Reduce Greenhouse Gas Emissions Research Articles

Comparative Analysis of the use of Band Heaters and Infrared Heaters to Save Energy on Injection Molding Machines Type Borche Bi 320T

This study aims to compare the energy efficiency between the use of a heater band and an infrared heater on an injection molding machine type borche bi 320T. The injection molding machine is one of the main pieces of equipment in the manufacturing process of plastic products and plays an important role in shaping various consumer and industrial products. One of the critical aspects of the operation of injection molding machines is the significant energy consumption, especially related to heating. This study was conducted by measuring the energy consumption of both types of heaters under the same operational conditions. The results showed that the energy consumption of using a band heater was 46.9 kW, while the infrared heater was 38.9 kW, significantly more energy efficient by 17.1% compared to the band heater. Although the initial installation cost of the infrared heater is 87% higher than that of the band heater, the energy savings generated from the infrared heater can reduce operating costs by approximately $39 million per year. Higher energy efficiency means lower electricity costs and, thus, more efficient total production costs. The use of infrared heaters also has a positive impact on the environment. Reduced energy consumption means reduced greenhouse gas emissions from power generation. Therefore, besides the economic benefits, the use of infrared heaters is also in line with sustainability and environmentally friendly practices.

Reduced Kinetic Mechanism for Modeling High-Temperature Ignition and Flames for n-Pentanol.

n-Pentanol has emerged as a promising substitute for fossil fuels due to its potential in reducing greenhouse gas emissions. This work presents a reduced combustion mechanism for modeling high-temperature ignition (T > 1000 K) and flames for n-pentanol/air mixtures. The model comprises only 64 species and 282 chemical reactions. As we know, this is the first comprehensive study to include all available experimental data for these phenomena and this specific fuel/oxidizer mixture, reported in the literature. Our approach involves coupling a detailed submechanism for n-pentanol to the San Diego mechanism, a reduced scheme for C1-C4 hydrocarbons, followed by a systematic reduction process, mainly using sensitivity analysis and steady-state approximation. We quantitatively assessed the agreement between experimental data and simulation results using deviation or error indicators along with graphical comparisons. Remarkably, the ignition delay times and flame speeds calculated using the reduced kinetic model exhibit a high agreement with the experimental data reported in the literature.

Mitigating GHG Emissions from Military Supply Chain by Use of Aerial Cable Way

The transportation sector being one of the significant contributors to greenhouse gas (GHG) emission, there is growing concerns about environmental sustainability, and reducing GHG emissions which has prompted re-evaluation of transportation systems. The 1.5 million strong Indian defence forces have huge transport fleet and this study delves into the potential of Aerial Cableway (ACW) as a promising alternative mode of transport that can significantly reduce emissions of military supply chain in mountainous terrain. The study takes a case of Himalayan terrain to investigate how ACWs offer a low-impact, energy-efficient, and environmentally friendly solution compared to conventional ground-based transportation. It takes a case of Pharkian Pass in North Kashmir where defence forces has presence and this pass is often exposed to frequent landslides, snowfall and avalanches. Every year, on an average, approximately 12,000 trucks cross Pharkian pass in a year for purpose of logistics and sustenance. Without touching sensitive issues and by using a multi-criteria-based cost-benefit analysis, the study establishes that even if 75 % of road transport trips are shifted to ACWs, the reduction of GHG emissions is by 57.7 % in addition to significant benefits of the social cost of carbon, environmental costs, economic savings and ensuring strategic advantage like all-weather connectivity.

