Reduction In Global Warming Potential Research Articles

American Chemistry Council issues reports on plastics and reacts to proposed EPA plastics-rules

On December 7, 2023, the American Chemistry Council issued a new report, spanning data from 2005 to 2017, showing a decline in greenhouse gas emissions (GHGs) and energy consumption during the production of plastic resins. The plastics manufacturing industry reportedly showed a significant reduction in global warming potential even though consumers and businesses demanded the material for cars and trucks, new homes, packaged goods, and other products that rely on plastics. The new report, “A Decreasing Footprint: A Review of Resin Life Cycle Assessments,” the second in a series of three of life cycle assessment reviews, looks at trio of thermoplastics (HIPS, GPPS and ABS) commonly used in automotive, construction, protective packaging and household items.

Selective thermal recycling for graphene growth on natural substrates: A comparative study on life cycle assessment, energy consumption, and mechanical performance in recompounding

AbstractManufacturing of carbon‐based materials from waste thermoplastics is a keystone to reduce adverse environmental impacts. There are numerous attempts for sustainable graphene manufacturing from various waste sources by thermal treatment but there is no clear distinction on the effective conversion process by addressing reliable CO2 footprints. This study provides a comprehensive benchmarking study on the conversion of waste polypropylene plastics coming from yogurt containers into graphene on the substrate of talc by applying two upcycling techniques of catalytic carbonization (CC) and flash pyrolysis (FP) by comparing energy and speed of the processes and a dimensional stability and physical characteristics of the produced graphene substances by adopting a comparative life cycle assessment. FP led to the sphericalization of graphenes due to fast dehydration, cross‐linking, and carbonization of aromatic structures. On the other hand, gradual heating in CC caused the formation of tubular‐like graphene structures. In addition, FP became advantageous by resulting in 52% of CO2 emission compared with CC process. On the other hand, graphenes separated from talcs exhibited a remarkable 70% reduction in global warming potential compared with conventional graphene production from graphite. In order to complete the value chain and circularity, the mechanical performance of two different hybrid additives produced by selective thermal recycling in recompounding with copolymer polypropylene was examined, and additives from CC enhanced the flexural and tensile properties two times better than the one from FP. With this study, it becomes possible to compare analysis of graphene growth on natural substrates by exploring life cycle assessment, energy consumption, and mechanical performance with selective thermal recycling and recompounding.

Evaluating the Circular Economy Potential of Modular Construction in Developing Economies—A Life Cycle Assessment

Circular economy (CE) is an emergent concept that promotes resource circularity in multiple product systems. Modular construction (MC), an evolving construction technique, which includes an off-site manufacturing environment, increasingly supports CE strategies such as reuse due to the elevated potential for design for disassembly (DfD). Design-stage environmental assessments are paramount in aiding the early decision making of modular construction projects to successfully plan and implement DfD strategies. Research on synergising modular construction, circular economy and environmental sustainability is rare in developing economies. Thus, the current study aims to conduct a design-stage life cycle assessment of a DfD and linear versions of a modular building unit in Sri Lanka to evaluate the potential environmental benefits. The life cycle assessment results highlight that the DfD strategy has the lowest environmental impacts in all categories, with a 63% reduction in global warming potential and an approximately 90% reduction in terms of human toxicity compared to the linear version. Further, it showed the elevated potential of reuse compared to recycling practices in improving the environmental performance. Sensitivity assessment revealed that steel was the most sensitive to the change in reuse percentage among main building materials. The analysis outcomes highlight the importance of long-term thinking, architectural design creativity and industrial and technology development to uptake the CE-driven MC in the Sri Lankan context. Finally, strategies are proposed to support the CE approach in MC in developing regions. Both quantitative and qualitative outcomes provide a basis for construction industry stakeholders, academia, and policy makers to explore further and promote modular construction practices to enhance the circularity of building materials and components in developing regions.

