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Highlights: [•] Bio-oil, biochar and gas can be easily produced from microwave pyrolysis of cellulose at low temperatures (200–280°C). [•] The highest bio-oil yield (45%) from microwave pyrolysis of cellulose was obtained at 260°C. [•] Water and activated carbon were used as microwave absorbers and had significant influences on product yields. [•] Amorphous cellulose gave significantly higher amounts of levoglucosan than from microcrystalline cellulose. [ABSTRACT FROM AUTHOR]

Highlights: [•] Production of bio-oil from sewage sludge. [•] Iron mass balance. [•] Characterization of bio-oil, char and gases. [ABSTRACT FROM AUTHOR]

Highlights: [•] Solids decomposition and hydrochar production modelled by first order kinetics. [•] Arrhenius rate constant characterisation of sewage sludge carbonisation. [•] The activation energy of synthetic faeces was higher than that of sewage sludge. [•] Reaction temperature had more effect on solids decomposition than reaction time. [•] Feedstock moisture content affected hydrochar yield and extent of carbonisation. [Copyright &y& Elsevier]

Highlights: [•] Four types of Canadian waste biomass were used for the fast pyrolysis using a mobile pyrolysis unit. [•] The effects of pyrolysis temperature were investigated on the properties of pyrolysis products for each precursor. [•] Comprehensive characterization of 4 feedstocks collected from 3 main sources of Canadian biomass (agricultural wastes, forest residue and animal manure) was performed. [•] Bio-char and bio-oil are characterized to evaluate their energy and agronomic potentials. [Copyright &y& Elsevier]

Abstract: Seed mill screenings would be a considerable biofeedstock source for bioenergy and char production. Char produced from the gasification of residues resulting from cleaning of grass seed and small grains could be recycled to a cropping system as a soil amendment if chemical characterization determined that the gasification process had not produced or concentrated deleterious chemical or physical factors that might harm the environment, crop growth or yield. Previous reports have shown that char derived from the pyrolysis of a variety of biomass feedstocks has potential to enhance soil quality by pH adjustment, mineral amendment, and improved soil porosity. The objective of this research was to characterize char produced from Kentucky bluegrass seed mill screenings (KBss) by a small-scale gasification unit, operated at temperatures between 600 and 650°C, with respect to polycyclic aromatic hydrocarbons, selected heavy metals, as well as other physical and chemical characteristics, and determine its suitability for agricultural application as a soil amendment. We utilized KBss as a model for seed and grain-cleaning residues with the understanding that chemical and physical characteristics of char produced by gasification or other cleaning residues may differ based on soil and environmental conditions under which the crops were produced. Our results support the hypothesis that KBss char could be applied in a cropping system without toxic environmental consequences and serve multiple purposes, such as; recycling critical plant macro- and micro-nutrients back to existing cropland, enhancing soil carbon sequestration, managing soil pH, and improving water holding capacity. Crop field trails need to be implemented to further test these hypotheses. [Copyright &y& Elsevier]

Effective management and utilization of food waste and agricultural crop residues are highly crucial to mitigate the challenges of greenhouse gas generation upon natural decomposition and waste accumulation. Conversion of biogenic wastes to biofuels and bioproducts can address the energy crisis and promote environmental remediation. This study was focused on exploring the characteristics of food waste and agricultural crop residues (e.g., canola hull and oar hull) to determine their candidacy for slow pyrolysis to produce biochar and bio-oil. Process parameters of slow pyrolysis such as temperature, reaction time and heating rate were optimized to obtain maximum biochar yields. Maximum biochar yield of 28.4 wt% was recorded at optimized temperature, heating rate and reaction time of 600 °C, 5 °C/min and 60 min, respectively. Furthermore, the physicochemical, spectroscopic and microscopic characterization of biochar, bio-oil and gases were performed. The carbon content and thermal stability of biochar were found to increase at higher temperatures. Moreover, bio-oil generated at higher temperatures showed the presence of phenolics and aromatic compounds. [Display omitted] • Process optimization for slow pyrolysis of food waste, canola hull, and oat hull. • Highest yield of biochar obtained at 600 °C with 5 °C/min heating rate in 60 min. • Biochar yields at optimized conditions: food waste (28.4 wt%) < canola hull (28.8 wt%) < oat hull (29.1 wt%). • Calorific values of food waste biochar: 300 °C (20.5 MJ/kg) < 400 °C (21.2 MJ/kg) < 500 °C (22 MJ/kg) < 600 °C (22.3 MJ/kg). • Biochar at high temperature showed greater thermal stability and aromaticity of carbon. [ABSTRACT FROM AUTHOR]