A numerical feasibility study of CO2 foam for carbon utilization and storage in a depleted, high salinity, carbonate oil reservoir

Carbon Capture, Utilization, and Storage (CCUS) offers a viable solution to reduce the carbon footprint in the petroleum industry, and foam injection presents a promising method to achieve this while simultaneously increasing oil recovery. In this work, we studied the feasibility of CO2 foam for co-optimizing enhanced oil recovery and CO2 storage in a high-salinity carbonate formation. The simulated hydrodynamic model is a depleted formation containing 30% residual oil, with three mechanisms for CO2 storage: solubility, residual, and mineralization trapping mechanisms. The results showed that after 20 years, oil recovery during foam injection was 2.7 times higher than CO2 injection, and the CO2 stored during foam flooding was 38% higher than CO2 injection. Notably, foam injection also increased CO2 storage capacity by 2.6 times, indicating the potential to store around 2 gigatons of CO2 in the simulated model. This was attributed to the ability of foam to significantly reduce gas mobility and thus form isolated bubbles through its Jamin effect. Residual trapping was the dominant trapping mechanism, contributing to over 70% of the total CO2 trapped, attributed to the reduction in the dissolution of CO2 in brine due to the high salinity of the aqueous medium. CO2 mineralization was also studied, showing the least trapping efficiency and the dissolution trend of all the carbonate minerals. This study illustrates a novel CO2 utilization and storage technique in which CO2 is concurrently sequestered while enhancing oil recovery in a depleted oil reservoir by injecting CO2 as foam. The relevance of this study lies in its potential to provide a dual benefit of reducing greenhouse gas emissions and boosting oil production, offering a sustainable approach for the petroleum industry.

Effects of clean fracturing fluids on coal microstructure and coalbed gas adsorption

Nowadays, some fracking fluids can enable resourceful extraction of coalbed methane and reduce greenhouse gas emissions. However, their toxicity or corrosiveness will cause harm to downhole workers and pollute groundwater resources. Thus, five kinds of clean composite fracturing fluids were developed in this paper by using starch solution as the matrix and adding various preparations. The change rule of methane adsorption capacity by microstructure changes of coal samples was investigated systematically, and the optimal composite fracturing fluid was determined. The results showed that the new fracturing fluid increased the degree of aromatic ring condensation by 43.3% and the average pore size by 52.1%. Also, the adsorption constants of a value decreased by 11.6% and b value decreased by 23.9%, which can remarkably reduce the methane adsorption. The experimental results provide theoretical support for the clean production of coalbed methane.

The social cost of carbon falling on the wealthy

Under the Paris Agreement, the responsibility for reducing greenhouse gas emissions lies with individual countries, which submit pledges to the United Nations Framework Convention on Climate Change (UNFCCC) outlining their ambitions and timelines for emission reductions. Within countries, emissions are unevenly distributed among individuals, with the wealthy known to emit disproportionately more. Since greenhouse gas emissions represent a social cost, this paper investigates the economic implications of the lifestyles of the wealthy. The social cost of carbon (SCC) attributed to millionaires—defined based on their assets, including property—is calculated using national emissions data, distributional data, and SCC assessments for both historical (1990–2022) and future periods (2023–2050). The results suggest that only 1.3% of the global SCC, estimated at US$8.7 trillion, was covered by any form of carbon pricing in 2022. Of this amount, 16.5% (US$1.4 trillion) is attributable to millionaires, who represent just 0.8% of the world's population. The most cost-effective climate policy would be to internalize the SCC, ensuring that the carbon price is equal to the SCC. If the SCC remains externalized, the wealthiest individuals could benefit by an estimated US$25.1 trillion over the period from 2023 to 2050. Other market-based mechanisms will be necessary to curb the carbon-intensive consumption patterns of the wealthy.

