Substantial Emission Reductions Research Articles

Deep-RNN based model for short-time forecasting photovoltaic power generation using IoT

Global warming is one of the most significant issues of the century due to climate change caused by increased carbon emissions resulting from the exploitation of fossil fuels. Consequently, renewable energies are considered an alternative that promotes cleaner production and offers a substantial reduction in carbon emissions. Therefore, accurately forecasting photovoltaic (PV) power generation is crucial for controlling and distributing electrical inventory and ensuring the stability and reliability of power systems. In this paper, we develop a model for forecasting short-term PV power generation based on deep Recurrent Neural Networks (deep-RNNs). To improve efficiency, our model uses weather and PV generation dataset on-site collected in real-time using IoT technology. Specifically, by leveraging deep-RNN, particularly the long short-term memory network (LSTM) and gated recurrent units (GRU), which excel at capturing long-term dependencies in time series data, this article proposes a combination of LSTM and GRU models to take advantage of both in different weather conditions. The results of the experiments show that the LSTM-GRU model that has been proposed performs better in PV power forecasting than both the LSTM and GRU models together.

Data-Science-Informed Operation, Maintenance Practices Reduce Emissions

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper URTeC 3866061, “Reducing Methane Emissions: Implementing Data-Science-Informed Operation and Maintenance Work Practices Using Continuous Monitoring Technology,” by Kathleen Jenkins, Carol A. Brereton, and Alex MacGregor, Qube Technologies, et al. The paper has not been peer reviewed. _ Diverse methods are used by oil and gas operators for methane leak detection and repair (LDAR). Deploying continuous monitoring (CM) point-sensor technologies to an oil and gas facility allows operators to implement novel operation and maintenance work practices to respond efficiently to methane emissions. The authors examine how data-science-driven work practices can result in substantial reduction in methane emissions compared with other LDAR methods. CM Technology CM point sensors track changes in parts per million of methane in the air. When several fixed sensors are deployed at a site, a large area can be surveilled. Using proprietary algorithms based on a plume-dispersion model, the volume and site rate of the methane emission are calculated. The probable location of the emission is estimated and, together with the volume, is shown on a Web-based dashboard that displays the changes in site rate through time. Alerts generated by the CM system allow the operator to respond to leaks more quickly than when waiting for data from an intermittent inspection to provide emission data. CM was deployed by a Permian Basin operator with a desire to operate cleanly, with transparency. The devices were installed with the operator beginning in March 2022 and continue to be active at the time of writing. Alerts generated by the system are delivered to operations personnel, including control-room operators, and investigated by field operators. When the source is identified, repairs are scheduled or completed on the spot and recorded for review. The operator has expanded the deployments throughout the field and uses the data to identify and repair leaks. Theory and Methods The CM devices were deployed around the fence line at several production facilities in the Permian Basin. The optimal number and placement of sensors was determined by analyzing publicly available wind data and sources of emissions at the facility. The CM devices have an inlet port that allows the ambient air to enter the device and flow across a metal oxide sensor. Metal oxide sensors measure the change in conductivity as the air flows across them as a result of the methane adhering to the metal. The change in conductivity, directly correlated with the parts per million of methane in the air, is recorded. Also measured are temperature and wind data, read by temperature sensors and anemometers on each device. This data is sent through a mobile telecommunications network to cloud-based servers that apply an emission-estimation model based on a plume dispersion and a localization algorithm to the data. Cloud services facilitate the transfer of information from devices to Web-based software. Each methane sensor is calibrated in the laboratory before installation by exposing it to known levels of methane. In this process, the temperature and humidity are systematically varied while the methane concentrations are changed and the reported conductivity is recorded. The resulting coefficients of conductivity are stored with the serial number of the device and sent to the device through the mobile network when it is deployed in the field.

The sustainability impacts of a web-based outpatient booking application.

Climate change is a critical global issue, impacting ecosystems, economies and communities worldwide. The shift from paper-based to digital systems is becoming increasingly prevalent across industries, with downstream positive impacts on sustainability. In 2020, Austin Health, a public tertiary hospital in Victoria, Australia, adopted a web-based outpatient booking application, which succeeded the prior paper-based system. The application served as an integrated platform for administrative staff to access various Austin Information Technology platforms and replaced previous mail-based outpatient appointment notifications with Short Message Service-based notifications. This study aimed to assess the environmental impact and organisation-wide economic cost of a web-based outpatient booking application compared to the prior paper-based system across the same time period. A retrospective environmental and economic assessment was conducted for both the web-based booking application and the paper-based system. The evaluation covered 36,925 outpatient diagnostic imaging studies - including CT, MRI, ultrasound and mammography - performed at Austin Health from 1st July 2023 until 30th June 2024. The environmental impact was assessed by calculating the expected carbon dioxide equivalent (CO2e) emissions produced by each system. The economic cost analysis was conducted from the perspective of the hospital and included the direct costs of labour and materials/consumables. CO2e emissions were significantly reduced using the web-based outpatient booking application compared to the prior paper-based system (38.5 tonnes compared to 0.002 tonnes), predominantly attributable to the elimination of postage-related fuel emissions (27.7 tonnes). The estimated net operating cost savings across the year was at least AUD 175,000 (in 2024 Australian Dollars, adjusted for inflation). This was primarily due to labour savings from the elimination of workflow inefficiencies (at least 2342 h saved) amounting to at least AUD 85,272 in salary, followed by savings from eliminated pathology tests (AUD 57,422) and postage costs (AUD 55,193). The adoption of the web-based outpatient booking application led to a substantial reduction in carbon emissions and operating costs, alongside enhanced operational efficiency and productivity. These benefits are anticipated to be enduring, especially in the face of an ever-increasing demand for medical imaging services.

The atmospheric oxidizing capacity in China – Part 2: Sensitivity to emissions of primary pollutants

Abstract. Despite substantial reductions in anthropogenic emissions, ozone (O3) pollution remains a severe environmental problem in urban China. These reductions affect ozone formation by altering levels of O3 precursors, intermediates, and the oxidation capacity of the atmosphere. However, the underlying mechanisms driving O3 changes are still not fully understood. Here, we employ a regional chemical transport model to quantify ozone changes due to a specified emission reduction (50 %) for winter and summer conditions in 2018. Our results indicate that reductions in nitrogen oxide (NOx) emissions increase surface O3 concentrations by 15 %–33 % on average across China in winter and by up to 17 % in volatile organic compound (VOC)-limited areas during summer. These ozone increases are associated with a reduced NOx titration effect and higher levels of OH radicals. Reducing NOx emissions significantly decreases the concentration of particulate nitrate, which enhances ozone formation through increased HO2 radical levels due to reduced aerosol uptake and diminished aerosol extinction. Additionally, an enhanced atmospheric oxidative capacity, driven by larger contributions from the photolysis of oxidized VOCs (OVOCs) and OH-related reactions, also favors urban ozone formation. With additional reductions in anthropogenic VOC emissions, increases in summertime ozone (VOC-limited areas) can be offset by reduced production of radicals from VOC oxidations. To effectively mitigate ozone pollution, a simultaneous reduction in the emission of NOx and specific VOC species should be applied, especially regarding alkenes, aromatics, and unsaturated OVOCs, including methanol and ethanol.

Mitigating Risk and Emissions in Power Systems: A Two-Stage Robust Dispatch Model with Carbon Trading

The large-scale integration of renewable energy sources is crucial for reducing carbon emissions. Integrating carbon trading mechanisms into electricity markets can further maximize this potential. However, the inherent uncertainty in renewable power generation poses significant challenges to effective decarbonization, renewable energy accommodation, and the security and cost efficiency of power system operations. In response to these challenges, this paper proposes a two-stage robust power dispatch model that incorporates carbon trading. This model is designed to minimize system operating costs, risk costs, and carbon trading costs while fully accounting for uncertainties in renewable energy output and the effects of carbon trading mechanisms. This model is solved using the column-and-constraint generation algorithm. Validation of an improved IEEE 39-bus system demonstrates its effectiveness, ensuring that dispatch decisions are both robust and cost-efficient. Compared to traditional dispatch models, the proposed model significantly reduces system risk costs, enhances the utilization of renewable energy, and, through the introduction of a ladder carbon trading mechanism, achieves substantial reductions in carbon emissions during system operation.

Technical efficiency of SO2 scrubbers with byproduct contracts

This paper explores the impact of synthetic gypsum, a byproduct of sulfur dioxide (SO2) abatement, on the technical efficiency of SO2 scrubber technology. On average SO2 scrubbers are 60% efficient suggesting substantial emission reductions are possible by narrowing the efficiency gap. Gypsum marketability provides an economic incentive for improved power-plant operation of scrubbers with 8.8% average increases in technical efficiency. By contrast, we do not find any statistically significant evidence of innovative change in scrubbing technology.

Preliminary analysis of an integrated ICE-gasifier plant for power generation from plastic waste material

Abstract The escalating global production of plastic waste is a challenge that must be rapidly addressed, but it also conceals opportunities. Currently, only a minor portion of the worldwide plastic waste is recycled, with the remainder destined for either incineration or landfill. In this context, gasification emerges as a sustainable alternative to conventional waste management methods, offering a substantial reduction in pollutant emissions. Dioxins and furans emissions, in fact, are drastically reduced when compared to incineration. Additionally, in contrast to landfill disposal, gasification allows for the recovery of chemical energy contained in plastic that would otherwise be wasted. The study of plastic gasification is gaining attention and several studies demonstrated feasibility and effectiveness, despite it is not as established as biomass gasification. The present paper aims at taking a step forward by conceptualizing an integrated gasifier-internal combustion engine power plant, operating in a closed-loop system. This layout offers potential benefits from both energetic and environmental points of view, respectively related to the recovery of engine waste gas and CO2 emission reduction. The proposed plant is based on the steam/CO2 gasification technique, which allows the complete conversion of input CO2 into syngas under certain thermochemical conditions. This feature enables the operation of engine and gasifier in a closed-loop system, directly exploiting the exhaust gas to perform plastic gasification. A thermodynamic feasibility study is performed, accounting for the efficiency of the main components, the heat fluxes and the heat absorbed by the endothermic reactions inside the gasifier. The setup of the proposed power plant shows an energy conversion efficiency up to 18% in a pure electric generation scenario and up to 56% in a cogeneration scenario.

Examining the synergy of green supply chain practices, circular economy, and economic growth in mitigating carbon emissions: Evidence from EU countries

Integrating green supply chain strategies and circular economy (CE) practices holds substantial potential for promoting environmental sustainability and reducing CO2 emissions. This study investigates the synergy between green supply chain practices, circular economy, and economic growth (RGDP) impacts on carbon emissions in 13 selected European Union (EU) countries, using a comprehensive panel dataset from 2000 to 2022. We employ both linear and nonlinear panel ARDL models, along with causality tests, to examine how CO2 emissions respond to changes in green supply chain management (GSCM), real GDP (RGDP), and various recycling practices, including bio-waste, municipal waste, and packaging waste. Our findings reveal that GSCM practices significantly reduce carbon emissions in the long run, while economic growth (RGDP) and municipal waste generation correlate positively with increased CO2 emissions. Interestingly, the nonlinear ARDL model highlights that only recycling packaging waste (RWP) exhibits a positive long-run effect on reducing emissions. Additionally, the method of moments quantile regression (MMQR) analysis indicates that the impact of GSCM is more pronounced at higher quantiles of CO2 emissions, whereas the effect of RGDP on emissions remains inconsistent. These results underscore the crucial need to adopt and enhance green supply chain practices within a circular economy framework to achieve substantial carbon emission reductions, holding significant implications for carbon emissions policies in the selected EU countries.

Hybrid and Electric Vehicle (EV) integration in public transport: Challenges and opportunities

As cities worldwide grapple with the dual challenges of increasing urbanization and climate change, the integration of hybrid and electric vehicles (EVs) into public transport systems emerges as a critical solution. This article examines the multifaceted challenges and opportunities associated with adopting hybrid and EV technologies for buses and coaches. Key challenges include the high initial costs, the need for robust infrastructure, and concerns regarding vehicle reliability. Conversely, the transition offers significant benefits, such as substantial emissions reductions, improved operational efficiency, and enhanced public perception of sustainable practices. Through an evaluation of successful case studies from cities like London, Amsterdam, and Shenzhen, this article highlights effective strategies and outcomes achieved in the realm of public transport electrification. Ultimately, the findings underscore the necessity for collaborative efforts among stakeholders to drive the successful integration of hybrid and EV technologies, paving the way for a more sustainable urban mobility future.

Progress in Corrosion Protection Research for Supercritical CO2 Transportation Pipelines

Carbon Capture, Utilization, and Storage (CCUS) technology is an emergent field with the potential for substantial CO2 emissions reduction, enabling low-carbon utilization of fossil fuels. It is widely regarded as a critical technology for combating global climate change and controlling greenhouse gas emissions. According to recent studies, China has identified CCUS as a key emissions reduction technology in climate change response and carbon neutrality objectives. Within this framework, supercritical CO2 (SC-CO2) transport pipelines are an essential means for efficient and safe transportation of CO2. Corrosion protection of pipelines enhances the efficiency and safety of CCUS technology and supports broader implementation and application. This paper reviews the current research on corrosion protection for SC-CO2 transport pipelines, discusses effect factors, compares various corrosion protection strategies, and analyzes the challenges in corrosion protection of SC-CO2 transport pipelines. It concludes with a perspective on future research and development directions in this field. This paper is dedicated to providing new research strategies for pipeline corrosion protection in CCUS technology in the future, and providing technical support for pipeline corrosion protection in CCUS industrial applications.

The impact of calcined mud on the rheological properties of eco-friendly concretes using the equivalent mortar method (CEM)

In order to harmonise technical and environmental aspects, people today focus not only on concrete's technical characteristics but also on environmental imperatives. Thus, the emphasis is on the development of concrete and cements that offer ecological and sustainable advantages. Commonly, people use various natural materials as cement additives, demonstrating their effectiveness by replacing a significant portion of the cement in the hardened state of concrete. This substitution leads to a substantial and remarkable reduction in carbon dioxide emissions. However, when it comes to the physical properties of the material in its fresh state, challenges may arise. Indeed, the rheological changes induced by these additives may hinder the on-site use of this eco-concrete. The main purpose of this study is to find out how adding minerals to environmentally friendly concrete changes its rheological parameters (yield stress, plastic viscosity) and fresh properties (slump, flow time). We will approach this using the concept of mortar equivalent to concrete (CEM). We developed five formulations of CEM’s by substituting cement with calcined mud (CM) in binary mixing systems at a temperature of 20 °C. The results showed that adding binary cements with calcined mud had a negative effect on the fresh properties and rheological parameters. However, when substitution happens at a low rate, it behaves almost like control mortar (OPC).

Study on properties and CO2 emission of self-pulverizing calcium sulfoaluminate (SPCSA) after carbonization curing

The extensive use of Portland cement (OPC) has resulted in a steady rise in CO2 emissions from the construction industry, posing a significant climate threat. While adopting low-carbon cement enriched with belite minerals holds promise for substantial CO2 emission reduction in the cement industry, the limited early hydration activity of C2S constrains its engineering applications. Carbon capture, storage, and utilization (CCUS) technology, capable of rapidly developing the strength of C2S, opens up a new avenue for utilizing low-carbon cement. This study evaluated the properties of self-powdering calcium sulfoaluminate (SPCSA) cements with different C2S contents, and the carbon emissions during production and application were analyzed. The samples' carbonation area, compressive strength, and capillary water absorption properties were tested. The carbonation products and pore structures were also characterized using XRD, TGA, SEM, and Low-NMR. The results show that when the molar ratio of C4A3S̅ to C2S is 1:12 (S̅12), the compressive strength and CO2 sequestration of SPCSA are 69.78 MPa and 0.15 g/g, respectively. When CCUS technology is adopted, the CO2 emission during the production and application of SPCSA is 585.78 kg/t, much lower than that of OPC of 878.28 kg/t. This is significant as a reference for realizing carbon neutrality in the cement industry.

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.

A System Dynamics Supply Chain Analysis for the Sustainability Transition of European Rolled Aluminum Products

This research presents a system dynamics model to study the interaction among demand and supply evolutions, government regulations, sustainable adoption trends, investments in different decarbonization technologies, and environmental requirements for the European Aluminum Rolled Product Supply Chain (ARPSC). It allows stakeholders to assess the quantitative impact of investing in decarbonization technologies on supply chain sustainability. Investing in decarbonization technologies reduces greenhouse gas (GHG) emissions. The most substantial GHG emission reductions can be achieved if upstream ARPSC actors invest according to an aggressive investment strategy between 2031 and 2040. However, even with an aggressive investment strategy, investing in decarbonization technologies alone is likely to be insufficient to achieve the European Green Deal goals. Furthermore, barriers to investment in decarbonization technologies and a low rate of progress in doubling the European Union’s circularity rate may put extra stress on achieving the European Green Deal goals for the European ARPSC. Instead, ARPSC actors will additionally need to optimize the recycling of aluminum rolled products and adopt strategies for resource sufficiency, e.g., by sharing cars and using packaging multiple times.