The objective of this study was the full characterization of pruning residue from macrophyte Cyperus giganteus from tertiary wastewater treatment plant (WTP), Ponte dos Leites, located in Araruama, RJ, Brazil. Analyses aimed to systematically assess the feasibility of using the pruning residues as an energy resource. To do so, macrophytes were submitted to experimental analyses of their physical properties (real density: 0.44–0.77 g cm−3, bulk density: 0.08–0.09 g cm−3, among other characteristics), chemical and proximate analyses, and thermal analysis. Results of thermal behavior characterized the biomass as a viable energy source (high heat value, 14–16 MJ kg−1). C. giganteus different samples fractions analyses confirmed that molecular structures of the macrophyte (lignin: 17.3–26.8 wt %, cellulose: 27.8–32.6 wt %, hemicellulose: 30.1–31.5 wt %; depending on the plant part) affect thermal decomposition behavior. Maximum mass losses ranged from 83.43 to 75.91%. Energy production potential from biomass pruning residues generated at Ponte dos Leites was estimated to be around 92,400 MJ mês−1. This shows the effectiveness of using pruning residues biomass from macrophyte Cyperus giganteus for energy production, highlighting its energy potential, and support its use as inputs in thermal conversion processes. [Display omitted] • Physical-chemical characterization of Cyperus giganteus pruning residues from CW. • Assessment of C. giganteus biomass thermal properties (TGA, LHV, HHV and UHV). • Potential use of C. giganteus biomass for bioenergy production (biochar). • Potential use of biochar from C. giganteus biomass for agricultural purposes. [ABSTRACT FROM AUTHOR]

Abstract: Biomass thermochemical decomposition products have been extensively studied as renewable substitutes of fossil fuel. The approach proposed in this work considers vegetal waste as a source of both energy and matter through the production of a vapor phase fuel, highly diluted in steam, suitable to be burned in non-conventional combustion systems and a char with soil amending and fertilizing properties. To demonstrate the feasibility of such a process an experimental set-up has been designed with the aim to investigate the effect of pressure, heating rate and final temperature in proper variation ranges (P =1–5×105 Pa, HR=5–40K/min, T =473–973K) on the yields and on the chemical and physical properties of gaseous and solid products. In this paper the effect of temperature at constant pressure (P =5×105 Pa) and heating rate (HR=5K/min) has been investigated in order to explore all the stages of the thermochemical degradation from torrefaction to mild gasification passing through devolatilization. For real biomasses a basic study on characterization of biomass components is needed. Knowledge of dependences on feedstock nature and process conditions is crucial for the comprehension of phenomena occurring during steam pyrolysis of real complex biomasses and for the optimization of the process operating variables. This study characterizes steam pyrolysis up to 873K (at pressure P =5×105 Pa and heating rate HR=5K/min) both of three single biomasses constituents (cellulose, hemicellulose and lignin) and of three binary mixtures in order to evaluate possible interactions between the biomass components. The results obtained highlight the importance of the interactions between components, mainly cellulose and lignin, on the yield and characteristics of solid and gaseous products. In particular, strong components interactions have been detected on the specific surface area of the solid product. [Copyright &y& Elsevier]

Abstract: Torrefied biomass samples were produced from hardwood and switchgrass pellets using the biochar experimenter''s kit (BEK) reactor and analyzed for their utility as pretreated feedstocks for biofuels production via fast pyrolysis. The energy efficiency for the BEK torrefaction process with propane gas as fuel source was about 50% for hardwood pellets and over 67% for switchgrass, but the energy retained in the torrefied product ranged between 72 and 92% of the initial biomass energy content resulting from a high product yield of 70–88wt%. The liquid pyrolysate by-product of the torrefaction process was an aqueous solution of mainly acetic acid and levoglucosan associated with dehydration of the carbohydrate fraction of the raw biomass. Subsequent fast pyrolysis in a fluidized bed led to production of pyrolysis oil with lower acidity and increased energy content compared with pyrolysis of non-torrefied biomass. However, the yield, carbon conversion and energy conversion to these pyrolysis oils were decreased with the torrefection pretreatment which predisposed the biomass for conversion to biochar rather than liquid products. [Copyright &y& Elsevier]

