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Renewable energy sources, such as biofuels, represent promising alternatives to reduce dependence on fossil fuels and mitigate climate change. Their production through enzymatic hydrolysis has gained relevance by converting agro-industrial waste into fermentable sugars and residual oils, which are essential for the generation of bioethanol and biodiesel. The fungus Aspergillus stands out as a key source of enzymes, including cellulases, xylanases, amylases, and lipases, which are crucial for the breakdown of biomass and oils to produce bioethanol and fatty acid methyl esters (FAME). This review examines the current state of these technologies, highlighting the significance of Aspergillus in the conversion of energy-rich waste materials. While the process holds significant potential, it faces challenges such as the high costs associated with enzymatic production and final processing stages. Agro-industrial waste is proposed as an energy resource to support a circular economy, thereby eliminating reliance on non-renewable resources in these processes. Furthermore, advanced pretreatment technologies—including biological, physical, and physicochemical methods, as well as the use of ionic liquids—are explored to enhance process efficiency. Innovative technologies, such as genetic engineering of Aspergillus strains and enzyme encapsulation, promise to optimize sustainable biofuel production by addressing key challenges and advancing this technology towards large-scale implementation. Full article

Global fossil fuel consumption, including diesel and gasoline, significantly contributes to emissions. Understanding emission percentages and types is critical. Alternative energies, like hydrogen mixed with gasoline, help mitigate emissions in sectors such as transport and energy. Hydrogen-gasoline blends in internal combustion engines improve the combustion process but require studying engine behavior and carbon footprint. This research designs a low-cost sensor network to monitor combustion emissions and provide reliable data for statistical comparison across vehicles. Two synchronized client–server software systems are proposed. The client software runs on an IoT development board (ESP32) and communicates with sensors via the ESP-NOW protocol to detect and collect gas data, transmitting it wirelessly to the web server. The server software provides a user-friendly interface for data control and visualization from a ground station. Tests used 100% Mexican gasoline (G100) and hydrogen-gasoline blends (GH) with a hydrogen cell electrolyte concentration of 0.0211 mL/gal (80 mL). A single vehicle followed the same route at 40–60 km/h, collecting data every 30 s over three trials. Results showed average reductions of 5% and 10% in CO and CO₂ emissions, respectively, with GH fuel. Full article

The study assessed the yield and quality as well as the energy potential of biomass from stalks and pomace of four grape varieties, Riesling, Chardonnay, Zweigelt, and Merlot Vitis vinifera L., grown in temperate climate conditions. The research is innovative because the evaluation of the energy potential of biomass originating from Vitis vinifera L. has not been carried out so far in the northern wine-growing regions. Field studies were conducted in 2023 in the Experimental Vineyard of the University of Life Sciences in Lublin, located in southeastern Poland. Biometric yield assessment showed that Chardonnay vines were characterized by the lowest mass of clusters and peduncles, number of berries in the cluster, berry diameter, and peduncle size, and at the same time the highest berry mass among the assessed biotypes. Merlot clusters were characterized by the highest mass of clusters and the largest peduncles. Riesling had the most berries in the cluster, the heaviest peduncles, and the highest share of peduncles in the cluster mass (8.99%). For grape pomace, the LHV values range from 15.98 MJ kg⁻¹ for the Chardonnay variety to 16.91 MJ kg⁻¹ for Riesling, while for peduncles, these values range from 15.11 MJ·kg⁻¹ for Merlot and Riesling to 15.26 MJ kg⁻¹ for Chardonnay. The differences in pollutant emissions are more pronounced between grapevine varieties than between types of biomass (pomace vs. peduncles). The greatest variation among varieties was observed for carbon dioxide (CO₂) emissions in the pomace category, while the smallest differences were noted for sulfur dioxide (SO₂) emissions. Total gas emissions were highest for Zweigelt pomace (7.72 Nm³ kg⁻¹) and lowest for Merlot (6.99 Nm³ kg⁻¹), while for stalks, Chardonnay had the highest values (6.77 Nm³ kg⁻¹) and Merlot the lowest (7.32 Nm³ kg⁻¹). The largest variation among varieties was observed in the pomace category. These results indicate differences in exhaust gas emissions for different plant parts and grape varieties, which are relevant for optimizing production processes and ensuring sustainable development. Full article