CRITERIA FOR ASSESSING THE EFFECTIVENESS OF TRANSPORT POWER PLANTS DECARBONISATION IN ACCORDANCE WITH IMPLEMENTATION OF THE SUSTAINABLE DEVELOPMENT CONCEPT

The directions of restoration and further development of the energy sector in Ukraine are considered in accordance with power plants with internal combustion engines, taking into account the widespread implementation of the Sustainable Development concept, which allows solving existing modern social, economic and environmental problems. For Ukraine, taking into account the economic opportunities and selected priorities for the chosen path of development, it is necessary at this time to choose gradual and specific directions to implement the Sustainable Development concept. The most priority areas of practical implementation of the concept are determined and it is indicated that the effectiveness of this implementation is associated with the development of the industry on the basis of the fourth and fifth industrial revolutions (Industry 4.0 and Industry 5.0). One of the main tasks in solving the problems of the concept is to ensure the environmental component. Notwithstanding the noted progress in improving the environmental efficiency of internal combustion engines, further attention needs to be paid to the task of spreading the introduction of “green energy”, i.e. decarbonisation – reducing greenhouse gas emissions into the environment (CO2). The issue of decarbonisation in the future should be given the greatest attention both in the development and in the manufacture and operation of engines. It is shown that the assessment of the impact of CO2 emitted with the exhaust gases of internal combustion engines into the environment is carried out taking into account the model of operation of engines and the justification of the introduced adjustments. A new criterion is proposed, which is called: “ICE criterion of environmental thermal pollution”, which is proposed for use in studies to assess the effectiveness of the implementation of decarbonisation strategies in all modes of transport at implementation of the Sustainable Development concept in global transport power plants. A method for determining the efficiency of physical and chemical processes of mixture formation and combustion in internal combustion engine cylinders is proposed when using hybrid fuel with “green hydrogen” as its component, which allows determining the dependence of hydrogen influence on the level of engines effective performance and formation of harmful emissions in exhaust gases.

Prospects of green hydrogen production in the Philippines from solar photovoltaic and wind resources: A techno-economic analysis for the present and 2030

As global temperatures continue to rise, reducing greenhouse gas emissions is more important than ever – demanding an urgent transition to renewable energy systems. In this study, the potential for green hydrogen production from solar and wind sources in the Philippines is explored. Renewable energy systems can yield higher decarbonization by producing green hydrogen, potentially an ‘energy vector’ for industrial, power, and transportation applications, thereby representing a promising solution for the nation's energy transition. This study explores the competitiveness of green hydrogen production in the Philippines through a comprehensive techno-economic analysis to predict the levelized cost of hydrogen (LCOH) derived from solar- and wind-powered electrolysis. The 2030 projections explore three scenarios, each representing varying research and development intensities resulting in different electrolyzer costs. The resulting LCOH values underscore the need for economic policy interventions to slash hydrogen costs to a competitive level. The present and near-future costs and attributes of electrolysis technologies still fall short compared to fossil fuel-based pathways. Furthermore, sensitivity and uncertainty analyses are conducted to investigate subsidy and policy requirements, and random changes to costs. The findings of this work provide a comprehensive understanding of the potential fluctuations and challenges in the economic landscape in the Philippines.

Demonstrating clean energy transition scenarios in sector-coupled and renewable-based energy communities.

Energy communities facilitate several advantages, including energy autonomy, reduced greenhouse gas emissions, poverty mitigation, and regional economic development. They also empower citizens with decision-making and co-ownership prospects in community renewable projects. Integrating renewable energy sources and sector coupling is a crucial strategy for flexible energy systems. However, demonstrating clean energy transition scenarios in these communities presents challenges, including technology integration, flexibility activation, load reduction, grid resilience, and business case development. Based on the system of systems approach, this paper introduces a 4-step funnel approach and a 4-step reverse funnel approach to systematically specify and detail demonstration scenarios for energy community projects. The funnel approach involves four steps. First, it selects demonstration scenarios promoting energy-efficient state-of-the-art renewable technologies and storage systems, flexibility through demand side management techniques, reduced grid dependence, and economic viability. Second, it lists all existing and planned project technologies, analysing energy flows. Third, it plans actions at different levels to implement the demonstration scenarios. Fourth, it validates the strategies using key performance indicators (KPI) to quantify the effectiveness of the planned measures. Furthermore, the reverse funnel approach delves deeper into the demonstration scenarios. The four steps involve identifying stakeholder perspectives, describing scenario scopes, listing conditions for realisation, and outlining business models, including value chains and economic assumptions. This approach provides a detailed analysis of the demonstration scenarios, considering actors, objectives, boundary conditions, and business assumptions. The methodologies are exemplified in three diverse European energy communities extending across residential, commercial, tertiary, and industrial establishments, allowing power-to-x and sector coupling opportunities. The paper also suggested thirteen KPIs for validating renewable-focused energy community projects. Finally, the paper recommends increased collaboration between energy communities, knowledge sharing, stakeholder engagement, transparent data collection and analysis, continuous feedback, and method improvement to mitigate policy, technology, business, and market uncertainties.

