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Bangladesh has encountered several challenges, including issues like overpopulation, energy shortage, and global warming for the last few decades. Addressing the increasing energy demand has become a crucial concern because of rapid increase in population and lack of growth in the economic. The electricity production of a country heavily relies on fossil fuels, particularly natural gas, which makes up approximately 54% of the current installed capacity. Bangladesh is an agrarian nation and biomass stands out as a source of renewable energy having significant potential to mitigate the demand for heat and electricity. Biomass resources in the country mainly comprise animal dung, agricultural crop residuals, solid waste from municipalities and forest residues. The existing biomass resources contribute to producing a high amount of energy and content of around 1574.16 PJ of energy equivalent to 437.28 TWh of electricity in which agricultural residues, animal manure, municipal solid waste, and forest residues impart around 852.32 PJ, 399.04 PJ, 112.16 PJ, and 210.64 PJ of energy respectively. This paper explores the extent, possibilities, and technologies associated with biomass energy conversion. Additionally, the study delves into the several biomass projects that the government, as well as non-governmental groups, are working on for environmental sustainability along with plans, challenges, and methods that are being utilized to encourage biomass technologies across Bangladesh. [Display omitted] • The biomass potentiality in Bangladesh for heat and electricity generation is emphasized. • The energy scenario and necessity of alternative energy sources in Bangladesh are discussed. • The available energy conversion technologies from biomass in Bangladesh are presented. • The existing biomass resource content of around 1574.16 PJ (437.28 TWh of electricity) of energy. • The economic aspects and challenges of biomass conversion into energy are discussed. [ABSTRACT FROM AUTHOR]

Recirculation of hydrothermal carbonization (HTC) process water (PW) has been revealed as an effective strategy to promote the recovery of lost dissolved organics in the spent solvent. However, the role of operating parameters such as temperature, time and solid load during recirculation needs to be clarified and better investigated in order to achieve a successful PW valorization. In this paper, the effects of different reaction conditions during HTC with PW recirculation were studied by using orange peel waste as feedstock. The results showed that strong synergistic interactions occurred between the biomass and the recycled solvent, leading to a hydrochar mass yield increase between 0.5 and 11 wt% on a dry basis (d.b.), according to the reaction conditions. PW recirculation, especially at low conversion severity and solid load, increased hydrochar carbon content while drastically reduced the oxygen fraction. The reason was probably related to promoted dehydration and decarboxylation. As result, carbon and energy yields were respectively increased by 26.1 % and 27.0 %, on average. The energy balance outcomes showed that the energy recovery rose up to 8 times by recycling PW compared to phases with deionized water as HTC solvent. [Display omitted] • Hydrochar recovery enhancement is obtained by solvent recirculation. • Intense synergistic effects in hydrochar formation occur at low temperatures. • Dehydration and decarboxylation are promoted by solvent recycling. • Hydrochar carbon retention is increased by 6.2 % after recirculation at 180 °C. • Process water recirculation improves the conversion energy efficiency. [ABSTRACT FROM AUTHOR]

Abstract The CarbOn pilot plant is a continuous biomass carbonization system, rated for a capacity of up to 50 kg h−1 and based on open top, downdraft technology, operating in oxidative pyrolysis in the temperature range of 500–650 °C and equivalence ratio (ER) between 0.1 and 0.2. In the reported validation tests, carried out on small size chestnut woodchips, charcoal mass yield in excess of 22.4 ± 0.7 wt% (dry base) has been achieved, with a fixed carbon content higher than 85 wt% (dry base). The fixed carbon yield (FCy) was 18.2 ± 2.2 wt% (dry base), the char carbon yield (CCy) 38.3 ± 1.6 wt% (dry base) and the net energy conversion efficiency to char (ε) equal to 41.2 ± 2.2% (wet base). Volume concentration of permanent gases in the pyrolysis vapors and condensable species were also measured before incineration and critically compared against literature data. The organic condensate from oxidative pyrolysis was obtained as 4.9 wt% of the dry biomass, and around 58 wt% of its constituents have been identified; in order of decreasing abundance, the organic fraction of condensate was composed of organic acids, aromatics, furans, anhydrous sugars, phenols, methanol, PAHs, acetaldehyde, ketones. Measured and calculated performance data shows that the pilot unit can produce high quality charcoal, meeting and exceeding the product specifications set by standard EN 1860-2 for BBQ lump charcoal as well as those set forth by international voluntary standards on biochar quality for soil application. Graphical abstract Image 1 Highlights • Charcoal yield in excess of 22 wt% were obtained in autothermal carbonization. • Yield of condensable organics was 4.91 wt% of the dry biomass. • Attained energy yield in autothermal carbonization exceeding 41%. • Lower stack emission than traditional carbonization process, high T heat as co-product. • Charcoal has FC = 80.8 wt%, VM 17 wt%, Ash 2.2 wt%, BET 135.4 m2 g−1, PAH <2.5 mg kg−1. [ABSTRACT FROM AUTHOR]

