Lower Greenhouse Gas Emissions Research Articles

Ascertaining the Environmental Advantages of Pavement Designs Incorporating Recycled Content through a Parametric and Probabilistic Approach.

Reclaimed asphalt pavement (RAP) is a widely used end-of-life (EoL) material in asphalt pavements to increase the material circularity. However, the performance loss due to using RAP in the asphalt binder layer often requires a thicker layer, leading to additional material usage, energy consumption, and transportation effort. In this study, we developed a parametric and probabilistic life cycle assessment (LCA) framework to robustly compare various pavement designs incorporating recycled materials. Our framework is built upon thermodynamic and physical principles to reveal the complex relationship among the parameters. Mechanistic-Empirical Pavement Design Guide (MEPDG) models and Highway Development Management (HDM4) models are integrated into the framework to estimate pavement roughness and vehicle fuel consumption during the use phase. The pedigree approach and Monte Carlo simulation are integrated into the framework to reflect data uncertainty at the parameter level. We applied the framework to evaluate 66 Flemish motorway segments, revealing that using RAP in the binder layer with increased thickness does not necessarily guarantee lower greenhouse gas (GHG) emissions for pavement construction. However, it may lead to lower GHG emissions due to fuel savings when considering the use phase, highlighting the vital role of the use phase in pavement LCA. Our global sensitivity analysis highlights several contributors (out of 87 parameters) to GHG emissions variance depending on the LCA scope: fuel consumption during the use phase, transport distances, mass of fine aggregate, and machine power and machine productivity during pavement construction. Reducing uncertainties in these parameters can decrease the variance by up to 60%, enhancing discernibility by up to 11%. In conclusion, our parametric and probabilistic LCA framework provides a nuanced understanding when comparing various pavement designs incorporating recycled content, enabling robust decision-making through improved data quality.

Advancing Food Security with Farmed Edible Insects: Economic, Social, and Environmental Aspects.

Farmed edible insects are considered a potential resource to help address food security concerns toward the year 2050. The sustainability (e.g., lower environmental impact), nutritional (e.g., high-quality proteins, essential amino acids, fiber, unsaturated fats, vitamins, and minerals) and health (e.g., antioxidant, antihypertensive, anti-inflammatory, antimicrobial, and immunomodulatory) benefits are the main reasons for the rise in interest for insects as alternative protein sources for food and feed production. Thus, edible insects can address the future global protein demand of an ever-increasing world population. In this context, several aspects related to their sustainability have been explored and addressed from an environmental perspective. This review describes the rationale for using insects as alternative protein sources and provides a comprehensive viewpoint, integrating economic, environmental, and social aspects into their sustainability framework toward addressing food insecurity concerns. For example, edible insects offer a more sustainable protein source comparable to, or even better than, that of conventional livestock. Considering their sustainability advantages, insects are noted for their lower impact on natural resources (e.g., water and agrarian land) and lower greenhouse gas emissions (e.g., carbon dioxide and methane). From a socioeconomic point of view, edible insects have lower production costs compared to conventional animal protein sources because of their high feed efficiency conversion, rapid growth rate, and short life cycles. Currently, the market for edible, farmed insects is becoming a significant economic activity that not only meets the needs of industry and consumers but also supports the ability of future generations to maintain a secure and sustainable community.

Processing poultry manure with black soldier fly technology lowers N2O and CO2 gas emissions from soil

Abstract Soil amended with poultry manure has many benefits including increased nutrient and organic carbon supply, enhanced soil structure and improved crop yield. However, the direct application of poultry manure to land can be associated with significant greenhouse gas (GHG) emissions. Black soldier fly (BSF) farming (Hermetia illucens) is an emerging technology that can convert manure into protein for animal feed, with larvae casting or frass produced as a waste by-product. BSF frass produced from poultry manure has potential to be used as a soil amendment with potentially lower GHG emissions than manure, but this has not been tested. To test this, a two-week microcosm experiment was used to investigate the impact of different soil amendments (poultry manure, BSF frass from poultry manure, urea and an unamended control) on nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) emissions. This study also aimed to examine bacterial populations associated with frass and poultry manure, as well as factors regulating their composition and the production of GHGs. Frass produced by BSF larvae fed poultry manure had up to 1.4 times lower N2O and 1.5 times lower CO2 cumulative emissions than poultry manure. Methane emissions were either minimal and/or balanced by oxidation across all treatments. Processing poultry manure with BSFL also altered the bacterial community composition and resulted in a proliferation of bacteria that were specific to BSFL frass, some of which have putative plant growth promoting properties. These results indicate that BSF technology holds promise for both reducing greenhouse gas emissions from poultry manure, as well as providing a sustainable soil amendment for productive agriculture.

