CO2 Equivalent Emissions Research Articles

Carbon Emission Reduction Associated With Utilisation Of Telehealth In Outpatient Clinics In An Australian Quaternary Health Service

Objective: To assess the impact of implementing telehealth in outpatient clinics on the carbon emissions associated with the delivery of health care. Design & Setting: Retrospective cohort study in large metropolitan quaternary referral health service from January 2021- December 2022. Participants: All patients who attended an outpatient clinic appointment during the study period, either in-person, via telehealth or via telephone. Main outcome measures: The estimation of carbon emissions in tonnes (t) of CO2-equivalent (CO2-e) associated with in-person and telehealth appointments based on emissions associated with travel, telehealth platform usage and N95 mask usage. Results: There were 571,121 outpatient clinic appointments during the study period. Of the appointments, 251,458 (44%) were conducted remotely, resulting in an estimated reduction in 3,629t of CO2-e emissions in the two-year period. Telehealth consultations in this time contributed 4.5t of CO2-equivalent emissions. The total emission usage of telehealth clinic was only 0.12% of emissions generated from face-to-face clinic appointments. Conclusion: Telehealth offers the opportunity of substantial carbon emissions reduction within the healthcare sector, while also providing cost and time-saving benefits for healthcare services and patients. Limitations include generalisation of transportation modes and the retrospective nature of the data collection.

Quantifying global warming potential variations from greenhouse gas emission sources in forest ecosystems

Forest ecosystems play a crucial role in regulating greenhouse gas (GHG) emissions and mitigating climate change. This research aimed to evaluate the GHG emissions of various sources within forested ecosystems and assess their respective contributions to global warming potential (GWP), vital for developing more targeted strategies to mitigate climate change, shaping climate policies, carbon accounting, sustainable forest management, and advancing scientific comprehension of ecosystem-climate dynamics. The study comprehensively analysed carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions EDGAR data of deforestation, fires, and natural processes such as organic soil decomposition within forested ecosystems. The assessment quantified the CO2 equivalent emissions for each category from 1990 to 2022 and forecasted till 2030. Our forecast shows that CO2 emissions from deforestation could reach between 3,990 and 4,529 metric ton (Mt) by 2030, with forest fires contributing an additional 750 Mt. Forestland CO2 absorption is expected to decline to -5134.80 Mt by 2030. There is uncertainty surrounding the forecasts for Organic soil CO2 (829.78 Mt) and Other land CO2 (-764.53 Mt). In addition, deforestation was a significant contributor to CO2 emissions, with a GWP ranging from 4000 to 4500, highlighting the complex interplay between natural processes and human activities in shaping atmospheric warming patterns. Additionally, forest fires emit a complex mix of GHGs. The potency of these gases in warming the planet varies considerably, with CH4 exhibiting a GWP range of 500 to 700 Mt CO2 equivalent, and CO2 ranging from 900 and 1350 Mt. These variations depend on fire intensity and its overall impact on the climate system. Forestland acts as powerful carbon sink, capturing atmospheric CO2 with negative GWP values between -7000 and -6000. Researchers suggest a multifaceted strategy such as stricter enforcement of sustainable forestry regulations, investing in projects that promote carbon sequestration, and reforestation. Additionally, advancements in drone technology, satellite imagery, remote sensing and advanced data analytics can aid in detecting and mitigating climate change impacts, ultimately paving the way for carbon neutrality.Graphical

Environmental impact of intravenous versus oral administration materials for acetaminophen and ketoprofen in a French university hospital: an eco-audit study using a life cycle analysis.

