Search Results (370)

The valorization of spent coffee grounds (SCGs) into solid biofuels represents a promising pathway toward sustainable energy and waste reduction. The objective of this study is to upgrade SCGs into high-quality solid biofuels through an integrated process of activated carbon filter offcuts (ACFO)-assisted drying and microwave torrefaction. The methodology involves employing ACFO as a layered drying enhancer to facilitate moisture removal from SCGs at 85–125 °C, followed by microwave torrefaction at 200–300 °C to evaluate fuel properties and environmental sustainability via life cycle assessment (LCA). Results reveal that the alternating layered ACFO-SCG configuration accelerates drying kinetics and improves heat transfer uniformity. Under optimal conditions (85 °C), the specific power consumption decreased from 3.13 to 2.64 kWh per 1% moisture removal, achieving 15.6% energy savings compared with conventional convective drying. Microwave torrefaction at 300 °C yields high-quality biochar comparable to lignite with a higher heating value of 30.61 MJ·kg⁻¹. Furthermore, LCA indicates that torrefaction at 220 °C minimizes the carbon footprint (0.216 kg CO₂-eq per kg), whereas increasing the temperature to 300 °C reverses this advantage due to rising electricity demands. This finding concludes that ACFO can effectively bypass biomass-drying energy barriers, enabling the efficient upcycling of SCGs into high-quality solid biofuels with limited energy input. Full article

When a fuel briquette is pressed using solar electricity in summer and burned for heating in winter, the briquette functions as a seasonal energy store—without batteries, self-discharge, or capital investment in storage infrastructure. This paper quantifies such “indirect energy storage” at an operating briquette production facility in Sumy, Ukraine, using 2024 operational data from a 34 kW hybrid solar power plant integrated into the production process without battery storage under continental climate conditions (50°55′ N) and full-scale military conflict. The objective was to determine the contribution of the solar power plant (SPP) to energy supply, analyse the structure of electricity consumption, and quantify the mechanism of indirect accumulation of renewable energy through transformation into solid biofuels. The study tested two hypotheses: (H1) that integration of a solar power plant into industrial daytime operation (6:00–22:00) achieves a self-consumption rate close to 100%, displacing grid electricity without curtailment or storage losses; and (H2) that the solar fraction embedded in produced briquettes constitutes a quantifiable mechanism of indirect seasonal energy storage despite a temporal mismatch between solar peaks (summer) and product demand (winter). Methods included statistical analysis of monthly and intraday operational data; Pearson correlation analysis between solar generation and production cycles; energy audit of production processes; decomposition of specific consumption into pressing and packaging components; and a simple economic assessment (NPV, IRR, LCOE, payback) with sensitivity analysis. Annual production reached 1222.975 t of briquettes. Total specific electricity consumption (including two short packaging campaigns in June and July only) was 141.3 ± 12.6 kWh/t (CV = 8.9%). After deducting 4962 kWh of dedicated packaging electricity (2.9% of annual consumption), the specific consumption for briquette pressing alone was 136.7 ± 5.0 kWh/t (CV = 3.7%)—within the European benchmark range of 80–150 kWh/t for wood densification, with tight monthly variation indicating a stable, well-tuned pressing operation throughout the year. The SPP supplied 18.3% of total annual electricity, peaking at 33.06% in May and averaging 29.95% from March to August. Intraday analysis of 530 five-minute intervals confirmed a 100% self-consumption rate across all seasons (H1 supported). A total of 223.4 t of briquettes containing accumulated solar energy were produced during the spring–summer period. A weak negative correlation (r = −0.28) between monthly SPP generation and briquette production was observed but did not reach statistical significance (p = 0.385); this descriptive—rather than causal—relationship is consistent with the expected temporal shift between summer surpluses and winter demand, and is itself a signature of indirect rather than direct energy coupling (H2 supported in a descriptive sense). The compound efficiency along the solar-to-stored-fuel chain was estimated at approximately 68%, providing a quantitative indicator for the indirect-storage concept. Economic analysis yielded a simple payback period of about 3 years, NPV (20 yr, 12%) ≈ 1.15 million UAH, IRR ≈ 33%, and LCOE ≈ 3.28 UAH/kWh—61% below the prevailing industrial tariff of 8.45 UAH/kWh—with sensitivity analysis showing positive NPV across ±20% variation in electricity price and ±15% in CAPEX. To the best of the authors’ knowledge, this is the first empirical quantification of biomass-solar integration as a seasonal energy buffer operating without battery storage. The solar energy accumulated in briquettes is sufficient to heat 56–74 households for a full winter season. Regional scaling of the present configuration—under explicit assumptions of comparable facility sizes and operating regimes—could in principle provide fuel for 15,000–20,000 households (8–12% of regional heating needs during energy crises). These findings are directly relevant to post-conflict energy recovery and to regions where attacks on energy infrastructure have left solid biofuels as the primary available heating source. Full article