A Study on the Potential of Carbon Dioxide Utilization Through its Co‐Injection with Hydrogen into the Blast Furnace Tuyeres

The potential of CO2 utilization through its injection into blast furnace (BF) tuyeres is studied using the 1D steady‐state zonal model. Scenarios with the injection of CO2, hydrogen, and their co‐injection at various H2/CO2 mass ratios are analyzed. The impacts on factors affecting vertical temperature patterns and the position of the cohesive zone in the BF are identified. A life cycle assessment for several scenarios with various carbon emissions intensities of hydrogen production, carbon capture, and grid electricity generation is performed. Injection of CO2 without the addition of hydrogen increases the coke rate, reduces productivity, and increases direct CO2 emissions; however, thanks to producing top gas with higher calorific value, injection of CO2 may reduce the global warming potential (GWP) if the electric grid carbon intensity is above 654 kg‐CO2 kWh−1, while carbon capture is powered by green electricity. Although the injection of hydrogen alone would result in a more substantial reduction of GWP from the baseline than the injection of H2/CO2 mix at any mass ratio, considering the identified impacts on heat exchange and the position of the cohesive zone in the BF, co‐injection might be an enabling solution for the adoption of hydrogen injection.

Influences of Management Practices and Methodological Choices on Life Cycle Assessment Results of Composting Mixtures of Biowaste and Green Cuts

This paper presents an analysis that aimed to quantify the consequences of modelling choices in the life cycle assessment of composting by investigating the influence of composting management practices and the influence of the selected marginal product for substitution. In order to investigate the different influencing factors, a set of 11 scenarios were defined. The scenario results revealed that increasing the turning frequency of the input material leads to a Global warming potential (GWP) reduction of approx. 50%. However, there is a trade-off between GWP reduction and increases in other environmental impacts, including acidification potential (AP), ozone formation potential (OFP), and stratospheric ozone depletion potential (ODP). GWP and AP can also be reduced by optimal exhaust gas filter maintenance, although this causes OFP and ODP to increase. The most relevant factor for GWP is the choice of substituted products. When peat for horticulture can be replaced, GWP can be substantially lowered while hardly affecting other environmental impacts.

Life cycle assessment and thermophysical properties of a fly ash-based geopolymer containing drinking water treatment sludge.

Fly ash-based geopolymers have emerged as a sustainable alternative in construction, leveraging industrial by-products to mitigate CO2 emissions. This study investigates the novel incorporation of drinking water treatment sludge (DWTS) into fly ash-based geopolymers at varying proportions (5-40%). Authors focus is to analyze the thermophysical properties and environmental implications, including a robust life cycle assessment case study conducted within the Moroccan context. The comprehensive analysis encompassed X-ray powder diffraction, apparent porosity, water absorption, scanning electron microscopy, hot disc, compressive strength, and a comparative assessment of fly ash-based geopolymer containing 20% of DWTS (GP-DWTS-20) and ordinary Portland cement (OPC). Notably, the results reveal that DWTS enhances thermal performance, with a remarkable 33% reduction in thermal conductivity observed in geopolymers containing 20% DWTS. This enhancement motivates the potential for innovative fly ash-based geopolymers. Moreover, the study contributes quantifiable evidence of a substantial 48% reduction in global warming potential for DWTS-based geopolymers compared to OPC. These findings underscore the environmental benefits of this alternative while emphasizing avenues for optimization in alkaline solution, curing, and renewable energy integration.

How to build green substations? An LCA comparison of different sustainable design strategies for substations

The growing industry of Information and Communication technology necessitates an increase in the construction of data centers and substations that supply them with electricity at high voltage levels. The increase in the construction of data centers and therefore substations on the one hand, and their high energy consumption on the other hand, makes sustainable substation design of utmost importance to prevent environmental degradation. However, current studies often consider only the operation phase of the building and neglect other life cycle stages, resulting in biased decisions that shift the environmental problems from one stage to another that were not included in the scope of these studies. This paper investigates Life Cycle Assessment (LCA) of a typical substation located in Germany, and applies three sustainable design strategies by creating scenarios, each varying in building material composition, waste heat utilization from data centers, and incorporation of green electricity from the grid. The environmental performance of these scenarios was evaluated using the One-Click LCA. Results indicate that switching to green electricity is the most impactful strategy that reduces the Global Warming Potential (GWP) to approximately 33 % compared to the base case. In the best solution which mixed all strategies, sharp reduction of GWP to 17.5 % was achieved. The highest impactful element of the building was its structure where the major building weight and a considerable amount of concrete cause the most GWP. Furthermore, the choice of materials is mainly important because of their embodied emissions, rather than their energetic values.