The cultivation of energy cane throughout the Southeastern United States may displace grazed pastures on organic soil (Histosols) to meet growing demands for biofuels. We combined results from a field experiment with a biogeochemical model to improve our understanding of how the conversion of pasture to energy cane during early crop establishment affected soil GHG (CO 2 , CH 4 , and N 2 O) exchange with the atmosphere. GHG fluxes were measured under both land uses during wet, hot and cool, dry times of year, and following a fertilization event. We also simulated the impact of changes in precipitation on GHG exchange. Higher fertilization of cane contributed to greater emission of N 2 O than pasture during warmer and wetter times of the year. The model predicted that energy cane emitted more nitrogen than pasture during simulated wetter than drier years. The modeled emission factor for N 2 O was 20 to 30-fold higher than the default value from IPCC (1%), suggesting that the default IPCC value could dramatically underestimate the consequences of this land conversion on the climate system. Predicted soil CH 4 and CO 2 fluxes were higher in pasture than energy cane, and this difference was not affected by increasing precipitation. Model simulations predicted that soils under first year cane emit more GHGs than pasture, particularly during wet years, but this difference disappeared two years after energy cane establishment. Our results suggest that management practices may be important in determining soil GHG emissions from energy cane on organic soils particularly during the first year of cane establishment. [ABSTRACT FROM AUTHOR]

Seaweeds are considered a viable feedstock for producing energy through the anaerobic digestion conversion process. Its exploitation and use as an alternative renewable energy source; however, remains marginal in the EU. This study aims to evaluate BMP in batch tests of the brown algae Fucus vesiculosus from the Baltic Sea and collected from the Latvian coast. The lab scale BMP tests were oriented towards the evaluation of the effects of mechanical and microwave pre-treatment methods, as well as the impact of a different algae-to-inoculum (A/I) ratio using: i) cutting blades together with mortar and pestle (C&PM) in combination with the use of a 700 W capacity microwave, ii) 1:3 and 1:5 A/I ratios. The cumulative CH 4 yields show a value in the range of 68 ± 21 mL CH 4 /g VS – a trial with no microwave treatment and A/I of 1:3) and 144 ± 28 mL CH 4 /g VS – a trial including a microwave treatment for 3 min, and A/I ratio of 1:3. The results show effectiveness in the range of 7.8%–43.7%, when the microwave pre-treatment is applied for 1.5 min, and a range of 37.2%–45.2% when the pre-treatment is applied for 3.0 min. The results of this study suggest promising potential for F. vesiculosus for biogas production, especially in the Baltic region. [ABSTRACT FROM AUTHOR]

The use of woody biomass in thermochemical conversion is still the most popular method of obtaining bioenergy from this material. Elemental composition has a significant effect on biomass quality and parameters of the combustion process. The aim of this study was to determine the content of selected macroelements (phosphorus, potassium, magnesium, calcium, sodium and sulphur), microelements (boron, copper, iron, manganese and zinc) and trace elements (cadmium, chromium, nickel and lead) in willow biomass of two different varieties and three clones, harvested in annual, biennial and triennial cycles in north-eastern Poland. The study found significant variability between varieties/clones and harvest cycles. Biomass of the UWM 200 clone of Salix alba in triennial harvest rotation had the best parameters as a potential fuel source; it was found to contain the significantly smallest concentrations of P, K, Na, S (1.48, 5.45, 0.08, 0.35 g kg −1 DM, respectively) and Fe, Cr, Pb (208.85, 4.91, 0.83 mg kg −1 , respectively). The content of all of the elements under study decreased significantly with an extended harvest cycle, and the differences, when comparing the triennial to the annual cycle, ranged from −9% to −29% for macroelements, from −7% to −48% for microelements and from −11% to −20% for trace elements. [ABSTRACT FROM AUTHOR]

