Search Results (266)

The growing demand for air connectivity, coupled with the forecasted increase in passengers by 2040, implies an exigency in the aviation sector to adopt sustainable approaches for net zero emission by 2050. Sustainable Aviation Fuel (SAF) is currently the most promising short-term solution; however, ensuring its overall sustainability depends on reducing the life cycle carbon footprints. A key challenge prevails in hydrogen usage as a reactant for the approved ASTM routes of SAF. The processing, conversion and refinement of feed entailing hydrodeoxygenation (HDO), decarboxylation, hydrogenation, isomerisation and hydrocracking requires substantial hydrogen input. This hydrogen is sourced either in situ or ex situ, with the supply chain encompassing renewables or non-renewables origins. Addressing this hydrogen usage and recognising the emission implications thereof has therefore become a novel research priority. Aside from the preferred adoption of renewable water electrolysis to generate hydrogen, other promising pathways encompass hydrothermal gasification, biomass gasification (with or without carbon capture) and biomethane with steam methane reforming (with or without carbon capture) owing to the lower greenhouse emissions, the convincing status of the technology readiness level and the lower acidification potential. Equally imperative are measures for reducing hydrogen demand in SAF pathways. Strategies involve identifying the appropriate catalyst (monometallic and bimetallic sulphide catalyst), increasing the catalyst life in the deoxygenation process, deploying low-cost iso-propanol (hydrogen donor), developing the aerobic fermentation of sugar to 1,4 dimethyl cyclooctane with the intermediate formation of isoprene and advancing aqueous phase reforming or single-stage hydro processing. Other supportive alternatives include implementing the catalytic and co-pyrolysis of waste oil with solid feedstocks and selecting highly saturated feedstock. Thus, future progress demands coordinated innovation and research endeavours to bolster the seamless integration of the cutting-edge hydrogen production processes with the SAF infrastructure. Rigorous techno-economic and life cycle assessments, alongside technological breakthroughs and biomass characterisation, are indispensable for ensuring scalability and sustainability. Full article

In response to growing pressures for sustainability in tourism, this paper examines the techno-economic evaluation of green innovations in small and medium-sized tourism enterprises (SMEs). Focusing on a single case study of a hotel in Greece, the research investigates how and why specific sustainability interventions were implemented and assesses their operational and economic impacts. The study adopts an interpretivist approach, combining process tracing with thematic analysis. The analysis is guided by innovation diffusion theory, supported by organizational learning perspectives, to explain the stepwise adoption of sustainability practices and the internal adaptation processes that enabled them. The techno-economic evaluation draws on quantitative indicators and qualitative assessments of perceived benefits and implementation challenges, offering a broader view of value beyond purely financial metrics. Data were collected through semi-structured interviews, on-site observations, and internal documentation. The findings reveal a gradual, non-linear path to innovation, shaped by adoption dynamics and organizational learning, reinforced by leadership commitment, contextual adaptation, supply chain decisions, and external incentives. Key interventions, including solar energy adoption, composting, and the formation of zero-waste partnerships, resulted in measurable reductions in energy use and landfill waste, along with improvements in guest satisfaction, operational efficiency, and local collaboration. Although it is subject to limitations typical of single-case designs, the study demonstrates how even modest sustainability efforts, when integrated into daily operations, can generate multiple types of outcomes (economic, environmental, and operational). The paper offers practical implications for tourism SMEs and policymakers and formulates propositions for future testing on sustainable innovation in the tourism sector. Full article