A comprehensive investigation on the impacts of steel slag aggregate on characteristics of high-performance concrete incorporating industrial by-products

Steel slag (SS), an industrial by-product of the steel industry, has the potential to serve as a natural aggregate alternative in concrete production to not only mitigate the exploitation of natural resources but also minimize the environmental impact of its treatment and disposal. This study was designed to investigate comprehensively the impacts of using SS as a full replacement for coarse aggregate and of using fly ash (FA) and ground granulated blast-furnace slag (GGBFS) as partial replacements for Portland cement on the engineering properties (i.e., workability, fresh unit weight, porosity, compressive and flexural strengths, ultrasonic pulse velocity, and drying shrinkage), durability (i.e., water absorption, surface electrical resistivity, and rapid chloride ion penetration), and microstructure (i.e., scanning electron microscopy observation) of high-performance concrete (HPC). A comparative analysis of the economic and environmental benefits of SS concrete versus natural aggregate concrete was also performed. The test results revealed that SS, FA, and GGBFS all impacted the properties of HPC significantly. The HPC mixtures in which natural aggregate had been completely replaced with SS exhibited about 20.4–21.3% higher unit weight than the natural aggregate concrete. The HPC samples with added FA and GGBFS exhibited enhanced performance in terms of mechanical strength, durability, and microstructure. Moreover, total material cost, global warming potential (GWP), and ozone depletion potential (ODP) were all found to be significantly lower in the HPC samples produced using SS and either GGBFS or a combination of FA and GGBFS. As a result, after 210 days of normal curing, the 100% SS concrete containing 15% FA and 35% GGBFS as a Portland cement substitution (S100F15G35 specimen) exhibited compressive and flexural strength values of 110.3 and 11.1 MPa, which were approximately 9.0% higher than the corresponding values of the reference concrete. Also, the S100F15G35 specimen registered the respective ultrasonic pulse velocity, surface electrical resistivity, and rapid chloride ion penetration values of 5328 m/s, 113.3 kΩ.cm, and 203 Coulombs, indicating high-quality and durable concrete. Moreover, incorporating 15% FA and 35% GGBFS in SS concrete resulted in a reduction of 15.7% drying shrinkage and 24.4% total material cost, especially reduced environmental impacts with a significant reduction in GWP and ODP by 43.5% and 29.2%, respectively. These findings further demonstrate the potential of using SS in combination with FA and GGBFS to create high-quality HPC that is both more economical and significantly more sustainable than conventional HPC.

Environmental burdens analysis of current music player devices through Life-Cycle Assessment methodology and optimum lifespan of these apparatus

Listening to music has unavoidable environmental impacts due to the technology used to reproduce it. The primary goal of this research is to calculate the impacts of streaming music data on the latest technological appliances, namely a smart TV (STV) and a smartphone (SPH). Furthermore, we have virtually modelled potential new sustainable scenarios, assessing their entire cradle-to-grave life cycle, through Life-Cycle Assessment (LCA) methodology, in order to understand within how many years of its lifespan an old appliance ought to be replaced with a new one for the purpose of reducing the Global Warming Potential (GWP) affections.According to the results, the selected 6.5-inch-screen smartphone emits 49.28 kg CO2-eq during its lifespan (9.00 g CO2-eq per hour), while the smart TV emits 406.40 kg CO2-eq throughout its average lifetime (32.56 g CO2-eq per hour). More specifically, the impacts associated with their use as music players are 2.58 g CO2-eq per listened hour in the case of the smartphone and 8.18 in that of the smart TV, taking music as occupying 25 % of the use phase of the SPH and 29 % of the use phase of the STV, as global averages. In the sustainable scenarios modelled, when the old appliances are replaced with new more efficient ones (Scenarios 1 and 2), GWP could be reduced by up to 8.82 % and 3.15 % for the SPH and the STV respectively. However, if old appliances are instead run on renewable energy and an efficient use of them is made (Scenarios 3 and 4), GWP could be reduced by up to 9.77 % and 60.75 %, respectively. Meanwhile, the optimum substitution lifespan for the SPH increases from 27.78 to 175.76 years, and that of the STV increases from 4.64 to 29.33 when this renewable energy and efficient use scenario is simulated.Thus, this research serves to confirm that the replacement of appliances is not justifiable as an attempt to reduce their environmental impact, unless renewable energy is used in our music reproduction appliances. Therefore, from an environmental point of view, the environmental effectiveness of substituting old appliances with new ones when listening to music is not supported by the data presented in this research. Rather, this research supports the view that the public funds should prioritise the goal of running appliances on renewable energy, rather than classic “renovation plans” or scrappage schemes of old music player appliances. The research shows how different policy-making strategies could bring numerous GWP reductions on account of the whole life cycle of these appliances, and underlines the significance of LCA calculations in determining public policy.

