Search Results (403)

The present research features an experimental comparative design and the objective of this work was to determine the susceptibility to microbiological contamination in fatty acid methyl esters (FAMEs) and the FAME–water interface of residual and refined lard, large volume simulating storage conditions as fuel supply chain, and to identify the microorganisms developed. The plates were seeded according to ASTM E-1259 and the instructions provided by the manufacturer of the Bushnell Haas agar. Microbiological growth was observed at the FAME–water interface of FAME obtained from residual lard. Using the MALDI-TOF mass spectrometry technique, Pseudomonas aeruginosa and Streptomyces violaceoruber bacteria were identified in the residual lard FAMEs, with the latter being previously reported in FAMEs. The implications of microorganism development on the physicochemical quality of FAMEs are significant, as it leads to an increase in the acid index, which may negatively impact metals by inducing corrosion. The refined lard FAMEs did not show any development of microorganisms. The present research concluded that residual lard tends to be more prone to microbiological attack if the conditions of water and temperature affect microbial growth. The findings will contribute to the knowledge base for a safer introduction of FAMEs into the biofuel matrix. Full article

Catalytic upgrading of pyrolysis oils is an important step for producing replacement hydrocarbon-rich liquid biofuels from biomass and can help to advance pyrolysis technology. Catalysts play a pivotal role in influencing the selectivity of chemical reactions leading to the formation of main compounds in the final upgraded liquid products. The present work involved a systematic study of solvent-free catalytic reactions of cyclohexanone in the presence of hydrogen gas at 160 °C for 3 h in a batch reactor. Cyclohexanone can be produced from biomass through the selective hydrogenation of lignin-derived phenolics. Three types of catalysts comprising undoped NbOPO₄, 10 wt% NiO/NbOPO₄, and 30 wt% NiO/NbOPO₄ were studied. Undoped NbOPO₄ promoted both aldol condensation and the dehydration of cyclohexanol, producing fused ring aromatic hydrocarbons and hard char. With 30 wt% NiO/NbOPO₄, extensive competitive hydrogenation of cyclohexanone to cyclohexanol was observed, along with the formation of C₆ cyclic hydrocarbons. When compared to NbOPO₄ and 30 wt% NiO/NbOPO₄, the use of 10 wt% NiO/NbOPO₄ produced superior selectivity towards bi-cycloalkanones (i.e., C₁₂) at cyclohexanone conversion of 66.8 ± 1.82%. Overall, the 10 wt% NiO/NbOPO₄ catalyst exhibited the best performance towards the production of precursor compounds that can be further hydrodeoxygenated into energy-dense aviation fuel hydrocarbons. Hence, the presence and loading of NiO was able to tune the activity and selectivity of NbOPO₄, thereby influencing the final products obtained from the same cyclohexanone feedstock. This study underscores the potential of lignin-derived pyrolysis oils as important renewable feedstocks for producing replacement hydrocarbon solvents or feedstocks and high-density sustainable liquid hydrocarbon fuels via sequential and selective catalytic upgrading. Full article

The food industry consumes large amounts of water across various processes, and generates wastewater characterized by parameters like biochemical oxygen demand, chemical oxygen demand, pH, suspended solids, and nutrients. To meet environmental standards and enable reuse or valorization, treatment methods such as physicochemical, biological, and membrane-based processes are applied. This review focuses on the valorization of food industry wastewater in the biotechnological production of high-value products, with an emphasis on starch-rich wastewater, wineries and confectionery industry wastewater, and with a focus on new technologies for reduces environmental burden but also supports circular economy principles. Starch-rich wastewaters, particularly those generated by the potato processing industry, offer considerable potential for biotechnological valorization due to their high content of soluble starch, proteins, organic acids, minerals, and lipids. These effluents can be efficiently converted by various fungi (e.g., Aspergillus, Trichoderma) and yeasts (e.g., Rhodotorula, Candida) into value-added products such as lipids for biodiesel, organic acids, microbial proteins, carotenoids, and biofungicides. Similarly, winery wastewaters, characterized by elevated concentrations of sugars and polyphenols, have been successfully utilized as medium for microbial cultivation and product synthesis. Microorganisms belonging to the genera Aspergillus, Trichoderma, Chlorella, Klebsiella, and Xanthomonas have demonstrated the ability to transform these effluents into biofuels, microbial biomass, biopolymers, and proteins, contributing to sustainable bioprocess development. Additionally, wastewater from the confectionery industry, rich in sugars, proteins, and lipids, serves as a favorable fermentation medium for the production of xanthan gum, bioethanol, biopesticides, and bioplastics (e.g., PHA and PHB). Microorganisms of the genera Xanthomonas, Bacillus, Zymomonas, and Cupriavidus are commonly employed in these processes. Although there are still certain regulatory issues, research gaps, and the need for more detailed economic analysis and kinetics of such production, we can conclude that this type of biotechnological production on waste streams has great potential, contributing to environmental sustainability and advancing the principles of the circular economy. Full article