This paper makes projections of the theoretical and technical potentials of bioenergy supply for 2050. The projections consider changes in available land for bioenergy and food for the global demand and advancements in yield, productivity, expansion of bio-waste recovery, and energy conversion. We present a literature review on projections. We introduced a novel logical and transparent forecasting model. Three future scenarios were established: business as usual (BUS), optimistic trends (OPT), and full adaptation response (FAR). The projection is carried out based on four adjusting factors. An uncertainty analysis was carry-out based on a Monte-Carlo method. Projections of bioenergy production in 2050 were compared with other projections in the literature. The FAR scenario showed that it would be possible to produce twenty-one times the current primary bioenergy supply and to even supply all global primary energy demand in 2050, mostly by energy crops. The assumptions adopted for the BUS and OPT scenarios make their projections more likely. Therefore, the contribution of bioenergy in the global energy matrix is expected to be between 64 and 313 EJ (7.5%–37%) in 2050. There would be a significant change in the composition of the bioenergy supply from today's mostly firewood to energy crops and biowastes. The technical potential for fuel and electric power mostly follow the supply trends for primary bioenergy (theoretical). The potential avoided greenhouse emissions are estimated. The heuristics and the level of transparency of the novel model will allow adjustments and exploration of other scenarios as time passes. • Novel model for projections of the potential of global primary bioenergy supply. • Bioenergy supply potential is shown for 11 different groups of biomass. • Global primary bioenergy supply could increase up to 6 times by 2050 (37% of demand). • Full adaptation response scenario could meet 100% of the global energy demand. • Bioenergy can play a major role in the global energy supply. [Display omitted] [ABSTRACT FROM AUTHOR]

This work concerns the first stage of combustion in a small, air-staged, wood-chip boiler because comprehensive experimental data on the release of wood-volatiles during thermal conversion of solid biomass on grates are necessary to provide reliable data for the validation and optimization of fuel bed models and gas phase combustion models. Despite this importance, data especially from small-scale boilers are rare. This work provides detailed information about the spatial distribution of gaseous species, water and tar above the fuel bed of a commercial boiler with a nominal heat output of 40 kW. Furthermore, the influence of the primary air ratio and the wood-chip moisture on the fuel gas composition and the quantity of fine particulate matter emissions were investigated. Fuel gas volume fractions were: 16.6% CO, 3.6% H 2 , 1.8% CH 4 , 6.3% CO 2 , 0.2% O 2 , 28.3% H 2 O , 43.2% N 2 for wood-chips with a fuel water content of 12% and a primary air ratio of 0.25. The corresponding tar content and the lower calorific value amounted to 78 g m −3 at standard temperature and pressure (STP) and 5.14 MJ kg −1 , respectively. The locally different concentration of species and temperature above the fuel layer resulted from the fuel bed movement. Strong gradients in species fraction were detected in direction of the fuel flow while species fraction gradients perpendicular to fuel bed movement were marginal. Particulate matter emissions of the investigated boiler were 7 mg m −3 (at STP and O 2 volume fraction of 13% in the dry exhaust gas) with aforementioned testing conditions. [ABSTRACT FROM AUTHOR]

The potential of sweet sorghum as an alternative crop for ethanol production was investigated in this study. Initially, the enzymatic hydrolysis of sorghum grains was optimized, and the hydrolysate produced under optimal conditions was used for ethanol production with an industrial strain of Saccharomyces cerevisiae , resulting in an ethanol concentration of 87 g L −1 . From the sugary fraction (sweet sorghum juice), 72 g L −1 ethanol was produced. The sweet sorghum bagasse was submitted to acid pretreatment for hemicellulose removal and hydrolysis, and a flocculant strain of Scheffersomyces stipitis was used to evaluate the fermentability of the hemicellulosic hydrolysate. This process yielded an ethanol concentration of 30 g L −1 at 23 h of fermentation. After acid pretreatment, the remaining solid underwent an alkaline extraction for lignin removal. This partially delignified material, known as partially delignified lignin (PDC), was enriched with nutrients in a solid/liquid ratio of 1 g/3.33 mL and subjected to simultaneous saccharification and fermentation (SSF) process, resulting in an ethanol concentration of 85 g L −1 at 21 h of fermentation. Thus, from the conversion of starchy, sugary and lignocellulosic fractions approximately 160 L ethanol.ton −1 sweet sorghum was obtained. This amount corresponds to 13,600 L ethanol.ha −1 . [ABSTRACT FROM AUTHOR]

