Search Results (156)

Multi-objective evolutionary algorithms (MOEAs) have emerged as powerful optimization tools for addressing the complex, often conflicting goals present in modern waste disposal systems. This review explores recent advances and practical applications of MOEAs in key areas, including waste collection routing, waste-to-energy (WTE) systems, and facility location and allocation. Real-world case studies from cities like Braga, Lisbon, Uppsala, and Cyprus demonstrate how MOEAs can enhance operational efficiency, boost energy recovery, and reduce environmental impacts. While these algorithms offer significant advantages, challenges remain in computational complexity, adapting to dynamic environments, and integrating with emerging technologies. Future research directions highlight the potential of combining MOEAs with machine learning and real-time data to create more flexible and responsive waste management strategies. By leveraging these advancements, MOEAs can play a pivotal role in developing sustainable, efficient, and adaptive waste disposal systems capable of meeting the growing demands of urbanization and stricter environmental regulations. Full article

Waste-to-energy (WtE) are clean technologies that support a circular economy by providing solutions to managing non-recyclable waste while generating alternative energy sources. Despite the promising benefits, technology adoption is challenged by financing constraints, technical maturity, environmental impacts, supporting policies, and public acceptance. A growing number of studies analyzed the acceptability of WtE and identified the factors affecting the adoption of WtE technologies. This study aims to analyze these research hotspots, technologies, and acceptability factors by combining bibliometric and systematic analyses. An initial search from the Web of Science and Scopus databases identified 817 unique documents, and the refinement resulted in 109 for data analysis. The results present a comprehensive overview of the state-of-the-art, providing researchers a basis for future research directions. Among the WtE technologies in the reviewed literature are incineration, anaerobic digestion, gasification, and pyrolysis, with limited studies about refuse-derived fuel and landfilling with gas recovery. The identified common factors include perceived risks, trust, attitudes, perceived benefits, “Not-In-My-BackYard” (NIMBY), awareness, and knowledge. Moreover, the findings present valuable insights for policymakers, practitioners, and WtE project planners to support WtE adoption while achieving sustainable, circular, and low-carbon economies. Full article

The imperative to decarbonize global energy systems and enhance energy security necessitates a transition towards ecofuels, broadly classified as biofuels, waste-derived fuels, and electrofuels (e-Fuels). The primary goal of this review is to provide a holistic and comparative evaluation of these three pivotal ecofuel pillars under a unified framework, identifying their strategic niches in the energy transition by critically assessing their interconnected technical, economic, and policy challenges. It offers a comparative dissection of inherent resource constraints, spanning biomass availability, the immense scale of renewable electricity required for e-Fuels, sustainable carbon dioxide (CO₂) sourcing, and the complexities of utilizing non-biodegradable wastes, identifying that true feedstock sustainability and holistic lifecycle management are paramount, cross-cutting limitations for all pathways. This review critically highlights how the current global reliance on fossil fuels for electricity production (approx. 60%) and the upstream emissions embodied in renewable energy infrastructure challenge the climate neutrality claims of ecofuels, particularly e-Fuels, underscoring the necessity for comprehensive well-to-wheels (WtW) lifecycle assessments (LCAs) over simpler tank-to-wheels (TtW) approaches. This perspective is crucial as emerging regulations demand significant greenhouse gas (GHG) emission reductions (70–100%) compared to fossil fuels. Ultimately, this synthesis argues for a nuanced, technologically neutral deployment strategy, prioritizing specific ecofuels for hard-to-abate sectors, and underscores the urgent need for stable, long-term policies coupled with robust and transparent LCA methodologies to guide a truly sustainable energy transition. Full article