The combination of acetaminophen with a nonsteroidal anti-inflammatory drug is the cornerstone of perioperative multimodal analgesia. These drugs can be administered intravenously or orally as premedication, consistent with the concept of pre-emptive and preventive analgesia. We aimed to assess the environmental impact of their intravenous and oral administration in a French university hospital. We carried out a life cycle assessment to determine the amount of greenhouse gas emissions and depletion of water resources resulting from the oral vs intravenous administration of 1g acetaminophen and 50mg ketoprofen. We assessed two schemes of intravenous administration, depending on the use of the same or a different infusion set for each drug. At our centre, the intravenous administration of both drugs was associated with the emission of 444-556g CO2 equivalent (CO2e), and with 9.8-12.2 L of water waste. The oral administration of both drugs generated 8.36g of CO2e emissions and consumed 1.16 L of water. At a national level, the switch from intravenous to oral premedication of the drugs could avoid the emission of 2,900-3,700 tons of CO2e and the waste of 58,000-74,000 m3 of water each year. This eco-audit indicates that oral administration of acetaminophen and ketoprofen results in significantly lower carbon emissions and water consumption than intravenous administration. These findings highlight the importance of using the oral route for most patients, limiting intravenous administration for those with specific needs because of higher environmental impact and cost.

Lifecycle Assessment Analysis of Recycled Concrete Aggregate Incorporating Fly Ash and Hemp

The critical roles of recycling are increasing depending on depleted natural resources and its devastating consequences. Concrete has been one of the most used building materials for many years to response the basic need of human beings for shelter. The studies on the recycling of concrete are crucial to minimize negative effects of both the high amount of energy consumed during the production phase and the limited recycling opportunities after destruction. Considering the amount of construction and demolition waste (CDW) after the February 6, 2023 earthquakes in Türkiye, it is clear that recycling concrete (RC) may make a positive contribution to environmental sustainability and natural resources usage. In addition, as a result of the ongoing urban transformation projects throughout Türkiye, especially in Istanbul, there is a need to recycle CDW, the majority of which consists of concrete. This paper examines the equivalent CO2 emissions of recycled concrete aggregate (RCA) incorporation of various proportion fly ash and hemp based on previous studies by applying the Excel-based GreenConcrete LCA software developed at the University of California Berkeley Campus (UC Berkeley). As a result of the investigations, it is seen that the use of RCA, which is generated in large quantities both as a result of earthquakes and urban transformation projects, reflects positively on the environmental impacts in the LCA analysis. In addition, the use of concrete mixtures that contribute to the recycling of wastes such as fly ash and hemp used as admixtures contributes to reducing the environmental damage of these wastes and improving the concrete content.

Modeling building energy self-sufficiency of using rooftop photovoltaics on an urban scale

The significant contribution of buildings to global energy-related CO2 emissions and climate change has led to projections of a carbon–neutral building stock by 2050. This study evaluates the potential contribution of rooftop photovoltaics to urban energy self-sufficiency by developing an enhanced CityBEM framework, our in-house urban building energy model (UBEM). This methodology enables city-scale, simultaneous simulations of building energy use and rooftop photovoltaic retrofitting with low computational time. CityBEM’s robustness and high spatiotemporal resolution facilitate transient simulations of individual buildings with diverse usage types across large urban areas, addressing common computational constraints and input data limitations in UBEM applications. The rooftop photovoltaic model in CityBEM utilizes a comprehensive approach with physics-based modeling of crystalline PVs, model validation, and a proper design of array networks to manage self-shading effects. More than 57,000 buildings with a combined footprint of 32.37 million square meters are located in the simulation test case covering downtown Montreal (Quebec, Canada) and the surrounding areas. Results indicate that rooftop PV adoption in these buildings could potentially generate 5.9 TWh of electricity annually, reduce energy demand by 27.3%, and achieve an average annual energy saving of 40%. This local generation could also reduce operational CO2 equivalent emissions by over 0.2 megatons. Overall, this study highlights the significant potential of rooftop photovoltaics for a cleaner, more energy self-sufficient urban future.

Carbon Footprint of Fluorinated Gases Used in Endothelial Keratoplasty.