USE OF METHANOL AS MOTOR FUEL FOR MARINE INTERNAL COMBUSTION ENGINES

The international maritime organization's intention to reduce greenhouse gas emissions to the atmosphere by two times compared to 2008 by 2050 prompted manufacturers of marine engines to start actively searching for ways to solve this problem. Since significant global changes in the structure of ship power equipment are not expected during this period, the main efforts of researchers are aimed at solving the problem of reducing emissions based on piston engines, which today form the basis of ship power. The technology of the first stage of reducing greenhouse gas emissions was the conversion of marine diesels to gas fuels, and primarily to methane. These technologies, which are already widely used in water transport today, make it possible to reduce greenhouse gas emissions by 20...25%, but do not solve the problem completely. Today it is clear that a global solution to the problem is possible only when using as motor fuel compounds that are either carbon-free, i.e. do not contain carbon in their composition at all, or are carbon neutral, i.e. contain carbon extracted from the atmosphere by biological or technological means. One such compound is methyl alcohol or methanol. Today, most of the methanol in the world is produced either from coal or from natural gas, so the total emissions of greenhouse gases when burning such methanol even exceed emissions from burning petroleum fuels, however, unlike the latter, this compound can be obtained from biological raw materials, or by binding atmospheric carbon. Today, such methanol, which has received the name «green», is too expensive, and its production technologies require further development. This can happen only if there is international stimulation and regulation of this area of production. But the introduction of such regulation requires a clear understanding of the technical feasibility and economic and environmental feasibility of using methanol as a motor fuel. That is why leading manufacturers today are working on solving these issues. Their solution is considered the second stage on the way to the complete decarbonization of shipping, and at this stage there has been significant progress in recent years. This article is devoted to the analysis of the current state of the question regarding the use of methanol as motor fuel for ship engines of all types and sizes.

The long-term nitrogen fertilizer management strategy based on straw return can improve the productivity of wheat-maize rotation system and reduce carbon emissions by increasing soil carbon and nitrogen sequestration

