Feedstock Type Research Articles

The value of externalities for biofuels and implications for policy-led development: A discrete choice experiment with Australian consumers

The sustainability credentials of biofuels, as substitutes for petrol and diesel, are in question with several economic and environmental issues through their lifecycle of production depending on the feedstock. The lack of understanding of the external impacts—or externalities—of different feedstocks impact policy interventions with environmental objectives. In this study, the value of externalities associated with different types of biofuel feedstock is estimated using discrete choice experiments with a sample of Australian fuel consumers. The results indicate that newer biofuel feedstock, like microalgae, can generate high consumer values relative to its agricultural-based predecessors. Consumers were found to be willing to pay more than double for biofuels that avoid a 10 % increase to food prices, an issue that has plagued the long-term viability of agricultural-based biofuels. Consumer values for biofuels with low lifecycle emissions were also substantial. Further modelling also revealed that existing biofuel policies and higher incomes had contradictory associations with consumer values. The results should inform policy on biofuels. In particular, the high non-market values for externalities suggest that policies should encourage the development of a more diversified range of feedstock use and related technologies—rather than prioritising market transition away from fossil fuels—to increase the production of more sustainable fuel alternatives. This will ensure that the transition from fossil fuels for transport maximises societal benefits.

Uranium and Fluoride Removal from Aqueous Solution Using Biochar: A Critical Review for Understanding the Role of Feedstock Types, Mechanisms, and Modification Methods

Uranium (U) and fluoride (F−) are the major global geogenic contaminants in aquifers and pose serious health issues. Biochar, a potential adsorbent, has been widely applied to remediate geogenic and anthropogenic contaminants. However, there is a lack of research progress in understanding the role of different feedstock types, modifications, adsorption mechanisms on physico-chemical properties of biochar, and factors affecting the adsorption of U and F− from aqueous solution. To fill this lacuna, the present review gives insight into the U and F− removal from aqueous solution utilizing biochar from various feedstocks. Feedstock type, pyrolysis temperature, modifications, solution pH, surface area, and surface-charge-influenced biochar adsorption capacities have been discussed in detail. Major feedstock types that facilitated U and F− adsorption were crop residues/agricultural waste, softwood, grasses, and animal manure. Low-to-medium pyrolyzing temperature yielded better biochar properties for U and F− adsorption. Effective modification techniques were mainly acidic and magnetic for U adsorption, while metal oxides, hydroxides, alkali, and magnetic modification were favourable for F− adsorption. The major mechanisms of U adsorption were an electrostatic attraction and surface complexation, while for F− adsorption, the major mechanisms were ion exchange and electrostatic attraction. Lastly, the limitations and challenges of using biochar have also been discussed.

Ecotoxicological characterization of engineered biochars produced from different feedstock and temperatures

Biochar (BC) engineering, which has recently gained a lot of interest, allows designing the functional materials. BC modification improves the properties of pristine biochar, especially in terms of adsorption parameters. An interesting type of modification is the introduction of metals into the BC's structure. There is a knowledge gap regarding the effects of modified BC (e.g., BC-Mg, BC-Zn) on organisms. The aim of this study was the ecotoxicological evaluation of BC-Mg and BC-Zn composites, received under diverse conditions from willow or sewage sludge at 500 or 700 °C. The ecotoxicological tests with bacteria Vibrio fischeri (V. fischeri) and invertebrates Folsomia candida (F. candida) were applied to determine the toxicity of BC. The content of toxic substances (e.g., polycyclic aromatic hydrocarbons (PAHs), heavy metals (HMs), environmentally persistent free radicals (EPFRs)) in BC were also determined and compared with ecotoxicological parameters. The ecotoxicity of studied BCs depends on many variables: feedstock type, pyrolysis temperature and the modification type. The Zn and Mg modification reduced (from 28 to 63 %) the total Ʃ16 PAHs content in willow-derived BCs while in SL-derived BCs the total Ʃ16 PAHs content was even 1.5–3 times higher compared to pristine BCs. The Zn modified willow-derived BCs affected positively on F. candida reproduction but showed inhibition of luminescence V. fischeri. BC-Mg exhibited harmful effect to F. candida. The ecotoxicological assessment carried out sheds light on the potential toxicity of BC-Zn and BC-Mg composites, which are widely used in the removal of heavy metals, pharmaceuticals, dyes from waters and soils.

Metastable Phase Formation, Microstructure, and Dielectric Properties in Plasma-Sprayed Alumina Ceramic Coatings

The need for new solutions for electrical insulation is growing due to the increased electrification in numerous industrial sectors, opening the door for innovation. Plasma spraying is a fast and efficient way to deposit various ceramics as electrical insulators, which are used in conditions where polymers are not suitable. Alumina (Al2O3) is among the most employed ceramics in the coating industry since it exhibits good dielectric properties, high hardness, and high melting point, while still being cost-effective. Various parameters (e.g., feedstock type, spray distance, plasma power) significantly influence the resulting coating in terms of microstructure, porosity, and metastable phase formation. Consequently, these parameters need to be investigated to estimate the impact on the dielectric properties of plasma-sprayed alumina coatings. In this work, alumina coatings with different spray distances have been prepared via atmospheric plasma spray (APS) on copper substrates. The microstructure, porosity, and corresponding phase formation have been analyzed with optical microscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Moreover, we present an in-depth analysis of the fundamental dielectric properties e.g., direct current (DC) resistance, breakdown strength, dielectric loss tangent, and permittivity. Our results show that decreasing spray distance reduces the resistivity from 6.31 × 109Ωm (130 mm) to 6.33 × 108Ωm (70 mm), while at the same time enhances the formation of the metastable δ-Al2O3 phase. Furthermore, space charge polarization is determined as the main polarization mechanism at low frequencies.

Microwave pyrolyzed sewage sludge: influence on soil microbiology, nutrient status, and plant biomass

BackgroundSewage sludge (SS) has been considered a potent source of soil nutrients. However, its direct application to agricultural soils have been discouraged owing to its toxic nature. Therefore, conversion and modification of SS to decrease its toxicity has resulted in advanced methods. Co-pyrolysis of SS with other amendments is an ideal treatment resulting in an environmentally safe and nutrient rich final products with additional properties to sequester carbon. In the present study, a novel biochar was produced through the microwave pyrolysis of SS mixed with zeolite and sawdust. The pyrolysis product was thus characterized for elemental composition, polycyclic aromatic hydrocarbons, via Fourier Transform Infrared Spectroscopy (FTIR), and for its effects on soil microbial characteristics, soil health and plant biomass after soil application.ResultsResults revealed that, the SS modification resulted in stable product with higher nutrients which further depend on the type and ratio of feedstock used. Its application to soil significantly improved soil chemical and microbiological properties and altered lettuce biomass.ConclusionsWe concluded that sawdust feedstock promoted nutrient availability in the resulting biochar and induced higher activity of nutrient mineralizing enzymes, whereas zeolite slowed down the release of nutrients from soil and putatively immobilized enzymes. This joint effect of sewage sludge biochar, sawdust and zeolite benefited the plant acquisition of nutrients in comparison with the microbial nutrient uptake. We thus conclude that microwave pyrolyzed SS could be used as a soil enhancer.Graphical

Characterizing Nanoparticle Release Patterns of Laser Powder Bed Fusion in Metal Additive Manufacturing: First Step Towards Mitigation Measures.

Laser Powder Bed Fusion (L-PBF) is a well-known Additive Manufacturing (AM) technology with a wide range of industrial applications. Potential occupational exposures to metal nanoparticles (NP) as by-products could occur in these processes, and no cogent occupational exposure limits are available. To contribute to this assessment, a monitoring campaign to measure the NP release pattern in two metal L-PBF facilities was carried out in two academic laboratories adopting L-PBF technology for research purposes. The monitored processes deal with two devices and three feedstock types, namely stainless steel (AISI 316L), aluminium-silicon alloy (A357) and pure copper, which are associated with different levels of industrial maturity. Prolonged environmental and personal real-time monitoring of NP concentration and size were performed, temperature and relative humidity were also measured during environmental monitoring. The measurements reveal a controlled NP release of the monitored processes, resulting in an average reduced exposure of the operators during the whole working shift, in compliance with proposed limit values (20 000 n cm-3 for density >6000 kg m-3 or 40 000 n cm-3 for density <6000 kg m-3). Nonetheless, the monitoring results show release events with an increase in NP concentration and a decrease in NP size corresponding with several actions usually performed during warm-up and cleaning, leading to exposures over 40-50 000 n cm-3 during a considerable time interval, especially during the manufacturing of pure copper powder. The results show that the actions of the operators, boundary conditions (relative humidity) and set-up of the L-PBF device have an impact on the amount of NP released and their size. Several release events (significant increase in NP concentration and decrease in NP size) are identified and associated with specific job tasks of the workers as well as building conditions. These results contribute to the definition of NP release benchmarks in AM processes and provide information to improve the operational conditions of L-PBF processes as well as safety guidelines for operators.

Kinetic Modelling of Esterification and Transesterification Processes for Biodiesel Production Utilising Waste-Based Resource

Process optimisation and reaction kinetic model development were carried out for two-stage esterification-transesterification reactions of waste cooking oil (WCO) biodiesel. This study focused on these traditional processes due to their techno-economic feasibility, which is an important factor before deciding on a type of feedstock for industrialisation. Four-factor and two-level face-centred central composite design (CCD) models were used to optimise the process. The kinetic parameters for the esterification and transesterification processes were determined by considering both pseudo-homogeneous irreversible and pseudo-homogeneous first-order irreversible processes. For the esterification process, the optimal conditions were found to be an 8.12:1 methanol to oil molar ratio, 1.9 wt.% of WCO for H2SO4, and 60 °C reaction temperature for a period of 90 min. The optimal process conditions for the transesterification process were a 6.1:1 methanol to esterified oil molar ratio, 1.2 wt.% of esterified oil of KOH, reaction temperature of 60 °C, and a reaction time of 110 min in a batch reactor system; the optimal yield was 99.77%. The overall process conversion efficiency was found to be 97.44%. Further research into reaction kinetics will aid in determining the precise reaction process kinetic analysis in future.

Emerging Technologies for Enhancing Microalgae Biofuel Production: Recent Progress, Barriers, and Limitations

The world has heavily relied on fossil fuels for decades to supply energy demands. However, the usage of fossil fuels has been strongly correlated with impactful problems, which lead to global warming. Moreover, the excessive use of fossil fuels has led to their rapid depletion. Hence, exploring other renewable and sustainable alternatives to fossil fuels is imperative. One of the most sustainable fossil fuel alternatives is biofuel. Microalgae-based biofuels are receiving the attention of researchers due to their numerous advantages compared with those obtained from other types of feedstocks. Hence, it is essential to explore the recent technologies for biofuel produced from microalgae species and define the possible challenges that might be faced during this process. Therefore, this work presents the recent advancements in biofuel production from microalgae, focusing on emerging technologies such as those using nanomaterials and genetic engineering. This review focuses on the impact of nanoparticles on the harvesting efficiency of various microalgae species and the influence of nanoparticles on biofuel production. The genetic screening performed by genome-scale mutant libraries and their high-throughput screening may assist in developing effective strategies for enhancing microalgal strains and oil production through the modification of enzymes. Furthermore, the barriers that limit the production of biofuels from microalgae are introduced. Even though microalgae-based biofuels are perceived to engage with low negative impacts on the environment, this review paper touches on several environmental issues associated with the cultivation and harvesting of microalgae species. Moreover, the economic and technical feasibility limits the production of microalgae-based biofuels.

Screening tests for N sorption allow to select and engineer biochars for N mitigation during biomass processing