This study examines the maritime trade of biofuels in Spain, focusing on its contribution to the global energy transition and sustainable development. Using data from Spain’s 28 port authorities, the research identifies key trends, trade dynamics, and port-specific roles. This study reveals that Spain is a net biofuel exporter, maintaining a positive balance of 5.20 million tons throughout the study period. Export volumes peaked in 2021 at 1.63 million tons, while imports have shown steady growth over the past seven years. Barcelona and Bilbao emerge as strategic ports with robust connections to the Netherlands, Italy, and Belgium, reinforcing Spain’s role in the international biofuel market. This study incorporates hierarchical decision models, including classification trees, to analyze sustainability and efficiency factors in biofuel trade. These models unveil key interactions between variables such as cargo type, origin country, and port characteristics, offering actionable strategies to optimize port operations and enhance Spain’s standing in the global biofuels sector. This research highlights the importance of sustainable port infrastructure and international collaboration to strengthen Spain’s position as a pivotal player in the global energy transition. Full article

Energy demand is continuously increasing owing to rapid technological developments and population growth. Additionally, it has been shown that the consumption of fossil fuels contributes to the emission of gases that increase the greenhouse effect. An alternative for addressing the problems of greenhouse gas emissions and dependence on oil is to replace fossil fuels with biofuels. This article presents the combustion gas emissions and performance assessment of a used car using gasoline–bioethanol blends at concentrations free of mechanical risk to contribute information for energy transition. The tests were carried out using the mixtures E0, E5, and E10 at speeds of 1500, 2500, and 4500 rpm for the evaluation of emissions. Meanwhile, for the performance assessment, the speed was varied from 2500 rpm to 8000 rpm. The vehicle was analyzed under functional operating conditions, and no mechanical modifications were made to the alcohol mixtures. Testing was performed using a gas analyzer with non-dispersive infrared (NDIR) electroluminescence and electrochemical cells to measure the emissions, and a computerized chassis dynamometer was used to measure the torque and speed. From the results shown here, it can be concluded that the use of bioethanol at low concentrations in the range without mechanical risk, such as E0, E5, and E10, can be utilized in used cars and in functional operating conditions, improving the thermal efficiency of the engine by 2% and 1.2% with the E5 and E10 mixtures. The specific consumption increased up to 3% with the E10 mixture owing to the lower energy capacity of the mixture. Meanwhile, HC polluting emissions decreased by up to 8.44%, 20%, and 100 at speeds of 1500 rpm, 2500 rpm, and 4500 rpm, respectively. The nitrogen oxide emissions decreased by up to 5% for mixtures E5 and E10. The results presented in this article may be useful for decision making in the use of biofuels in automobiles used in the energy transition. In addition, our study can be taken as a reference for studies on cars that are more than 20 years old. Full article

The increasing emission of greenhouse gases that comes with the rise in industrialization is harmful to the environment. Thus, finding new renewable energy sources is becoming increasingly important in the energy field. One such renewable energy source is biomass, which provides valuable energy carriers—for example, biofuels. The objective of this work was to evaluate the release of total reducing sugars (TRSs) from mesquite pod seed hulls by chemical and enzymatic hydrolysis. The husks were crushed and separated by screens (#16, #30 and #50). The effect of hydrolysis time (10, 20, and 30 min) and sulfuric acid concentration (0, 0.25, and 0.5 N) was analyzed. The #50 mesh showed the highest TRS release, increasing from 3.19 to 17.49 g/L as the reaction time was extended. Additionally, enzymatic hydrolysis with endo-1, 4-β-xylanase and β-glucanase enzymes was evaluated on the solid and liquid fractions obtained. Statistical analysis with Design Expert showed that, for the solid fractions, after 31 h there were no significant differences, reaching 79.46 g/L TRS. In the liquid fractions, the TRS released reached 113.37 g/L after 54 h of enzymatic treatment. The release of TRS by chemical hydrolysis was also modeled with artificial neural networks, considering the particle size, the hydrolysis time, and the sulfuric acid concentration. The coefficient of determination (r²) indicates that the ANNs present a better data fit (r² > 0.99) to predict the experimental conditions that maximize the study variables. Full article

Utilization of various biomasses as raw materials in biorefineries represents a promising alternative for the production of valuable chemicals and biofuels. This study investigates the potential of the fungus Mucor indicus DSM 2158, cultivated on media containing the liquid phase of grass hydrolysates (LGH) and various nitrogen sources (yeast extract and corn steep liquor), for the production of valuable metabolites, such as ethanol, chitin, chitosan, and fatty acids. The ethanol yield varied depending on the cultivation media and conditions. The highest substrate-into-ethanol conversion coefficients (0.14–0.2 g g⁻¹) were achieved during M. indicus cultivation on the LGH medium containing 5 g L⁻¹ CSL in Erlenmeyer flasks and a bubble column bioreactor. In these cultivations, the highest fungal biomass concentrations (5.61–5.91 g L⁻¹) were also observed. In flask cultivations, the highest content of total lipids in fungal dry biomass (15.76%) was observed. The obtained fungal biomass contained up to 22 fatty acids, with oleic acid (≈50%) being the most predominant. Chitin and chitosan yields were from 0.1 g g⁻¹ to 0.3 g g⁻¹ of dry biomass depending on the cultivation media and conditions. The residual media from the cultivation of M. indicus were used for the growth of the non-sulfur purple bacterium Rhodovulum adriaticum DSM 2781. Cultivations of R. adriaticum DSM 2781 on the residual media, in Erlenmeyer flasks and a stirred-tank bioreactor, resulted in a biomass yield of 0.50 to 2.26 g L⁻¹. After extraction of bacterial biomass, total pigments (expressed as bacteriochlorophyll-a) were obtained in the range from 1.8 to 48.1 mg g⁻¹ dry biomass depending on the media and cultivation conditions. The highest titer of bacteriochlorophyll-a was achieved during cultivation on the exhausted LGH medium with 5 g L⁻¹ yeast extract. The established biorefinery system has to be optimized in order to reach capacity for transfer to a larger scale. Full article