Environmentally-viable utilization of chicken litter as energy recovery and electrode production: A machine learning approach

Waste-to-energy could eventually be a crucial role in new disposal strategy for organic waste like chicken litter. Herein, a pyrolysis-based process that fully utilize the pyrolysates of chicken litter as energy sources (gas and liquid fuels) and energy storage material (supercapacitor (SC) electrode), which significantly contributes to carbon neutrality, has been proposed. Feasibility and readiness of the proposed process were estimated by combining various approaches such as lab-scale experiment, full-scale process simulation, life cycle analysis, and machine learning. Pyrolytic products other than the SC electrode material, such as gas and liquid, could be considered as fuels given their higher heating values ranging from 6 to 7 MJ kg−1. The SC electrode is comprised of porous carbon and delivers a large specific capacitance of 90 F g−1 at a constant specific current of 0.1 A g−1, demonstrating a potential for use in energy storage. Compared with fossil-based electrode materials, the chicken litter-based electrode material had 49%–64% reduction in global warming potential (GWP) and 83% of abiotic depletion of fossil fuels. The implementation of an SC system using the chicken litter-derived electrode therefore has potential to reduce global warming and fossil resource depletion. In addition, a case study on Jeju Island in the Republic of Korea incorporating renewable energy networks was considered based on diverse samples and their forecasts from machine learning algorithms. The chicken litter-based SC system in Jeju Island could reduce 63,191 t CO2 eq. per year of GWP.

Toward Zero Emission Construction: A Comparative Life Cycle Impact Assessment of Diesel, Hybrid, and Electric Excavators

Due to an extensive usage of heavy machinery, the construction sector is criticized as one of the major CO2 emitters. To address climate concerns, mitigating these greenhouse gas (GHG) emissions is important. This study aimed to strategize for “zero emission construction” by assessing the life cycle environmental impacts of diesel, electric, and hybrid construction machinery. By applying life cycle assessment (LCA) principles with adherence to ISO 14040/44 methodologies, this study scrutinizes the environmental repercussions of a standard excavator over 9200 effective operational hours, from raw material acquisition to end-of-life disposal. The results demonstrate a significant reduction in global warming potential (GWP), ozone depletion potential (ODP), and acidification potential (AP) in transitioning from diesel to hybrid and fully electric machines. A nominal increase due to this shift also occurred and impacted categories such as human carcinogenic toxicity (HT), freshwater eutrophication (EP), and marine ecotoxicity (ME); however, a more significant upsurge was noted in terrestrial ecotoxicity (TE) due to battery production. Thus, this study highlights the need for a careful management of environmental trade-offs in the shift toward electrified machinery and the importance of centering on the environmental profile of the battery. Future work should focus on enhancing the environmental profile of battery production and disposal, with policy decisions encouraging holistic sustainability based on green energies in construction projects.

Evaluation of the optimal concrete mix design with coconut shell ash as a partial cement replacement

Concrete is a major construction material with a significant environmental impact. Among other materials, coconut shell ash could be used as a partial replacement of cement to produce sustainable concrete. This study aimed to investigate the use of coconut shell ash as a partial cement replacement to reduce the environmental impact whilst achieving the predefined structural performance of concrete. The fresh, hardened and microstructural properties were investigated, and a life cycle assessment within the product stage was conducted in this study. When considering 15%, 20%, 25% and 30% replacement level concrete mixes, compressive strength was 27.31 MPa, 26.94 MPa, 25.60 MPa and 21.40 MPa at 28 days and environmental impact reduction in global warming potential were over 10%, 15%, 20% and 25% respectively. Based on the structural performance and environmental impact, 20% was the optimal replacement level. Therefore, cement can be replaced by coconut shell ash up to 20% to achieve the average target compressive strength as 25 MPa by reducing the environmental impact in global warming potential over 15%.