The purpose of this study was to examine the direct impact on carbon emissions attributed to the use of fluorinated gases in endothelial keratoplasty (EK) procedures using gas tamponade and to evaluate the respective carbon footprint of different gas delivery systems used in EK procedures. In this retrospective, single-center environmental impact study, all corneal procedures using fluorinated gases between January 2021 and January 2024 at the Royal Liverpool University Hospital were reviewed and included. The CO2 equivalent emissions were calculated based on the mass of each fluorinated gas used, following the guidelines of the Intergovernmental Panel on Climate Change. Of 357 total procedures (160 Descemet membrane endothelial keratoplasty [44.8%], 118 Descemet stripping automated endothelial keratoplasty [33.1%], and 79 rebubbling [22.1%]), single-use sulfur hexafluoride (SF6) canisters were used in 278 (77.9%) procedures. SF6 canisters used in corneal transplantation emitted nearly 1.5 tons of CO2 over 3 years. The 30-mL canisters emitted twice the CO2 per GBP compared to SF6 15-mL canisters and 4 times that of C2F6 or C3F8 15-mL canisters. Fluorinated gas use in corneal transplantation has a significant environmental impact, which can be reduced by the use of smaller single-use canisters with lower carbon footprint, although manufacturing and disposal concerns remain. Our findings advocate for a more environmentally conscious approach to EK, favoring the use of smaller, more cost-efficient canisters and considering air as an alternative tamponade where possible.

A-198 ESG Opportunities Harnessed During Pathology Transformation

Abstract Background Synnovis (a SYNLAB business) is in the process of delivering one of the largest Pathology transformation programmes in the UK, moving to a seven-site hub and spoke model from 89 laboratories over a dispersed geography. This remit also presented an opportunity for SYNLAB to deliver on its Environmental Social Governance (ESG) ambitions, by embedding ESG principles into programme delivery. There are several examples within each ESG pillar that demonstrate the benefits to be leveraged during transformation. Methods SYNLAB’s vision is to deliver sustainable diagnostic services. The integration of ESG into both the decision-making process and transformation structure ties these ambitions into programme benefits realisation. As well as setting performance level targets, the delivery of ESG benefits provide measures of success throughout the transformation journey, motivating stakeholders and building confidence along the way. Results Environment: The efficient use of space and LEAN principle design has consolidated the fragmented laboratory services spanning 15,000m2 into a bespoke, cutting-edge Pathology Hub with 6 spokes (hospital based services). The new hub building was designed to achieve BREEAM Excellent standards which measure performance against criteria such as energy management and efficiency, sustainable design and materials. The hub’s energy is from renewable-backed sources, and we will achieve a 47% reduction in CO2 equivalent (CO2e) emissions by unifying a significant proportion of its legacy footprint in this way. Further energy savings will be achieved through the associated analytical equipment consolidation, including a decrease from 50 to 14 microtomes, a decrease of 29 to 15 ventilated benches and a reduction of over 200 fridges and freezers across the service. In addition, substantial CO2e emissions savings are also being delivered by moving to a greener logistics provider, utilising electric vehicles and bikes. 2023 saw such emissions fall by 60% across Synnovis, helping to keep London’s air cleaner. Social: The transformation programme enables the hand back of over 6,000m2 of real estate to Synnovis’ NHS partners to use for critical hospital services (the equivalent of over 150 operating theatres). Governance Both internally and externally, ESG is integrated within the Synnovis organisational culture. For example, internally it applies mandatory sustainability metrics to its solution selection processes. These influenced the selection of Abbott’s Indexor solution to support the transformation of Blood Sciences, delivering a saving of over 2.8 million plastic sample bags every year. Externally, SYNLAB works with its partners to manage this substantial and complex transformation programme. Risk management is assured through transparency, securing confidence in the good use of public funds, ensuring responsiveness to customer and partner feedback, and ensuring accountability for and the delivery of targeted healthcare outcomes. Conclusions The integration of SYNLAB’s ESG strategy within the transformation programme is delivering tangible benefits across all ESG pillars. It has highlighted that in addition to the core outcome of services transformation, there are many more opportunities that can be realised as a result of making ESG an integral part of the pathology transformation programme.

