Search Results (108)

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

The global emphasis on clean energy has increased interest in producing hydrogen from petroleum reservoirs through in situ combustion-based processes. While field practices have demonstrated the feasibility of co-producing hydrogen and oil, the question of which offers greater economic potential, oil, or hydrogen, remains central to ongoing discussions, especially as researchers explore ways to produce hydrogen exclusively from petroleum reservoirs. This study presents the first integrated techno-economic model comparing oil and hydrogen production under varying injection strategies, using CMG STARS for reservoir simulations and GoldSim for economic modeling. Key technical factors, including injection compositions, well configurations, reservoir heterogeneity, and formation damage (issues not addressed in previous studies), were analyzed for their impact on hydrogen yield and profitability. The results indicate that CO₂-enriched injection strategies enhance hydrogen production but are economically constrained by the high costs of CO₂ procurement and recycling. In contrast, air injection, although less efficient in hydrogen yield, provides a more cost-effective alternative. Despite the technological promise of hydrogen, oil revenue remains the dominant economic driver, with hydrogen co-production facing significant economic challenges unless supported by policy incentives or advancements in gas lifting, separation, and storage technologies. This study highlights the economic trade-offs and strategic considerations crucial for integrating hydrogen production into conventional petroleum extraction, offering valuable insights for optimizing hydrogen co-production in the context of a sustainable energy transition. Additionally, while the present work focuses on oil reservoirs, future research should extend the approach to natural gas and gas condensate reservoirs, which may offer more favorable conditions for hydrogen generation. Full article

Increasing the cell mass used as an inoculum is an effective strategy for enhancing productivity in alcoholic fermentation processes. In batch processes without cell recycling, such as those used in maize ethanol production, this objective can be achieved through two main approaches: (i) increasing the amount of commercially acquired dry cell mass or (ii) extending the propagation time. In this study, an economic assessment of both approaches was carried out, considering the Brazilian industrial context of maize ethanol production. Fermentation assays demonstrated that specific substrate consumption decreases with increasing initial cell concentration, following a hyperbolic model. This experimental behavior was used to simulate different operational scenarios and estimate productivity gains and economic impacts. The results showed that both strategies increase ethanol production and revenue, although the associated costs vary significantly. Based on this model, productivity and revenue gains were estimated for both approaches. The findings suggest that extending the propagation time is the most economically viable strategy to increase the initial cell concentration, even in scenarios where the plant lacks existing infrastructure and additional equipment investments are required. The analysis also accounted for operational costs associated with increased energy consumption during extended aeration time. Full article

The world is facing climate change, biodiversity loss, and pollution, significantly impacting lower-middle-income countries like Egypt, Morocco, and Tunisia, which depend heavily on tourism. Poor waste management, unclear responsibilities, and weak policies contribute to environmental degradation. Tourism, a key economic driver, also increases the problem by high plastic use and waste generation during peak seasons. This study evaluates current waste management practices in Alexandria (Egypt), Essaouira (Morocco), and Hammam Sousse (Tunisia) and proposes improvements using a newly developed “Extended Sector Responsibility” (ESR) model, which introduces an innovative organizational approach to waste management in touristic destinations. Using a combination of desk research, questionnaires, waste sorting analyses, and expert interviews, our research identifies systemic deficiencies. None of the studied locations have formal source separation systems, and waste management heavily depends on the informal sector. Hotels exhibit limited capacity for effective waste practices due to the lack of municipal infrastructure for separate collection. Economic analysis of the ESR model, which involves the establishment of a new waste recovery facility, demonstrates that while such facilities can generate revenue exceeding operational costs under specific scenarios, their long-term viability hinges on additional funding, possibly through Extended Producer Responsibility (EPR) mechanisms. Although Egypt and Tunisia have EPR legislation, implementation remains inadequate, and Morocco lacks such frameworks. The study emphasizes the critical need for investments in municipal waste management infrastructure, including logistics, sorting, and recycling systems. It also highlights actionable opportunities for the tourism sector to reduce waste by minimizing single-use plastics and food waste. By adopting the ESR model, the tourism sector can play a pivotal role in transitioning to a circular economy, ultimately mitigating environmental impacts and enhancing sustainability in the region. Full article