The conversion of biomass to hydrocarbon transportation fuels presents unique challenges that generally focus on maintaining high mass and energy yields while removing oxygen from the biomass. Among the many processes proposed and demonstrated, processes that can achieve this efficiently and economically will have a clear advantage. Currently, there is no graphical method to analyze such conversion processes. In this work, we introduce a Funnel Plot to indicate both product quality, in terms of oxygen removal, and energy yield, the energy retained in the product oil from the original biomass. The Funnel Plot is applied to literature data for several processes and compared to an idealized chemical conversion of biomass revealing some of the current challenges associated with biofuel production. [ABSTRACT FROM AUTHOR]

Herein, a novel hierarchical porous carbon nanosheet with high N content was successfully prepared by pyrolyzing a spidroin heterologously expressed in engineered Escherichia coli through a pre-carbonization process and a subsequent KOH activation process. The as-obtained carbon materials absolutely inherited the characteristics of natural spidroin at the molecular level and presented a nanosheet structure. At an activation temperature of 800 °C, the material exhibited a large specific surface area (2170 m2 g−1) and a high N content (2.83 wt%). As a result, this material (AS-PC 800) displayed a specific capacitance (C g) of 561 or 384 F g−1 at 0.5 A g−1 in 6 M KOH electrolyte, based on a three- or two-electrode system, respectively. The assembled symmetrical coin-like supercapacitor showed a good rate capability (C g held 353 F g−1 at 20 A g−1) and cycling stability (C g retained over 95.8% after 10000 cycles at 5 A g−1). The symmetrical device delivered a high energy density of 85.84 Wh kg−1 at a power density of 800 W kg−1 with the [BMIm]BF 4 /AN electrolyte. Additionally, AS-PC 800 exhibited the optimal oxygen reduction properties. The onset reduction potential began at 0.98 V vs. RHE which is very close to that of the commercial 20% Pt/C (1.04 V) catalyst. This work provides an innovative method for exploring novel biomass precursors in the development of porous carbon materials for energy conversion and storage applications. [Display omitted] • A new carbon nanosheet derived from a native-sized recombinant spidroin is prepared. • This carbon nanosheet inherits the trait of the spidroin at the molecular level. • The carbon nanosheet exhibits excellent supercapacitance and ORR property. • This work uses the synthetic biology means to explore new carbon materials. [ABSTRACT FROM AUTHOR]

The present study aims to quantify the main biomass resources in South Tyrol (Northern Italy) and estimate the potential contribution for the energy sector. Moreover, four representative feedstocks have been tested in a domestic pellet boiler under standard conditions in order to assess its performance and pollutant emissions. The unexploited biomass potential for energy conversion applications, expressed as dry weight, has been estimated to be 135 000 t y −1 from forest, 14 950 t y −1 for apple pruning residues and 12 000 t y −1 from the industrial sector. The scenario of utilizing the unexploited local biomass resources – in energy systems such as the ones deployed in South Tyrol – would contribute with an annual bioenergy production contribution of 130–270 TJ of electricity and 1700–2100 TJ of heat. Finally, the tested feedstocks can be used in domestic boilers, however, some modifications are required when using agricultural residues. [ABSTRACT FROM AUTHOR]

At pH 4.8 and 50 °C, semi-continuous countercurrent saccharification was performed using α-cellulose. Every second day, solids and liquids were transferred countercurrently and liquid samples were taken to determine sugar concentration in each stage. Train 1 (5 mg protein/g biomass, 8 stages) achieved 87.8% glucose conversion and 102 g/L total sugar. Train 2 (2 mg/g, 8 stages) achieved 56.1% glucose conversion and 65 g/L total sugar. