Search Results (2,549)

Climate change and land-use intensification are speeding up the loss of ecosystem services that support human health, food security, and environmental stability. Vegetative interventions—such as urban forests in cities and cover crops in farming systems—are increasingly seen as nature-based solutions for climate adaptation. However, their benefits are often viewed separately. This review combines 20 years of research to explore how these strategies, together, improve provisioning, regulating, supporting, and cultural ecosystem services across various landscapes. Urban forests help reduce urban heat islands, improve air quality, manage stormwater, and offer cultural and health benefits. Cover crops increase soil fertility, regulate water, support nutrient cycling, and enhance crop yields, with potential for carbon sequestration and biofuel production. We identify opportunities and challenges, highlight barriers to adopting these strategies, and suggest integrated frameworks—including spatial decision-support tools, incentive programs, and education—to encourage broader use. By connecting urban and rural systems, this review underscores vegetation as a versatile tool for resilience, essential for reaching global sustainability goals. Full article

Driven by the energy transition within the framework of the United Nations Framework Convention on Climate Change, second-generation (2G) ethanol stands out as a technical and sustainable alternative to fossil fuels. Although first-generation ethanol, produced from saccharine and starchy feedstocks, represents an advance in mitigating emissions, its expansion is limited by competition with areas destined for food production. In this context, 2G ethanol, obtained from residual lignocellulosic biomass, emerges as a strategic route for diversifying and expanding the renewable energy matrix. Thus, this work discusses the current state of 2G ethanol technology based on the gradual growth in production and the consolidation of this route over the last few years. Industrial second-generation ethanol plants operating around the world demonstrate the high potential of agricultural waste as a raw material, particularly corn straw in the United States, which offers a lower cost and significant yield in the production of this biofuel. Similarly, in Brazil, sugarcane by-products, especially bagasse and straw, are consolidating as the main sources for 2G ethanol, integrated into the biorefinery concept and the valorization of by-products obtained during the 2G ethanol production process. However, despite the wide availability of lignocellulosic biomass and its high productive potential, the consolidation of 2G ethanol is still conditioned by technical and economic challenges, especially the high costs associated with pretreatment stages and enzymatic cocktails, as well as the formation of inhibitory compounds that compromise the efficiency of the process. Genetic engineering plays a particularly important role in the development of microorganisms to produce more efficient enzymatic cocktails and to ferment hexoses and pentoses (C₆ and C₅ sugars) into ethanol. In this scenario, not only are technological limitations important but also public policies and tax incentives, combined with the integration of the biorefinery concept and the valorization of (by)products, which prove fundamental to reducing costs, increasing process efficiency, and ensuring the economic viability and sustainability of second-generation ethanol. Full article

Biofuels have emerged as a promising alternative to conventional fuels, offering improved environmental sustainability. Nevertheless, inadequate control of their physicochemical properties can lead to increased emissions and potential engine damage. Existing methods for regulating these properties depend on costly and sophisticated laboratory equipment, which poses significant challenges for integration into industrial production processes. Three-dimensional printing technology provides a cost-effective alternative to traditional fabrication methods, offering particular benefits for the development of low-cost designs for detecting liquid properties. In this work, we present a sensor system for assessing biofuel solutions. The presented device employs piezoelectric sensors integrated with 3D-printed, liquid-filled cells whose structural design is refined through experimental validation and novel optimization strategies that account for sensitivity, recovery and resolution. This system incorporates discrete electronic circuits and a microcontroller, within which artificial intelligence algorithms are implemented to correlate sensor responses with fluid viscosity and density. The proposed approach achieves calibration and resolution errors as low as 0.99% and $1.48\times {10}^{-2}$ mPa·s for viscosity, and 0.0485% and $1.9\times {10}^{-4}$ g/mL for density, enabling detection of small compositional variations in biofuels. Additionally, algorithmic methodologies for dimensionality reduction and data treatment are introduced to address temporal drift, enhance sensor lifespan and accelerate data acquisition. The resulting system is compact, precise and applicable to diverse industrial liquids. Full article