Experimental study on racking resistance of timber double-skin façade elements

The use of double-skin façade (DSF) is a quite new approach in building renovation process, complementing conventional renovation strategies. A double-skin facade is an envelope wall construction that consists of two transparent surfaces separated by a cavity and can essentially improve thermal and acoustic resistance of building envelope. Main double-skin wall components are usually composed of hardened external single glazing pane and internal three-layer insulation glass unit (IGU) which are rigidly bonded to the frame structure. Recently, many studies have analysed thermal and acoustic performance of DSF elements, but practically none in a sense of structural behaviour, especially in determination of racking resistance of such wall elements. Moreover, in terms of reduction of global warming potential, an eco-friendly timber frame instead of common used steel, aluminium or plastic frame is investigated in this analysis. The developed load-carrying real-size composite timber-glass DSF wall elements are subjected to experimental racking test using two different types of adhesives (polyurethane and epoxy) and consequent bonding type alternatives of connecting the internal three-layered thermal glazing to the timber frame. The obtained results for the maximal fracture force and racking stiffness are compared with previously tested prefabricated timber-glass wall elements using a single-skin three-layered thermal insulating glazing only. The results evidently demonstrate that this new approach of prefabricated load-bearing double-skin façade elements can essentially improve racking resistance and stiffness comparing with previously studied timber-glass wall elements and can thus be fully recommended especially in structural renovation process of old buildings. However, a lot of parameters still significantly effect racking resistance of such elements and thus have to be further numerically or parametrically investigated.

Impact of Refrigerants Transition on HVAC System Performance and Environmental Sustainability

This study investigates the impact of refrigerant transitions on Heating, Ventilation, and Air Conditioning (HVAC) system performance and environmental sustainability. Through simulation-based analysis, the research evaluates the performance of three refrigerants: HFC-134a, R-410A, and HFO-1234yf. The study assesses cooling efficiency, energy consumption, and global warming potential (GWP) as key performance metrics. Results reveal that transitioning to low-GWP alternatives, particularly HFO-1234yf, enhances cooling efficiency and reduces energy consumption by 12% and 24% compared to R-410A and HFC-134a, respectively. HFO-1234yf also demonstrates a notable 98% reduction in GWP compared to HFC-134a. The discussion highlights the potential of low-GWP refrigerants to balance system performance gains with environmental concerns. Consideration of system design, operating conditions, and trade-offs further underscores the significance of responsible refrigerant choices in achieving sustainable HVAC practices. This research contributes to the ongoing discourse on sustainable technologies, offering practical insights for HVAC practitioners, designers, and policymakers striving to align efficiency with environmental responsibility in HVAC systems

Assessment of Carbon Footprint and Possible Interventions to Reduce its Impact at University of Balochistan, Quetta, Pakistan: The First Attempt

Environmental sustainability does not mean living without luxuries but rather being aware of consumption of resources in a way that is environment friendly. Carbon footprint is one of the many environmental traces that has come to prominence because of its connection with global warming and subsequently climate change as the most renowned environmental indices. In 2018, prior to pandemic period, the University of Balochistan (UoB) participated for the first time in the UI Green Metrics world universities ranking and stood 346 globally and fourth position in Pakistan. It was recorded before the pandemic period that 19.12 Metric Ton (MT) per year of carbon footprint was produced within the premises of the UoB. Multiple interventions were carried out after post pandemic period such as to develop policies to (a) reduce carbon footprints, (b) increase the use of energy saving appliances, (b) recycling of wastewater, (c) regular plantation, and (d) conservation strategies for existing 400 pine trees, greenbelts and ornamental plants. It is suggested that universities may adopt the energy efficient criteria of UI GreenMetric with a focus of public awareness towards reduction in Global Warming Potential (GWP), Climate Change by sustainable universities model.