Objective: To examine the economic, environmental, and sociopolitical aspects of waste-to-energy incineration (WtE-I) and to provide recommendations for the Australian context. Methods: A scoping review of the literature published from 2016 to 2024 was conducted, adhering to the PRISMA guidelines. Results: This review identifies WtE-I as a dual-purpose tool for energy production and waste management. However, its environmental profile is unclear, with potential significant environmental and health risks due to the emission of toxins and heavy metals and diminished air quality. The economic feasibility of WtE-I varies, with high initial costs and operational expenses offset by subsidies, revenue from energy, and material recovery. Public opposition to WtE-I is prevalent, driven by health concerns, and this raises important environmental justice issues, especially for marginalised communities. Conclusions: The present study provides economic, environmental, and sociopolitical recommendations against WtE-I. When compared to landfill, WtE-I demonstrates economic and environmental benefits. The transition to a circular economy with renewables-derived electricity attenuates the benefits of WtE-I. This, combined with grassroots opposition to WtE-I and its violations of social justice, renders future WtE-I projects unjustifiable. Public health practitioners need to promote primary waste reduction, recycling/composting, and other non-incinerator waste management practices in Australia. Full article

Palm oil production generates substantial underutilized biomass wastes, including empty fruit bunches, fiber, palm kernel shells, and palm oil mill effluent (POME). Waste-to-energy systems offer a viable pathway to convert these residues into electricity and fertilizer, supporting circular economy goals and sustainability targets. This study takes an example of palm oil waste from the Indragiri Hulu region in Riau Province in Indonesia. It develops a multi-objective optimization framework to evaluate palm oil mill WtE systems from economic, environmental, and energy output. Three scenarios are analyzed: maximal profit (MP), maximal profit with carbon tax (MPCT), and all waste processing (AWP). The MP scenario favors high-return technologies such as gasification and incineration, leading to significant greenhouse gas emissions. The MPCT scenario favors lower-emission technologies like composting and excludes high-emission, low-profit options such as POME digestion. In contrast, the AWP scenario mandates the processing of all wastes, leading to the lowest profits and the highest emissions among all scenarios. The sensitivity analysis reveals that POME processing is not feasible when electricity prices are below the government-set rate, but becomes viable once prices exceed this threshold. These findings offer valuable insights for companies and policymakers seeking to develop and implement effective strategies for optimal waste utilization. Full article

Waste-to-energy (WTE) is considered the most promising method for municipal solid waste treatment. An integrated energy system (IES) with carbon capture systems (CCS) and power-to-gas (P2G) can reduce carbon emissions. The incorporation of a “green-carbon” offset mechanism further enhances renewable energy consumption. Therefore, this study constructs a WTE-IES hybrid system, which conducts multi-dimensional integration of IES-WTP, CCS-P2G, photovoltaic (PV), wind turbine (WT), multiple energy storage technologies, and the “green-carbon” offset mechanism. It breaks through the limitations of traditional single-technology optimization and achieves the coordinated improvement of energy, environmental, and economic triple benefits. First, waste incineration power generation is coupled into the IES. A mathematical model is then established for the waste incineration and CCS-P2G IES. The CO₂ produced by waste incineration is absorbed and reused. Finally, the “green-carbon” offset mechanism is introduced to convert tradable green certificates (TGCs) into carbon emission rights. This approach ensures energy demand satisfaction while minimizing carbon emissions. Economic incentives are also provided for the carbon capture and conversion processes. A case study of an industrial park is conducted for validation. The industrial park has achieved a reduction in carbon emissions of approximately 72.1% and a reduction in the total cost of approximately 33.5%. The results demonstrate that the proposed method significantly reduces carbon emissions. The energy utilization efficiency and system economic performance are also improved. This study provides theoretical and technical support for the low-carbon development of future IES. Full article