Lignocellulosic bioethanol is a promising renewable energy source that can reduce greenhouse gas emissions and improve energy security. However, its commercialization faces significant economic and environmental challenges, including high feedstock costs, complex pretreatment processes, expensive enzyme formulations, and substantial energy and water requirements. This review examines the key factors affecting its viability, including feedstock costs, enzyme efficiency, co-product generation, greenhouse gas emissions, water use, energy efficiency, and land use impacts. Recent advancements in pretreatment technologies, enzyme recycling, genetically engineered microbial strains, and fermentation strategies are discussed for their potential to improve process efficiency and reduce production costs. This review also explores co-product valorization, including lignin and biogas utilization, which can enhance the economic sustainability of bioethanol production by generating additional revenue streams, offsetting operational costs, and improving overall process efficiency. Identifying research gaps, it highlights the need for cost-effective feedstock supply chains, advanced enzyme technologies, and optimized fermentation methods. Additionally, the role of life cycle assessments and government policies, including subsidies, is considered in shaping production costs and the environmental impact. By integrating economic and environmental perspectives, this review provides insights into advancing the sustainable production of lignocellulosic bioethanol, emphasizing the importance of continued innovation to overcome existing challenges. Full article

The transition to sustainable mobility is one of the most pressing and complex challenges for the automotive industry, with impacts that extend beyond the mere reduction of emissions. Electric vehicles, while at the center of this evolution, raise questions about the consumption of natural resources, such as lithium, copper, and cobalt, and their long-term sustainability. In addition, the introduction of advanced technologies, including artificial intelligence (AI) and autonomous systems, brings new challenges related to the management of components and materials needed for their production, creating a significant impact on supply chains. The growing demand for electric and autonomous vehicles is pushing the industry to rethink production models, favoring the adoption of circular economy principles to minimize waste and optimize the use of resources. To better understand the implications of this transition, this study adopts a multiple case study methodology, which allows in-depth exploration of different contexts and scenarios, and analysis of real cases of dismantling and recycling of internal combustion engines (ICEs) and electric vehicles (EVs). The research includes a financial simulation and a comparison of revenues from the dismantling of ICE and EV vehicles, highlighting differences in the value of recycled materials and the effectiveness of circular economy practices applied to the two types of vehicles. This approach provides a detailed overview of the economic benefits and challenges related to the management of the end of life of vehicles, helping to outline optimal strategies for a sustainable and cost-effective future in the automotive sector. Full article

In recent years, the rapid growth in electric vehicle ownership has resulted in a significant number of decommissioned traction batteries that will require recycling in the future. As consumer expectations for electric vehicle range continue to rise, the turnover of traction batteries has accelerated substantially. Consequently, there is an urgent need for electric vehicle manufacturers to establish an efficient, recyclable supply chain for the return of end-of-life (EOL) electric vehicle (EV) traction batteries. In this paper, we investigate the closed-loop recycling supply chain for retired power batteries in electric vehicle manufacturers, taking into account blockchain technology and the high range preferences in the electric vehicle market, which are influenced by varying demand for different levels of electric vehicle capacitance. Blockchain, as a distributed and decentralized technology, offers features such as consensus mechanisms, traceability, and security, which have been effectively applied across various fields. In this study, we construct four models involving EV battery manufacturers, EV retailers, and battery comprehensive utilization (BCU) enterprises participating in the recycling process. Through the analysis of a Stackelberg response model, we find that (1) single-channel recycling is less efficient than dual-channel recycling models, a difference driven by the diversity of recycling channels and the variability in recycling markets; (2) Recycling models incorporating blockchain technology demonstrate superior performance compared to those that do not utilize blockchain technology, particularly when the intensity of recycling competition is below 0.76; (3) Traction batteries integrated with blockchain technology exhibit higher recycling rates when the optimization index is below 0.96. Electric vehicle battery manufacturers must evaluate the benefits and costs of adopting blockchain technology; (4) With lower recycling incentive levels and EV range preferences, the single-channel recycling model yields better returns than the other three recycling models. EV manufacturers can enhance overall battery supply chain revenues by establishing varying incentive levels based on market demand for different capacitance levels. Full article

In view of the uncertainty regarding consumers’ perceived value of remanufactured products, a remanufacturing supply chain system with the manufacturer as the Stackelberg leader is constructed, in which the manufacturer faces three modes, namely the manufacturer recycling mode (M), the retailer recycling mode (R), and the entrusted third-party recycling mode (3P). The remanufacturing supply chain is analyzed using the game theory approach in these three recycling modes. Using game theory to analyze the optimal pricing and profits of each supply chain participant, we also discuss the impact of consumers’ perceived value uncertainty on the profits of each party under the different recycling modes, and we then explore the selection of recycling channels in the remanufacturing supply chain. The results show that when the perceived value uncertainty is at a medium or low level, retailers are responsible for recycling used products and producing remanufactured products, which brings higher profits to the supply chain system; when the perceived value uncertainty is high, the demand for remanufactured products in the market decreases, and the recycling revenue of remanufactured products is lower. Finally, the validity of the theoretical model is verified by a numerical simulation. Full article

Electric vehicles (EVs) have seen significant advancements and mainstream adoption, prompting in-depth analysis of their economic, technical, and environmental impacts. Economically, while EVs offer lower operational costs than internal combustion engine vehicles, challenges remain, particularly for urban users reliant on public charging stations and the potential implementation of new road taxes to offset declining fuel tax revenues. Technically, electric motors in EVs have fewer moving parts, but battery management and cybersecurity complexities pose new risks. Transitioning from Nickel-Manganese-Cobalt (NMC) to Lithium-Iron-Phosphate (LFP) batteries reflects efforts to enhance thermal stability and mitigate fire hazards. Environmentally, lithium extraction for batteries has profound ecological impacts, including for water consumption and pollution. Battery production and the carbon footprint of the entire lifecycle remain pressing concerns, with battery recycling and second-life applications as crucial mitigation strategies. Smart integration of EVs with the energy infrastructure introduces challenges like grid stability and opportunities, such as smart, intelligent, innovative charging solutions and vehicle-to-grid (V2G) technology. Future research should develop economic models to forecast long-term impacts, advance battery technology, enhance cybersecurity, and conduct comprehensive environmental assessments to optimise the benefits of electromobility, addressing the multidimensional challenges and opportunities presented by EVs. Full article

This study analyzed environmental impacts and economic feasibility to evaluate whether recycling fly ash, which has rarely been addressed in previous studies, as a raw material for lightweight aggregates can be a sustainable waste management alternative. This study presents a comparative analysis of three disposal scenarios: landfill disposal, recycling as cement raw material, and recycling as lightweight aggregate raw material. Nine environmental impacts were assessed through life cycle assessment (LCA): acidification, global warming, eutrophication, photochemical oxidation, stratospheric ozone depletion, human toxicity, freshwater aquatic ecotoxicity, marine aquatic ecotoxicity, and terrestrial ecotoxicity. The results showed that the landfill disposal scenario posed the greatest threat to global warming, eutrophication, and marine aquatic ecotoxicity, while the cement scenario had the greatest impact on stratospheric ozone depletion, human toxicity, and other ecotoxicity items while recycling as lightweight aggregate showed the lowest environmental impacts in most items except acidification and photochemical oxidation. Life cycle costing (LCC) analysis was also performed to compare the economic aspects of each scenario. The lightweight aggregate scenario is more energy-intensive and costly, but it has significant economic benefits due to the significant revenues from the products produced. Therefore, even though the cost is high, this scenario is considered economically advantageous. This study highlights that recycling fly ash into lightweight aggregate reduces environmental impacts, provides economic benefits, and is a better alternative to landfilling and recycling cement raw materials. It will also contribute to promoting sustainable practices of fly ash recycling. Full article

Building on updated estimates of the social cost of carbon obtained from the most recent literature, this article proposes a social cost of carbon-based benchmark for carbon pricing to drive world countries’ carbon pricing policies up to 2050, consistent with the Paris Agreement targets. By using a dataset on net effective carbon rates developed by the Organisation for Economic Co-operation and Development (OECD), we firstly compare both explicit and implicit carbon pricing in 2021 in 71 OECD and non-OECD countries with the social cost of carbon benchmark for 2021 and calculate the degree of internalization of the social cost of carbon averagely related to their carbon pricing instruments. We find that there is a serious gap in current climate policies, which are far from creating optimal pricing conditions to reduce global emissions to levels needed by the Paris Agreement. The economic and distributional feasibility of a full implementation of the carbon pricing benchmark is tested in the same set of countries using two indicators, which are calculated for 2025, 2030, 2040 and 2050. Since the test results are income-regressive among income country groups, benchmark implementation by countries within the cooperative approaches of Paris Agreement art. 6 should be accompanied by the creation of an international cooperative fund aimed to recycle at least part of the revenues collected by high-income countries to compensate affected population in lower-income countries. Full article

The quality control of remanufactured products in a closed-loop supply chain (CLSC) can significantly influence consumers’ decision-making, and the contract coordination of CLSC has also become a research hotspot. This paper explores the quality control problem in a three-level remanufacturing CLSC consisting of a remanufacturer, a retailer, and a recycler by constructing a system dynamics (SD) model, which contains two contract schemes: quality control contract and quality control–revenue-sharing contract. Subsequently, the proposed SD model is analyzed using various schemes. The findings suggest that without mandatory contracts, CLSC members are frequently unable to fulfill their quality improvement commitments. Among them, recyclers are less likely to improve quality and more prone to breaking promises. The quality control problem in CLSC can be addressed through contract coordination, and the quality control contract scheme can avoid non-compliance with quality improvement commitments. The application of the quality control–revenue-sharing combination contract scheme not only resolves the quality control issue but also promotes profit improvement in the CLSC. Full article

Municipal solid waste (MSW) management in Spain, particularly in the Valencian Community, heavily relies on mechanical–biological treatment (MBT) plants followed by landfill disposal. These MBT facilities utilize mechanical processes like shredding, screening, and sorting to segregate recyclables (metals, plastics, paper) from organic material and other nonrecyclables. While public funding supports these plants, private entities manage them through complex, long-term concession contracts. This structure restricts access to crucial data on the sale prices of the byproducts generated during MBT. Publicly available information on relevant company and administration websites is typically absent, hindering transparency surrounding byproduct revenue. This study addresses this gap by analyzing 2012’s available data on revenues obtained from byproduct sales following mechanical treatment at MBT plants within the Valencian Community and comparing them with Spanish national data. This research revealed a significant finding—the statistical distribution of average prices obtained from Ecoembes auctions in the Valencian Community mirrored the corresponding distribution for prices calculated from auctions conducted in other Spanish regions. This suggests a potential uniformity in byproduct pricing across the country. It has also been found that none of the analyzed price distributions exhibited a normal (Gaussian) distribution. The findings also highlight the need for alternative pricing models that move beyond simple averages and account for regional variations and outliers. As actual prices are not available after 2012, this lack of transparency poses a challenge in comprehensively evaluating the economic viability of MBT plants. Furthermore, it raises concerns regarding whether the revenue generated from byproduct sales reflects fair market value. Limited public access to this information can potentially indicate conflicts of interest or inefficiencies within the waste management system. Full article

Recycling plastics on an industrial scale is a key approach to the circular economy. This study presents a techno-economic analysis aimed at recycling polypropylene waste, one of the main consumer plastics. Specifically, it evaluates the technical and economic feasibility of achieving a large-scale cracking process that converts polypropylene waste into an alternative fuel. Pyrolysis is considered as a promising technique to convert plastic waste into liquid oil and other value-added products, with a dual benefit of recovering resources and providing a zero-waste solution. This study concerns a fast catalytic pyrolysis in a fluidized bed reactor, with the presence of a fluid catalytic cracking catalyst of low acidity for high heat transmission, for an industrial plant with a capacity of 1 t/h of polypropylene waste provided by the Greek Petroleum Industry. From the international literature, the operational conditions were chosen pyrolysis temperature at 430 °C, pressure at 1atm, heating rate at 5 °C/min, and yields of products to 71, 14, and 15 wt.%, for liquid fuel, gas, solid product, respectively. The plant design includes a series of apparatuses, with the main one to be the pyrolyzer. The catalytic method is selected over the non-catalytic because the presence of catalyst increases the quantity and quality of the liquid product, which is the main product of the plant. The energy loops of recycling pyrolysis gas and char as a low-carbon fuel in the plant were considered. The production cost, annual revenue, for 2023, are anticipated to reach €13.7 million (115 €/t) and €15 million (15 €/t), respectively, with an estimated investment equal to €5.3 million. The Payback Time is estimated to 2.4 years to recover the cost of investment. The endeavor is rather economically sustainable. A critical parameter for large scale systems is securing feedstock with low or negligible price. Full article

The impacts that the available energy sources have had on society, the environment, and the economy have become a focus of attention in recent years, generating polarization of opinions. Understanding these impacts is crucial for rational evaluation and the development of strategies for economic growth and energy security. This review examines such impacts of the main energy resources currently exploited or in development, including fossil fuels, geothermal, biomass, solar, hydropower, hydrogen, nuclear, ocean, and wind energies on society through analysis and comparison. It is essential to consider how high energy demand influences energy prices, the workforce, and the environment and to assess the advantages and disadvantages of each energy source. One significant finding from this review is that the levelized cost of energy (LCOE) may vary substantially depending on the energy source used and show substantial ranges for different applications of the same energy source. Nuclear energy has the lowest LCOE range whereas ocean energy has the highest LCOE range among the nine energy sources considered. Fossil fuels were found to have the most substantial societal impacts, which involved on the positive side providing by far the largest number of jobs and highest tax revenues. However, on the negative side, fossil fuels, biomass, and nuclear energy sources pose the most significant health threats and social well-being impacts on communities and societies compared to other energy sources. On the other hand, solar, ocean and wind energy pose the lowest risk in terms of health and safety, with solar and wind also currently providing a substantial number of jobs worldwide. Regarding environmental consequences, fossil fuels generate the highest greenhouse gas (GHG) emissions and have the highest adverse impacts on ecosystems. In contrast, nuclear, ocean, solar and wind energies have the lowest GHG emissions and low to moderate impacts on ecosystems. Biomass, geothermal and hydropower energy sources have moderate to high ecosystem impacts compared to the other energy sources. Hydropower facilities require the most materials (mainly concrete) to build per unit of energy generated, followed by wind and solar energy, which require substantial steel and concrete per unit of energy generated. The lack of substantial materials recycling causes associated with solar and wind energy sources. All the energies that use thermal power generation process consume substantial quantities of water for cooling. The analysis and comparisons provided in this review identified that there is an urgent need to transition away from large-carbon-footprint processes, particularly fossil fuels without carbon capture, and to reduce the consumption of construction materials without recycling, as occurs in many of the existing solar and wind energy plants. This transition can be facilitated by seeking alternative and more widely accessible materials with lower carbon footprints during manufacturing and construction. Implementing such strategies can help mitigate climate change and have a positive impact on community well-being and economic growth. Full article