BioEnergy Research最新文献

Year after year, there are alarming data concerning the excessive release of greenhouse gases into the atmosphere, especially CO₂ from the burning of fossil fuels. In this context, the development of renewable energy sources has evolved considerably, mainly due to the incentive use of biofuels, such as bioethanol. The second-generation bioethanol production from lignocellulosic biomasses has interesting potential to meet this energy demand. The Eucalyptus tree stands as a primary example of cultivated hardwoods, owing to its lignocellulosic structure and the biomass residues generated during its processing, where these attributes make it a significant candidate for the production of fuels. The industrial potential of these materials can be explored in the fractionation of their components to reduce their recalcitrance due to the triad formed by cellulose, hemicellulose, and lignin, for further processing and obtaining the products of interest. This paper comprehensively gathers the current technological progress employed for processing Eucalyptus wood biomasses for second-generation bioethanol production. Discussion regarding their chemical composition, the main forms of pretreatments that are being applied, and ways to minimize the generation of fermentative inhibitors during these processes is addressed. Finally, recent researches focused on Eucalyptus biomass-based bioethanol production and techno-economic considerations are discussed. The feasibility of the process is closely tied to the comprehensive utilization of products derived from this biomass. While production appears relatively effective at the laboratory scale, further research is required to develop a cost-effective process that fully harnesses the potential of the biomass.

Wood pellet is an important biomass-based source of cleaner and renewable energy with a growing global demand. Populus spp. (poplars) are fast-growing trees with high productivity potential in the southeastern US. Selected pellet-quality parameters were examined as a proxy for assessing if the feedstock quality of poplar stem wood was affected by stand location (Coastal, Piedmont, Mountains of North Carolina, clone “140”), stand age (five vs. seven years, clone-“140”), clones (“140”, “176”, “230”, “185”, “356”) and stem sections (clone-“356”) by examining sulfur, ash, volatile-matter, fixed-carbon, gross caloric, carbon, hydrogen, and nitrogen contents of moisture-free samples. Location-study samples significantly varied (p≤0.027) in ash (0.6–0.9 wt%), and gross caloric (19.75–19.89 MJ/kg) contents and study clones significantly differed (p≤0.0271) in ash (means: 0.75–0.97 wt%), volatile-matter (means: 80.5–82.7 wt%), fixed-carbon (means: 16.5–18.7 wt%) and hydrogen (means: 4.19–4.78 wt%) contents. The only other significant variations were hydrogen (mean: 4.19–4.67 wt%) content with stand age (p≤0.009) and gross caloric values (19.5–19.9 MJ/kg) among stem sections (p = 0.0003). This study showed that poplars have stem-wood quality suitable for pellet production and most of the studied feedstock samples had ash, nitrogen, sulfur, and caloric (at 10% moisture content) contents that would meet the ENplus pellet-quality standards. Results from this study can be used for facilitating decisions about managing poplar stands for sustainable pellet feedstock production in the southeastern US, including selecting optimum rotation length, pellet-suitable clones, and sites.

The toxicity of hemicellulosic hydrolysates is one of the main bottlenecks of the biotechnological production of xylitol, as inhibitors released/generated during plant cell wall deconstruction impair xylitol production. Yeast adaptation can be applied to overcome this issue through the development of tolerant strains, improving microbial performance. Herein, we evaluated Candida tropicalis FTI20037 pre-cultivation in original, concentrated, and concentrated/detoxified sugarcane bagasse and straw hemicellulosic hydrolysate (SBSHH) to reduce hydrolysate’s toxicity during concentrated/detoxified SBSHH fermentations. Regarding glucose uptake, there were no differences between the evaluated conditions. In turn, lignocellulosic inhibitors negatively affected xylose uptake. The evaluated adaptive strategies did not improve xylose uptake at SBSHH fermentations. Xylitol production was also impaired by lignocellulosic inhibitors. However, pre-cultivation in concentrated/detoxified SBSHH increased xylitol yield and xylose-to-xylitol bioconversion efficiency by 13.3%, xylitol volumetric productivity by 7.1%, and xylitol specific production rate by 9.7%. A 21.5% reduction in glycerol production was also observed in this condition, indicating an increased tolerance to lignocellulosic inhibitors. Arabinose assimilation started slowly in all fermentations. Increased arabinose uptake rates were observed after xylose depletion, suggesting the existence of a carbon catabolite repression tendency between xylose and arabinose. Pre-cultivation in concentrated/detoxified SBSHH reduced this repression tendency, increasing arabinose consumption. Regarding lignocellulosic inhibitors, 5-HMF degradation was increased by pre-cultivation. No differences were observed for acetic acid and phenolic compounds consumption. The combination of SBSHH detoxification and C. tropicalis pre-cultivation was effective to improve xylitol production possibly due to the development of a more tolerant phenotype against SBSHH toxicity.

Microalgae are lipid-rich microscopic eukaryotic algae that can be used aiming for more sustainable biodiesel production by employing environmentally sound processes. The present work evaluates biodiesel production using a biocatalyst and two microalgae species as oil feedstock (Chlorella vulgaris and Aurantiochytrium sp.). Lipid extraction was performed using different techniques, namely, Soxhlet extractions (8 h — both species) with different solvents (hexane; hexane:ethanol (1:1 v/v); and chloroform) and room temperature hexane extraction (72 h — Aurantiochytrium sp.). Transesterification occurred for 24 h (150 rpm), using 30 % lipase loading. The results showed that high extraction temperatures cause microalgae oil degradation, focused on unsaturated fatty acids, leading to a lower biodiesel conversion yield. Using Aurantiochytrium sp. oil, it was possible to obtain around 55 %wt. of biodiesel conversion yield using oil extracted at room temperature (6:1 methanol:oil molar ratio), whereas for the oil extracted in the Soxhlet apparatus, the biodiesel conversion yield was around 30 %wt.. The low lipid content (1.0 %wt.) and biodiesel conversion yield (up to 25 %wt.) obtained using C. vulgaris show that the biomass used in the current study has low potential for biodiesel production. However, enzymatic biodiesel production from microalgae represents a promising avenue for sustainable energy generation, offering a renewable and environmentally responsible solution to the world’s energy needs. For that purpose, further studies, such as the optimisation of the extraction and transesterification of Aurantiochytrium sp. oil, should be carried out.

Tomato waste (TW) is a plentiful lignocellulosic resource, mainly composed of seeds and skins, that can be converted into high-value compounds. This study explored the enhancement of TW enzymatic and fungal biovalorization using novel ecofriendly approaches, including advanced technology, pulsed electric fields (PEF). Crude laccase first produced on TW was used for enzymatic treatment, and the white rot fungus Trametes versicolor K1 was used in fungal treatment under SmF (submerged) or SSF (semi-solid) fermentation conditions. The physical PEF treatment had increased tenfold sugar extraction yield (83.4 mg/g) and twofold polyphenol extraction yield (4.43 g/g), with respect to the control. PEF–laccase innovative combination, reported for the first time, has enhanced significantly sugar extraction yield (100.6 mg/g), twofold higher than those released from TW after laccase treatment alone. However, the PEF treatment had no effect on polyphenol extraction yield when combined to laccase or fungal treatments. The treated TW was subjected to polysaccharide enzymatic hydrolysis. The combination of PEF with laccase or fungal treatment did not impact sugar yields; however, it allowed polyphenol liberation. During fungal treatment (i.e., T. versicolor K1 grown on TW), comparable maximal laccase activities of 2574.28 U/L and 2577.06 U/L were measured in the culture supernatants, in SmF and SSF conditions, respectively. The findings demonstrate the high potential of PEF for recovering phenols and sugars. When combined to fungal treatment, it offers high yields of valuable products, making it a potential cost-effective approach, providing new prospects for TW valorization.

This study investigated the behavior and syngas characteristics of oil palm biomass fluidized bed gasification (FBG) with alternative inlet air configurations. The air was supplied to the combustion zone of the FBG with tangential and updraft air inlet (TI and UI) modes. A mixed oil palm decanter cake was used as feedstock at 3 kg/h feed rate. The experiments were done at the equivalence ratios (ERs) from 0.1 to 1.0. The experimental results showed that the air supply mode and ER affected the temperature distribution inside the gasifier. Operation with TI mode had combustion initiated at the side, then propagated through the middle section, while in UI mode, the combustion reaction was at the center of the chamber. With TI mode, the temperature at combustion zone was around 600 °C. At ER 0.5, this zone covered the heights from 0.25 to 0.75 m. In UI mode, the highest temperature was near 800 °C, but combustion was prominent only in a zone near the bottom. The CFD simulations showed that the alternative inlet air configurations and the ER influenced flow patterns. CFD confirmed the swirling streamlines in TI mode, while UI mode showed a localized elevated temperature, particularly at 0.25 m height. Syngas composition analysis indicated that operation in TI mode at ER of 0.7 provided the larger combustion zone, leading to better syngas product in terms of CO (> 20%) and H₂ (> 8%) components. This mode also provided the best 5.1 MJ/m³ energy content for syngas. The results of this study can provide useful guidelines for further investigations of FBG with tangential air inlet.

The development and use of renewable energy resources is a crucial solution for a sustainable energy strategy to decrease the dependence on fossil fuels. Lignocellulosic ethanol has gained recognition as a renewable energy resource vital for sustainable development. Currently, the research and industry sectors utilize a single type of lignocellulose biomass for ethanol production. However, this biomass dependency is a potential risk due to the global warming effect on biomass plantations. This study assessed the versatility of rice straw (RS), Napier grass (NG), and sugarcane bagasse (SB) as a mixed biomass for bioethanol production. The mixture of equal proportion of RS, NG, and SB in a 1:1:1 ratio produced higher concentration of bioethanol than individual biomasses. NaOH-pretreated samples were more effective than H₂SO₄ pretreated and untreated samples in bioethanol production. The NaOH-pretreated mixed sample yielded maximum bioethanol of 0.82% (v/v). About 0.43 g/g and 0.12 g/g of reducing sugars and ethanol, respectively, could be produced using RS, NG, and SB in the ratio of 1:1:1. This research indicates that different biomass types can replace one another in the event of limited resources, thus reducing the dependency on a particular biomass type for biorefinery.

Hydrogen, a form of energy that is both clean and renewable, is now being researched and developed as a potential source of alternative energy. There are many different kinds of microbial systems that have the potential to be utilised in the manufacturing of biohydrogen. Thermophiles are found as potential producers of hydrogen, at a high rate, in adverse operating conditions. Temperature, pH, and concentration of substrates play a crucial role in affecting the metabolism of these microorganisms. Sustainable production of hydrogen is feasible when organic waste is employed as a potential feedstock. The overall yield of hydrogen production procedures demands improvements, to turn them into commercial applications. The integration of two-stage processes may contribute to an overall increase in energy output. As examples of second-stage processes, biomethanation, microbial electrolysis cells, photo-fermentation, and microbial fuel cells have been the subject of extensive research. This article provides an overview of the photocatalytic method for producing biohydrogen, including its fundamentals and underlying mechanisms, as well as other biological methods of hydrogen production. This process exhibits reduced energy consumption and demonstrates environmental friendliness by potentially utilising waste material as a substrate.

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Bio-oils produced through thermochemical conversion processes such as pyrolysis from streamside products obtained from a bio-jet fuel production facility may be used as promising low-carbon alternative feedstocks in the aviation industry. The present investigation applied slow pyrolysis that was conducted at different temperatures to produce bio-oils from hexane-defatted Brassica carinata oilseed meals. The pyrolysis experiments proved that the highest temperature (550℃) produced the maximum bio-oil yield (55.01%), while the lowest temperature (350℃) produced the maximum bio-char (34.93%) and gas (45.84%) yields. An in-depth characterization was performed on the bio-oils to investigate whether they may be employed as alternative feedstocks for bio-jet fuel production. As a result, properties were studied using physicochemical characterization, ultimate analysis, atomic ratios analysis, heating value analysis, inductively coupled plasma-optical emission spectrometry analysis, gas chromatograph-mass spectroscopy, and Fourier-transform infrared spectroscopy. The characterization results of the bio-oils revealed that they had moisture (35.38 − 48.64%), pH (8.50), kinematic viscosity (14.10 − 16.05 cSt), ash content (0.17 − 0.208%), carbon (55.4 − 62.3%), hydrogen (9.02 − 9.29%), nitrogen (6.08 − 6.20%), sulfur (0.61 − 0.69%), oxygen (21.47 − 28.56%), and higher heating value (26.98 − 30.45 MJ/kg). Furthermore, it was found that the major classes of compounds identified include saturated hydrocarbons (13.56 − 14.52%), saturated fatty acids (2.33 − 3.67%), monounsaturated hydrocarbons (30.28 − 34.62%), monounsaturated fatty acids (6.54 − 11.23%), polyunsaturated fatty acids (1.41 − 2.82%), and Others (such as nitrogenated compounds) (38.44 − 39.62%). In conclusion, because of their remarkable excellent characteristics, and because they can be catalytically upgraded into advanced fuels by catalytic hydrotreatment methods (like hydrodeoxygenation and hydrodenitrogenation), and hydrocracking reactions, the oils can be used as promising alternative feedstocks for the aviation industry.