The aviation industry is responsible for approximately 2–3% of worldwide CO₂ emissions and is increasingly subjected to demands for the attainment of net-zero emissions targets by the year 2050. Traditional fossil jet fuels, which exhibit lifecycle emissions of approximately 89 kg CO₂-eq/GJ, play a substantial role in exacerbating climate change, contributing to local air pollution, and fostering energy insecurity. In contrast, Sustainable Aviation Fuels (SAFs) derived from renewable feedstocks, including biomass, municipal solid waste, algae, or through CO₂- and H₂-based power-to-liquid (PtL) represent a pivotal solution for the immediate future. SAFs generally accomplish lifecycle greenhouse gas (GHG) reductions of 50–80% (≈20–30 kg CO₂-eq/GJ), possess reduced sulfur and aromatic content, and markedly diminish particulate emissions, thus alleviating both climatic and health-related repercussions. In addition to their environmental advantages, SAFs promote energy diversification, lessen reliance on unstable fossil fuel markets, and invigorate regional economies, with projections indicating the creation of up to one million green jobs by 2030. This comprehensive review synthesizes current knowledge on SAF sustainability advantages compared to conventional aviation fuels, identifying critical barriers to large-scale deployment and proposing integrated solutions that combine technological innovation, supportive policy frameworks, and international collaboration to accelerate the aviation industry’s sustainable transformation. Full article

Global concerns about resource depletion, climate change, and nutrient pollution in aquatic systems are compelling a transition towards zero-waste industries. With the skyrocketing carbon footprint of the modern fertiliser industry, sustainable options are highly sought after. Anaerobic digestion of organic waste to generate renewable biogas and fertiliser production from the residual nutrient-rich digestate are promising nutrient recovery and recycling avenues. This review explores the potential use of anaerobic digestate to develop value-added agronomic products, focusing on the quality and safety parameters pivotal to its fertiliser value. A comprehensive review of conventional and cutting-edge technologies available for digestate processing into organic/organo-mineral fertilisers has been conducted, highlighting emerging sustainable approaches. Specifically, this review unravels novel aspects of enhancing digestate quality with biostimulants such as plant growth-promoting rhizobacteria, humic substances and biochar for biofertiliser/slow-release fertiliser production. Additionally, methods and guidelines to assess and address environmental impacts by digestate application on croplands and challenges in the commercialisation of digestate-based fertilisers were analysed. This review also underscores the importance of valorising anaerobic digestate as a fertiliser in implementing a circular bioeconomy within the agroindustry. Full article

Modern research laboratories are constantly evolving to meet the growing demands for precision, quality, and flexibility in scientific work. The modernization of existing experimental test benches plays a crucial role in improving efficiency, optimizing processes, and ensuring operational safety. This requires updates to their design, experimental methods, data collection, and results recording—all of which provide the foundation for developing new research concepts. An increasing number of innovations are now guided by the principle of minimizing environmental impact. In line with this approach, an innovative modernization of a tube furnace research station was carried out, based on the concepts of sustainable development and the zero-waste philosophy. To enable thermogravimetric analyses of coffee waste, a previously incomplete tube furnace was refurbished using recycled components. The primary objective was to expand the research capabilities of the existing workstation. As part of the modernization, three indicators of reuse efficiency were calculated: the quantitative indicator W_re-use, the mass indicator $W_{re\text{-}use}^{mass}$, and the cost indicator $W_{re\text{-}use}^{value}$. A quantitative index of 78% and a mass index of approximately 76% were achieved, while the economic value of the recovered components accounted for 11% of the total value of the revitalized research station. This strategy significantly reduced waste generation, carbon dioxide emissions, and the consumption of primary raw materials. Full article

In this study, the use of spent coffee waste as a green precursor of polyphenolic compounds, which are subsequently employed as reducing agents for the synthesis of zero-valent iron nanoparticles (nZVI) aimed at the efficient removal of dyes from aqueous systems, has been investigated. The nanoparticles, generated in situ in the presence of controlled amounts of hydrogen peroxide, were applied in the removal of organic dyes—including methylene blue, methyl orange, and orange G—through a heterogeneous Fenton-like catalytic process. The synthesized nZVI were thoroughly characterized by nitrogen adsorption at 77 K, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and powder X-ray diffraction (XRD). A statistical design of experiments and response surface methodology were employed to evaluate the effect of polyphenol, Fe(III), and H₂O₂ concentrations on dye removal efficiency. Results showed that under optimized conditions, a 100% removal efficiency could be achieved. This work highlights the potential of nZVI synthesized from agro-industrial waste through sustainable routes as an effective solution for water remediation, contributing to circular economy strategies and environmental protection. Full article