Environmental Management and Decarbonization Nexus: A Pathway to the Energy Sector’s Sustainable Futures

This paper examines the complex interplay between environmental management (EM) and decarbonization, highlighting how these domains can be seamlessly integrated to create a comprehensive framework for sustainable futures in the energy sector. The framework emphasizes the adoption of green technologies, energy efficiency measures, and innovative carbon capture, utilization, and storage (CCUS) technologies and infrastructures. Central to this approach are circular economy principles, low-greenhouse gas (GHG) emissions production processes, and CCUS strategies. A conceptual model of the EM–decarbonization nexus, comprising six enablers, was developed and illustrated with practical examples from various countries and regions worldwide. The findings reveal significant progress in advancing EM and decarbonization efforts. However, additional support from governments and the private sector is imperative in areas such as research and development, equitable transfer of renewable energy technologies, infrastructure for energy transitions, energy storage systems, green financing mechanisms, public education and community outreach, public–private partnerships, international cooperation, active engagement in global organizations, and the deployment of digital solutions. By addressing these areas, a sustainable future for the energy sector can be realized.

A Review on Ferry Electrification: A Path towards Sustainable Maritime Transport

This paper reviews research and development efforts for ferries' electrification, focusing on energy supply grids, communication networks, charging systems, and energy storage. It analyzes energy storage technologies, battery charging requirements, shore side infrastructure design, power system architecture, and alternative battery charging stations[1]. The study evaluates the effectiveness of using an electric/hybrid ferry boat for tourist transportation in a real case. The optimal system configuration depends on engine power, energy storage, photovoltaic system sizes, and percentage of hybrid or pure electric usage. The analysis can be replicated to other cases, showing the potential of new technologies for sustainable boating and improving passenger service, especially in terms of comfort[15]. One of the most important steps in lowering greenhouse gas emissions and the marine industry's reliance on fossil fuels is the electrification of ships. This analysis examines the technical developments, difficulties, and environmental effects of switching from conventional fossil fuel-powered ships to electric and hybrid ships. The future of fully electric ships, legislative efforts, and how these advancements relate to international sustainability goals are also covered in the study.

Harnessing low-temperature geothermal resources in the state of Jalisco, Mexico

Despite Jalisco's rich geothermal resources, its low-temperature energy has primarily been used in recreational facilities like spas. However, the state offers significant potential for a broader range of applications, including space heating, industrial processes, and agriculture. While the Federal Electricity Commission has focused on high-temperature reservoirs for electricity generation, the potential of low-temperature geothermal energy has been largely overlooked. Although the private sector has begun exploring this resource, its involvement remains limited. Jalisco possesses substantial reserves of both high and low-temperature geothermal energy. Harnessing this energy can contribute to reducing fossil fuel dependency, lowering greenhouse gas emissions, and fostering sustainable development. Its utilization can yield economic, social, and environmental benefits, such as job creation, reduced energy costs, and climate change mitigation.

Novel Study of Reaction Kinetics and Mass Transfer in Bioreactor Modelling: Prediction of Bioethanol Fermentation Performance by Saccharomyces cerevisiae on Continuous Fixed Bed Biofilm Plug Flow Reactor

Bioethanol implementation as a renewable fuel has yielded economic, social, and environmental benefits, including reduced fossil fuel consumption, enhanced energy diversity and supply security, lower greenhouse gas emissions, and support for agricultural communities. These impacts underscore the importance of advancing innovation and optimizing processes to increase bioethanol production. Therefore, basic knowledge of chemical engineering in bioethanol fermentation is important to be learnt as a preliminary study, such as reaction kinetics and transport phenomena. This work studies the reaction kinetics and mass transfer in continuous fixed bed biofilm plug flow reactor modelling to predict anaerobic Saccharomyces cerevisiae fermentation performance, which is still not studied comprehensively. This modelling provides an overview of the influence of various independent variables, namely temperature, initial substrate concentration, cell concentration, superficial flow rate, reactor diameter, and solid particle diameter on various dependent variables, namely final product concentration, residence time, reactor length, reactor volume, product productivity, and pressure drop. The most sensitive parameters related to product productivity are temperature and cell concentration, so in its implementation, the temperature must be controlled at its optimum temperature, and the inoculum must be prepared with high cell concentration. For the next study, it is recommended to study the optimization of reactor design and operation (i.e. the pumping system, cooling system, and pH control of the reactor) and the implementation of the reactor on the plant scale. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Greater adherence to the Mediterranean diet pattern in the United States is associated with sustainability trade-offs

BackgroundThe Mediterranean diet pattern has been consistently associated with health benefits but less is known about the association with environmental and economic sustainability in the United States (US). This information is needed to support sustainable policy agendas and provide consumers with evidence-based information needed to make informed food choices. This study fills this research gap by evaluating the environmental sustainability and diet cost associated with adherence to the Mediterranean diet pattern in the US.MethodsDietary data from the National Health and Nutrition Examination Survey (2011–2018, n = 17,079) were merged with data on environmental impacts (greenhouse gas emissions, cumulative energy demand, water scarcity footprint), agricultural resource demand (land, fertilizer nutrients, and pesticides), and food prices from multiple publicly available databases. The Mediterranean Diet Score was used to evaluate adherence to the Mediterranean diet pattern. Multivariable linear regression models were used to evaluate the association between adherence to the Mediterranean diet pattern and environmental impacts, agricultural resource demand, and diet cost. Sensitivity analyses were used to evaluate adjustment of loss and waste and food-away-from-home prices.ResultsGreater adherence to the Mediterranean diet pattern was associated with lower greenhouse gas emissions (p < 0.001), land use (p < 0.001), fertilizer nutrient use (p < 0.001), and pesticide use (p < 0.001), higher water scarcity footprint (p < 0.001) and diet cost (p < 0.001), and no change in cumulative energy demand (p = 0.147). These changes were driven primarily by reduced intake of animal-sourced foods such as beef dishes, meat sandwiches, and dairy, as well as decreased intake of refined carbohydrate foods such as refined grain dishes and soft drinks.ConclusionsThis nationally representative study demonstrates that greater adherence to the Mediterranean diet pattern is associated with sustainability trade-offs. These findings have implications for the development of sustainable dietary guidelines and clinical practice guidelines that can be used to inform consumer food choices.

Slow Steaming as a Sustainable Measure for Low-Carbon Maritime Transport

Reducing greenhouse gas (GHG) emissions is essential across all sectors, including the maritime transport industry. Speed reduction is a key short-term operational measure for lowering GHG emissions from ships, and its implementation has already begun. While speed reduction offers significant benefits, particularly in terms of GHG emissions reduction potential, there are concerns about its application, including increased voyage times, an increase in the number of ships required, and the fact that ships may operate in conditions quite different from those for which they were designed and optimized. This study investigates the impact of speed reduction on ship performance in calm water, using a post-Panamax container ship as an example. Numerical simulations of resistance, open-water, and self-propulsion tests were conducted for a full-scale ship and propeller, and the results were validated against extrapolated towing tank data. Hydrodynamic characteristics, fuel consumption, and carbon dioxide emissions at various speeds were then estimated. The results indicated that when constant transport work was maintained, yearly CO2 emissions decreased by −16.89% with a 10% speed reduction, −21.97% with a 20% speed reduction, and −25.74% with a 30% speed reduction. This study demonstrates that the classical cubic law for fuel oil consumption and speed dependence is not valid, as the speed exponent is lower than 3. The potential benefits and drawbacks of implementing slow steaming are discussed. Finally, this research contributes to the existing literature by evaluating the CO2 emissions reduction potential of slow steaming.

USING AMMONIA FUEL AS A MEASURE TO REDUCE GREENHOUSE GASES

The presented work highlights the possibilities of using ammonia as an alternative fuel in order to achieve low-carbon development of the state and strengthen the fight against greenhouse gases. Since the Industrial Revolution, combustion has been the primary method of energy conversion for human activities, including power generation and transportation. Today, these sectors continue to rely heavily on hydrocarbon fuels. As a result, the largest absolute increase in carbon dioxide emissions in 2022 was from electricity and heat production. With global electricity demand increasing by 2.7%, emissions in the energy sector increased by 1.8% (or 261 Mt), reaching an all-time high of 14.6 Gt. Thus, a large part of CO2 emissions is produced through these sectors, which is the main culprit of global warming, undermining the fight against climate change. The need for decarbonization is taken into account by program documents, including government strategies, which not only warn but also prohibit the excessive formation of pollutants and stimulate the promotion of carbon-free technologies in energy sectors. It is common knowledge that the innovative development of fuel combustion technologies is necessary to achieve the future goals of a carbon-neutral system. Despite the considerable efforts made to reduce greenhouse gas emissions during the combustion of hydrocarbons, for example, by increasing the combustion efficiency, these efforts are not enough to achieve low greenhouse gas emissions. The progress in this field is analyzed and it is found that ammonia is receiving increasing attention as one of the most attractive energy carriers due to its carbon-free nature. However, the use of ammonia in combustion is not without problems, including low flame speed, narrow flammability limits, and tendency to NOx formation. Therefore, the further introduction of ammonia as a fuel in energy and industry requires comprehensive studies of the combustion working process. Research should be based on determining the influence of the main technological factors, the possibility of using mixed fuels, as well as establishing the optimal geometric and mode parameters of the fuel combustion system.

Sustainability assessment of solar‐powered drip irrigation for sugarcane in Egypt: A water–energy–food–ecosystem nexus perspective

AbstractThis study investigates the adoption of solar‐powered drip irrigation systems in Egypt's sugarcane agriculture, analyzing the potential for improved sustainability through the water–energy–food–ecosystems (WEFE) nexus. Located in Qena Governorate, the research utilizes the Q‐Nexus model to compare traditional diesel‐powered irrigation with solar‐powered drip irrigation, focusing on their impacts on resource efficiency, agricultural productivity, and environmental services. Through a comprehensive methodological framework that incorporates input–output analysis, the interactions between water, energy, food production, and ecosystem services were quantified. Primary data was gathered from field interviews and surveys, supplemented by national agricultural statistics, enabling a detailed scenario analysis of current and sustainable practices. These scenarios were then used to assess the potential implications for water and energy conservation, emissions reduction, and overall sustainability. Results demonstrate significant benefits of solar‐powered drip irrigation, including a 48% reduction in water usage and a 93% decrease in diesel fuel consumption compared to diesel‐powered surface irrigation. Additionally, this approach resulted in a 34% reduction in labor and a 55% decrease in fertilizer use, while increasing sugarcane yield by 16%. Environmentally, the shift to solar‐powered systems drastically lowered greenhouse gas emissions and reduced toxicity from fertilizer runoff, underscoring the potential for enhancing agricultural sustainability and efficiency. Conclusively, the findings support the viability of integrating solar‐powered drip irrigation systems in Egyptian agriculture as a sustainable solution to improve resource efficiency, enhance productivity, and minimize environmental impacts. This study contributes to the broader discourse on sustainable agriculture by providing empirical evidence of the economic and ecological benefits of adopting advanced irrigation and energy technologies. Recommendations for policy include investment in infrastructure, subsidies for sustainable technologies, and farmer training to promote widespread adoption. Future research directions should explore the scalability of such systems and their long‐term impacts on soil health and biodiversity.HIGHLIGHTS Resource efficiency and productivity improvement: The water–energy–food–ecosystems (WEFE) nexus assessment shows that solar‐powered drip irrigation in Egypt's sugarcane agriculture can potentially reduce water usage by 48%, diesel fuel consumption by 93%, and increase sugarcane yield by 16%, significantly improving resource efficiency and agricultural productivity. Environmental and economic benefits: The shift to solar‐powered irrigation systems can potentially lower greenhouse gas emissions, reduce labor by 34%, and decrease fertilizer use by 55%, minimizing toxicity from runoff and enhancing environmental sustainability while achieving cost savings. Policy and implementation recommendations: To support the WEFE nexus and encourage widespread adoption, investment in infrastructure, subsidies for sustainable technologies, and comprehensive farmer training are crucial. This study highlights the need for policies that integrate advanced irrigation and energy technologies to achieve sustainable agriculture.

Potential for Lowering Greenhouse Gas Emissions With the Addition of Hydrogen or Ammonia to Different Natural Gas Compositions—Application in Internal Combustion Engines

ABSTRACTInternal combustion engines (ICEs) can be used in power plants to ensure flexibility in electricity generation. The use of carbon‐free fuels, such as hydrogen and ammonia, in ICEs is a way to decrease greenhouse gas emissions gradually until new carbon‐neutral technology has been fully implemented. By mixing small amounts of these compounds into natural gas (NG), the gas quality requirements can still be achieved and the modification work on the engine can be minimized. In this study, the CO2eq emission intensity was calculated for different NG compositions blended with hydrogen or ammonia while the mixture was within the gas quality specifications. The results showed that the addition of ammonia reduces the CO2eq emission intensity more than hydrogen and that the reduction depends on the NG quality. By utilizing H2‐NG and NH3‐NG mixtures as fuels in ICEs, the emissions can be reduced by 37%–44% and 3%–8%, respectively, compared to engines running on diesel oil or natural gas. The novelty of this study is to demonstrate the potential of cutting GHG emissions in power production using ICEs, new fuel blends, and fulfilling existing fuel requirements agreed on for engines.

Varying aggregate sizes, plasticizers, and supplementary cementitious materials to efficiently use Portland clinker in concrete

Abstract Mitigating greenhouse gas (GHG) emissions from the production of concrete, a critical infrastructure material around the world, has been highlighted as necessary to meet climate change goals. Concrete is made of water, aggregates (e.g., crushed rocks), and Portland cement (PC), a hydraulic binder. PC is the primary source of GHG emissions from concrete, a function of the emissions derived from the production of its clinker, a kilned, quenched material composed of calcium silicates that, by mass, makes up the majority of PC. While considerable attention has been given to reducing the GHG emissions from PC manufacture, better utilization of other resources used in concrete can lower the demand for the level of clinker necessary in any given mixture. In this work, we examine how changing the size of aggregates, the use of a superplasticizer (SP), and the use of supplementary cementitious materials (SCMs) can lower GHG emissions from concrete. We derive a system of equations based fundamentally on standard mixture proportioning guidelines to determine the most efficient use of PC in a concrete mixture for specified strength and workability and quantify GHG emissions using life cycle assessment methods. Findings show that the use of reactive SCMs can contribute to reduced GHG emissions, as can the use of a higher maximum aggregate diameter and higher SP dosage. Our models also suggest that a concrete producer could follow standard mixture proportioning guidelines and yield a mixture that has over 2 times the PC content needed. The efficient use of PC within concrete mixtures by appropriately selecting other constituents can lower GHG emissions, contributing to GHG emissions reduction goals.

Green Hydrogen and Its Supply Chain. A Critical Assessment of the Environmental Impacts

AbstractGreen hydrogen produced via electrolysis powered by renewables can greatly contribute to achieving carbon neutrality. The analysis of 35 papers reporting the life cycle assessment (LCA) of green hydrogen supply chains confirms the lower greenhouse gas (GHG) emissions with respect to other hydrogen forms and conventional fossil fuel and carbon systems. However, the global warming potential of green hydrogen worsens if grid electricity is used to back up renewable sources. Green hydrogen is also responsible for water consumption and for land use, while offshore platforms may be responsible for the loss of marine biodiversity. Another potential environmental hotspot is the depletion of rare metals and critical materials employed in the electrolyzer and in the power generation plants. This issue is exacerbated by the lack of information about the management of the end‐of‐life stage of this equipment. Notably, the delivery along the supply chain is responsible for hydrogen leaks, whose environmental consequences are still uncertain.

Contribution of goats to climate change: how and where?