Biodegradable, eco-friendly, and hydrophobic drinking straws based on delignified phosphorylated bamboo-gelatin composites

Single-use plastic straws have become one of the major global challenges due to its abundant consumption, non-degradability, and accumulation as a waste causing detrimental effects on humans, aquatic life, and the ecosystem. Recently, plastic straws have been replaced with paper straws, however, it has multiple shortcomings, such as poor water stability, wet strength, utilize non-degradable adhesives or coatings, and are of single-use only. Therefore, finding new alternative straws which are sustainable, biodegradable, mechanically robust, and water-stable is the need of the hour. The current work reports the fabrication of gelatin-infiltrated and crosslinked, mechanically robust, biodegradable, and hydrostable straws prepared using delignified phosphorylated bamboo (DPB). The presence of both charge-based electrostatic interactions (positively charged gelatin and negatively charged phosphate in DPB) and hydrogen bonding were responsible for uniform distribution of cross-linked gelatin in porous bamboo, which was optimized by varying pH and gelatin concentration. The drinking straws infiltrated with 7.5% gelatin at pH 4, shows high mechanical strength of 138 MPa, Young’s modulus of 1.38 GPa, hydrophobic surface wettability with a contact angle of 103.3°, and water stability upto ∼ 24 h. The bamboo-gelatin straws also show improved biodegradability (degradation up to 98% in 36 days), with a reduction in global warming potential by 54% and 17.6% less damage to ecosystems during end-of-life, compared to plastic straws. The migration values of straws were within the standard limits when in contact with various types of simulants such as acidic, alkaline, alcoholic, carbonated, and fatty foods tested in temperature range of 0–95 °C, making it suitable for both hot and cold beverages. In the present work, bamboo-gelatin straws derived from abundantly available biomass have the required properties to become a sustainable alternative to single-use plastic or paper straws, a step towards reducing global plastic waste and our dependency on petroleum-based products.

A combination of organic fertilizers partially substitution with alternate wet and dry irrigation could further reduce greenhouse gases emission in rice field

Alternate wet and dry (AWD) irrigation and organic fertilizers substitution (OFS) have contrasting effects on CH4 and N2O emissions in rice cultivation. Combining these two practices may be feasible for simultaneous reduction of CH4 and N2O emission from paddy. Hence, we conducted a two-year field experiment to explore the reduction of greenhouse gases under the combination of AWD and OFS. The field experiment which was designed with two irrigation methods (continuous flooding (CF) irrigation and AWD irrigation), and five nitrogen regimes (N0, N135, and N180 represent 0, 135, and 180 kg N ha-1, respectively, ON25 and ON50 represent 25% and 50% OFS for inorganic fertilizer, respectively). The results showed a single-peak emission for CH4 fluxes during the whole rice growing season in all water and nitrogen treatments while the N2O fluxes peak only observed during tillering period with AWD irrigation. AWD irrigation and OFS showed a limited reduction in global warming potential (GWP). These were owing to that AWD irrigation reduced 38.3% CH4 emissions while increase 145.9% N2O emissions when compared to CF irrigation, and the low rate (25%) OFS only reduced CH4 emission by 29.4% while high rate (50%) only reduce N2O emission by 38.8% when compared to conventional inorganic nitrogen fertilizer (N180). Combined AWD and ON25 could maximize the reduction in GWP and yield-scaled GWP, which were reduce 58.0% and 52.5%, respectively, compare to the conventional water and nitrogen management (CF and N180). Furthermore, the structural equation modelling (SEM) indicated that the soil dissolved organic carbon (DOC) and rice aboveground biomass showed a significant positive effect on CH4 fluxes while soil NH4+ with a negative effect, and the soil NH4+, nitrification potential, denitrification potential significant affected N2O fluxes with a positive effect while DOC with a negative effect. These results investigated that 25% OFS rate for inorganic fertilizer could further reduce warming potential in AWD irrigation rice field.

Structural design of hybrid steel-timber buildings for lower production stage embodied carbon emissions

Using cross laminated timber (CLT) floor panels in combination with steel framing has been identified as a promising new structural configuration that can reduce the embodied greenhouse gas emissions of buildings. This project evaluated efficient structural design of hybrid steel-timber floor sections for a wide range of design parameters to determine the reductions in global warming potential possible relative to a conventional steel-concrete cross section. Each of the structural designs was checked for strength limit states, deflection, and minimum fire rating of either unrated, 1-h, or 2-h for a range of deck spans between 2.3 m and 4.6 m and beam spans between 5.5 m and 13.5 m. For an unrated floor assembly there is little global warming potential benefit to use steel-timber floors if a topping slab is included on top of the CLT slab. Whereas, using steel-timber configurations without a topping slab result in the largest global warming potential reductions. For the 1-h and 2-h ratings, even steel-timber configurations with a 64 mm thick topping slab had up to 20% reduction in global warming potential compared to the steel-concrete alternative. Additionally, several considerations that can drastically affect the global warming potential results were discussed. The results from this project demonstrate the best practices for structural design of hybrid steel-timber buildings to reduce global warming potential of the superstructure frame by between 5% and 35% relative to conventional steel and concrete construction.