Abstract: Converting lignocellulosic municipal waste to biochar represents a carbon sequestration mechanism and a production route that diverts potentially useful feedstocks from landfills. In this preliminary investigation, slow pyrolysis to 480°C was used to produce biochars from 18 different wastes which were characterized by proximate analysis to determine ash, volatile matter and fixed carbon content. Desirable soil amendment properties such as cation exchange and gas adsorption capacities and pH were also measured. Pristine wood and several closely related products exhibited low ash and high fixed carbon content while paper and cardboard products were found to have higher ash and volatile matter content. Cation exchange capacity (CEC) values were comparable to activated carbon (AC) and within a similar range for most feedstock biochars, with grass and cardboard biochars having the highest CEC. All biochars were found to have similar gas adsorption capacities (GAC) that were lower than AC while newsprint biochar had a GAC twice as high as other samples. All biochars showed neutral to slightly alkaline pH values. In general, lignocellulosic municipal waste biochars exhibited a diverse range of potentially beneficial properties and should be further investigated as prospective soil amendments. [Copyright &y& Elsevier]

Abstract: Pyrolysis of rice straw to create biochar for soil amendment appears to be a promising method to address concerns with regard to improving soil fertility, increasing Carbon storage and decreasing Green House Gas emissions. However, the ability of rice straw-derived biochar to affect these factors might vary depending on its characteristics. It is therefore essential to investigate the properties before large-scale application of rice straw-derived biochar. In this study, rice straw-derived biochars produced at different temperatures (300, 400, 500, 600 & 700 °C) and residence time (1, 2, 3 & 5 h) were characterized using a suite of analytical techniques. Results showed that pyrolysis temperature had a greater influence than residence time on the chemical composition and structure of rice straw-derived biochar produced at low heating rate. The rice straw-derived biochars especially produced at 400 °C had high alkalinity and cation exchange capacity, and high levels of available phosphorus and extractable cations. These properties indicate potential application of rice straw-derived biochar as a fertilizer and soil amendment. Fourier transform infrared spectra showed that higher pyrolysis temperatures promote condensation reactions. Rice straw-derived biochars contained turbostratic crystallites at 400 °C, and displayed a high level of aromatization at 500 °C. Increasing charring temperature will increase the aromaticity of biochar, and might include its recalcitrance. [Copyright &y& Elsevier]

Abstract: Gorse species (Ulex sp.) are ubiquitous in the shrublands of NW Spain and have the potential to become key players in an integral biofuel/biochar program in NW Spain. Here we present molecular characterization (using pyrolysis–GC/MS) of a biochar “thermosequence” obtained by laboratory heating of Ulex europaeus wood in a muffle furnace between 200 and 600°C (T CHAR). Low temperature chars (T CHAR ≤350°C) produced significant amounts of pyrolysis products of which the precursor biopolymer could be recognized, while high-temperature chars (T CHAR ≥400°C) produced mainly phenols and monocyclic and polycyclic aromatic hydrocarbons, which are not specific for any biopolymer. Carbohydrate could hardly be recognized at T CHAR ≥350°C. The thermal rearrangement of polyphenols, mainly lignin, was reflected in more detail (1) C3-side chain shortening and probably depolymerization (T CHAR 200–350°C), (2) demethoxylation of syringyl and probably also some guaiacyl lignin (T CHAR 300–400°C), (3) elimination of virtually all remaining methoxyl groups (T CHAR 350–400°C), through dehydroxylation and demethoxylation, (4) almost complete dehydroxylation of lignin and other biopolymers (T CHAR 400–500°C), (5) progressive condensation into polyaromatic structures (T CHAR 300–500°C) and (6) partial elimination of alkyl bridges between (poly)aromatic moieties (T CHAR 450–500°C). These results were supported by Fourier transform infrared spectroscopy (FTIR) of the same samples. We conclude that pyrolysis–GC/MS can be used as a rapid molecular screening method of gorse-derived biochar. Molecular properties elucidation is an essential part of predicting the stability and agronomical behavior of gorse-derived biochar after future implementation in soils. [Copyright &y& Elsevier]