ProblemFacing the multiple objectives of increasing production, carbon sequestration, and nitrogen reduction in farmland, optimizing straw and nitrogen fertilizer management to achieve a balance between grain production and ecological safety in the wheat-maize rotation system has become increasingly critical and urgent. MethodsThis study conducted a five-year field experiment in the Guanzhong Plain of China from 2017 to 2021 to investigate the effects and synergistic regulatory mechanisms of straw disposal methods (straw return, no-straw return) and nitrogen application rates (0, 150, 225, 300 kg ha−1) during the maize season on soil greenhouse gas (GHG) emissions, crop yield, and soil organic carbon (SOC) and soil toatl nitrogen (STN) content. ResultsThe results showed that under the scenario of no-straw return, fertilization increased soil nitrous oxide (N2O) emissions by 35.9–64.0 %, and annual total crop yield by 16.4–22.8 %; however, under the straw return scenario, the increase in soil N2O emissions due to fertilization decreased to 26.7–62.0 %, while the yield increase rose to 19.5–25.9 %. The interaction effect between straw return and nitrogen application was significant, with straw return boosting the contribution rate of nitrogen application to yield (2.2–4.4 %) and simultaneously reducing the contribution rate of nitrogen application to N2O emissions (3.0–27.5 %). The study also indicated that the yield-increasing effect of straw return continued to increase with the duration of straw return, with the contribution rate to yield reaching 9.9 % after three years of continuous straw return, while the contribution rate of nitrogen application to yield increased by an average of 3.0 % per year. This suggests that there is significant potential for coupling straw return with reduced nitrogen application. Straw return combined with nitrogen fertilizer increased SOC content by 7.9–40.1 % and 3.7–12.5 %, STN content by 1.0–22.8 % and 6.1–13.9 %, respectively, compared to sole nitrogen application and sole straw return. Pathway analysis indicated that straw return combined with nitrogen fertilizer mainly enhanced soil carbon-nitrogen sequestration, improved fertilizer utilization efficiency and crop nutrition levels, reduced net global warming potential (GWP) and greenhouse gas intensity (GHGI), and synergistically regulated to increase yield while reducing GHG emissions. ConclusionThe study highlights that straw return lowers the threshold for nitrogen application levels, suggesting that regulating nitrogen application levels between 224 and 256 kg ha−1 during the maize season, and maintaining a nitrogen application level of 195 kg ha−1 during the wheat season, is beneficial for long-term stable production and emission reduction in the wheat-maize rotation system farmland.

Optimizing the greenhouse gas emissions of waste transfer and transport: An integration of life cycle assessment and vehicle routing problem

This study presents a comprehensive analysis of greenhouse gas (GHG) emissions associated with waste transfer and transport, incorporating derived leachate treatment—a factor often overlooked in existing research. Employing an integration model of life cycle assessment and a vehicle routing problem (VRP) methods, we evaluated the GHG reduction potential of waste transfer and transport system. Two Chinese counties with different topographies and demographics were selected, yielding 80 scenarios that factored in waste source separation as well as vehicle capacity, energy sources, and routes. The functional unit (FU) is transferring and transporting 1 tonne waste and treating derived leachate. The GHG emissions varied from 12 to 39 kg CO2 equivalent per FU. Waste source separation emerged as the most impactful mitigation strategy, not only for the studied system but for an integrated waste management system. Followings are the use of larger capacity vehicles and electrification of the vehicles. These insights are instrumental for policymakers and stakeholders in optimizing waste management systems to reduce GHG emissions.

Role of biochar as a greener catalyst in biofuel production: Production, activation, and potential utilization – A review

BackgroundBiochar is an affordable carbonaceous product produced through a combination of thermochemical conversion processes using organic feedstock in the absence or constrained supply of oxygen. Biochar-based catalysts are promising in numerous catalytic applications for sustainable bioenergy production. MethodsHydrothermal carbonization, gasification, and pyrolysis are conventional biochar production techniques. The biochar must be activated to improve its physiochemical characteristics. The activation is generally classified into three types: physical, chemical, and impregnation. The biochar-based catalysts are categorized into different types, such as pristine, heteroatom-doped, metal-loaded, magnetic, and nanometallic oxide/hydroxide biochar. Significant findingsThese biochar-based catalysts effectively catalyze various biochemical reactions and are extensively used in biofuel production. This article extensively explores various biochar production and activation strategies and their applications as a catalyst for biofuel production. Activated biochar with improved surface properties has a high surface area and adaptable surface chemistry, making it a sustainable alternative to conventional catalysts. Biochar from renewable biomass has advantages in waste management, carbon sequestration, and reduced greenhouse gas emissions. Further research and innovation using nanomaterials, artificial intelligence, and machine learning are needed to utilize biochar as a sustainable and potential green catalyst for advanced biofuel production.

Fundamentally understanding carbonation-induced corrosion of steel in environmentally friendly concretes

Reducing greenhouse gas emissions in concrete production is crucial to achieve sustainability goals. One of the primary solutions is employing environmentally friendly cements with lower clinker content, such as those containing supplementary cementitious materials. However, concretes produced with some of these cements are vulnerable to fast carbonation, which raises durability concerns regarding corrosion of the steel reinforcement. While traditional approaches focus on preventing concrete carbonation and corrosion initiation, evidence shows that corrosion rates of steel in carbonated concrete do not necessarily compromise durability. In this context, the fundamental understanding of the kinetics of carbonation-induced corrosion must be improved, considering the role of the concrete pore solution, pore structure, and moisture content, as discussed in this paper. Open questions and promising approaches to clarify them are also discussed. Based on this knowledge, corrosion propagation can be properly included in the service life design of reinforced concrete structures, reconciling the goals for both sustainable and durable structures.

Mitigating nitrogen loss in paddy field microcosms through indigenous arbuscular mycorrhizal fungi assemblage

AbstractWhether farmers should consider the role of arbuscular mycorrhizal fungi (AMF) in agriculture is a hotly debated topic. We aimed to investigate the role of indigenous AMF in reducing nitrogen (N) loss from paddy fields via runoff, leaching, NH3 volatilization, and N2O emission. We conducted a pot experiment employing a mycorrhiza‐defective rice mutant (non‐mycorrhizal) as the control, grown in soil containing indigenous AMF. The corresponding AMF treatment used the progenitor of this mutant with the same soil. The plants were fertilized with nitrogen, phosphorus and potassium 6 weeks after sowing. The root colonization was 23% in mycorrhizal rice, and no typical AMF structures were observed in the roots of non‐mycorrhizal rice. Our findings indicated that the mycorrhizal system exhibited lower N concentrations of runoff and leachate further compounded by reduced fluxes of N2O and NH3. This led to 14% decrease (mycorrhizal rice 111 kg N ha−1; the non‐mycorrhizal rice: 129 kg N ha−1) in cumulative N loss within 3 days post‐fertilization. While this AMF effect was consistent across the four tested N loss pathways, differences were observed between NH4+‐N and NO3−‐N in the runoff pathway. Notably, our results revealed no evidence of trade‐offs in AMF effect on N loss among the tested pathways. Additionally, mycorrhizal rice had larger shoots and roots than their non‐mycorrhizal counterparts. Our study underscores the potential benefits of indigenous AMF in paddy fields for mitigating water pollution and reducing greenhouse gas emission.

The role of value, belief and norm in shaping intentions to use residential rooftop solar for environment sustainability

The ongoing climate crisis presents a formidable global challenge, driving the urgent need for both technological advancements and a deeper understanding of the psychological factors that influence sustainable energy practices. Among the various technologies available, solar photovoltaic (PV) systems are pivotal in reducing greenhouse gas emissions. However, the adoption of residential rooftop solar systems, particularly from a psychological perspective, remains underexplored. Hence, this study aims to investigate the influence of personal values, beliefs, and norms on the intention to adopt residential rooftop solar systems. By integrating the Value-Belief-Norm (VBN) framework with Norm Activation Theory (NAT) and the norm internalization process, the research seeks to provide a more nuanced understanding of the environmental and sustainability context. This study employs a non-probability purposive sampling method, collecting 303 valid responses from individuals who do not currently use residential rooftop solar systems, live in landed houses, and are involved in primary household decision-making. Data were analyzed using SmartPLS software. The findings confirm all hypothesized relationships, except for the impact of egoistic values on both the new ecological paradigm and awareness of consequences, as well as the influence of descriptive norms on personal norms. This paper introduces a novel approach by adapting the VBN model to predict the intention to use residential rooftop solar systems through several key modifications: integrating ecological values and openness to change, establishing connections between different values and beliefs (such as altruistic, biospheric, egoistic, openness to change, and ecological values) and awareness of consequences, and incorporating the influence of response efficacy, injunctive social norms, and descriptive norms in positively shaping personal norms.