In recent times, microalgae have emerged as powerful hosts for biotechnological applications, ranging from the production of lipids and specialized metabolites (SMs) of pharmaceutical interest to biofuels, nutraceutical supplements, and more. SM synthesis through bioengineered pathways relies on the availability of aromatic amino acids (AAAs) as an essential precursor. AAAs, phenylalanine, tyrosine, and tryptophan are also the building blocks of proteins, maintaining the structural and functional integrity of cells. Hence, they are crucial intermediates linking the primary and specialized metabolism. The biosynthesis pathway of AAAs in microbes and plants has been studied for decades, but not much is known about microalgae. The allosteric control present in this pathway has been targeted for metabolic engineering in microbes. This review focuses on the biosynthesis of AAAs in eukaryotic microalgae and engineering techniques for enhanced production. All the putative genes involved in AAA pathways in the model microalgae Chlamydomonas reinhardtii and Phaeodactylum tricornutum are listed in this review. Full article

Synechocystis sp. PCC 6803 is a highly promising organism for the production of diverse recombinant compounds, including biofuels. However, conventional genetic engineering in Synechocystis presents challenges due to its highly polyploid genome, which not only results in low product yields but also compromises the reliability of recombinant strains for biomanufacturing applications. The CRISPR/Cas9 system, renowned for its precision, efficiency, and versatility across a wide range of chassis, offers significant potential to address the limitations posed by polyploid genomes. In this study, we developed and optimized an effective sgRNA for the targeted knock-in of nucleotide sequences of varying lengths into the neutral locus slr0168 of polyploid Synechocystis using CRISPR/Cas9. The gene encoding di-geranylgeranylglycerophospholipid reductase from Sulfolobus acidocaldarius and the methyl ketone operon from Solanum habrochaites were chosen as the exemplar nucleotide sequences for incorporation into the chromosome of Synechocystis. Our results demonstrate that the designed sgRNA effectively facilitated both knock-in events and that CRISPR/Cas9 enabled complete mutant segregation in a single round of selection and induction. Full article

Microalgae have attracted wide attention due to their extensive application potential. Dewatering is a necessary work for the application of microalgae, especially in biofuel production, where forward osmosis (FO) research is relatively advanced but still faces technical bottlenecks hindering large-scale commercialization. Based on the current research in recent years, the research progress in the causes and control of membrane fouling, the development of membrane materials and optimization of membrane structure, and the energy saving and efficiency of the process are reviewed in this paper. We found that different species of algae have direct effects on membrane fouling. Chlorella vulgaris has a low membrane fouling trend, but the mechanisms of fouling need further investigation. The material development and structure optimization of membranes are the main research methods to reduce membrane fouling, but there are still some defects, such as complicated preparation and low water flux, which are difficult to apply on a large scale. The research progress of reducing costs by using seawater, urine, fertilizer, etc. as new draw solutions (DS) is reviewed. At present, many aspects of FO microalgae dewatering technology are still not well understood, and future research should focus on scaling up the existing technologies. Full article

The use of polyhydroxybutyrate (PHB) can help diminish fossil chemical dependency because it can partially replace petrochemical plastics due to its biodegradability and similar mechanical properties. However, its production costs are high compared with fossil-based plastics. Alternative carbon sources can be used in the fermentation media because they are renewable and low-cost. Vegetable oils are especially attractive due to their high carbon content, contributing to high production rates per gram of substrate. This work aimed to produce PHB from Cupriavidus necator LPB1421 using either corn or soybean oil as the sole carbon source. Urea was the best nitrogen source, enabling a DCW production of 4.35 g/L (corn oil) and 10.4 g/L (soybean oil). After media optimization, the DCW of corn oil reached 22.13 g/L, with 57.46% PHB accumulation (12.71 g PHB/L), whereas soybean oil led to a DCW of 19.83 g/L, with 54.91% PHB accumulation (10.89 g PHB/L). This media composition was employed in a kinetics assay, revealing similar fermentation parameters among both oils and a yield of 0.2118 g PHB/g for corn oil and 0.1815 g PHB/g for soybean oil. These results open the possibility of integrating PHB production with biofuel manufacturing in a bioethanol/biodiesel biorefinery concept. Full article