Multi-objective optimization of a solar-biomass multi-generation system with dual-stage desalination for brine minimization

A hybrid solar-biomass multi-generation system feeding an off-grid community is proposed in this study. An organic Rankine Cycle (ORC) generates electricity by harnessing the thermal energy supplied by the hybrid heat generation system. Part of the produced electricity is utilized to meet the community's electricity needs, while another fraction powers a brackish water reverse osmosis unit (RO). The waste heat from the ORC is recovered to produce domestic hot water and to drive a membrane distillation (MD) unit for RO brine minimization. A multi-objective optimization of the proposed system is conducted using the NSGA-II algorithm and TOPSIS decision-making tool considering plant's overall energy efficiency, exergy efficiency, and the total exergoeconomic cost of the useful products as objective functions. The study's results indicate that the overall optimal solution is achieved using R1336mzz(Z), with corresponding energy efficiency, exergy efficiency and hourly exergoeconomic cost of 45.31%, 5.39%, and 87.68 €/h, respectively. Moreover, the unitary costs associated with the useful products are 0.207 €/kWh, 0.029 €/kWh, 0.683 €/m3, and 3.36 €/m3 for the produced electricity, domestic hot water, RO permeate and MD distillate, respectively. In terms of sustainability, the system is not only renewable-driven but also achieves a 21% reduction in brine discharge through heat recovery at the ORC condenser compared to single-stage RO desalination. Additionally, using R1336mzz(Z) with its low global warming potential of 2 significantly lowers CO2 equivalent emissions compared to R245-fa. Lastly, sensitivity analysis indicates that hybridization ratios of up to 80% can result in a 10.6% reduction in CO2 emissions originating from biomass combustion compared to biomass-only solutions.

Impact of COVID-19 led transition of work culture and travel to work patterns on society and environment in Delhi

Globally, COVID-19 has led to changes in daily lifestyle and travel behavior. There was a shift from in-person physical jobs to work-from-home culture, even for those jobs that required in-person presence at the job location. However, this was not true for everyone, and a majority continued to travel to work. The limited capacity of public transport services and the fear of exposure to the virus restrained people from practicing their conventional mobility choices. We explore the impact of COVID-19 on the nature of jobs and related changes in work travel patterns by population groups for Delhi using in-person surveys conducted during 2021 in six localities of Delhi. We also estimated the short- and long-term impacts of altered behavior on expenditures and equivalent CO2 emissions.As per the analysis, lower income groups, having no vehicles, with lesser qualifications, and employed as daily wagers, had limited capacity to change to work-from-home during COVID-19. We observed an increased dependency on personal motorized vehicles, leading to increased expenditures and reduced affordability. Adopting work-from-home during COVID-19 helped reduce equivalent CO2 emissions per working member by 39%. However, as the work at the site resumes, the emissions are expected to increase. The study shows that COVID-19 led to short-term benefits, but in the long term, the externalities will likely increase. Working from home during the pandemic provides short-term benefits; the social benefits are not equally distributed, and the transport emissions shall increase in the long term.

Development of a sustainable stabilized macadam road base using steel slag as supplementary cementitious material

As the main waste product of iron and steel industry, steel slag possesses considerable cementitious activity, making it a promising alternative to cement in Cement Stabilized Macadam (CSM). However, CSM was inevitably exposed to groundwater and rainwater when served as the pavement base course, leading to concerns over poor early strength and potential pollutant leakage, which are the main factors that may hinder the widespread utilization of steel slag in CSM base. To address these issues, this study investigated the feasibility of using steel slag powder to produce CSM. Steel Slag Powder-Cement Stabilized Macadam (SSCSM) samples were prepared and the hydration products, microstructure, mechanical properties, water damage resistance and heavy metal ions leaching behavior were investigated. The results show that the nucleation effect of steel slag powder accelerates the early hydration, but the C-S-H produced by hydration is not sufficient to form a stable hydration product network, so the microstructure of SSCSM is looser than that of CSM. The addition of steel slag powder improved the shrinkage performance of SSCSM, and the mechanical properties and heavy metal ion leaching concentration of SSCSM meet the engineering application requirements when the steel slag powder replacement level does not exceed 30 %. It was also found that the addition of steel slag powder promoted the development of pores in SSCSM samples after dry-wet cycles, resulting in the reduction of water damage resistance. Compared with conventional CSM, the use of SSCSM can not only reduce 4 % of raw material cost and 23.5 % of equivalent CO2 emission, but also mitigate the heavy metal ions leaching risk associated with steel slag, making it an effective and sustainable solution for steel slag recycling.

A novel life cycle assessment methodology for transitioning from nZEB to ZEB. Case-study

This study analyzes the CO2 equivalent emissions of a LEED-certified nearly Zero Energy Building (nZEB) using a simplified Life Cycle Assessment (LCA) methodology, aligned with EN 15978. Focusing on the building's energy performance across its life cycle, the study demonstrates that in 2022, 95 % of the energy used for heating came from renewable sources, which decreases to 86 % by 2050 due to milder winters. However, the need for cooling increases by 9 % over the same period due to hotter summers. By 2050 and 2080, if the EU transitions to renewable electricity, the operational Global Warming Potential (GWP) could approach zero. The study highlights that embodied emissions (69 %) outweigh operational emissions (31 %) in 2022, emphasizing the need to reduce embodied GWP through material reuse and recycling. Notably, concrete and aluminum were found to contribute the most to embodied emissions. The research also shows that nZEBs can exceed the EU's 2030 energy targets, with renewable energy contributing 67 % of the building's total consumption. As climate change favors nZEB performance, the operational emissions will trend towards zero, but embodied emissions will become increasingly significant. To achieve the EU's zero-emission goals, it is crucial to prioritize reducing embodied GWP in future nZEBs. This study underscores the importance of nZEBs in mitigating climate change impacts, offering a pathway toward sustainable construction and energy efficiency.

Complacency in the quantification and reporting of climate impacts as carbon dioxide equivalent emissions

PurposeThe choice of characterization model has the potential to profoundly influence LCA results and conclusions. It is therefore a requirement of ISO 14044:2006 that the selection of characterization model shall be both justified and consistent with goal and scope. The purpose of this article was to examine current practices regarding the characterization of GHG emissions and reporting as CO2 equivalent emissions.MethodsA survey of practice was conducted across articles recently published in the International Journal of Life Cycle Assessment. Each article was examined using seven predetermined questions covering reporting of CO2 equivalent emissions and justification of climate metric used, interpretation of results in relation to climate measures or goals, and the implications of choosing an alternative climate metric.Results and discussionOf the sample of 85 articles, more than half reported GHG emissions as CO2 equivalent emissions. Of these, 81% unambiguously reported the climate metric used. Most often, there was no justification for the choice of a characterization model. Where a justification was given, the most common reason was alignment with the requirements of a program or PCR document. In some cases, the choice of characterization model was determined by the choice of impact assessment method (e.g., CML, ReCiPe). In other cases, the choice of characterization model was based on the desire to compare results to other studies. It is noted that none of the abovementioned reasons is scientific justification related to a stated climate objective. Not surprisingly, most studies made no attempt to interpret results reported as CO2 equivalent emissions in relation to climate measures or goals, and most did not discuss the potential implications of alternative climate metrics. For almost half of the articles, the choice of climate metric was assessed as potentially having major implications for decision-making or comparison to alternative systems.ConclusionsBased on this survey, it is evident that key aspects of ISO 14044:2006 are routinely not being followed. When GHG emissions are aggregated into a single impact category indicator result, there is a loss of transparency about climate impacts over time and the potential to unknowingly trade short-term climate benefits against the exacerbation of the difficulties of achieving long-term climate stabilization. As such, whenever GHG emissions are reported as CO2 equivalent emissions, it is imperative that the choice of characterization model is unambiguously reported and justified, that results are interpreted in relation to environmental outcomes, and that the potential implications of selecting alternative models are discussed.Graphical