Many decommissioned wind turbines (WTs) present significant recycling management challenges. Improper disposal wastes resources and generates additional carbon emissions, which contradicts the Sustainable Development Goals (SDGs). This study constructs a sine cosine algorithm (SCA)–ITransformer–BiLSTM deep learning prediction model, integrated with dynamic material flow analysis (DMFA) and a multi-dimensional Energy–Economy–Environment–Society (3E1S) sustainability assessment framework. This hybrid approach systematically reveals the spatiotemporal evolution patterns and circular economy value of WTs in China by synthesizing multi-source heterogeneous data encompassing policy dynamics, technological advancements, and regional resource endowments. Results demonstrate that China will enter a sustained wave of WT retirements post-2030, with an annual decommissioned capacity exceeding 15 GW. By 2050, new installations and retirements will reach a dynamic equilibrium. North and Northwest China are emerging as core retirement zones, accounting for approximately 50% of the national total. Inner Mongolia and Xinjiang face maximum recycling pressures. The recycling of decommissioned WTs could yield approximately CNY 198.5 billion in direct economic benefits and reduce CO₂ equivalent emissions by 4.78 to 8.14 billion tons. The 3E1S framework fills critical gaps in quantifying the comprehensive benefits of equipment retirement, offering a theoretically grounded and practically actionable paradigm for the global wind industry’s circular transition. Full article

This study aims to evaluate various waste-to-energy conversion scenarios in terms of their potential to reduce greenhouse gas (GHG) emissions and improve sustainability based on economic and environmental outcomes. To achieve this, a comprehensive waste management model was developed using the system dynamics approach in the Vensim software to predict waste generation and composition and compare pyrolysis, incineration, gasification, and sanitary landfill scenarios with the baseline scenario over 25 years (2025–2050). The analysis of different waste management scenarios highlights the superior performance of pyrolysis in terms of energy recovery, economic profit, GHG emissions reduction, environmental outcomes, and long-term sustainability. Results show that the pyrolysis scenario generates the highest electricity, with a cumulative net electricity output of 10,469 GWh. Although pyrolysis has GHG emissions due to energy consumption and direct process emissions, it results in the largest net reduction in GHG emissions, primarily due to avoided emissions from increased electricity generation, leading to a 346% reduction compared to the baseline scenario. Furthermore, the pyrolysis scenario demonstrates the highest economic profit at 354 million USD and the highest sustainability index (SI) at 499 million USD. The cumulative SI from 2025 to 2050 shows a 503% increase compared to the business-as-usual scenario, highlighting its superior sustainability performance. This study highlights the importance of strategic waste-to-energy planning in reducing GHG emissions and promoting sustainability. It also offers valuable insights for policymakers and researchers, supporting the development of sustainable waste management strategies and effective efforts for climate change mitigation. Full article

This paper provides a comprehensive review of the integration of carbon capture, utilization, and storage (CCUS) technologies in waste-to-energy (WtE) plants, specifically focusing on incineration, the most adopted process for managing residual waste fractions that cannot be recycled. The review examines the current CO₂ capture technologies, including the widely used monoethanolamine (MEA) absorption method, and explores emerging alternatives such as molten carbonate fuel cells and oxyfuel combustion. Additionally, the paper discusses the management options for the captured CO₂, exploring both storage (CCS) and utilization (CCU) options, with a focus on current storage projects involving CO₂ from WtE plants and the potential for its use in sectors like chemicals, construction materials, and synthetic fuels. Currently, only four large-scale WtE plants worldwide have successfully implemented carbon capture technologies, with a combined capacity of approximately 78,000 tons of CO₂ per year. However, numerous feasibility studies and pilot-scale projects are ongoing, particularly in northern Europe, with countries such as Norway, the Netherlands, Sweden, the United Kingdom, and Finland leading the way in the development of CO₂ capture, storage, and utilization strategies within the WtE sector. The paper further discusses techno-economic issues for CCUS implementation, including energy demands and associated costs. The use of MEA systems in WtE plants leads to significant energy penalties, reducing plant efficiency by up to 40%. However, alternative technologies, such as advanced amines and calcium looping, could provide more cost-effective solutions by improving energy efficiency and reducing the overall costs. Life cycle assessment studies indicate that CCUS has the potential to significantly reduce CO₂ emissions, but the achievable environmental benefits depend on factors such as energy consumption, process efficiency, and system integration. Overall, while the implementation of CCUS in WtE plants presents CO₂ mitigation potential and may also be exploited to achieve other benefits, energy requirements and economic viability remain challenging. Full article

The COVID-19 pandemic posed challenges to pre-crisis waste management systems. In this study, two sequential scenarios were identified and compared to investigate the quantitative and environmental impacts of COVID-19 induced changes in the generation and management of residual municipal waste (RMW) in two provincial territories (PT_PU, PT_MC) of the Marche region (Central Italy, Adriatic Sea side). The pandemic implied, in 2020 (COVID-19 scenario), quantitative reductions in RMW compared to the preceding year, 2019 (Pre-COVID-19 scenario), which were limited to −3.9 and −1.9% in PT_PU and PT_MC, respectively. Life cycle assessment (LCA) results showed that adapted RMW management practices in 2020 (COVID-19 scenario) improved all the considered environmental indicators in PT_MC, compared to the preceding year, 2019 (Pre-COVID-19 scenario), and most of them in PT_PU, with the exception of climate change (CC), human toxicity, non-cancer (HTnc), and eutrophication, marine (Em). The hypothetical option of waste-to-energy (WtE) for the RMW, originally destined for direct landfilling in 2020 (COVID-19 scenario), would have represented a safe and environmentally sound option in terms of health protection and CC indicator. Full article

The development of biogas technology is essential as a renewable energy source, aiding global initiatives in sustainable energy production and waste management. Geographical, technological, and economic factors significantly vary the efficiency and viability of biogas facilities by area. This study compares the techno-economic, social, and environmental impacts of biogas plants in Germany and Pakistan using a multicriteria decision-making method that combines the Analytic Hierarchy Process and SMARTER. This research has determined the weighting factors and then assessed the comparative performance of six selected biogas facilities based on five different scenarios: (i) comprehensive base-case, (ii) environmental performance, (iii) economic performance, (iv) social performance, and (v) per-kW energy efficiency. Three of these biogas facilities are in Pakistan (a low–medium-income developing country) and three in Germany (a high-income developed country). The findings of the study indicate that technical performance is the most heavily weighted criterion, playing a crucial role in determining the overall sustainability scores. Germany’s Bioenergie Park Güstrow stood out as the leading performer, achieving sustainability scores of 63.1%, 72.9%, and 73.0% across the comprehensive base-case, environmental, and per-kW efficiency scenarios, respectively. In the same scenarios, the Gujjar Colony Biogas Plant in Pakistan recorded the lowest scores of 25.4%, 43.2%, and 53.0%. The plants selected from a developed country showed a progressive score of high impact towards sustainability in most of the scenarios. In contrast, plants selected from a developing country showed low bioenergy deployment due to various factors, highlighting the gaps and flaws in achieving optimized energy generation and sustainable growth. The critical techno-economic and socio-environmental findings of the study are vital for policymakers, industry, engineers, and other relevant stakeholders seeking to enhance the performance, scalability, and sustainability of biogas technologies across developing and developed economies. Full article

In modern nickel mineral processing operations, the aim is to separate pentlandite from gangue minerals. One of these gangue minerals, pyrrhotite, contains up to 1 wt% Ni but is disposed of as waste, i.e., as tailings. Declining sulfide ore grades and increasing nickel demand have led to renewed interest in extracting nickel from pyrrhotite tails. One proposed process is thermal concentration, which aims to recover the nickel as a ferronickel alloy via thermal treatment at temperatures greater than 900 °C. Achieving these temperatures requires substantial energy input as the reactions involved are highly endothermic. In the present research, microwave radiation was used to process a reaction mixture consisting of a concentrate of pyrrhotite tails, iron ore, and metallurgical coke. The fundamental property that determines the interaction of microwaves with a material is complex permittivity. It was found that the reaction mixture had very high real and imaginary permittivities, making it a good candidate for microwave treatment. An input power of 800 W of microwave radiation (2450 MHz) was then employed to heat various reaction mixtures for thermal treatment times of 120, 300, and 600 s. The ferroalloy grades (6–7.5 wt% Ni) were comparable to those produced by conventional heating and to those obtained by other authors using conventional heating techniques. The microwaved samples had increased metallization of nickel, which was attributed to increased melting due to the higher internal temperatures. Full article