Evapotranspiration (ET) is a fundamental process within the water cycle and the agricultural water balance, optimizing resource allocation, maintaining soil health, and enhancing ecosystem resilience to climate change. Because ET represents a primary consumptive use of irrigation on agricultural lands, enhancing water-use efficiency and sustainable water management requires accurate estimation of evapotranspiration to support long-term sustainability and productivity. This study offers an effective means to visualize spatial and temporal patterns of reference evapotranspiration (ETo) across various vegetation management practices. This study examined the impacts of agroforestry buffers (ABs), grass buffers (GBs), biofuel crops in an agroforestry watershed (BCa), and biofuel crops in a grass buffer watershed (BCg) on ETo, compared to a corn (Zea mays L.)–soybean (Glycine max L.) rotation (RC) for claypan soil in Northern Missouri, USA. The experimental watersheds were located at the Greenley Memorial Research Center, Missouri, USA. Campbell Scientific sensors and Photosynthetically Active Radiation (PAR) smart sensors were installed to measure net radiation, anemometers, humidity, and air temperature. All instruments were mounted on masts at a height of 2 m above ground level in crop, tree, grass, and biofuel areas. Measured meteorological data were recorded hourly from April to October during 2017 and 2018. Daily ETo predictions were calculated using the Penman–Monteith model. These ETo predictions were displayed across the landscape using Python-based GIS for selected dates (each Saturday) for the watersheds. The methodology was implemented using the software programs of Python 2.7.10 and ArcGIS 10.3.1. The results indicated that ETo increased by 11%, 17%, 18%, and 25% in 2017, and by 7%, 9%, 14%, and 20% in 2018 for AB, BCa, BCg, and GB, respectively, compared to RC management. This process may improve soil water recharge in perennial management systems. Accurate estimation of ET in agricultural regions is critical for understanding water balance, hydrological and ecosystem processes, and climate variability. Given that agriculture constitutes the majority of global water consumption, precise ET estimation is particularly significant for sustainable water management, especially in regions experiencing water scarcity. These outcomes may support effective planning and management of agricultural water resources by enabling optimized irrigation and agricultural production. Full article

Green shipping corridors have become a key strategic initiative for advancing maritime decarbonization. This study develops an AIS-based bottom–up framework for estimating carbon emissions and compliance costs in green shipping corridors. The framework combines corridor fleet identification, AIS-based energy consumption and emission estimation, and compliance-cost modeling under the IMO CII and GFI requirements. On this basis, eight alternative energy options—HFO, fossil LNG, bio-LNG, e-LNG, bio-methanol, e-methanol, green ammonia, and biofuel B100—together with carbon capture technology, are incorporated into the analysis and applied to the Shanghai–Los Angeles/Long Beach green shipping corridor. The results show that before 2035, the emission reduction requirements of CII can cover the basic compliance requirements of GFI. Without carbon capture, the combined use of fossil LNG and bio-LNG appears to be a relatively favorable transition pathway. When carbon capture is considered, LNG with carbon capture and HFO with carbon capture emerge as two relatively advantageous transition pathways. During 2025–2035, it is recommended that ships first adopt fossil LNG, then gradually introduce limited amounts of bio-LNG, and subsequently integrate carbon capture once the technology becomes mature. Full article