The imperative to decarbonize global energy systems and enhance energy security necessitates a transition towards ecofuels, broadly classified as biofuels, waste-derived fuels, and electrofuels (e-Fuels). The primary goal of this review is to provide a holistic and comparative evaluation of these three pivotal ecofuel pillars under a unified framework, identifying their strategic niches in the energy transition by critically assessing their interconnected technical, economic, and policy challenges. It offers a comparative dissection of inherent resource constraints, spanning biomass availability, the immense scale of renewable electricity required for e-Fuels, sustainable carbon dioxide (CO₂) sourcing, and the complexities of utilizing non-biodegradable wastes, identifying that true feedstock sustainability and holistic lifecycle management are paramount, cross-cutting limitations for all pathways. This review critically highlights how the current global reliance on fossil fuels for electricity production (approx. 60%) and the upstream emissions embodied in renewable energy infrastructure challenge the climate neutrality claims of ecofuels, particularly e-Fuels, underscoring the necessity for comprehensive well-to-wheels (WtW) lifecycle assessments (LCAs) over simpler tank-to-wheels (TtW) approaches. This perspective is crucial as emerging regulations demand significant greenhouse gas (GHG) emission reductions (70–100%) compared to fossil fuels. Ultimately, this synthesis argues for a nuanced, technologically neutral deployment strategy, prioritizing specific ecofuels for hard-to-abate sectors, and underscores the urgent need for stable, long-term policies coupled with robust and transparent LCA methodologies to guide a truly sustainable energy transition. Full article

Jatropha curcas L. is a shrub of the Euphorbiaceae family with non-toxic varieties found in Mexico that holds significant potential for biofuel production and other industrial applications. However, its limited in vitro regenerative capacity is a barrier to the development of productive species. Somatic embryogenesis (SE) offers a strategy to establish a regeneration system to overcome these challenges and enable genetic improvement. In this work, proteomic and gene expression analyses were utilized to identify key factors involved in SE induction in a non-toxic variety of J. curcas. Two-dimensional electrophoresis (2-DE) in combination with mass spectrometry was used to compare the proteomes of pre-globular and globular somatic embryos. RT-qPCR was used for gene expression analysis of the BBM, AGL15, SERK, IAA26 and eIF3f genes. The globular stage showed enrichment in the pathways related to carbohydrate and energy metabolism, protein folding, and stress response. In addition, the gene expression analysis of selected genes revealed a significantly elevated expression of BBM, AGL15, and IAA26 in globular embryos compared to pre-globular embryos. In contrast, SERK expression was low, and eIF3f expression remained unchanged between stages. These expression patterns may contribute to developmental arrest at the globular stage. These findings provide new insights into the molecular mechanisms regulating early SE in J. curcas and offer potential strategies for improving its propagation and industrial applications. Full article

Low-carbon liquid fuels are needed for decarbonization of hard-to-decarbonize segments of the transportation sector. This decarbonization can be limited by the amount of renewable carbon. Thermochemical conversion of biomass/municipal solid waste (MSW) through gasification is a promising route for producing low-carbon fuels. There are two major opportunities for increasing the amount of low-carbon liquid fuel that can be produced from gasification in any region. One is to increase the amount of liquid fuel from a given amount of biomass/MSW, particularly by hydrogen-enhancement of gasification synthesis gas. Second is the potential for large expansion of use of biomass feedstocks from its present level. Such biomass feedstocks include agricultural waste, forestry waste, MSW, and specially grown biomass that does not interfere with food production. The use of MSW may provide advantages of an established network for pickup and transportation of feedstock to disposal sites and the avoidance of methane produced from landfilling of MSW. As a case study, we looked at potential expansion of US low-carbon fuel production, considering the recent projections of the 2024 USDOE report, which estimated potential production of a billion tons/yr of biomass/MSW feedstocks in the US. This report included an estimated potential for liquid biofuel production of 60 billion gallons/yr of diesel energy equivalent fuel without the use of hydrogen enhancement. By hydrogen-enhanced biomass/MSW gasification, this projection could be doubled to 120 billion gallons/yr of diesel energy equivalent fuel. Furthermore, the co-location potential of biomass/MSW resources with potential renewable energy generation sites is explored. This overlap of hydrogen production and biomass production in the US are located in regions such as the US Midwest, Texas, and California. This co-location strategy enhances logistical feasibility, reducing transport costs and optimizing energy system integration; and can be applied to other geographical locations. Hydrogen-enhanced biomass/MSW gasification offers a promising route to substantially increase low-carbon liquid fuel production (e.g., methanol) and support increased liquid fuel production and greenhouse gas reduction goals. Full article

This study reports the effects of pH culture on multi-biofuel production (hydrogen, ethanol, and 2,3-butanediol) by Enterobacter cloacae K1ga, isolated from koala and adapted to grow in 100 g dm⁻³ glucose. Batch cultures were performed in 1 dm³ bioreactors, controlling the pH at 5.5, 6.5, 7.5, and 9.2. Furthermore, cultures without pH control (with an initial pH of 9.2) were used as reference cultures. Controlling pH at 9.2 was detrimental to E. cloacae K1ga as no growth or biofuel production was observed. In contrast, reference cultures reached a maximum 2,3-butanediol (BDO) production (BDOP) of 22.9 ± 2.1 g dm⁻³ and ethanol production (EP) of 9.9 ± 0.7 g dm⁻³ and the highest hydrogen production (HP) of 2013.1 ± 275.7 cm³ dm⁻³. Meanwhile, a pH of 7.5 increased the accumulation of ethanol, obtaining the highest EP (14.0 ± 0.05 g dm⁻³). On the contrary, a pH of 5.5 was unfavourable for the fermentative metabolism of E. cloacae K1ga, showing the lowest production rates for the three biofuels and also the lowest EP (8.05 ± 0.35 g dm⁻³). The results demonstrate that the natural progression of pH during the growth of E. cloacae K1ga is an advantageous strategy for multi-biofuel production, since no tight pH control system is required. Full article

From the perspective of biogas plant (BGP) operators, it is highly challenging to make a profitable decision on optimal biomethane production and allocation across interconnected markets. The aim of this study is to analyze the dynamics of biomethane markets, develop the gas allocation portfolio (GAP) for BGPs, investigate the impact of GHG quota price on the market dynamics and substrate mix consumption, and evaluate the profitability of the biomethane market system under various demand-based scenarios. A two-step optimization approach based on linear programming is adopted. Firstly, the optimized substrate mix and corresponding GAP are determined for all BGPs. Secondly, by leveraging the options flexibility created by the interconnected nature of biomethane markets, the BGPs’ GAP is further developed. Through an in-depth sensitivity analysis, the effects of GHG quota price variations on the market dynamics are assessed. The results indicate that integrated production, obtained by implementing the improved GAP across all BGPs, maximizes the profitability of the system. At higher quota prices, the consumption of manure, residuals, and grass is encouraged, while the use of energy crops declines. Furthermore, higher quota prices lead to a substantial increase in biomethane price in the EEG market, highlighting the need for further governmental support for biomethane CHP units. The anticipated competition between hydrogen and biomethane to achieve a greater share in the heating sector could pose risks to long-term investments in biomethane. The system achieves its highest profitability, a total contribution margin of EUR 2254.8 million, under the Transport Biofuels Expansion scenario. Generally, policies and regulations that raise the quota price (e.g., the 36. BImSchV) or promote biomethane demand in the heating sector (e.g., the GEG) can provide both economic and ecological benefits to the system. Full article

Cottonseed is a valuable source of high-quality proteins and oils. Defatted cottonseed meal (DCSM), a by-product of cottonseed oil extraction, holds significant potential as a sustainable protein resource. This review outlines the chemical composition, structural features, and unique properties of cottonseed, with a focus on its inherent antinutritional factors, such as gossypol. Strategies for enhancing the utilization of DCSM as a protein source are systematically evaluated, including physical, chemical, and biological methods used to eliminate or reduce antinutritional components. Among these, microbial fermentation, particularly solid-state fermentation, is highlighted as a promising, eco-friendly approach for detoxification and nutritional improvement. This review further discusses critical factors influencing the removal of anti-nutritional compounds, such as pretreatment methods, fermentation parameters, and microbial strains. The efficacy of probiotic strains (e.g., Bacillus and yeasts) in enhancing the protein digestibility, amino acid profiles, and functional properties of DCSM is discussed. Additionally, recent advances in the application of fermented cottonseed protein in foods (e.g., animal feed, functional peptides, and food additives) and non-food sectors (e.g., biofuels and bioplastic) are explored. The integration of probiotic-driven fermentation processes is proposed as a strategy to exploit the full nutritional and economic potential of DCSM, paving the way for its broader and sustainable use in foods and non-food applications. Full article

Thermostable β-glucosidases (E.C. 3.2.1.21) are essential enzymes used in second-generation biofuel production. However, little is known about the structural characteristics that lead to their thermostability. In this study, I used graph-based structural signatures to represent three-dimensional structures of β-glucosidase enzymes extracted from thermophilic organisms. I collected 1717 structures from thermophilic (n = 890) and non-thermophilic (n = 827) organisms and divided them into two datasets: training (n = 1134) and test (n = 583). I then used seven machine learning algorithms to classify them. The best model achieved 77.1% accuracy using logistic regression in training with 10-fold cross-validation and 81.6% accuracy in testing using the CatBoost algorithm. I hypothesize that the signature model proposed here can help understand the structural patterns in thermostable enzymes and shed light on the design of more efficient enzymes for biofuel production. Full article

Based on Life Cycle Assessment (LCA) and ISO standards, we compared the global environmental sustainability (ES) of two technologies that process the organic fraction of municipal solid waste (OFMSW) in Mexico. The first technology was a biorefinery (BRF) known as HMEZSNN-BRF (abbreviation for Hydrogen-Methane-Extraction-Enzyme-Saccharification/Nanoproduction Biorefinery); it produces the gas biofuels hydrogen (H) and methane (M), organic acids (E), enzymes (Z), saccharified liquors (S), and bionanobioparticles (BNBPs) in a nanoproduction stage (NN). The second technology was incineration with energy recovery (IER). An LCA was performed with a functional unit (FU) of 1000 kg of OFMSW. The BRF generates 166.4 kWh/FU (600 MJ) of net electricity, along with bioproducts such as volatile organic acids (38 kg), industrial enzyme solution (1087 kg), and BNBPs (40 kg). The IER only produces 393 net kWh/FU electricity and 5653 MJ/FU heat. The characterization potential environmental impacts (PEIs) were assessed using SimaPro software, and normalized PEIs (NPEIs) were calculated accordingly. We defined a new variable alpha and the indices σ-τ plane for quantifying the ES. The higher the alpha, the lower the ES. Alpha was the sum of the eighteen NPEIs aligned with the ISO standards. The contributions to PEI and NPEI were also analyzed. Four NPEIs were the highest in both technologies, i.e., freshwater and marine ecotoxicities and human non-carcinogenic and carcinogenic toxicities. For the three first categories, the NPEI values corresponding to IER were much higher than those of the BRF (58.6 and 8.7 person*year/FU freshwater toxicity; 93.5 and 13.6 marine ecotoxicity; 12.1 and 1.8 human non-carcinogenic toxicity; 13.7 and 13.9 human carcinogenic toxicity, for IER and the BRF, respectively). The total α values were 179.1 and 40.7 (person*yr)/FU for IER and the BRF, respectively. Thus, the ES of IER was four times lower than that of the BRF. Values of σ = 0.592 and τ = −0.368 were found; the point defined by these coordinates in the σ-τ plane was located in Quadrant IV. This result confirmed that the BRF in this work is more environmentally sustainable (with restrictions) than the IER in Mexico for the treatment of the OFMSW. Full article

Agrophotovoltaic (APV) systems represent innovative agricultural farms and solar power plants, capable of producing electricity and crops simultaneously. Since the solar radiation required to optimize harvests varies by crop type, traditional PV panels face challenges in efficiently adjusting the shading ratio of APV systems. This study evaluates the economic viability of APV systems integrated with building-integrated photovoltaic (BIPV) systems for biofuel production. Specifically, it assesses the production forecast for corn-based biofuel—demand for which is rising due to the mixed-fuel use policy of the Korean government—and the economic feasibility of production in the APV system enhanced by BIPV integration (i.e., the APV–BIPV system). To this end, LCOE (levelized cost of energy) and NPV (net present value) are employed as performance indicators. Additionally, yield data from corn and corn stover harvested in actual APV facilities are utilized to predict bioenergy production. Consequently, the study will analyze the impact of renewable energy production from the proposed APV–BIPV system on achieving the Korean government’s renewable energy production goals and will provide guidelines on the potential benefits for farmers involved in renewable energy production and energy crop harvesting. Full article