This study investigates the valorization of refuse-derived fuel (RDF), waste glass, and mill scale for sustainable ferrosilicon alloy production, contributing to zero-waste practices. RDF was blended with anthracite at ratios of 100, 90, 80, 70, 60 and 50 wt% (designated R1–R6) and applied as a reducing agent in the carbothermic reduction of SiO₂ and Fe₂O₃, thereby decreasing reliance on conventional fossil-based reductants. Ferrosilicon synthesis was conducted at 1550 °C using glass–mill scale blends with reducing agents R1–R6, producing samples named blends A–F. XRD analysis confirmed that the metallic products consisted predominantly of the FeSi intermetallic phase, with characteristic (110) and (310) peaks at 2θ ≈ 45.02° and 78°. The metallic products appeared as numerous small, shiny droplets, with yields ranging from 14.85 to 19.47 wt%; blends D–F exhibited the highest yields. In contrast, blends A–C produced metals with higher Si contents (23.34–27.11 wt%) due to enhanced SiO₂ reduction and efficient Si incorporation into the Fe matrix. Gas analysis and oxygen removal showed that blend B achieved the highest CO generation and reduction extent. Cl removal during RDF heat treatment indicated minimal potential for dioxin and furan formation. Overall, blends A and C were identified as optimal, providing high Si content, satisfactory metallic yield, and reduced CO/CO₂ emissions, demonstrating the effectiveness of RDF-based carbons for environmentally friendly ferrosilicon production. Full article

Global waste generation is a ubiquitous challenge, driving a paradigm shift towards viewing waste as a valuable resource for a circular economy across diverse sectors. While innovative waste-to-resource pathways are crucial, rigorous Life Cycle Assessment (LCA) is essential to ensure the pathways are an important part of current practices. However, LCA application to waste valorization varies, leading to incomparable results due to differing methodological choices. This paper examines three key nuances in waste-as-resource LCAs: the zero-burden assumption, the biogenic carbon neutrality assumption, and the benchmark assumption for emissions avoidance. Using a waste gasification to hydrogen case study, we demonstrate how these methodological decisions impact LCA outcomes. Our findings reveal that waste composition significantly influences the results and highlight challenges associated with biogenic carbon accounting under various system boundary assumptions. Emissions avoidance accounting requires multi-functional unit perspectives and robust benchmark selection. This paper clarifies these accounting approaches, empirically illustrates their influence, and discusses broad implications for accurate sustainability assessment, emphasizing the critical role of transparent LCA choices for effective policy and investment in circular economy solutions. Full article

The widespread use of activated carbon (AC) as an adsorbent in diverse applications generates substantial amounts of AC waste, posing environmental and disposal challenges. Therefore, effective AC regeneration is essential to enhance the sustainability of adsorption-based technologies. However, conventional regeneration methods often involve harsh chemicals or energy-intensive processes, limiting environmental and economic feasibility. In this study, the regeneration of commercial AC saturated with synthetic dyes Acid Blue 9 (AB9) and Acid Yellow 23 (AY23) is investigated using aqueous solutions of ionic liquids (ILs) as a green alternative. A set of ILs with varying cation–anion structures was synthesized and screened for regeneration performance, where [TBP][Sal] was identified as the most effective. Process parameters such as IL concentration, temperature, time, and solid-to-liquid ratio were optimized using response surface methodology, achieving regeneration efficiencies of up to 99% for AB9-AC and 80% for AY23. These efficiencies persisted over three cycles, while adsorption capacity remained unchanged for AY23 and decreased by ~40% for AB9. To improve sustainability, a preliminary study was conducted by implementing an aqueous biphasic system for IL and dye concentration from the post-regeneration solution. This integrated strategy presents a promising step toward the development of near-zero waste adsorption–regeneration cycles for AC adsorption applications. Full article

The exponential increase in global solid waste generation poses significant environmental, economic, and social challenges, particularly in rapidly urbanizing regions. Traditional waste management methods that focus on handling and disposal have proven unsustainable because of their negative impacts on air, soil, and water quality, and their contribution to greenhouse gas emissions. In response, the concept of zero-waste cities, rooted in circular economy principles, has gained increasing attention in recent years. This study proposes a comprehensive and integrated waste management system designed to optimize resource recovery across four distinct waste streams: household, healthcare, green/organic, and inert. The system integrates four specialized facilities: a Secondary Sorting Facility, Energy Recovery Facility, Composting Facility, and Inert Processing Facility, coordinated through a central Primary Sorting Hub. By enabling interconnectivity between these processing units, the system facilitates material cascading, maximizes the reuse and recycling of secondary raw materials, and supports energy recovery and circular nutrient flow. The anticipated benefits include enhanced operational efficiency, reduced environmental degradation, and generation of multiple revenue streams. However, the implementation of such a system faces challenges related to high capital investment, technological complexity, regulatory fragmentation, and low public acceptance. Overcoming these limitations will require strategic planning, stakeholder engagement, and adaptive governance. Full article

Lubricating oils are utilised in equipment and machinery to reduce friction and enhance material utilisation. The utilisation of oil leads to an increase in its thickness and density over time. Current methods for assessing oil life are slow, expensive, and complex, and often only applicable in laboratory settings and unsuitable for real-time or field use. This leads to unexpected equipment failures, unnecessary oil changes, and economic and environmental losses. A comprehensive review of the extant literature revealed no studies and no national or international patents on neural network algorithm-based oil life modelling and classification using green sensors. In order to address this research gap, this study, for the first time in the literature, provides a green conductivity sensor with high-accuracy prediction of oil life by integrating real-time field measurements and artificial neural networks. This design is based on analysing resistance change using a relatively low-cost, three-dimensional, eco-friendly sensor. The sensor is characterised by its simplicity, speed, precision, instantaneous measurement capability, and user-friendliness. The MLP and LVQ algorithms took as input the resistance values measured in two different oil types (diesel, bench oil) after 5–30 h of use. Depending on their degradation levels, they classified the oils as ‘diesel’ or ‘bench oil’ with 99.77% and 100% accuracy. This study encompasses a sensing system with a sensitivity of 50 µS/cm, demonstrating the proposed methodologies’ efficacy. A next-generation decision support system that will perform oil life determination in real time and with excellent efficiency has been introduced into the literature. The components of the sensor structure under scrutiny in this study are conducive to the creation of zero waste, in addition to being environmentally friendly and biocompatible. The developed three-dimensional green sensor simultaneously detects physical (resistance change) and chemical (oxidation-induced polar group formation) degradation by measuring oil conductivity and resistance changes. Measurements were conducted on simulated contaminated samples in a laboratory environment and on real diesel, gasoline, and industrial oil samples. Thanks to its simplicity, rapid applicability, and low cost, the proposed method enables real-time data collection and decision-making in industrial maintenance processes, contributing to the development of predictive maintenance strategies. It also supports environmental sustainability by preventing unnecessary oil changes and reducing waste. Full article

Integrating renewable energy with biomass valorization offers a scalable pathway toward circular and climate-resilient campus operations. This study presents a replicable model implemented at Alanya Alaaddin Keykubat University (ALKU, Türkiye), where post-consumer food waste from 30 cafeteria menus is converted into pet food and compost using a 150 L ECOAIR-150 thermal drying and grinding unit powered entirely by a 1.7 MW rooftop photovoltaic (PV) system. The PV infrastructure, established under Türkiye’s first public-sector Energy Performance Contract (EPC), ensures zero-electricity-cost operation. On average, 260 kg of organic waste are processed monthly, yielding 180 kg of pet food and 50 kg of compost, with an energy demand of 1.6 kWh h⁻¹ and a conversion efficiency of 68.4%, resulting in approximately 17.5 t CO₂ emissions avoided annually. Economic analysis indicates a monthly revenue of USD 55–65 and a payback period of ~36 months. Sensitivity analysis highlights the influence of input quality, seasonal waste composition, PV output variability, and operational continuity during academic breaks. Compared with similar initiatives in the literature, this model uniquely integrates EPC financing, renewable energy generation, and waste-to-product transformation within an academic setting, contributing directly to SDGs 7, 12, and 13. Full article

In the digital era, online search patterns provide a practical way to track changes in the public interest in sustainability. This study analyzes monthly Google Trends data in the United States (January 2019–December 2024) for five keywords: two institutional (“ESG”, “carbon neutral”), and three consumer-oriented (“eco friendly”, “zero waste”, and “plastic free”). Drawing on agenda-setting theory and the diffusion-of-innovations framework, we test the directional links between institutional and consumer attention. The methods include Granger causality tests, impulse response functions, and cross-correlation analysis. The findings reveal a consistent lead–lag structure in which institutional terms precede consumer-oriented searches, but the timing and persistence of influence vary across concepts. A broad discourse such as ESG produces slower, yet more sustained, effects, whereas action-oriented concepts like carbon neutrality generate quicker but shorter-lived responses. Seasonal analysis also shows recurring peaks in consumer interest around events such as Earth Day and Plastic-Free July, underscoring the cyclical nature of attention to sustainability. By integrating communication theory with multi-year digital trace data, this study provides evidence of how institutional messaging diffuses into consumer behavior, while highlighting the roles of timing and message framing. The results contribute to sustainability communication research and offer practical insights for policymakers, NGOs, and marketers relevant to aligning campaigns with evolving public attention. Full article

Biomass gasification represents a pivotal technology for sustainable energy and chemical production, yet its efficiency and product quality are critically dependent on catalyst performance. This comprehensive review systematically synthesizes recent advancements in catalyst design, mechanistic insights, and process integration in biomass gasification. Firstly, it details the development and performance of catalysts in diverse categories, including metal-based catalysts, Ca-based catalysts, natural mineral catalysts, composite/supported catalysts, and emerging waste-derived catalysts. Secondly, this review delves into the fundamental catalytic reaction mechanisms governing key processes such as tar cracking/reforming, water–gas shift, and methane reforming. It further explores sophisticated strategies for catalyst structure optimization, focusing on pore structure/surface area control, strong metal–support interactions (SMSIs), alloying effects, nanodispersion, and crystal phase design. The critical challenges of catalyst deactivation mechanisms and the corresponding activation, regeneration strategies, and post-regeneration performance evaluation are thoroughly discussed. Thirdly, this review addresses the crucial integration of zero CO₂ emission concepts, covering in situ CO₂ adsorption/conversion, carbon capture and storage (CCS) integration, catalytic CO₂ reduction/valorization, multi-energy system synergy, and environmental impact/life cycle analysis (LCA). By synthesizing cutting-edge research, this review identifies key knowledge gaps and outlines future research directions towards designing robust, cost-effective, and environmentally benign catalysts for next-generation, carbon-neutral biomass gasification systems. Full article

This study combines convolutional neural network (CNN) recognition technology, Greenwich engineering software, and statistical yearbook methods to evaluate rural solar, wind, and biomass energy resources in pilot cities in China, respectively. The CNN method enables the rapid identification of the available roof area, and Greenwich software provides wind resource simulation with local terrain adaptability. The results show that the capacity of photovoltaic power generation reaches approximately 15.63 GW, the potential of wind power is 458.3 MW, and the equivalent of agricultural waste is 433,900 tons of standard coal. The city is rich in wind, solar, and biomass resources. By optimizing the hybrid power generation system through genetic algorithms, wind energy, solar energy, biomass energy, and coal power are combined to balance the annual electricity demand in rural areas. The energy trends under different demand growth rates were predicted through the LEAP model, revealing that in the clean coal scenario of carbon capture (WSBC-CCS), clean coal power and renewable energy will dominate by 2030. Carbon dioxide emissions will peak in 2024 and return to the 2020 level between 2028 and 2029. Under the scenario of pure renewable energy (H_WSB), SO₂/NO_x will be reduced by 23–25%, and carbon dioxide emissions will approach zero. This study evaluates the renewable energy potential, power system capacity optimization, and carbon emission characteristics of pilot cities at a macro scale. Future work should further analyze the impact mechanisms of data sensitivity on these assessment results. Full article