Biochar amendment during biomass processing can improve those processes and products, and reduce the emissions of greenhouse gases and NH3, resulting in ecologic and economic benefits. The potential positive effects of biochar are related to NH4+-N and NH3 sorption, which in turn are depending on different biochar characteristics. By knowing the relationship between biochar characteristics and NH4+-N and NH3 sorption, biochar production can be steered towards a higher N sorption or existing biochars can be selected for targeted applications for high N sorption. Therefore, this study aims to develop fast screening tests to estimate the potential for both NH4+-N and NH3 sorption of biochar, before application in biomass processing. Further, the effects of feedstock, pyrolysis temperature, biochar characteristics and biochar treatments on N sorption are studied. The results show that NH4+-N sorption varied between 0 and 1.54 mg NH4+-N/g fresh biochar and was highest for manure-based biochars with a high nutrient content and cation exchange capacity, produced at lower temperatures (300–450 °C). For some biochars, the feedstock itself had a higher NH4+-N sorption than the biochar. Grinding and washing increased the NH4+-N sorption. In addition, a general linear model was proposed to predict the NH4+-N sorption based on three chemical characteristics· NH3 sorption varied between 0 and 100 % of the negative control and showed a linear positive relationship with the NH4+-N sorption, moisture retention factor and cation exchange capacity. Pyrolysis temperature and feedstock type did not significantly affect NH3 sorption. NH4+-N and NH3 desorption varied amongst biochar type.

Biochar reduces colloidal phosphorus in soil aggregates: The role of microbial communities

Colloidal phosphorus (Pcoll) in paddy soils can pose a serious threat to the water environment. Biochar amendment not only directly absorb Pcoll to reduce the runoff loss, but also create hotspots for microbial communities which simultaneously affects soil Pcoll. However, despite the crucial role of microorganisms, it remains elusive regarding how biochar and its feedstock types affect the relationships of soil microbial communities and Pcoll in soil matrix (such as at soil aggregate level). To address the knowledge gap, we explored the (in)direct effects of biochar on the soil Pcoll in physically separated fractions including micro- (53–250 μm) and macroaggregates (250–2000 μm). Results showed that straw and manure biochars decreased the soil Pcoll content by 55.2–56.7% in microaggregates and 41.2–48.4% in macroaggregates after 120 days of incubation, compared to the respective control. The fungal communities showed a significantly correlation (0.34, p < 0.05) with Pcoll content in the macroaggregates, whereas the bacterial communities were extremely significantly correlated (0.66, p < 0.001) with Pcoll content in the microaggregates. Furthermore, the partial least squares path model analysis indicated that biochar amendments directly increased Pcoll content (0.76 and 0.61) in micro- and macroaggregates, but the reduced Pcoll content by biochar was mainly derived from indirect effects, such as changed soil biological characteristics carbon (C)/P (−0.69), microbial biomass C (−0.63), microbial biomass P (−0.68), keystone taxa Proteobacteria (−0.63), and Ascomycota (−0.59), particularly for the macroaggregates. This study highlights that to some extent, biochar addition can reduce soil Pcoll content by affecting microbial communities (some keystone taxa), and soil biological characteristics at soil aggregate level.

Different performances in polyethylene or polystyrene plastics long-term feeding and biodegradation by Zophobas atratus and Tenebrio molitor larvae, and core gut bacterial- and fungal-microbiome responses

The biodegradation of plastics by insect larvae is considered as an emerging strategy for the resistant plastic wastes disposal. To uncover the correlation of insect larval gut-microbiome with plastics biodegradation, two worm species including superworm Zophobas atratus and yellow mealworm Tenebrio molitor were fed with either polyethylene (PE) or polystyrene (PS) foam as sole diet for a longer period of 45 days, sole bran diet was used as control. Rapid declines of survival rates and plastic ingestions after 30 days were observed, suggesting that long-term sole plastic diet was detrimental to growth and life cycle completion in both larval species. Both PE and PS plastics were found more extensively depolymerized and biodegraded in gut of yellow mealworms than that of superworms by GPC analysis. The larval gut bacterial- and fungal-microbiomes at day 45 were assessed by Illumina MiSeq. The results showed that both gut bacterial and fungal communities shifted upon sole plastic diet ingestion compared to the control. Gut bacterial communities were similar in PS-fed groups but significantly different in PE-fed groups between both species. In contrast, gut fungal communities were clustered by species in general, although they were similar between PE- and PS-fed yellow mealworms but were more divergent between PS- and PE-fed superworms. Analysis of the changes of relative abundances of dominant bacterial and fungal genera demonstrated the strong association between the distinctive gut microbiome and plastic degradation. For instance, Spiroplasma and Rhodotorula for PE degradation, Cryptococcus for PS degradation in mealworms. Issatchenkia for both PS and PE degradation, Pseudomonas for PS degradation in superworms. In conclusion, changes of both gut bacterial- and fungal-microbiomes diversities were associated with plastic feedstock types and larval species, especially fungal microbiomes were strongly associated with larval species.

