types of plastics that were identified in the single-use items, polyvinyl chloride (PVC) most contributed to depleting the ozone layer. PVC was most commonly found in suction tubing. Of the single-use materials, OR towels were the predominant source of cotton. Finally, the cumulative energy demand of producing materials for one ACL-R was 598 MJ, which was dominated by production of plastics-based materials (374 MJ). Conclusions: These findings help identify areas of improvement for the environmental sustainability of ACL-R using LCA. The initial total GWP from production of single-use materials was estimated as 24 kgCO2eq, which is similar to the CO2 emissions from driving a car for 60 miles. Of the single-use surgical items utilized, suction tubing and OR towels demonstrated a significant environmental impact due to their composition of PVC and cotton, respectively. Thus, strategies to minimize the use of these items will improve the environmental sustainability of ACL-R. Limitations of this study include the limited generalizability of these findings to other ACL-R surgeries using dissimilar materials, potential for error while weighing and determining the composition of surgical materials, and the focused evaluation of just single-use items for these preliminary results. To better identify opportunities to improve the environmental sustainability of ACL-R, further analysis of this data will aim to determine the additional impact of electricity usage, reusable surgical items, and anesthetic gases. The environmental impact from the production of single-use surgical materials for ACL-R was similar to the CO2 emissions from driving a car for 60 miles. Judicious usage of suction tubing and OR towels are opportunities for surgeons to improve the environmental sustainability of ACL-R.

Planting and mowing cover crops as livestock feed to synergistically optimize soil properties, economic profit, and environmental burden on pear orchards in the Yangtze River Basin.

Pears, as an important cash crop, are currently facing great issues due to unsustainable management practices. Cover cropping is a sustainable management strategy that can improve soil fertility and increase fruit yield, while it may also stimulate greenhouse gas emissions. Therefore, synergizing multiple indicators to achieve sustainable development is critical. This study introduces a new management system, namely the planting and mowing of ryegrass as a livestock feed system (PRSS), and analyzes its impact on soil quality, economic benefits, and environmental burdens. Our results indicated that PRSS could increase soil pH from 5.08 to 5.48 and decrease the content of soil alkali-hydrolyzable nitrogen, total phosphate, and available phosphate (26.96-59.89%) while also enhancing yield (+38.51%) compared with the traditional natural grass management system (TMS). The average soil methane fluxes in PRSS were 72.67 μg m-2 day-1 , higher than those of TMS (61.28 μg m-2 day-1 ). However, the gross primary production was lower than TMS (-37.24%), and no significant difference was observed in soil nitrous oxide fluxes. In different scenarios, the total profit of PRSS mode 1 (mowing ryegrass and selling to a livestock company) and PRSS mode 2 (mowing ryegrass and feeding own sheep) were 10 706.21 $ ha-1 and 26 592.87 $ ha-1 respectively. These values are respectively2.36 times and 5.85 times higher than that of TMS. The total global warming potential of TMS (18.19 t CO2 -eq ha-1 ) was 1.29 t CO2 -eq ha-1 higher and 2.89 t CO2 -eq ha-1 lower than that of PRSS mode 1 and mode 2 respectively. Compared with traditional natural grass, planting and mowing ryegrass in pear orchards can optimize soil properties, increase fruit yield, and reduce global warming potential. Different modes can greatly increase revenue but have varying impacts on environmental burdens. These findings can help rebuild the links between farmland and specialized livestock production, contributing to sustainable development in the pear industries. © 2023 Society of Chemical Industry.

Optimizing the Incorporated Amount of Chinese Milk Vetch (Astragalus sinicus L.) to Improve Rice Productivity without Increasing CH4 and N2O Emissions

Chinese milk vetch (CMV) is a leguminous green manure that is commonly cultivated in paddy fields and can partially substitute synthetic nitrogen fertilizer. However, the impacts of incorporating CMV on CH4 and N2O emissions are still a subject of controversy. Therefore, we conducted a field experiment over three years to investigate emissions under different substitution ratios: urea only (CF); incorporating a traditional amount of CMV (MV); and with incorporation ratios of 1/3 (MV1/3), 2/3 (MV2/3), and 4/3 (MV4/3) of MV for partial urea substitution. Compared with CF, MV2/3, MV, and MV 4/3 resulted in increased yields. MV and MV4/3 reduced N2O emissions but increased CH4 emissions by 28.61% and 85.60% (2019), 32.38% and 103.19% (2020), and 28.86% and 102.98% (2021), respectively, resulting in an overall increase in total global warming potential (except for MV in 2021). MV2/3 exhibited a low greenhouse gas intensity value ranging from 0.46 to 0.47. Partial least-squares-path model results showed that CH4 and N2O emissions were influenced by substitution ratios, which indirectly regulated the gene abundances of mcrA and nosZ. Overall, the impact of CMV on CH4 and N2O emissions was determined by substitution ratios. MV2/3, which involved partial substitution of synthetic N fertilizer with 15.0 t ha−1 of CMV, resulted in improved rice productivity without increasing CH4 and N2O emissions, making it a recommended approach in the study area.

Assessing the economic and ecological viability of generating electricity from oil derived from pyrolysis of plastic waste in China

The increased plastic waste generation worldwide poses ponderous issues for public health and the environment. China is the highest generator of plastic waste around the world. The current treatment process (incineration) of the increased plastic waste causes dangerous environmental consequences. Pyrolysis has recently surfaced as an ecologically friendly technique for energy and material recovery from plastic waste. The present study assesses the financial and ecological viability of power production from oil derived from the pyrolysis of mixed plastic wastes in China from 2009 to 2028. The prominent findings show that the amount of plastic waste collected in 2020 (24.16 Mt) increased by 53.19% in 2028.The pyrolysis of mixed plastic wastes during the project period yielded 359.29 Mt oil, which has a power potential of 1,060.86 GWh. The economic analysis indicated the project is viable and profitable with a positive net present value (US$8.80 million) and profitability index (1.26) greater than 1. The project has 10.6 y payback period, US$0.0752/kWh levelized cost of energy, 22.5% return on investment, and 13.0% internal rate of return. The life cycle assessment results show that conversion of mixed plastic waste to pyrolysis oil for electricity generation during the project period has a total global warming potential (GWP) of 1,311.4 kt CO2eq. The GWP is mainly from conversion of pyrolysis oil to electricity (73.42%), pyrolysis oil production (15.01%) and upgrading of pyrolysis oil (11.38%). The consumption of power from the project could avoid the combustion of 2,659.0 t coal, minimizing global warming by 11,278.8 kt CO2eq. Sensitivity analysis, which examines the influence of variation in sensitive factors on the success of the project, is presented. This paper provides scientific strategies for optimal investment and decision-making on the environmental sustainability of plastic waste-to-energy pyrolysis projects.

Effects of tillage method on the carbon footprint, energy budget, and net ecosystem economic efficiency of rice fields

Biaxial rotary tillage is considered an effective approach for enhancing the structure of soil in rice fields. There are few reports on the effects of biaxial rotary tillage on the carbon footprint (CF), energy budget, and net ecosystem economic efficiency (NEEB) of rice fields. Here, we evaluated the effects of dryland biaxial rotary tillage (DBRT), as well as two traditional tillage methods, dryland and paddy field in uniaxial rotary tillage (DPURT) and paddy field in uniaxial rotary tillage (PURT), on the CF, energy budget, and NEEB of rice production to clarify the economic and ecological utility of DBRT. The tillage depth was 9.5–15.4% higher under DBRT than under DPURT and PURT (p &amp;lt; 0.05). The soil bulk density was 5.4–12.1% lower under DBRT than under DPURT and PURT. The rice grain yield was 7.6–8.7% and 17.7–19.1% higher under DBRT than under DPURT and PURT, respectively (p &amp;lt; 0.05). The total global warming potential was 7.6–10.6% and 17.0–20.4% lower under DBRT than under DPURT and PURT, respectively (p &amp;lt; 0.05). The CF was 17.7–18.9% and 35.4–36.1% lower under DBRT than under DPURT and PURT, respectively. The energy use efficiency was 8.7–10.4% and 16.4–18.3% higher under DBRT than under DPURT and PURT, respectively. The NEEB were 13.2–15.7% and 28.6–32.1% higher under DBRT than under DPURT and PURT, respectively. In summary, DBRT is beneficial for increasing rice yield and reducing greenhouse gas emissions, thereby improving the economic and ecological benefits of rice.

Bridging the gap between mathematical optimization and structural engineering: Design, experiments and numerical simulation of optimized concrete girders

AbstractConcrete, as the most widely used construction material, is associated with a high environmental impact. Within the present study, structural optimization is the method of choice to counter this issue. The entire process, from optimization, to design, experiments and numerical simulation is outlined. Embedded in the framework of a design competition (Concrete Girder Optimization Competition 2021), a bridge between structural engineering and mathematical optimization is demonstrated. Two design concepts for optimized concrete girders, one with internal and one with external reinforcement, yet both based on strut‐and‐tie modeling, were investigated. Within the boundaries of the competition, several conclusions can be drawn: The results indicate the importance of an adequate structural interpretation of topology optimization results to obtain satisfying structural performance. The environmental evaluation outlines that the reinforcement mass has a substantial share in the total Global Warming Potential. A successful numerical re‐simulation of selected girders can serve as a modeling base for other researchers. Compared to a conventionally designed girder an increase in resource efficiency, measured by load‐carrying capacity versus environmental impact, of more than 30% was achieved.

Evaluation of environmental impacts in PVC sector: the case of Turkey

ABSTRACT This study aims to evaluate the environmental impacts of PVC and provide recommendations to the industry to increase sustainability. The analysis first takes into account the effects at the product level, then moves on to the national level. According to the findings, total global warming potential (GWP) is estimated at 3 kg CO2 eq./kg PVC. The raw material supply stage is the most significant hotspot for all environmental impacts. The emissions and energy consumption associated with the production of PVC have been significantly reduced by increasing the recycling rate. The total annual GWP of the PVC profile sector in Turkey is estimated at around 1294 kt CO2 eq., which corresponds to nearly 0.3% of the country’s total greenhouse gas emissions. Policymakers, construction companies, PVC manufacturers, and users will be interested in the findings of this paper, which will allow them to make more informed decisions about the plastic industry.