Beyond 4 × 4: Paramotoring a novel approach to accelerate plant exploration in challenging environments

Societal Impact StatementAddressing the burning environmental crisis, we explore how the ‘extreme sport’ of paramotoring can enhance and accelerate scientific exploration with minimal environmental impact compared to off‐road vehicles. Our study demonstrates the scientific potential of paramotoring to access fragile desert ecosystems and investigate unrecorded habitats and species. Comparisons with 4 × 4s showed significant reductions in CO2‐eq emissions for longer missions and ninefold faster travel times. Unlike off‐road vehicles, which can damage the equivalent of over one football pitch in area per linear kilometre driven, paramotors cause minimal damage. Integrating extreme sports and science can accelerate data and specimen collection for more effective habitat conservation. This has the potential to spark discoveries and engagement across diverse communities.Summary In the face of an urgent climate and environmental crisis, we explore the potential of paramotoring to expand scientific reach and collection capability without the environmental harm associated with off‐road vehicles. In Peru's fog oasis desert, we brought together paramotor experts and scientists to conduct missions involving monitoring, plant sampling, surveying, sensor placement and transportation. We compared the environmental impact and time taken by paramotoring with surveys conducted using off‐road vehicles and walking. Shorter paramotor missions showed small differences in CO2 equivalents and time efficiency compared to off‐road vehicles. However, longer missions (28 km from base camp) revealed up to nine times faster travel and two thirds less CO2 equivalent emissions. Notably, off‐road vehicles left a substantial environmental footprint (700 to 8000 m2 per km), whilst paramotors had a minimal impact, with a tiny surface ‘footprint’ of just a few square metres, representing orders of magnitude (1000 to 10,000) less environmental impact. With basic training in identification and sampling, paramotorists collected plant specimens that are invaluable for ongoing and future scientific study. Whilst logistical and safety challenges in transporting scientists via paramotors need further investigation, the benefits, especially compared to surface travel, are evident. Integrating extreme sports into scientific endeavour promises wider and more comprehensive exploration, new discoveries and increased engagement across diverse communities—and in summary—offers significant potential to address urgent environmental challenges.

Towards circular manufacturing systems implementation: An integrated analysis framework for circular supply chains

The transition to circular manufacturing systems (CMS) is crucial for achieving sustainable growth, addressing the environmental concerns and resource scarcity challenges. Shifting towards CMS requires a systemic approach that integrates value proposition models, product design, and supply chains (SCs). Circular supply chains (CSCs) emerge as a core pillar of CMS, incorporating value delivery, use, recovery, and reuse. CSCs are inherently more complex and dynamic than linear SCs requiring a holistic analysis approach to capture their complex and dynamic attributes. This research proposes an integrated analysis framework combining qualitative and quantitative approaches to explore the complexities and dynamics of CSCs and assess their economic, environmental, and technical performance. Through the lens of two different CMS implementation case studies, one in automotive parts remanufacturing and one in white goods manufacturing, this research illustrates the framework's applicability. In the automotive case, centralizing core management activities was found to improve economic performance by 50-54 %. However, the introduction of regional logistics hubs, while economically efficient, led to a 20 % increase in CO2-equivalent emissions. On the other hand, the white goods case study highlighted the trade-offs in centralizing end-of-life recovery facilities, where financial savings of up to 60 % were offset by increased transportation costs and increased CO2 emissions. The analysis of CSCs in these two distinct manufacturing sectors underscores the relevance and flexibility of the proposed framework, providing decision-makers with a tool to examine how different CSCs configurations and strategies impact overall performance. This guidance is crucial for developing optimal CSCs design and implementation strategies.