Coarse bubble mixing in anoxic zone greatly stimulates nitrous oxide emissions from biological nitrogen removal process

The biological nitrogen removal process in wastewater treatment inevitably produces nitrous oxide (N2O), a potent greenhouse gas. Coarse bubble mixing is widely employed in wastewater treatment processes to mix anoxic tanks; however, its impacts on N2O emissions are rarely reported. This study investigates the effects of coarse bubble mixing on N2O emissions in a pilot-scale mainstream nitrite shunt reactor over a 50-day steady-state period. Online and offline N2O monitoring campaigns show that coarse bubble mixing in the anoxic zones significantly elevates N2O emissions, yielding an extremely high emission factor of 15.5 ± 3.5 %. Intensive sampling and isotopic analyses suggest that the elevated emissions are primarily due to the inhibition of the N2O denitrification process by oxygen in the anoxic phase introduced by coarse bubbling. Substituting coarse bubble mixing with submersible pump mixing resulted in a substantial reduction of N2O emissions, decreasing the emission factor by an order of magnitude to 1.2 ± 0.8 %. The findings reveal that a previously overlooked factor, coarse bubble mixing, can significantly stimulate N2O emissions. The use of coarse bubble mixing in anoxic tanks of biological nitrogen removal warrants caution.

A-124 Sustainable Transport: Assessing Environmental Impact in Medical Sample Transit via Drones and Vehicles

Abstract Background This research explores the ecological implications associated with different methods of transporting medical samples, specifically focusing on drones, combustion cars, and electric cars within two laboratories in central European countries. With the primary goal of assessing and comparing CO2 consumption, delivery time, and overall environmental impact, the study aims to provide a basis for adopting sustainable practices in healthcare logistics. Methods The transportation of medical samples occurred between two laboratories in the Principality of Liechtenstein and Switzerland, utilizing authorized aerial and road routes. Various weather conditions and distances were considered for sample transports using different vehicles (8 combustion cars, two electric cars, and one drone model). Energy consumption was documented, and the CO2 footprint was calculated based on data from the Swiss Federal Office for the Environment (FOEN) for both imported and renewable electricity. Comparative analyses were conducted to quantify the environmental impact of each transportation method. Results In terms of CO2 footprint, combustion cars exhibited a CO2 release of 159.5 g/km, while electric cars showed 3.43g (2.15 to 4.08% of combustion cars). Drones demonstrated a minimal 0.09g CO2 emission per kilometer (0.066% of combustion car CO2 emission; 2.6% of electric car CO2 emission). The distance traveled by drones was significantly shorter (16.7% to 50%). Additionally, the efficiency of drone transport was emphasized by its ability to avoid traffic jams and associated detours, resulting in time savings ranging from 31.25 to 50% per delivery when comparing transport times during rush hour and regular hours in the selected setting. Conclusions The integration of drone technology emerges as a crucial strategy for establishing a “green laboratory.” The substantial reduction in CO2 emissions and enhanced delivery efficiency position drone transport as a sustainable and operationally effective solution for medical sample logistics, offering shorter delivery times. These findings highlight the potential for transformative change in healthcare logistics, aligning with the global shift towards sustainability and green practices.

An Immersive VR Training Scenario for Safe Methanol Bunkering in the Maritime Industry

Abstract The maritime industry, pivotal in global commerce, faces critical challenges in mitigating environmental impacts, especially greenhouse gas emissions. The International Maritime Organization (IMO) targets a substantial reduction in emissions by 2050, necessitating innovative approaches to fuel usage. Methanol, recognized for its lower carbon intensity, emerges as a viable alternative fuel. However, its flammability and toxicity introduce complex safety and operational demands. To address these challenges, we have developed a state-of-the-art Virtual Reality (VR) training program specifically for methanol bunkering operations. This training, utilizing Unity 3D and Meta Quest 2, offers a highly interactive and realistic experience. Trainees engage in a comprehensive simulation that covers the entire bunkering process, including safety checks, equipment handling, and emergency response protocols. The VR environment allows for dynamic adjustments by trainers, enhancing the realism and educational value of the scenario. Our program also includes an assessment component that evaluates the trainee’s performance across various metrics such as safety protocol adherence, decision-making, and situational awareness. The anticipated outcome of this VR training initiative is to significantly improve the preparedness of maritime personnel in handling alternative fuels, thereby supporting the industry’s transition towards sustainable practices and contributing to broader environmental protection goals.