Greenhouse gas emissions during the rice season are reduced by a low soil C:N ratio using different upland-paddy rotation systems

ContextUpland-paddy rotation can improve multiple-cropping index and crop yields; however, the mechanisms underlying the effects of dry-season crop diversification on rice yields and greenhouse gas (GHG) emissions under multiple rotation systems remain unclear. ObjectiveHere, we aimed to clarify the intrinsic mechanisms whereby rice yields and GHG emissions respond to the diversification of dry-season crops and lay a theoretical foundation for developing agronomic measures that can stabilize yields and reduce GHG emissions. MethodsUsing a positioning experimental site for upland-paddy rotation, we measured rice-season CH4 and N2O emissions, crop yields, GHG-emission intensity (GHGI) levels, soil physical and chemical properties in garlic–rice (GR), wheat–rice (WR) systems for 3 years (2019–2020, and 2022), and in a rapeseed–rice (RR) system for 1 year (2022). The soil microbial dynamics of the three systems were only tested in 2022. ResultsThe WR system had the highest CO2 emission equivalent (CO2-eq), with a 3-year interval value of 1898.24–16794.30 kg·ha−1, the lowest yield (8490.10–9773.46 kg·ha−1), and the highest GHGI (0.22–1.83). The GR system had the highest rice yield (9718.91–10769.75 kg ha−1), a lower CO2-eq (1588.55–12567.51 kg·ha−1), and therefore a lower GHGI (0.16–1.24). The RR system had the lowest GHGI in 2022 (benefiting from the lowest CO2-eq) and a slightly higher yield than that of the WR system. CH4 contributed to >88 % of the CO2-eq under the three systems in 2020 and 2022. The higher soil C:N ratio of the WR system stimulated methanogenic microorganisms, coupled with higher microbial biomass C levels, and ultimately increased CH4 emissions substantially. The soil C:N ratios of the GR and RR systems were significantly lower than that of the WR system because the soil total nitrogen (TN) of both systems was higher and increased CH4 emissions were avoided. The higher levels of N nutrients (TN, NO3--N, and NH4+-N) in the GR and RR systems also enhanced rice yields, with respective increases of 10.37 % and 1.22 %, compared with that of the WR system. ConclusionsThe diversified cultivation of dry-season crops in upland-paddy rotation systems affected rice yields and GHG emissions by changing the ratios of C and N. ImplicationsOur findings highlight the importance of future research involving comprehensive agronomic measures to help reduce emissions, including fertilizer management, straw management, and tillage methods.

Enhancing circular plastic waste management: Reducing GHG emissions and increasing economic value in Rayong province, Thailand

This study evaluates the greenhouse gas (GHG) emissions and economic value creation of plastic waste (PW) management in Rayong, Thailand, a city on the eastern Gulf Coast with a significant amount of generated and leaked PW. By analyzing current practices, and developing and evaluating improvement scenarios, the study explores strategies for reducing GHG and enhancing economic benefits across the PW management chain. Four primary routes with varying capacities handle approximately 5,445.55 tonnes of PW via source separation recycling (5.18 %), post-sorting recycling (9.30 %), energy recovery (54.86 %), and landfills or opened dump disposal (30.66 %). About 83.21 % of the 16 ± 6.9 % PW in municipal solid waste (MSW) is recyclable, primarily consisting of high-density polyethylene (HDPE), polypropylene (PP), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and polyethylene terephthalate (PET). The current management practice generates an economic benefit of approximately 1.68 million USD/yr or 310 USD/t of PW, compared to the proposed scenarios, which enhances recycling efficiency and reduces landfill and energy recovery waste, yielding 2.27–6.48 million USD/yr or 420.64–1200.33 USD/t of PW. The practice emits about 7,028.47 tCO2e annually, while improved source and post-sorting efficiencies reduce GHG emissions by 2.86–3.17 times or −2.83 to −2.42 tCO2e/t of PW or a total of over 13,078.60–15,268.44 tCO2e. Burning PW increases approximately 1.6 times or 11,841.36 tCO2e/yr. Enhancing recycling efficiency, particularly through source separation, is key to promoting more productive and valuable PW separation, increasing economic value and GHG mitigation by approximately 3.87 and 3.17 times, respectively. These findings provide valuable insights for local authorities and policymakers to develop strategic interventions and policies that align with the improved scenario by enhancing source separation and recycling. The results demonstrate that improving the efficiency of separation at the source is critical for transitioning from a linear PW management strategy to a circular economy, significantly reducing landfill waste and mitigating environmental threats.