The transition to clean energy is crucial for mitigating the impacts of climate change and achieving sustainable development. Reliance on fossil fuels, which are integral to manufacturing and transportation, remains a major contributor to greenhouse gas (GHG) emissions. Biomass gasification presents a renewable energy alternative that can significantly reduce emissions. However, proper disposal of municipal solid waste (MSW) and agricultural residues, such as date palm waste (DPW), is an increasing global challenge, including in Qatar. This study evaluates the economic feasibility of implementing an MSW and DPW gasification plant for clean electricity generation in Qatar. The country’s growing population and economic development have led to substantial waste production, making it an ideal location for waste-to-energy (WTE) initiatives. Using discounted cash flow (DCF) analysis, the study estimates the capital cost of a 373 MW_th facility at approximately $12.07 million, with annual operating costs of about $4.09 million and revenue of $26.88 million in 2023. The results indicate a net present value (NPV) of $245.77 million, a return on investment (ROI) of 84.80%, a payback period of approximately 5 years over a 20-year project lifetime and a net reduction of 206,786 tonnes CO₂ annually. These findings demonstrate the economic viability of biomass gasification in Qatar while contributing to reduced GHG emissions and advancing the country’s sustainability goals under Qatar National Vision 2030. Full article

Waste-to-energy (WtE) is a key part of modern waste management. In the European Union, approximately 500 WtE plants process more than 100 million tons of waste yearly, while globally, more than 2700 plants handle over 500 million tons. Roughly 20% of the waste processed is bottom ash (BA). However, this ash can contain heavy metals in concentrations that may render it hazardous. This paper presents a study focusing on stabilizing municipal solid waste incineration BA using simple and industrially viable treatments. The Slovenian WtE plant operator wishes to install the stabilization process; thus, the samples obtained from the plant were treated (1) with a CO₂ gas flow, (2) with water spraying, and (3) with a combination of water spraying and a CO₂ gas flow under laboratory conditions. Thermodynamic calculations were applied to define potential reactions during the treatment processes in the temperature range from 0 to 100 °C and to define the equilibrium composition of the treated ash with additions of CO₂ and water. The standard leaching test EN 12457-4 of treated ash shows a reduction of over 40% in barium concentration and over 30% in lead concentration in leachates. Full article

Inadequate waste management strategies play a significant role in exacerbating environmental challenges, such as increased greenhouse gas emissions, resource depletion, and other adverse ecological impacts. These issues are aggravated by the global rise in municipal solid waste (MSW) generation, surpassing the rate of population growth. Simultaneously, there is an urgent demand for sustainable energy solutions to combat climate change and its wide-ranging impacts. In response, this study addresses a critical question: is methanol production from MSW, a waste-to-chemical (WtC) alternative based on circular economy principles, a more environmentally sustainable approach compared to traditional waste-to-energy (WtE) methods like landfilling with biogas recovery and incineration? To answer this, this study evaluates the environmental performance of MSW-to-methanol technologies using life cycle assessment (LCA), focusing on key indicators such as global warming potential, resource depletion, and impacts on human health and ecosystem quality. The results reveal that methanol production from MSW significantly reduces global warming potential (GWP) by 87% compared to landfilling and 56% compared to incineration. Additionally, the process demonstrates high energy efficiency in electricity generation, achieving 80% of the output of incineration. These findings position MSW-to-methanol as a promising alternative for advancing sustainable waste management and renewable energy transitions. While the technology is still in its developmental stages, this research highlights the need for further advancements and policy support to enhance feasibility and scalability. By providing a comparative environmental analysis, this study contributes to identifying innovative pathways for addressing pressing waste management and energy sustainability challenges. Full article