Multiyear methane and nitrous oxide emissions in different irrigation management under long-term continuous rice rotation in Arkansas.

Rice paddies are one of the major sources of anthropogenic methane (CH4 ) emissions. The alternate wetting and drying (AWD) irrigation management has been shown to reduce CH4 emissions and total global warming potential (GWP) (CH4 and nitrous oxide [N2 O]). However, there is limited information about utilizing AWD management to reduce greenhouse gas (GHG) emissions from commercial-scale continuous rice fields. This study was conducted for five consecutive growing seasons (2015-2019) on a pair of adjacent fields in a commercial farm in Arkansas under long-term continuous rice rotation irrigated with either continuously flooded (CF) or AWD conditions. The cumulative CH4 emissions in the growing season across the two fields and 5 years ranged from 41 to 123kg CH4 -C ha-1 for CF and 1 to 73kg CH4 -C ha-1 for AWD. On average, AWD reduced CH4 emissions by 73% relative to CH4 emissions in CF fields. Compared to N2 O emissions, CH4 emissions dominated the GWP with an average contribution of 91% in both irrigation treatments. There was no significant variation in grain yield (7.3-11.9 Mg ha-1 ) or growing season N2 O emissions (-0.02 to 0.51kg N2 O-N ha-1 ) between the irrigation treatments. The yield-scaled GWP was 368 and 173kg CO2 eq. Mg-1 season-1 for CF and AWD, respectively, showing the feasibility of AWD on a commercial farm to reduce the total GHG emissions while sustaining grain yield. Seasonal variations of GHG emissions observed within fields showed total GHG emissions were predominantly influenced by weather (precipitation) and crop and irrigation management. The influence of air temperature and floodwater heights on GHG emissions had high degree of variability among years and fields. These findings demonstrate that the use of multiyear GHG emission datasets could better capture variability of GHG emissions associated with rice production and could improve field verification of GHG emission models and scaling factors for commercial rice farms.

Potential global warming impact of 1 kW polymer electrolyte membrane fuel cell system for residential buildings on operation phase

This study established global warming potential(GWP) emission factors through a life cycle assessment on the operation phases of two different 1 kW polymer electrolyte membrane fuel cell (PEMFC) systems for residential buildings (NG-PEMFC, fed with hydrogen from natural gas reforming; WE-PEMFC, fed with hydrogen from photovoltaics-powered water electrolyzer). Their effectiveness was also compared with conventional power grid systems in Korea, specifically in the area of greenhouse gas emissions.The operation phases of the NG-PEMFC and the WE-PEMFC were divided into burner, reformer, and stack, and into water electrolysis and stack, respectively. The functional unit of each fuel cell system was defined as 1 kWh of electricity production. In the case of NG-PEMFC, the GWP was 3.72E-01 kg-CO2eq/kWh, the embodied carbon emissions due to using city gas during the life cycle process was about 20.87 %, the carbon emission ratio according to the reformer's combustion burner was 6.07 %, and the direct carbon emission ratio of the air emissions from the reformer was 73.06 %, indicating that the carbon emission from the reformer contributed over 80 % of the total GWP. As for the WE-PEMFC, the GWP was 1.76E-01 kg-CO2eq/kWh, and the embodied carbon emissions from photovoltaic power generation during the life cycle process contributed over 99 % of the total GWP.

Environmental impacts of a standalone solar water splitting system for sustainable hydrogen production: A life cycle assessment

Hydrogen is broadly utilized in various industries. It can also be considered as a future clean energy carrier. Currently, hydrogen is mainly produced from typical fuels such as coal; however, there exist some other clean alternatives which use water decomposition techniques. Water splitting via the copper-chlorine (Cu–Cl) thermochemical cycle is a superb option for producing clean carbon-free fuel. Here, the life cycle assessment (LCA) technique is used to investigate the environmental consequences of an integrated solar Cu–Cl fuel production facility for large-scale hydrogen production. The impact of varying important input parameters including irradiation level, plant lifetime, and solar-to-hydrogen efficiency on various environmental impacts are investigated next. For instance, an improve in the solar-to-hydrogen efficiency from 15% to 30%, results in a reduction in the GWP from 1.25 to 6.27E-01 kg CO2 eq. An uncertainty analysis using Monte Carlo simulation is conducted to deal with the study uncertainties. The results of the LCA show that the potential of acidification and global warming potential (GWP) of the current system are 8.27E-03 kg SO2 eq. and 0.91 kg CO2 eq./kg H2, respectively. According to the sensitivity analysis, the plant lifetime has the highest effect on the total GWP of the plant with a range of 0.63–1.88 kg of CO2 eq./kg H2. Results comparison with past thermochemical-based studies shows that the GWP of the current integrated system is 7% smaller than that of a solar sulfur-iodine thermochemical cycle.