Understanding the molecular basis of heat tolerance in microalgae is crucial for developing resilient strains for industrial biotechnology. This study identified two desert Chlorella strains, XDA024 (thermotolerant) and XDA121 (heat-sensitive), through short-term thermal screening. The thermotolerant strain XDA024 survived exposure to 50 °C for 3 h, whereas XDA121 succumbed within 1 h at 40 °C. Physiological analyses revealed that the superior heat resistance of XDA024 was associated with enhanced activities of key antioxidant enzymes, including superoxide dismutase, catalase, and peroxidase, which effectively mitigated oxidative damage, alongside an elevated proline content contributing to osmoregulation. Transcriptomic profiling under acute heat stress (45 °C, 3 h) revealed that the unique thermotolerance of XDA024 was underpinned by the upregulation of genes related to photosystem stability and lipid synthesis, processes supported by activated calcium signaling and antioxidant pathways. In contrast, XDA121 exhibited significant downregulation of photosynthesis-related genes and promoted lipid degradation, resulting in membrane instability. Exogenous application of phosphatidylethanolamine (PE) and monoethanolamine (MEA) markedly increased the survival rate of XDA121 by more than threefold, primarily by alleviating membrane damage through enhanced membrane integrity and modulated antioxidant enzyme activities. These findings indicate that thermotolerance in desert Chlorella (Chlorophyta) is governed by the integrated coordination of antioxidant defense mechanisms, lipid metabolism, and photosystem protection. This research provides crucial insights and practical strategies for engineering heat-resistant microalgal strains for sustainable biofuel and bioproduct production. Full article

Xylanases (EC 3.2.1.8) are value-added enzymes essential for biomass deconstruction and are widely used in the pulp and paper, food, feed, and biofuel sectors. This review provides a comprehensive analysis of the current state and future prospects of xylanase research and application. It begins by examining the structural diversity of xylan substrates and the corresponding classification of xylanase enzymes, their catalytic mechanisms, and methods for their functional study, such as inhibitor analysis. The discussion then covers the challenges and methods involved in the purification of xylanases from complex biological mixtures. While natural microbial sources (fungi and bacteria) remain important, the limitations of wild-type (WT) strains for industrial production are highlighted. The review assesses the most common recombinant production systems, including Escherichia coli, Bacillus subtilis, and Komagataella phaffii, comparing their advantages for high-yield enzyme production. Finally, the paper focuses on protein engineering strategies as powerful tools for enhancing key enzyme properties (thermostability, specific activity, and pH tolerance). By integrating fundamental knowledge with applied technological approaches, this review underscores the critical role of xylanases in industrial biotechnology and identifies future research directions for their optimization. Full article

The industrial transition to advanced biofuels is currently limited by the metabolic constraints and low inhibitor tolerance of wild-type microbial hosts. This review justifies the necessity of Precision Fermentation (PF) as the pivotal technological framework to overcome these barriers, providing a systematic synthesis of high-resolution genetic tools and intelligent bioprocess architectures. We analyze how the integration of CRISPR-Cas9, retron-mediated recombineering, and synthetic regulatory circuits enables the development of specialized microbial “chassis” capable of achieving 10- to 100-fold higher yields compared to native organisms, with industrial titers reaching 50 g/L for isobutanol and 25 g/L for farnesene. A major novelty of this work is the critical evaluation of Artificial Intelligence (AI), Soft Sensing, and Digital Twins in orchestrating real-time metabolic control and mitigating the toxic effects of advanced alcohols and drop-in hydrocarbons (C15–C20). Furthermore, the study concludes that the “scale-out” modular strategy, when integrated into hybrid thermochemical-biochemical biorefineries, allows for the full valorization of C5/C6 sugars and lignin, achieving a Minimum Selling Price (MSP) competitive with fossil fuels. By mapping the synergy between advanced metabolic engineering and data-driven process optimization, this review establishes PF as an indispensable driver for achieving carbon-neutral and carbon-negative energy systems in the circular bioeconomy. Full article

The worldwide transition to renewable energy systems is motivated by diminishing fossil fuel availability and the intensifying consequences of climate change. This study presents a Mixed-Integer Linear Programming (MILP) model for designing and optimising the bio-fuel and electricity supply chain in Colombia, using sugarcane as the main feedstock and integrating microalgae cultivation in vinasse. Six alternative biorefinery configurations and four microalgae conversion pathways were evaluated to inform strategic planning. The optimisation results indicate that microalgae achieve higher energy yields per unit of land than sugarcane. Ethanol production from sugarcane could meet all of Colombia’s gasoline demand, while diesel and sustainable aviation fuel derived from microalgae could supply around 9% and 16%, respectively, of the country’s consumption. Further-more, pelletised bagasse emerges as a viable alternative to replace part of the coal used in thermoelectric plants. From an economic perspective, all scenarios achieve a positive net present value, confirming their profitability. Sensitivity analysis highlights the critical factors influencing the deployment of distilleries as ethanol price, algae productivity, and sugarcane cost. Furthermore, transportation costs play a decisive role in the geographic location of microalgae-based facilities and the distribution of their products. Full article

Recently, as a result of growing interest in diatoms as sources of energy (biofuel) and valuable food components for humans and aquaculture organisms, new data on the structures and properties of diatom natural products have been obtained, including both endo- and exometabolites. Information about their biosynthesis, biological activity and roles, and their beneficial and hazardous properties has also emerged. The application of modern methods of molecular biology, metabolomics, and chemical ecology to the study of diatom natural products has improved the understanding of many important natural phenomena associated with diatoms, such as photosynthesis, harmful algal blooms, interactions of diatoms with other organisms of marine biota, and their impact on biogeochemical cycles and climate regulation. In this paper, we discuss various aspects of research on natural compounds from diatoms, covering the last decade, as well as prospects for their further development, which have become apparent in recent years. Full article