Biodiesel produced via oil transesterification often contains metallic impurities, such as copper, which affects its quality and engine performance. This study explores the use of activated carbon prepared from spent coffee grounds to remove copper from biodiesel. Activated carbon samples were prepared via biomass pyrolysis and chemical activation with KOH and HNO₃. The optimal conditions for copper adsorption were determined using a Taguchi L9 design. Maximum adsorption capacities were 13.4 and 17.3 mg/g at 30 and 40 °C, respectively, in batch adsorbers. In packed-bed columns, the axial dispersion reduced the adsorption efficiency obtaining bed adsorption capacities from 1.9 to 5.1 mg/g under tested experimental conditions. Adsorbent characterization and adsorption modeling indicated that copper removal was driven by multi-cationic interactions, where carboxylic groups from carbon surface acted as key active sites. The new adsorbent outperformed commercial bone char, making it a cost-effective alternative to improve biodiesel production contributing to the energy matrix diversification. Full article

Life Cycle Assessment (LCA) methodology can be used to quantitatively assess the greenhouse gas emissions of low- or zero-carbon marine alternative fuels throughout their life cycle (from well to wake) and is an important basis for ensuring a green energy transition in the shipping industry. This paper first clarifies the trends and requirements of low-carbon development in shipping and introduces the major ship emission reduction technologies and evaluation methods. Next, the characteristics of various alternative marine fuels (i.e., LNG, hydrogen, methanol, ammonia, and biofuels) are comprehensively discussed and analyzed in terms of production, storage, transportation, and ship applications. In addition, this work provides a comprehensive overview of LCA methodology, including its relevant standards and assessment tools, and establishes a framework for LCA of marine alternative fuels. On this basis, a literature review of the current research on LCA of marine alternative fuels from the perspectives of carbon emissions, pollution emissions, and economics is presented. The case review covers 64 alternative-fueled ships and 12 groups of fleets operating in different countries and waters. Finally, this paper discusses the main shortcomings that exist in the current research and provides an outlook on the future development of LCA research of marine alternative fuels. Full article

Fast pyrolysis of biomass is crucial for sustainable biofuel production, necessitating thorough characterization of feedstocks to optimize thermal conversion technologies. This study investigated the isothermal pyrolysis of bamboo and pinewood biomass in a sand-fluidized bed reactor, aiming to assess biomass suitability for commercial bio-oil production. The pyrolysis products and biomass species were characterized through proximate and ultimate analyses, along with GCMS, FTIR, SEM/EDX, and structural analysis to assess their chemical and physical properties. Results indicated that pine bio-oil possesses superior energy density, with a higher calorific value (20.38 MJ/kg) compared to bamboo (18.70 MJ/kg). Pine biomass yielded greater organic phase bio-oil (BOP) at 13 wt%, while bamboo produced 9 wt%. Energy yields were also notable, with pine exhibiting an energy yield of 15% for bio-oil organic phase (EBOP), compared to 11% for bamboo. The fibrous nature of bamboo biomass resulted in less-reacted biomass at constant reaction time due to flow resistance during pyrolysis. Pine bio-oil organic phase (P-BOP) demonstrated a higher heating value (23.90 MJ/kg) than bamboo (B-BOP). The findings suggest that while both biomass types are viable renewable energy sources, pine biomass is more favorable for commercialization due to its superior energy properties and efficiency in pyrolysis. Full article

The extraction of bioactive compounds, such as flavonoids and coumarins, from natural sources has gained significant attention due to their potential health benefits. This review aims to explore the application of high-pressure extraction processes, particularly supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE), for obtaining flavonoids and coumarins from flower seeds. These techniques offer a greener, more efficient alternative to conventional extraction methods, minimizing the use of harmful solvents and improving the yield and purity of the target compounds. Flower seeds, a rich source of bioactive molecules, are an underutilized reservoir for these valuable compounds. For example, seeds from plants such as Calendula officinalis (calendula) and Helianthus annuus (sunflower) are rich in flavonoids and coumarins. The proposed review will examine the influence of extraction parameters—such as temperature, pressure, solvent choice, and extraction time—on the yield and quality of flavonoids and coumarins. This review aims to provide a comprehensive understanding of high-pressure extraction methods and optimize protocols for the efficient, sustainable extraction of flavonoids and coumarins from flower seeds. Full article