Valorization of restaurant waste oil and cow-bone doped siliceous termite hills towards biodiesel production: Kinetics and thermodynamics

The type of feedstock and catalyst selected are major factors in determining the process efficiency, product cost and fuel yield obtained from a biodiesel production process. The use of termite hill as a highly reusable inert support, doped with cow bones in the synthesis of biodiesel from restaurant waste oil (RWO) could be a cost-effective alternative to other conventional catalyst types or processes. Therefore, two catalysts (raw cow-bone supported on silica; R–SC1.5 and calcined cow bone supported on silica; C-SC1.5) were developed and used in biodiesel production. The maximum conversion of RWO was 95.12% using C-SC1.5 at reaction time 2.5 h, methanol to oil ratio 9:1, temperature 65 °C and catalyst loading of 2 %w/w. The prepared catalysts were characterized using SEM, EDX, FTIR, XRD and BET analysis. The kinetics of the RWO with R–SC1.5 and C-SC1.5 was further studied. The activation energy (Ea) and frequency factor (A) were found to be 41.4 kJ/mol, 53.41 kJ/mol and 2.24 × 104 min−1, 2.29 × 106 min−1 respectively. The transesterification reaction adhered to first order law, while physicochemical properties of the biodiesel obtained were within the American Standard for Testing and Materials (ASTM) limits, since the product has low FFA content, low viscosity, high thermal stability with high energy content and improved combustion characteristics. Reusability of C-SC1.5 was also examined, which revealed effectiveness up to 5 reuses without significant reduction in biodiesel yield.

A Review on the Recent Breakthrough Methods and Influential Parameters in the Biodiesel Synthesis and Purification

Biodiesel has recently received much attention as an energy source with numerous benefits such as high degradability, negligible toxicity, and minimal emissions of carbon monoxide gases as well as particulates. Therefore, this research aims to compare, review, and summarize the conventional and advanced methods of biodiesel production. Currently, some emerging processes that were developed for advanced biodiesel production include microwave-assisted synthesis, ultrasonic-assisted synthesis, supercritical transesterification, and liquid phase plasma discharge technology. The types of feedstocks, catalysts, and operating conditions as the influential parameters in biodiesel synthesis are also discussed. Moreover, in the purification process, the effectiveness of purification depends on the type of catalyst applied in the synthesis process. This research also reviewed and compared several commonly used purification methods such as wet and dry washing, ion exchange and precipitation, complexation, and membrane-based separation that have shown significant results along with the impacts of biodiesel production on environmental and economic sectors

Content of adsorbed film water and density of oxygen-containing functional groups on surface of ageing biochar in sandy spodosol

Abstract Application of different types of feedstocks and conditions of their pyrolysis can result in different properties and sustainability of biochar during changes (aging) of its properties in soils. The aim of the studies was to assess the consequences of aging of biochar in soil for a content of adsorbed film water and a density of oxygen-containing functional groups on its surface. Sampling of soil and biochar was conducted in May and July of 2021 in a plot experiment with an applied rate of biochar of 20 t.ha−1 in 2016. WP4-T dew point potentiometer was used for measurements of relationships of potentials of adsorbed film water and its content in soil and biochar. Infrared Fourier FSM 2201/2202 spectrometer was applied for determination of densities of oxygen-containing functional groups on surface of biochar in a mid-infrared spectrum. Results showed that retention capacity of adsorbed film water by soil increased from May to July, possibly because of increasing content of hydrophilic organic compounds of plant origin. Aging of biochar in soil also resulted in an increase of retention capacity of adsorbed film water on its surface. The results of infrared Fourier spectroscopy confirmed that densities of oxygen-containing functional groups on the surface of biochar increased from May to July at spectra of wavenumbers of 1,600–1,400 cm−1 and 1,400–1,100 cm−1.

Impact of biochar, fertilizers and cultivation type on environmentally persistent free radicals in agricultural soil.

Environmentally persistent free radicals (EPFRs) have been considered as emerging contaminants due to their detrimental effects on human health. The adverse health impacts are attributed to oxidative stress induced by EPFRs through the formation of reactive oxygen species (ROS). In soils, it may also increase the degradation process of polymeric organic matter and/or undesired organic pollutants through hydroxyl radical activity. The biochar pyrolysis process entails the thermal decomposition of organic compounds in the biomass, with the carbonization conditions and feedstock type facilitating the formation of EPFRs. When biochar is used to amend soil, these radicals may promote the formation of ROS, and thus influence the transformation of organic and inorganic contaminants in soil and impact the rhizosphere. Agricultural soils are being amended with biochar to mainly increase carbon content and facilitate the plant growing conditions. Therefore, agricultural soils may become a source of EPFRs. However, the fate and transformations of EPFRs in soils after biochar amendment are not well understood or studied. This paper presents the first (to our knowledge) studies of EPFRs behaviour in agricultural soil with different input of biochar, cultivation types and residence time period. Different cultivation types, addition of fertilisers and variation in biochar input, on the one hand, and presence of metals in soil, biochar and fertilizers, on the other hand, provide different conditions for EPFRs formation, accumulation and fate in agricultural soils. Two significant factors have been found to determine the fate of EPFRs in soil: transition metal content (particularly those in reaction available form) and cultivation level of soil. Cultivation significantly decreased presence of EPFRs, both carbon-centered and oxygen-centered, in relatively short periods of time, while metal presence (and particularly through fertilizer supplementation) increases the half-life of radicals and transforms organic matter to more oxygen-centered EPFRs. The amount of biochar addition plays a secondary role as the EPFRs content in the soils is in a longer term primarily controlled by the other two factors.

The Blue Hydrogen Economy: A Promising Option for the Near-to-Mid-Term Energy Transition

Abstract Hydrogen is recently being promoted immensely as the primary energy carrier to replace fossil fuels for the envisioned environmentally friendly and sustainable future energy system, given its peculiar properties and advantages over conventional fuels and other alternative energy sources. Hydrogen is classified into various color categories based on the type of feedstock, technology, and CO2 emissions in its production pathway. This paper focuses on blue hydrogen, discussing its potential as the most promising hydrogen production pathway for the near-to-mid-term transition into a hydrogen economy. First, a comprehensive overview of the hydrogen economy is given with a detailed description of hydrogen's color-code categorization. Blue hydrogen production methods are explained, and blue and green hydrogen are compared on the subject of the grand energy transition. Furthermore, the arguments favoring blue hydrogen as the most promising alternative for the near-to-mid-term energy transition are explained. Finally, a comparative life cycle analysis (LCA) of environmental emissions and resource usage in blue hydrogen and other selected commonly used fuel production pathways is conducted using the greenhouse gases, regulated emissions, and energy use in technologies (GREET) model to analyze the potentials of the blue hydrogen production pathway. The LCA results showed that more efforts need to be committed to reducing nitrous and sulfur oxides in the blue hydrogen production pathway and improving energy and CO2 capturing efficiencies in carbon capture and storage (CCS) plants.

Adsorption of norfloxacin from wastewater by biochar with different substrates.

The type of feedstock and pyrolysis temperature are the main reasons affecting the properties of the resulting biochar. Therefore, this paper investigates the effects of different feedstocks (peanut shell, corn straw and soybean straw) and different pyrolysis temperatures (300, 450 and 600℃) on the structural morphology and elemental composition of the resulting biochar. The optimum pyrolysis temperature of 600℃ was selected based on the comparison of the adsorption of NFX (norfloxacin) by the biochar prepared at different temperatures. Characterization of biochar materials using x-ray diffractometer, fourier transform infrared spectrometer and scanning electron microscope to study the changes in the physicochemical and structural properties of biochar. The results showed that the pH, surface area and ash content of biochar are increased with increasing temperature. The results of isothermal adsorption and adsorption kinetics experiments showed that the adsorption processes of the three biochar species on NFX were consistent with the Langmuir model and Pseudo-second order kinetic model. The adsorption process occurred in the surface layer of the biochar and was dominated by chemisorption. The inhibition of the adsorption of NFX was more obvious with the higher valence state of cations and the higher ion concentration. The adsorption mechanism of biochar on NFX includes pore filling, hydrogen bonding and electrostatic interactions.

Effects of pyrolysis temperature and feedstock type on biochar characteristics pertinent to soil carbon and soil health: A meta‐analysis

AbstractBiochar amendment to soil is utilized globally as an approach to enhance carbon storage and to improve soil functioning. However, biochar characteristics and related improvements of soil functioning depend on biochar production conditions. Systematic evaluation of corresponding biochar characteristics is needed for more targeted and efficient biochar application strategies. Herein, we systematically review the effects of biochar pyrolysis temperature (175–950°C) and feedstock (corn stover, switchgrass and wood) on selected biochar characteristics (carbon content, H/C ratio, nitrogen content, pH, specific surface area, ash content and pore volume). These specific characteristics were selected as being pertinent to soil organic carbon sequestration and soil health improvement. Despite numerous studies on these topics, few have numerically quantified the effects of pyrolysis temperature. Our results show that high pyrolysis temperature (&gt;500°C) increased carbon content and pore volume for wood biochar compared with low pyrolysis temperature (≤500°C). The high pyrolysis temperature decreased the H/C ratio and nitrogen content but increased pH, specific surface area and ash content regardless of feedstock. Compared with corn stover biochar and switchgrass biochar, wood biochar had higher carbon content and larger specific surface area but lower nitrogen and ash contents regardless of pyrolysis temperature. The higher biochar carbon content might be derived from higher lignin and cellulose contents of wood feedstock. Wood feedstock had 76%–109% more lignin and 27%–47% more cellulose than corn stover and switchgrass. Corn stover biochar had higher pH, and switchgrass biochar had larger pore volume than wood biochar. Our study indicates that the targeted production of biochar with specific characteristics can be facilitated by the selection of pyrolysis temperature and feedstock type. For amending soil with biochar, more operationally defined biochar production conditions and feedstock selection might be a way forward to wider acceptance and better predictability of biochar performance under field conditions.

Low-Temperature Pretreatment of Biomass for Enhancing Biogas Production: A Review

Low-temperature pretreatment (LTPT, Temp. &lt; 100 °C or 140 °C) has the advantages of low input, simplicity, and energy saving, which makes engineering easy to use for improving biogas production. However, compared with high-temperature pretreatment (&gt;150 °C) that can destroy recalcitrant polymerized matter in biomass, the action mechanism of heat treatment of biomass is unclear. Improving LTPT on biogas yield is often influenced by feedstock type, treatment temperature, exposure time, and fermentation conditions. Such as, even when belonging to the same algal biomass, the response to LTPT varies between species. Therefore, forming a unified method for LTPT to be applied in practice is difficult. This review focuses on the LTPT used in different biomass materials to improve anaerobic digestion performance, including food waste, sludge, animal manure, algae, straw, etc. It also discusses the challenge and cost issues faced during LTPT application according to the energy balance and proposes some proposals for economically promoting the implementation of LTPT.

A Scientometric Review: Biomass Gasification Study from 2006 to 2020.

Biomass gasification represents a significant way to produce energy from biomass. It features renewable properties and offers great potential for utilization. The application of biomass gasification products, design of the gasifier, type of biomass feedstock, gasification agents, and gasification parameters are key for the biomass gasification process. This work applies bibliometric approaches to provide a comprehensive and objective analysis of worldwide biomass gasification study trends over the period from 2006 to 2020 according to the Web Of Science core collection data. A total of 3222 articles associated with biomass gasification was retrieved, and its number grew annually. The subjects of study are diversified, primarily classified into "Energy & Fuels", "Engineering Chemical", and "Green Sustainable Science Technology". Moreover, Energy was a top published journal in the field of biomass gasification. Austrian contributors had the majority of publications, next to China and the USA. Liejin Luo from Xi'an Jiaotong University possessed the greatest H-index. Keyword evaluation showed that biomass gasification is a current hotspot, among which life-cycle assessment, sustainability, and deep processing of gasification products are future research directions. This work is predicted to offer further research interest in biomass gasification.