The ever-growing global consumption of coffee generates millions of tons of spent coffee grounds (SCG) annually, posing a significant waste disposal problem. Although some SCG find use in composting or biogas production, a large portion remains underutilized. This study introduces a novel circular waste-to-energy pathway to tackle this challenge. Our proposed technology employs a cascading valorization approach, utilizing non-catalytic supercritical transesterification of pyrolytic oil derived from SCG for liquid hydrocarbon production. The process begins with pyrolysis, which converts SCG into pyrolytic oil. This oil is then upgraded via supercritical transesterification with methanol. Experiments were conducted using a 1:6 oil-to-methanol ratio at precisely controlled conditions of 239.4 °C and 1200 psi for 20 min. This optimized process yielded an impressive 96% of valuable liquid hydrocarbon product. The resulting product exhibited highly favorable characteristics, including a density of 755.7 kg/m³, a viscosity of 0.7297 mm²/s, and a high heating value (HHV) of 48.86 MJ/kg. These properties are remarkably comparable to conventional biofuels and standard fossil fuels, demonstrating the product’s potential as a viable energy source. Full article

Biomass gasification, as a thermochemical process, has attracted growing interest due to the increasing popularity of biofuel production based on syngas or pure hydrogen. Moreover, when integrated with CO₂ capture, this method of producing gaseous fuels can achieve negative CO₂ emissions, making it competitive with other production systems based on either fossil or renewable sources. This paper presents the results of a process and economic analysis of synthetic natural gas (SNG) production systems integrated with a commercial fluidized-bed gasification reactor based on Synthesis Energy Systems (SES) technology. The study examines the potential integration of the system with a water electrolyzer at two levels of coupling: one providing oxygen for the gasification process, and the other eliminating the need for CO₂ separation before the SNG synthesis stage. Using a single gasification unit with a raw biomass feed rate of 60 t/h, the system produces 188 t/d of SNG. Integration with a water electrolyzer increases SNG production to 259 and 621 t/d. For cases without electrolyzer integration and under the assumption of zero emissions from biomass processing, the application of CO₂ separation enables the achievement of negative CO₂ emissions. This creates an opportunity for additional revenue from the sale of CO₂ emission allowances, which can significantly reduce SNG production costs. In this analysis, the break-even CO₂ price, above which the SNG production cost becomes negative, is USD 251/t CO₂. In systems integrated with water electrolysis, the cost and carbon footprint of the electricity consumed in the electrochemical water-splitting process have a decisive impact on both the overall SNG production cost and its carbon intensity. Full article

Hydrothermal liquefaction (HTL) is a thermochemical process by which biomass feedstocks are converted into bio-oil and multiple by-products, including aqueous co-product (ACP), gaseous co-product (GCP), and biochar. Bio-oil produced from food waste feedstocks represents a potential candidate for use in commercial waste-to-energy conversions. The objective of this study is to further develop this technology by investigating the product distribution and quality from the HTL of food waste feedstocks. Four food waste feedstocks were selected for analysis: brewery grains, pear lees, coffee grounds, and honeydew skins. Solids analysis was conducted on each as-received feedstock, with the results determining dilution ratios for optimizing water content for HTL (≥80%). HTL conversions were conducted at 300 °C with a retention time of 30 min. Biochar was measured after product filtration, while ACP and bio-oil were measured via liquid–liquid phase separation. Coffee grounds produced the highest percentage of bio-oil (0.460%) and biochar (9.96%), while pear lees produced the highest percentage of ACP (89.5%). After quantification, ACP was characterized for nutrient concentrations. The quality of the ACP differed significantly from values in the literature, highlighting the influence of feedstock type and reaction conditions on HTL product characteristics (in addition to distribution) and underscoring the need for further research to optimize co-product utilization and process efficiency. Full article

Rapid industrialization has generated large volumes of acidic wastewater that, without adequate treatment, pose serious environmental and public health risks. Traditional remediation processes, such as chemical neutralization, ion-exchange, and membrane filtration, are effective but costly, energy-intensive, and generate toxic secondary waste. In contrast, acidophilic microalgae offer a sustainable, cost-effective, and eco-friendly alternative. Algae rely on their cellular structure and metabolism to adsorb, absorb, bioaccumulate, and transform toxic metals while simultaneously neutralizing wastewater with minimal secondary waste production. Although acidophilic algae tolerate highly toxic and low pH conditions, their growth rate and biomass productivity, key drivers of algae-based bioremediation, are often compromised under such conditions. Thus, identifying robust species and evolving strains to thrive in these wastewaters without compromising productivity will facilitate adoption of algae-based bioremediation on a large scale. Integrating algal wastewater remediation with biofuel and biofertilizer production can contribute to the circular economy. In this review, we synthesize mechanisms employed by acidophilic algal strains when exposed to acidic and metal-enriched environments to remediate wastewater. We highlight recent studies applying these strains to acidic wastewater remediation and biogas upgrading and discuss current biotechnological tools aimed at enhancing strain performance for future use in commercial systems. Full article