Quantifying benefits of renewable investments for German residential Prosumers in times of volatile energy markets

The COVID-19 pandemic and the Russian invasion of Ukraine have led to unseen disruptions in the global energy markets since the end of 2021. Residential renewable investments like photovoltaic systems, battery home storage systems, and heat pumps are therefore gaining traction. However, the benefits of those technologies during the energy crisis and beyond have not been fully quantified yet. Therefore, in this study, we benchmark renewable investments for a broad variety of single-family homes by evaluating potential cost savings and emission reductions. In addition, the study considers the influence of recent political incentives and subsidies. The results show that photovoltaic systems are a no-regret investment decision, both economically and environmentally. At the climax of the energy crisis, a typical German household with a heat pump could save 1850 € and reduce equivalent CO2 emissions by 250 g/kWh annually. Politically introduced price breaks on electricity and natural gas do not reverse this advantage. Furthermore, when owning an electric vehicle renewable investments are often more beneficial.

Thermodynamic, economic, and environmental analyses and multi-objective optimization of an organic flash regenerative cycle with an ejector for geothermal heat utilization

Based on the existing organic flash regenerative cycle (OFRC), this paper presents a novel OFRC system incorporating an ejector (E-OFRC). The ejector replaces the high-pressure throttle valve for initial flash evaporation and utilizes a low-pressure throttle valve for the second flash evaporation of saturated liquid separated from the first flash. The gaseous working fluid from the second flash is employed as the ejecting fluid. The E-OFRC system employs an ejector to mitigate irreversible losses associated with high-pressure throttle and to drive gaseous working fluids from secondary flash to circulate to enhance overall system performance. Thermodynamic, economic, and environmental models are established, and the impacts of flash pressure (P4), endothermic pressure (P3), and geothermal water temperature (THS,in) on system performance are analyzed and compared with those of the OFRC system. Multi-objective optimization using the Dragonfly algorithm is conducted, while the TOPSIS method is utilized to determine optimal operating parameters for the E-OFRC system. The findings indicate that, in comparison to the OFRC system, the thermal efficiency of the E-OFRC system is only lower under P3, while its thermodynamic, economic, and environmental performance is enhanced under other considered conditions. This underscores the advantages of the E-OFRC system. The optimal operating parameters for the E-OFRC system are THS,in = 423.53 K, P3 = 1.89 MPa, P4 = 0.96 MPa; yielding a net output power of 84.75 kW, a specific investment cost of 2833.54$/kW, and an annual CO2 equivalent emission reduction of 0.807 × 106kg − providing valuable technical support for engineering applications.

Seawater Mixed with One Part Alkali Activated Material: An Environmental and Cost Evaluation.

Concrete production is associated with extensive energy consumption and significant CO2 emissions. In addition, tremendous amounts of freshwater are used as a mixing agent. Urgency is increasing to develop sustainable cementitious materials and promote freshwater-saving strategies. An environmentally friendly alternative binder, seawater mixed with one part alkali activated material, is studied. In this work, a cradle-to-gate life cycle assessment was applied to study the equivalent CO2 emission and cost properties of the clinker-free binder. The seawater mixed mortar possesses comparable mechanical properties to Portland cement, with 3 d flexural and compressive strengths of 5.3 MPa and 25.2 MPa. In addition, the mortar developed in this work is of similar cost as commercial cement, but reduces CO2 emissions by 44.8%.