Co-pyrolysis of sewage sludge with lignocellulosic and algal biomass for sustainable liquid and gaseous fuel production: A life cycle assessment and techno-economic analysis

Biowastes are marked sources of global greenhouse gas emissions, however, locally accessible biowaste could be a sustainable source for biofuel production to generate clean energy. This study examined the environmental sustainability and economic feasibility of using co-pyrolysed sewage sludge (SS) with lignocellulosic and algal biomass for liquid and gaseous fuel production from the perspective of life cycle assessment and techno-economic analysis. Wastewater-grown microalgae, sawdust, and wheat straw were selected as co-feed materials, and three mixing ratios (25, 50, and 75 wt%) of each feedstock with SS were examined. Wastewater-grown microalgae and SS were obtained from wastewater treatment plants (WWTPs), which were assumed to be near the pyrolysis plant facility, obviating the need for transportation. An Aspen simulation was used to estimate the amount of energy recovered from the pyrolysis as gaseous fuel for electricity and heat generation via gas turbines. A sensitivity analysis was conducted to identify future considerations for SS co-pyrolysis to make it a more environmentally and economically viable industrial process for producing liquid and gaseous fuels. The co-pyrolysis of SS with biomass reduced the overall environmental burden, with sawdust co-pyrolysis outperforming wheat straw and microalgal co-pyrolysis. All scenarios achieved a high net positive energy balance (from 2,595 to 6,323 kWh/1,000 kg bio-oil) and reduced global warming potential (GWP) (from −793 to −1,970 kg CO2 eq/1,000 kg bio-oil). Sawdust co-pyrolysis resulted in the highest GWP reduction (from −1,510 to −1,970 kg CO2 eq/1,000 kg bio-oil) and energy recovery (from 5,551 to 6,323 kWh/1,000 kg bio-oil). Energy recovery from gaseous fuel through gas turbine operation generated a process energy demand of 23 %–224 %. Sawdust co-pyrolysis exhibited the highest net present worth (NPW) of 6.16 million CAD. Sensitivity analysis demonstrated that the GWP and terrestrial ecotoxicity potential were affected by the transportation of sawdust and wheat straw. Overall, the co-pyrolysis of SS with both lignocellulosic and algal biomass is sustainable and economically feasible for producing liquid and gaseous fuels and treating hazardous waste originating from WWTPs, thereby facilitating environmental sustainability and a circular economy from the sale of pyrolysis products. Broader implication of this study is using effective catalysts to further strengthen the sustainability and increase the profitability of the co-pyrolysis process, which has not been yet investigated.

Life cycle assessment of spectra-managed greenhouses for sustainable agriculture

Plants in agricultural greenhouses utilize the visible spectrum for photosynthesis, while the unused solar spectrum contributes to greenhouse temperature rise in hot climates. The spectra-managed greenhouses employ innovative techniques to mitigate the cooling load by means of solar spectrum filtering. This study aims to conduct a comprehensive comparative life cycle assessment (LCA) of conventional and spectra-managed greenhouses specifically designed for hot and arid climates. The novel roof greenhouse integrates photovoltaics and dielectric mirrors for solar spectrum optimization, while the nanofluid roof greenhouse uses spectrum-selective nanofluid for sustainable cooling. The LCA evaluates the environmental impacts of greenhouse components and processes, identifying the hot spots for environmental performance improvement at the early stage of development. The life cycle impact assessment (using TRACI approach) showed that novel roof greenhouse could reduce global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), smog formation potential (SFP), and fossil fuel depletion (FFD) by 52.4%, 47.7%, 49.8%, 53.2%, and 57.4%, respectively, compared to the conventional greenhouse. Electricity is a significant contributor to environmental emissions for all analyzed greenhouses; therefore, a sensitivity analysis is performed by varying the source of electricity. For photovoltaic-generated electricity to power the greenhouses, the implementation of a nanofluid roof greenhouse resulted in a 5.1% and 23.1% reduction in GWP compared to novel roof and conventional greenhouses, respectively.