Abstract: Alkali lignin as an example of waste plant biomass was subjected in a batch reactor to decomposition in sub- and supercritical water. Hydrothermolysis of alkali lignin with relatively highmolecular-weight led to the production of phenolic compounds such as guaiacol and catechol, as well as phenol, m-cresol, p-cresols and o-cresol. Both an increase growth in conversion time and an increase in reaction temperature promoted secondary reactions: degradation of alkali lignin decomposition products, leading to, their repolymerization and carbonization. The components of the liquid fractions of products were examined by GC–MS and HPLC, whereas the solid charred post-reaction residues were analyzed by elemental analysis and FTIR. [Copyright &y& Elsevier]

Abstract: Producing biochar and biofuels from poultry litter (PL) through slow pyrolysis is a farm-based, value-added approach to recycle the organic waste. Experiments were conducted to examine the effect of pyrolysis temperature on the quality PL biochar and to identify the optimal pyrolysis temperature for converting PL to agricultural-use biochar. As peak pyrolysis temperature increased incrementally from 300 to 600°C, biochar yield, total N content, organic carbon (OC) content, and cation exchange capacity (CEC) decreased while pH, ash content, OC stability, and BET surface area increased. The generated biochars showed yields 45.7–60.1% of feed mass, OC 325–380gkg−1, pH 9.5–11.5, BET surface area 2.0–3.2m2 g−1, and CEC 21.6–36.3cmolc kg−1. The maximal transformation of feed OC into biochar recalcitrant OC occurred at 500°C, yet 81.2% of the feed N was lost in volatiles at this temperature. To produce agricultural-use PL biochar, 300°C should be selected in pyrolysis; for carbon sequestration and other environmental applications, 500°C is recommended. [Copyright &y& Elsevier]

Abstract: Pyrolytic cook stoves in smallholder farms may require different biomass supply than traditional bioenergy approaches. Therefore, we carried out an on-farm assessment of the energy consumption for food preparation, the biomass availability relevant to conventional and pyrolytic cook stoves, and the potential biochar generation in rural households of western Kenya. Biomass availability for pyrolysis varied widely from 0.7 to 12.4 Mg ha−1 y−1 with an average of 4.3 Mg ha−1 y−1, across all 50 studied farms. Farms with high soil fertility that were recently converted to agriculture from forest had the highest variability (CV = 83%), which was a result of the wide range of farm sizes and feedstock types in the farms. Biomass variability was two times lower for farms with low than high soil fertility (CV = 37%). The reduction in variability is a direct consequence of the soil quality, coupled with farm size and feedstock type. The total wood energy available in the farms (5.3 GJ capita−1 y−1) was not sufficient to meet the current cooking energy needs using conventional combustion stoves, but may be sufficient for improved combustion stoves depending on their energy efficiency. However, the biomass that is usable in pyrolytic cook stoves including crop residues, shrub and tree litter can provide 17.2 GJ capita−1 y−1 of energy for cooking, which is well above the current average cooking energy consumption of 10.5 GJ capita−1 y−1. The introduction of a first-generation pyrolytic cook stove reduced wood energy consumption by 27% while producing an average of 0.46 Mg ha−1 y−1 of biochar. [Copyright &y& Elsevier]

Abstract: This paper examines some of the economic tradeoffs in the joint production of biochar and bio-oil from cellulosic biomass. The pyrolysis process can be performed at different final temperatures, and with different heating rates. While most carbonization technologies operating at low heating rates (large biomass particles) result in higher yields of charcoal, fast pyrolysis (which processes small biomass particles) is the preferred technology to produce bio-oils. Varying operational and design parameters can change the relative quantity and quality of biochar and bio-oil produced for a given feedstock. These changes in quantity and quality of both products affect the potential revenue from their production and sale. We estimate quadratic production functions for biochar and bio-oil. The results are then used to calculate a product transformation curve that characterizes the yields of bio-oil and biochar that can be produced for a given amount of feedstock, movement along the curve corresponds to changes in temperatures, and it can be used to infer optimal pyrolysis temperature settings for a given ratio of biochar and bio-oil prices. [Copyright &y& Elsevier]