Significant amounts of food waste come from fruit processing, causing economic and environmental impacts. The waste generated is a valuable source of compounds due to its concentration of nutrients, such as dietary fiber, vitamins, minerals, lipids with mono- and polyunsaturated fatty acids, and bioactive compounds. Despite the nutritional and functional qualities of the waste, it is still commonly discarded and underutilized, demonstrating the importance of studying it. The selected fruits described in this study are widely consumed by various populations around the world and are used at an industrial scale. The objective of this review is to discuss the use of seeds from grapes, passion fruit, melon, watermelon, papaya, guava, raspberry, and pomegranate and their benefits for human consumption. The seeds stand out for the possibility of oil extraction, creating a sustainable and healthy mode of production. Due to their nutritional composition rich in polyunsaturated fatty acids, they have been shown to be beneficial to health, promoting development, strengthening the immune system, and promoting the growth and maintenance of cell membranes, cardiovascular benefits, and antimicrobial and antioxidant activity, in addition to innovation in the cosmetics sector and applicability as biofuel. Therefore, the exploitation of this type of by-product shows promise in the search for alternative sources of vegetable oils and bioactive compounds with high added nutritional value and potential nutraceutical application, helping to increase the value of food waste and thus contributing to a better use of plant resources. Full article

Environmental and climatic alterations, coupled with increasing economic activity and increasing energy demand, have reinforced the global need to develop substitute fuels as a means of reducing reliance on fossil fuels. Saudi Arabia has shown increasing biofuel consumption (charcoal and fuelwood) in recent years. Thus, this study was designed to examine the relationship between biofuel energy consfumption, economic growth and the environment. Accordingly, the study comprises dual portions: the first tests the cointegration association among biofuel consumption and economic growth, while the second discovers a cointegration association among biofuel consumption and carbon dioxide emissions. The study also includes a forecasting analysis. Data on biofuel energy consumption, economic growth and the environment were compiled from numerous sources covering the period from 1990 to 2023. Engel–Granger method assessments revealed long-term relationships between bioenergy consumption, economic growth, and environmental quality. FMOLS and DOLS estimates yielded results well-matched with those acquired using the Engel–Granger method. Furthermore, the gross rates of biofuel consumption equal 2.40% for the period 2010–2023 and 2.80% for the forecast period 2023–2035. Similarly, the growth rates of gross domestic product were calculated at 7.50% for the period 2010–2023 and 11.00% for the projected period 2023–2035. Also, the gross rates of CO₂ emissions were calculated at 1.90% for the period 2010–2023 and 0.95% for the projected period 2023–2035. The results indicate that biofuel consumption is expected to continue growing at a faster rate, joined by strong economic growth. Particularly, the projected slowdown in carbon dioxide emissions suggests a possible decoupling of economic activity from environmental degradation. These findings underscore the need to promote biofuel development and clean energy policies to reinforce sustainable economic growth while reducing emissions in the long term. Full article

Waste-to-energy technology plays a crucial role in advancing the circular economy framework, a strategy that contributes to achieving the United Nations Sustainable Development Goals on responsible consumption and production, as well as the provision of affordable and clean energy. Hydrothermal co-liquefaction has emerged as a promising technology for addressing waste material challenges by converting them into valuable biofuels. This review focuses on biomass feedstock classification and provides an overview of hydrothermal co-liquefaction for sustainable waste management and improved energy production. Moreover, the article provides details on integrating other waste treatment methods with hydrothermal liquefaction to promote the circular economy. Research publications from 2015 to 2025 were obtained from Web of Science and Scopus to identify research trends and output across countries and map out future research directions. The retrieved data from Web of Science was analysed for mapping research, keyword occurrence, and network analysis using VOSviewer software. The study highlighted that waste treatment techniques not only mitigate environmental pollution but also provide a sustainable pathway for energy production and contribute to global carbon neutrality. The review shows that biocrude yield varies with blending ratio because of differences in the biochemical composition of feedstocks, which affect reaction pathways and lead to synergistic or antagonistic interactions during co-processing. Therefore, careful selection of biomass feedstock is essential to achieve optimal results. Full article

The pursuit of thermal comfort in buildings is one of the main sources of energy consumption worldwide. To mitigate this expenditure, thermal insulation is required in construction. However, most conventional insulation materials come from non-renewable resources. Recently, different alternatives for generating more environmentally friendly insulation from biomass have been studied. However, when using biomass, care must be taken to avoid negatively impacting the food industry. One way to address this is to use biomass waste from previous manufacturing processes. The use of waste from the production of biofuel derived from castor beans (Ricinus communis) for the manufacture of thermal insulation was successfully implemented. Castor beans were collected and used to obtain biofuel. The waste was mixed with construction materials (lime, marble dust, and cement) in different concentrations. A device for measuring thermal conductivity was built and validated. The results of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) are presented to characterize the material. A decrease in thermal conductivity was found in the construction material depending on the presence of micelle remnants left after oil extraction. Full article

This paper presents the analysis and results of the numerical simulation of the biofuel combustion process: namely, the volumetric mixture of diesel oil (ON) and camelina seed oil methyl ester (CSME) in a diesel engine. The mathematical model used in the simulation is based on a four-stroke diesel engine acting as a power generator. To enable simulations depending on the type of biofuel, a model algorithm was developed in the MATLAB/Simulink environment that allowed for the conditions and parameters to be adjusted according to specific test requirements. The numerical simulation was built on the basis of a real stand, in order to confirm the results of previous research both theoretically and in real applications. The calculation approach starts with the elemental composition of the fuel and goes through the intake, compression, combustion, and expansion stages, culminating in the thermal balance of the engine. The mathematical model confirmed the obtained results, which are comparable to the results from the research station. The obtained results confirm the legitimacy of using CSME as an additive to diesel and show its impact on engine performance that can be optimized to achieve the desired results. The use of pure CSME (100%) resulted in an increase in engine power and torque, probably due to the oxygen content of the biofuel molecules and its higher cetane number, which improves its ignition characteristics. However, an increase in unit fuel consumption has been observed, indicating lower energy efficiency compared to clean diesel, which is partially offset by the higher density of biofuel. The model takes into account the physicochemical properties of the fuel, such as the viscosity, cetane number and density, which significantly affect the fuel injection and atomization processes. Although the simulation is based on simplified assumptions, its results highlight the potential of biofuels in heavy transport and their cost-effectiveness as an alternative to fossil fuels. The developed model is used not only to evaluate the engine performance, but also as a tool for assessing the thermal efficiency, and optimizing the composition of the fuel mixture. Full article

While thinnings immediately reduce aboveground biomass, they promote growth by releasing the remaining trees from competition. The biomass removed in thinnings can be used for energy, thus enabling financial returns prior to final harvest and contributing to the global share of renewable energies. In this study, the effects of thinning on stand structure dynamics and potential residential bioheat utilisation scenarios are assessed for a broadleaved mixed even-aged stand. The results demonstrate that ten years after thinning, aboveground biomass increased, ensuring system sustainability and carbon stocks. Furthermore, an average potential yield of 1.1 Mg·ha⁻¹·a⁻¹ (dry basis) of low-ash forest by-products was obtained, offering a sustainable supply of solid biofuels. However, the energy conversion route chosen has major impacts on the solid bioenergy demand and sustainability. Based on theoretical scenarios, upgrading from traditional fireplaces to more efficient combustion systems may reduce the specific biomass consumption up to eight times for residential heat production. The results obtained in this study highlight the challenge and need to use thinning biomass sustainably in the face of growing bioenergy demands. Full article

The conversion of lignocellulosic biomass (LCB) into biofuels is hindered by its inherent resistance and the drawbacks of conventional pretreatment, which include high cost, intensive energy use, and inhibitor formation. Here, we present a novel, one-pot bioconversion process that bypasses pretreatment by integrating cerium-doped iron oxide nanoparticles (CeFeO₄NPs) with a specialized enzyme system. The system utilizes enzyme supernatant from Penicillium janthinellum mutant EU-30, a strain developed via chemical–physical mutagenesis, which exhibits stable hemicellulase activity and a 25–30% increase in cellulase activity. The integrated approach effectively saccharified raw sugarcane bagasse (SB) within 24 h, generating the highest yields of 12.8 ± 0.5 g/L glucose and 11.54 ± 0.5 g/L xylose compared to other substrates tested. Subsequent fermentation with Saccharomyces cerevisiae yielded 13.47 g/L ethanol (1.21 g/L/h productivity) and demonstrated concurrent consumption of both hexose and pentose sugars. We propose that residual CeFe₃O₄NPs in the hydrolysate mitigate carbon catabolite inhibition, thereby increasing xylose utilization. This was attributed to the residual CeFe₃O₄NPs in the hydrolysate, which are thought to upregulate xylose-metabolism-related genes in S. cerevisiae, thereby alleviating carbon catabolite inhibition. This method offers a streamlined, economical, and sustainable platform for producing carbon-neutral bioethanol from agricultural waste, eliminating costly pretreatment and simplifying downstream processing. Full article

In Mexico, mezcal production relies heavily on firewood, consuming up to 246 m³ per artisanal batch and producing approximately 2.4 t of bagasse for every 6 t of fermented Agave. This residue, with a calorific value of ≈19.4 MJ/kg, is a promising alternative to solid biofuels. Using a discrete-event simulation in Arena™ (version 16.20.09), the substitution of firewood with processed bagasse briquettes was evaluated at a distillery in the region of Tecamachalco. The model included drying, grinding, briquetting, and distillation, analyzing yield, resource use, and bottlenecks. Sensitivity analyses identified solar drying as the main constraint. The results show a reduction of up to ~30% in firewood consumption, promoting the principles of the circular bioeconomy and sustainable rural energy transition. Full article

Fermentation, one of the oldest biotransformation processes, has become a key element of contemporary sustainable biotechnology. In modern food systems, it enables the simultaneous resolution of environmental, nutritional, and economic challenges by converting agricultural and food residues into high-value-added products, such as bioactive compounds, organic acids, biofuels, enzymes, and proteins. Consistent with the concept of a circular bioeconomy, fermentation supports resource recycling, waste minimization, and greenhouse gas reduction, contributing to the achievement of selected United Nations Sustainable Development Goals (SDGs). The importance of fermentation extends beyond its environmental aspects—fermented foods and postbiotics support the modulation of the gut microbiome, strengthen immunity, and can act as a preventative measure against metabolic and inflammatory conditions. Simultaneously, the dynamic development of precision fermentation and synthetic biology enables the design of microorganisms that produce specific food ingredients without the use of animals or traditional agriculture, paving the way for more responsible production and consumption. This review presents the categories of organic residues valorized through fermentation, explains their role in circular food and healthcare systems, and identifies key technological and regulatory barriers limiting the scaling of this approach. Collectively, fermentation emerges as a biotechnology platform with significant transformative potential for future sustainable food systems. Full article

To mitigate the emission of greenhouse gases (GHG) from fossil fuel combustion, biomass-to-power development via biochemical or thermochemical pathways has been recognized as a sustainable route for advancing towards a society based on a circular bioeconomy. The key differences between these pathways lie in operating temperature, process design capacity, feedstock characteristics and primary products. The biochemical route focuses on specific biofuels (e.g., biogas), and the thermochemical route often offers broader energy forms like heat and electricity. This perspective paper updates Taiwan’s achievements of its installed capacity and power (electricity) generation over a period of five years (2020–2024) under regulatory promotion that echoes official policies for sustainable development goals (SDGs) and 2050 carbon neutrality. Furthermore, the challenges of the biomass-to-power development in Taiwan (especially biogas-to-power systems) are addressed in the present study. These key issues include biomass resource, promotion incentives, stationary air pollution, site land use requirements and units for meeting performance durability requirements. Based on installed capacity, the main findings showed that biomass-to-power systems using biochemical routes (i.e., anaerobic digestion) in Taiwan showed an increasing trend, as well as increasing results for those using thermochemical routes (direct combustion, gasification). Furthermore, the data on total power generation indicated an upward trend from 201.7 Gigawatt-hour (GWh) in 2021 to 237.7 GWh in 2024, regardless of the kind of route used, whether biochemical or thermochemical. In conclusion, biomass-to-power systems have provided sustainable waste management and a circular bioeconomy model in Taiwan, which can be linked to the targets of sustainable development goals (SDGs) like SDG-7 (i.e., affordable and clean energy) and SDG-12 (i.e., responsible consumption and production). Full article

Ammonia is considered as a promising hydrogen carrier and a carbon-free fuel. Methods for improving ammonia combustion characteristics often involve its co-firing with more reactive fuels (natural gas, biofuels, etc.). Among the natural gas components, ethane is second most abundant. Therefore, the development of detailed chemical–kinetic mechanisms that accurately consider the interactions between ammonia and each component of natural gas is very important. Such mechanisms must be based on experimental data obtained under a wide range of conditions. In this work, NH₃/C₂H₆/O₂/Ar blends were studied in JSR (φ = 0.5–2.0, p = 1 atm, τ = 1 s, T = 800–1300 K) and in a shock tube (p = 7.3–8.6 atm, T = 1260–1590 K). Additionally, the structure of premixed flames was investigated (φ = 0.8–1.2, p = 1–5 atm). Eleven recently published detailed chemical–kinetic mechanisms were tested. The model Shrestha-2025 was updated to achieve better agreement with the entire set of experimental data. The effect of p and φ on intermediate species concentration was analyzed. Ammonia and ethane consumption pathways were also examined. Full article