Several countries have cities located at elevations above 2000 m. Consequently, the internal combustion engines (ICEs) that operate there do not achieve the desired performance and emissions under these atmospheric conditions. One approach to mitigate these effects and, at the same time, address climate change is the use of biofuel–fossil fuel blends. However, ICEs must operate under a wide range of rpm to meet varying workload demands, raising concerns that these fuel blends may not be fully effective in achieving the desired performance and emission outcomes under such conditions. To address this issue, a series of experimental tests were conducted at low and high rpm of a spark-ignition (SI) ICE fuelled with bioethanol–gasoline blends in the ratios of E10, E15, E20, E40, E60, E85, and E100. The tests were conducted at 2600 m above sea level (masl) under various engine loads. The E20 and E40 blends showed outstanding performance at 2700 rpm, achieving high brake power and low emissions of CO₂ and HCs. At 4300 rpm, the E40 blend exhibited great performance because the engine produced high brake power and low emissions of CO and NOx. Based on these results, it can be concluded that bioethanol concentrations of between 20 and 40% in the blend effectively compensate for the reduced atmospheric oxygen at high altitudes, enhancing the combustion process in SI-ICEs. Full article

Feedstock plants for biofuel production can be cultivated on polluted sites that are unsuitable for edible crop production. This approach combines environmental restoration and renewable energy production, therefore enhancing the economic viability of plant-derived biofuels. Previous studies have indicated that exposure to environmental pollutants may elevate lignin levels in exposed plants, potentially impacting the biomass digestibility and the efficiency of bioethanol conversion. In this study, we investigated the impact of the antimicrobial agent chlortetracycline on lignin biosynthesis in the reference organism Arabidopsis thaliana. Toxicity testing showed that exposure to chlortetracycline significantly reduced plant growth at concentrations above 2.5 mg L⁻¹. Using Fourier-transform infrared spectroscopy (FTIR) analysis, we observed a significant increase in the lignin signature, ranging from 16 to 40%, in plants exposed to chlortetracycline as compared to non-exposed control plants. Transcriptomic analysis (RNA sequencing) was conducted to determine the molecular basis of plant response to chlortetracycline, revealing significant enrichment of several genes involved in lignin biosynthesis and the phenylpropanoid pathway, including cinnamyl alcohol dehydrogenase and peroxidases. Exposure to chlortetracycline also resulted in the overexpression of genes involved in the metabolism of xenobiotic compounds, including cytochrome P450 monooxygenases, glutathione S-transferases, and glycosyltransferases. Chlortetracycline also induced several genes involved in plant response to stress and defense mechanisms, including transcription factors (e.g., WRKY, MYB, AP2/ERF families), pathogenesis-related proteins, and genes involved in stress signaling. These results suggest that the antibiotic chlortetracycline triggers multiple stress responses in A. thaliana, which may cause changes in lignin biosynthesis, reductions in plant growth, increases in the lignin content, and induction of defense metabolic pathways. Full article

Water pollution from industrial, municipal, and agricultural sources is a pressing global concern, necessitating the development of sustainable and efficient treatment solutions. Algal biomass has emerged as a promising feedstock for the production of carbonaceous adsorbents due to its rapid growth, high photosynthetic efficiency, and ability to thrive in wastewater. This review examines the conversion of algal biomass into biochar and hydrochar through pyrolysis and hydrothermal processes, respectively, and evaluates their potential applications in wastewater treatment, carbon sequestration, and biofuel production. Pyrolyzed algal biochars typically exhibit a moderate to high carbon content and a porous structure but require activation treatments (e.g., KOH or ZnCl₂) to enhance their surface area and adsorption capabilities. Hydrothermal carbonization, conducted at lower temperatures (180–260 °C), produces hydrochars rich in oxygenated functional groups with enhanced cation exchange capacities, making them effective for pollutant removal. Algal-derived biochars and hydrochars have been successfully applied for the adsorption of heavy metals, dyes, and pharmaceutical contaminants, with adsorption capacities significantly increasing through post-treatment modifications. Beyond wastewater treatment, algal biochars serve as effective carbon sequestration materials due to their stable structure and high carbon retention. Their application as soil amendments enhances long-term carbon storage and improves soil fertility. Additionally, algal biomass plays a key role in biofuel production, particularly for biodiesel synthesis, where microalgae’s high lipid content facilitates bio-oil generation. Hydrochars, with energy values in the range of 20–26 MJ/kg, are viable solid fuels for combustion and co-firing, supporting renewable energy generation. Furthermore, the integration of these materials into bioenergy systems allows for waste valorization, pollution control, and energy recovery, contributing to a sustainable circular economy. This review provides a comprehensive analysis of algal-derived biochars and hydrochars, emphasizing their physicochemical properties, adsorption performance, and post-treatment modifications. It explores their feasibility for large-scale wastewater remediation, carbon capture, and bioenergy applications, addressing current challenges and future research directions. By advancing the understanding of algal biomass as a multifunctional resource, this study highlights its potential for environmental sustainability and energy innovation. Full article