Enhanced nitrogen removal and greenhouse gas reduction via activated carbon coupled iron-based constructed wetlands

Constructed wetlands (CWs) have been widely used to remove nitrogen in the effluent from sewage plants. Still, the removal capacity of nitrate (NO3−-N) in CWs is unsatisfactory due to the insufficient electron donor. This study explored the role of activated carbon (AC) in nitrogen removal and greenhouse gas (GHG) emissions reduction in different iron-based CWs. Long-term experimental results showed that pyrite and sponge iron-based CWs had higher NO3−-N removal rates (98.18 % and 94.10 %). Compared with the control group, AC promoted their total nitrogen (TN) removal efficiency (78.87–87.59 %) and reduced GHG emissions (CO2: 3.79–4.11 %, N2O: 2.97–8.78 %, CH4: 9.93–10.73 %). Moreover, AC not only promoted the values of electron transfer system activity (ETSA), the activity of nitrate reductase and nitrite reductase, but also significantly increased the microbial diversity and abundance of the substrate layer in pyrite/SI- based CWs. The relative abundance of the dominant bacteria in CWs with pyrite coupling with AC (PC-CW) was the highest (nirS: 77.60 %, nosZ: 88.98 %) compared with the other CWs. The higher relative abundance of Dechloromonas and Thiobacillus in PC-CW indicated that the composite substrates of pyrite and AC promoted the extracellular electron transfer of denitrifying microorganisms. This study provides new insights into optimizing inorganic electron donors to improve the removal of NO3−-N and the reduce of GHG emissions in CWs for low C/N wastewater treatment.

Greenhouse gas emissions of shipping with onboard carbon capture under the FuelEU Maritime regulation: A well-to-wake evaluation of different propulsion scenarios

International shipping has extended its decarbonization strategy to reduce greenhouse gas emissions beyond onboard CO2 emissions. Onboard carbon capture and storage systems are being investigated as a potential solution for fossil-fueled ships, however there is a lack of knowledge on the reduction of well-to-wake greenhouse gas emissions that could be enabled. Considering the ambitious emission reduction targets, this may lead to inaccurate estimations of the future fuel mix in the maritime sector and the market share of marine engines. This study defines nine ship propulsion scenarios based on combinations of fossil fuels and marine engines. To better understand the greenhouse gas emission reduction of onboard carbon capture, this study calculates the well-to-wake greenhouse gas intensity of each scenario with and without onboard carbon capture and storage from the ship’s main engine(s). Deploying onboard carbon capture and storage systems notably reduces the tank-to-wake greenhouse gas intensity (54–68 % depending on the scenario). Contrary to onboard emissions, oil-fueled ships with onboard carbon capture and storage are found to be less greenhouse gas intensive and more cost-effective than LNG-fueled ships. The four-stroke oil-fueled engine achieves the lowest well-to-wake greenhouse gas intensity of 38.31 gCO2eq/MJ, while the four-stroke LNG-fueled engine has the highest intensity of 50.34 gCO2eq/MJ. The greenhouse gas emission levels enabled by onboard carbon capture from the main engine would allow fossil-fueled ships to comply with the FuelEU Maritime greenhouse gas intensity requirement until 2044. To be compliant in subsequent periods, onboard carbon capture and storage systems will need to consider carbon capture from the auxiliary boiler and generator and higher capture rate, as well as measures to reduce upstream emissions from fossil fuel production and transport.