This review examines the contribution of domestic goats (Capra hircus) to climate change, particularly through greenhouse gas (GHG) emissions. The review seeks to outline the global numerical importance and physical characteristics of domestic goats; Compare goats with other main livestock species in terms of their climate impacts; Assess the types of environments and farmers most likely to raise goats; Investigate the climate change impacts of raising goats, focusing on variables such as feed sources, management systems (intensive vs. extensive), and methodologies used to measure these impacts. The conclusion is that the negative reputation of goats needs to be re-evaluated, given their importance to poorer farm families and the potential overstatement or misunderstanding of their climate impact. Goats are the third most common ungulate livestock globally, with an estimated population of 1.1 billion. They are particularly suited to harsh environments due to their physiological advantages, such as efficient utilization of fibrous woody material and resilience to extreme climates. Goats are crucial for poorer farmers, especially in lower and middle-income countries in Africa and Asia. They provide milk, meat, and other products, are readily sold and have low labour requirements, making them ideal for families with limited resources. Goats emit less methane per unit body weight compared to other ruminants like cattle and sheep. However, the extent of their greenhouse gas (GHG) emissions varies significantly based on their diet, management system (extensive vs. intensive), and environmental conditions. Extensive systems, where goats forage on natural pastures, may result in low GHG emissions per unit of land area due to carbon sequestration and minimal reliance on high-energy feed. Intensive systems, which use more cultivated energy feed, produce lower methane emissions per unit of product but incur carbon costs arising from feed production. In sum, this review suggests that the negative reputation of goats regarding climate change may be overstated or misunderstood. More research is needed to accurately measure the GHG impacts of goats, considering factors like feed quality, management practices, and carbon sequestration.

Optimal reconfiguration of a distribution network integrated photovoltaic and wind systems using blood-sucking leech optimizer

This paper presents a planning strategy for integrating renewable distributed generation (DG) units into a distribution network, incorporating network reconfiguration to enhance the network's technical, economic, and environmental performance. Utilizing a novel meta-heuristic algorithm, the Blood-Sucking Leech Optimizer (BSLO), the study addresses a multi-objective optimization problem aimed at determining the optimal placement and sizing of DG units, as well as the most effective network topology. This approach seeks to minimize active power losses, improve voltage profiles, reduce installation costs, and lower greenhouse gas emissions. The model accounts for variable load demands, climatic factors (such as ambient temperature, solar irradiation, and wind speed), and fluctuating energy prices, reflecting realistic operating conditions. Tested on the IEEE 69-bus distribution network, the BSLO algorithm demonstrated rapid convergence to the global optimum by effectively balancing exploration and exploitation phases. Compared to other meta-heuristic methods, such as the Grey Wolf Optimizer, Gorilla Troops Optimizer, Walrus Optimization Algorithm, and Artificial Hummingbird Algorithm, the BSLO consistently achieved superior accuracy and faster convergence, resulting in higher precision and optimization efficiency. The optimal deployment of two PV generators and two wind turbines, combined with selective line switch openings, resulted in an 87.66% reduction in active power losses, a 73.30% decrease in voltage deviation, a 51.91% reduction in overall system costs, and a 62.74% decrease in greenhouse gas emissions compared to the base case.

Developing a Water, Food, Energy, Economy, and Environment Nexus Index for Evaluating Centralized and Decentralized Wastewater Treatment Systems

ABSTRACTIn addressing the complex challenges of sustainable development, the Water‐Energy‐Food (WEF) nexus underscores the critical role of wastewater management. This study evaluates centralized and decentralized wastewater treatment systems using the innovative Water‐Energy‐Food‐Economy‐Environment Nexus Index (WEFEENI). Centralized systems are traditionally favored in urban settings due to economies of scale, yet they encounter high costs and environmental impacts. In contrast, decentralized systems offer flexibility and lower operational costs, making them suitable for less populated regions. Our findings reveal that decentralized systems significantly reduce energy consumption by 72.88%, investment costs by 52.01%, and operating costs by 87.98%, while also lowering greenhouse gas emissions. Although centralized systems excel in food production and annual income, decentralized systems perform better in water and energy productivity, green space development, and aquifer recharge. The study highlights the importance of adopting a holistic approach, tailored to specific contexts and priorities, to achieve sustainable wastewater management.