DESIGN and be SMART: Eleven engineering challenges to achieve sustainable air transportation under safety assurance in the year 2050

The aviation industry faces various challenges in meeting long-term sustainability goals amidst surging demand for air travel and growing environmental concerns of the general public. The year 2050 is set as an ambitious goal for net zero emissions, a substantial reduction in carbon dioxide emissions per passenger kilometer flown, major improvements in aircraft energy efficiency, and a development towards autonomous, intelligent operations. This review explores the pivotal role of advancements in engineering for achieving sustainability in aviation. Through a comprehensive review of existing literature and case studies, our work highlights how innovations in all aspects of aircraft engineering coupled with operations-related technologies, offer promising solutions to mitigate environmental impact, enhance efficiency, and ensure long-term sustainability in aviation operations. To discuss the necessary advances, we promote the so-called ‘DESIGN and be SMART’ framework, consisting of eleven complementary engineering challenges towards reaching sustainability. To address the high safety levels reached in air transportation, our DESIGN and be SMART framework also addresses the safety assurance challenge that is overarching each of the eleven engineering challenges. We believe that through an orchestrated integration of hardware advancements with innovative software solutions, and novel safety assurance methods, the aviation industry can realize synergistic benefits that drive sustainable growth of air transportation. Our review contributes to such an orchestration by describing the status quo and research challenges ahead.

Energy Transition Analysis and Climate Action Strategy in the Power Sector: A Case Study of the Java-Bali System

Abstract The transformation of societies over time has led to a marked shift in energy consumption patterns. In the face of rapid industrial growth and a burgeoning population, Indonesia confronts the multifaceted challenge of achieving a balance among energy trilemma: energy security, economic affordability, and environmental sustainability. This study assesses the feasibility of low-carbon energy systems in Indonesia, evaluating current policies and proposing a roadmap for net-zero emissions. Utilizing the Low Emissions Analysis Platform (LEAP) and the Next Energy Modeling System for Optimization (NEMO), the study explores multiple scenarios—namely, Business-as-Usual (BAU), Carbon Capture and Storage Mitigation (CCSM), and New and Renewable Energy Mitigation (NREM). Of these, the NREM scenario, emphasizing the integration of innovative and renewable energy sources, achieves the most substantial reduction in greenhouse gas emissions while maintaining economic viability. This strategy advocates for the comprehensive adoption of new and renewable energy, aiming to approximate zero emissions by 2060. The peak direct cost of production for this scenario is estimated at $270.8 billion. However, each scenario presents its own set of technological, economic, and policy-related challenges, necessitating strategic solutions for a successful transition to sustainable energy systems.

Exploring the long-term variations and high concentration episodes of peroxyacetyl nitrate in Megacity Seoul

Over the past few years, peroxyacetyl nitrate (PAN) has drawn significant attention as a key indicator of photochemical pollution owing to its intimate relationship with ozone and associated health effects. This study presents measurements conducted at the Korea University campus in Seoul during the high-ozone seasons from 2018 to 2021. PAN concentration was measured using fast gas chromatography with luminol chemiluminescence detection (GC-LCD), alongside measurements of O3, volatile organic compounds (VOCs), NO, NO2, and meteorological variables, including boundary layer height (BLH).The mean concentrations of PAN and O3 over the years were 0.56 ppbv and 35 ppbv in 2018, 1.29 ppbv and 58 ppbv in 2019, 0.21 ppbv and 50 ppbv 2020, and 0.53 ppbv and 46 ppbv in 2021, respectively. The annual variation observed in Seoul is consistent with trends seen in major cities worldwide during the COVID19 pandemic, reflecting a substantial reduction in urban emissions. Notably, the mean concentration of NOx and VOCs decreased significantly by more than 50 % and 25%, respectively, from 2019 to 2021.At temperatures above 30 °C, PAN decomposition was accelerated, decoupling a consistent positive relationship between PAN and O3 in 2020 and 2021. The results of a 0-D photochemical model (F0AM) calculation demonstrated that PAN formation primarily stems from anthropogenic VOCs, particularly > C2 alkenes. Elevated PAN concentrations during nighttime were attributed to boundary layer expansion and upper-air entrainment. Instances where PAN concentrations surged to at least 3 ppbv or higher in 2019 were attributed to biomass burning impacted air, as evidenced by concurrent elevations in K+ and OC in PM2.5, and O3.This study underscores the complex interplay of factors influencing PAN and ozone enhancements under decreased precursor levels, with an emphasis on dynamic change in the boundary layer, and long-distance transport of non-fossil sources during agricultural burning seasons.