Enhancing the commercial viability of commercial algal bioethanol production: The role of technological advancements

Malaysia's economic growth relies on depletable fossil fuels that raise atmospheric CO2. Accordingly, researchers search for sustainable fuels that sequester significant levels of CO2. Chlorella vulgaris meets these criteria, but high production costs hamper its adoption. The hypothesis is that technological advances improve the commercial viability of algal bioethanol. A large-scale agricultural model is modified to study algal cultivation. Algal bioethanol becomes competitive if algal producers experience an annual 2 % harvest yield gain or a 3 % annual production cost reduction. Algal bioethanol is predicted to produce 4249.21 megalitres in 2059 for harvest yield gains. It sequesters 9.72 megatons of CO2-equivalent tailpipe emissions and 12.78 megatons of flue gas in 2059. Meanwhile, production cost reductions yield 1607.61 megalitres in 2064. It sequesters 3.68 megatons of CO2-equivalent tailpipe emissions and 10.68 megatons of flue gas in 2059. Thus, the hypothesis is supported that technological advancements improve the commercial viability of algal bioethanol.

Selection of track form in railway tunnel from a life cycle analysis perspective

AbstractThe use of greenhouse gas (GHG) emissions as a criterion for decision-making within the rail industry is increasing. The demand for considering this criterion affects the type of decision models acceptable by railway infrastructure managers in the planning, construction, and maintenance of railway assets. The total amount of GHG emitted from a track solution in tunnels during its service life depends on the track form (i.e., ballasted track or ballastless track), the type of construction, maintenance machines used, current traffic profile, and tunnel length. However, the development in the design of ballastless track systems during recent decades to make them environmentally friendly motivates infrastructure managers to rethink and consider the use of the system. This study examines the effect of several design and maintenance factors not adequately addressed in previous research. These factors are (i) the modulus of elasticity of track support affecting the design of track forms, (ii) differences in maintenance and renewal required for track forms in the corresponding line condition, and (iii) recent developments in optimizing the environmental impact of ballastless tracks. The GHG emissions, represented by life cycle carbon dioxide equivalent (CO2e) emissions, are calculated using the climate impact software developed by the Swedish Transport Administration Trafikverket. The result is compared with the estimated emission from the conventional ballasted tracks. The method proposed in this paper is applied in a case study to study the effect of applying the optimized ballastless track system Rheda 2000® in a railway tunnel (the Hallsberg-Stenkumla tunnel) as part of a new line project in Sweden. The model applied in the study is an integral part of an integrated decision support system for effectively selecting track solutions from a lifecycle perspective. The study´s findings are: (i) the life cycle CO2 equivalent emissions by a ballastless track during its life cycle are 10% lower than that of the ballasted track, (ii) the primary total emission driver for both track form solutions is the emissions generated at the manufacturing of rails. (iii) the second important emission factor for the ballasted track solution is the emission from the renewal of the track form during its life cycle, and (iv) the second important emission factor for the ballastless track solution is concrete manufacturing.

Biomethane and Green Hydrogen Production Potential from Municipal Solid Waste in Cape Coast, Ghana.

Biomethane and hydrogen are promising elements in the transition towards sustainable energy, due to their capacity to mitigate greenhouse gas emissions. In Ghana, efforts to promote sustainable waste valorization for energy production are underway; however, organic waste conversion into biomethane and hydrogen still needs to be expanded. This study aims to evaluate the potential of producing biomethane and hydrogen from the municipal solid waste in Cape Coast, and their injection into the national gas grid. The upgrading biogas obtained from anaerobic digestion of food/organic wastes was used to generate biomethane. The modified Buswell Equation and data from literature were used to estimate the amount of biomethane and hydrogen. The environmental impact was assessed using the CO2 equivalent emissions. The findings reveal that Cape Coast generated approximately 6,400 tons of food waste in 2021, with a projection to 11,000 tons by 2050. Biomethane and hydrogen quantities was estimated at 3,700,000 m³ and 784,000 kg in 2021, respectively. Their projection reaches to 6,600,000 m³ and 1,400,000 kg by 2050. Converting waste into biomethane and hydrogen is an eco-friendly method of their management and use for renewable energy in Ghana. Strategies can be integrated into Ghana national energy policies to encourage waste-to-energy projects.