Investigation of nitrogen conversion in ditch-treated greywater: Contributions of biochar and aeration

This study aimed to assess the contribution of different combinations of uninterrupted aeration and tidal flow modes, as well as shallow and deep biochar landfill methods, to nitrogen removal pathways in ditches. Compared to natural ditches, the addition of biochar and aeration resulted in higher water pollution removal rates, lower Greenhouse Gas (GHG) emissions, and reduced sediment leaching. The nitrogen mass balance revealed that Total Nitrogen removal efficiency of each ditch group was 25.33% for CA-C, 43.75% for DBT-C, 49.08% for UBT-C, 30.75% for DBA-C, and 45.16% for UBA-C. Compared to the control group (CA-C), the tidal flow group with deep biochar landfill (DBT-C)demonstrated the highest efficiency in total nitrogen removal. To elucidate the fate of nitrogen elements, potential transformation processes of unexplained nitrogen were explored. The primary outflow pathway of nitrogen pollution in ditches is through liquids. The nitrogen composition in the liquid of each ditch indicated that for shallow biochar configurations (UBT-C/UBA-C), denitrification might be the main factor limiting TN removal efficiency. In contrast, for deep biochar configurations (DBT-C/DBA-C), hydrolysis and nitrification of organic nitrogen were identified as limiting factors, with tidal flow alleviating these limitations. Overall, the combination of shallow biochar and tidal flow aeration in a ditch is the most effective method for removing rural greywater, providing valuable insights for the development of design parameters in greywater removal systems.

Low-emission hydrogen supply chain for oil refining: Assessment of large-scale production via electrolysis and gasification

The refining industry is a major hydrogen consumer, mainly relying on fossil fuel-derived hydrogen. While recent literature has focused on the production of hydrogen from water electrolysis, (waste) biomass gasification is another effective method for low-emission hydrogen production, and the refining industry is well positioned for its rapid adoption. This study conducts a techno-economic assessment of the whole supply chain of hydrogen for oil refining and analyses the LCA-climate change for residual biomass gasification and water electrolysis pathways. The potential economic and environmental benefits of combining both production methods are also analyzed. A real case study featuring four different scenarios, using data from a refinery, coupled with local data and future projections for potential curtailment and electricity prices, is included. The hourly hydrogen generation and demand profiles of the refinery were analyzed to accurately assess storage requirements. Results indicate that combining both technologies does not result in clear environmental or cost benefits, with residual biomass gasification emerging as the most advantageous configuration for the base case. Sensitivity analysis reveals that hydrogen produced via electrolysis may become more cost-effective if residual biomass prices are high enough. The importance of underground storage (salt cavern) is highlighted due to its low investment, while other storage methods can significantly increase the Levelized Cost of Hydrogen (LCOH). This study demonstrates that hydrogen production through gasification can be less carbon-intensive and more cost-competitive than electrolysis. Achieving low LCOH values and greenhouse gas emissions is feasible in all scenarios, indicating that both water electrolysis and residual biomass gasification are economically viable options for contributing to a low-emission global energy system.

Synergistic impact of co-substrate of biodiesel crude glycerol and durian peel hydrolysate for biohydrogen and 1,3-propanediol synthesis by Clostridium butyricum

Aligning with Sustainable Development Goals 7 and 12, this project explores the utilization of durian peel and waste glycerol as sustainable carbon sources to produce green biohydrogen and 1,3-propanediol. The study elucidates the synergistic impact of the glucose-glycerol co-substrate ratio for the co-production of 1,3-propanediol and biohydrogen. Then, the ratio is applied to durian peel hydrolysate and biodiesel glycerol. A glycerol-to-glucose ratio of 10:1 by mass produces a maximum hydrogen productivity and yield of 67.46 mL/L∙h and 0.11 mol H2/mol substrate consumed and a fairly high 1,3-propanediol titer, yield and productivity. Moreover, the application of waste-derived carbon sources, i.e., durian peel hydrolysate and treated glycerol, enhances H2 yield and productivity by 18.9% and 7.5%, respectively. These findings promote biofuel and bioplastic application, establishing a flagship circular bioeconomy technology in the ASEAN region to cater to regional polyester, resin and energy demand while promoting waste reduction and lower greenhouse gas emissions.