Pili nutshell (PS), an abundant agro-industrial byproduct in the Bicol Region, Philippines, demonstrates substantial potential as a solid biofuel and bioenergy feedstock. Proximate and ultimate analyses revealed high volatile matter (72.00 ± 0.20 wt%), low ash content (4.33 ± 0.76 wt%), and a higher heating value of 20.60 MJ/kg, indicating strong suitability as a solid fuel for thermochemical conversion and biofuel production. Thermogravimetric analysis (TGA) was conducted from 30 °C to 900 °C at heating rates of 10, 15, and 20 °C/min under nitrogen to examine its thermal decomposition behavior. The process followed three stages: initial moisture loss, active devolatilization, and lignin-rich char formation. The resulting kinetic and thermodynamic parameters are directly relevant for designing fast pyrolysis processes aimed at liquid biofuel production and optimizing downstream fuel utilization of the derived bio-oil and char. Kinetic analysis using the Coats–Redfern method identified third-order reaction (CR03) and diffusion-controlled (DM6) models as best-fitting, with activation energies ranging from 64.03–96.21 kJ/mol (CR03) and 66.98–104.72 kJ/mol (DM6). Corresponding thermodynamic parameters—ΔH (58.67–90.95 kJ/mol), ΔG (201.51–231.46 kJ/mol), and ΔS (−174.57 to −255.08 kJ/mol·K)—indicated an endothermic, non-spontaneous, entropy-reducing reaction pathway. Model-free methods confirmed a highly reactive zone at α = 0.3–0.6, with consistent E_a values (~130–190 kJ/mol). These findings affirm the viability of PS for fast pyrolysis, offering data-driven insights for optimizing advanced fuel and bioenergy systems in line with circular economy objectives. Full article

Wood biomass ash (WBA) is a by-product from biofuel energy plants. The disposal of this waste is connected with numerous environmental concerns. A more sustainable choice is to recycle it as a raw material for building and construction materials. However, due to its unstable characteristics, its application in alkali-activated materials (AAM) poses a challenge. One issue is the development of the mechanical properties. To improve them, pozzolanic additives, including coal fly ash (CFA), metakaolin (MK), and natural zeolite (NZ), were added at replacement ratios of 10–40%. Calcium hydroxide, sodium hydroxide, and sodium silicate were used together as ternary activators. The samples were cured at 60 °C for the first 24 h and for the remaining 27 days at room temperature. Mechanical behavior, water absorption, and chemical compositions were examined. The results obtained from XRF were compared with the calculation results of the chemical compositions based on the mix design and oxide compositions of the raw materials. The results show that the respective optimum replacement ratios were 30% CFA, 20% MK, and 20% NZ, with the highest compressive strength corresponding to 22.71, 20.53, and 24.33 MPa, and the highest flexural strength of 4.49, 4.32, and 4.21 MPa. NZ was the most effective in AAM, due to the highest Si/Al ratio in the Ca-rich ambient. Then, CFA contributed less, and MK was the least efficient when used in combination with WBA in AAM. The reduction of Ca/Si ratios in the AAM caused by the pozzolanic additives favors the formation of a binder system made of different hydrates and facilitates the strength enhancement when the Ca/Si ratio is lower than 0.35. Full article

Corn processing generates substantial volumes of agricultural by-products, collectively referred to as corn stover, comprising husks, cobs, stalks, leaves, and silks. Although rich in bioactive compounds, these by-products are still predominantly destined for low-value uses such as landfilling and open-field burning. They contain valuable biomolecules such as lignocellulosic fibers, starch, pectin, proteins, and polyphenols, all of which hold significant potential for applications in agricultural and food industries. These compounds offer opportunities as sustainable alternatives to conventional ingredients and as novel functional additives. However, utilization of corn stover remains focused on biofuel production, limiting the development of applications in broader, high-value fields such as functional food ingredients. This review aims to highlight the opportunities that corn stover presents for developing solutions for food production, which is becoming increasingly important as the global population continues to grow and food demand rises, particularly in regions where access to sufficient and nutritious food remains limited. It also considers the challenges to be solved in order to incorporate corn stover in circular economies, like the impact of pesticide presence on derived products and gaps of emerging strategies for scaling up production in alignment with circular economy goals and the high-value utilization of corn stover. Full article