The depletion of fossil fuels as well as the greenhouse gas emissions from fossil fuel use have led to growing interest in biofuel production from biomass. A new technology, thermo-catalytic reforming (TCR), is one of the contributing interests. TCR technology integrates intermediate pyrolysis with a post-reforming stage to convert biomass into a high-quality bio-oil, biochar, and syngas. In this study, experiments were carried out using three Alberta-based biomass feedstocks – hardwood pellets, softwood pellets, and chips – in a 2 kg h−1 laboratory-scale TCR plant. The results show that the composition of the biomass has little effect on product yield and quality. The TCR gases had a higher heating value of 12.5–12.8 MJ kg−1 and a hydrogen content of 13–15 vol %. The produced TCR bio-oil had low water content (~5 wt %) and a heating value of 32–34 MJ kg−1. The high quality of the bio-oil is reflected in the low O/C ratio of 0.15 and TAN of 6–15 mg KOH g−1. The TCR biochar from all three feedstocks had a high heating value and a high carbon content, as well as low O/C and H/C ratios. A parametric study was conducted for the softwood pellets to observe the effect of reformer temperature (500–700 °C) and reactor temperature (400–550 °C). It was observed that at a reformer temperature of 700 °C, the gas yield increases at the expense of a reduction in bio-oil and biochar. The optimum reactor temperature for the TCR of softwood pellets was found to be 500 °C, in terms of both bio-oil quality and yield. • Thermo-catalytic reforming (TCR) technology incorporates intermediate pyrolysis with high temperature reforming. • The TCR bio-oil had low TAN (6–15 mg KOH/g), and high HHV (32–34 MJ kg−1). • The TCR gases had a hydrogen content of 13–15 vol % and HHV of 12–14 MJ kg−1. • Higher reforming temperature led to increase in gases at the expense of bio-oil. [ABSTRACT FROM AUTHOR]

In the current scenario of climate change, the search for alternative energy sources is very important to reduce the use of fossil fuels. Undesired biomass (weed) from agricultural fields can be used to produce biofuels through nano catalysts enhanced gasification and process. Lignocellulosic part of weedy plants represents a potential alternative feedstock for economic production of bioethanol. Large numbers of weedy plant species are growing all over the world. However, high energy requirements and poor-quality biofuel products are the major constraints for utilization of this technology. Nanomaterials could be used as a catalyst to enhance the energy use efficiency and product quality. So, present study was conducted to produce bio-gas, bio-diesel and bio-char from mixed weed biomass of weeds like Carthamous oxyacantha, Asphodelus tenuifolius and Chenopodium album through gasification process using nano-materials as catalysts. Nickel and cobalt nano-particles were used as nano-catalysts to expedite the bio-chemical reactions for the generation of these products at lower temperatures i.e. (400 C°) in a muffle furnace. Further, these products were characterized using GC-MS analysis. It was observed that biodiesel contained 65.47% esters, which indicates its better quality than the normally produced biodiesel having 15–20% esters contents. Similarly, GC-MS analysis of biogas produced from mixed weed biomass showed 3.76% Methane, 8.32% Propane, 50.16% Ethene, 3.12% Propyne and 34.64% Methanol. The present results clearly exhibited the improved product quality and better energy use efficiency in gasification of weed biomass for bioenergy production. Image 1 • Strategic recycling of weed biomass into useful biofuels and biochar using nano-catalysts. • Nano-catalysts can accomplish gasification of weed biomass at lower temperatures. • Biodiesel of weed biomass is of better quality and environment friendly. • The biochar produced from weed biomass can be used as soil amendment. • Biogas produced from weed biomass is a good source of hydrocarbon fuel gases. [ABSTRACT FROM AUTHOR]

Bioenergy can be produced from a wide range of feedstocks and can be utilised for production of renewable electricity, thermal energy, chemicals or transportation fuels. Anaerobic digestion technology (AD) for biogas production has an important role in achieving circular economy goals, as it may not only recover the energy contained in the biomass but also contribute to nutrient recovery and reduction of greenhouse gas emissions. The expansion of biogas production promotes the need for assessment of the technical potential of biomass, which is available for biogas production and is not in the competition with other purposes. This research work presents a Geographical Information System (GIS) based approach for the assessment of the spatial distribution of the biogas production potential by taking into consideration seasonal variation of biomass production, in order to assess the influence of biomass seasonality. The method developed in this research work is based on a combination of statistical and spatial explicit methods. The presented approach was tested in a case study of Croatia and the final results are representing the seasonal and spatial distribution of biogas potential at the spatial level of 1 km × 1 km. The results show that there is a strong need to include the influence of seasonality in assessment of biogas potential for lignocellulosic agricultural residues. The benefits are demonstrated in two examples that resulted in 12% and 40% lower storage facility capacity by using the proposed approach, compared to currently used approaches. [ABSTRACT FROM AUTHOR]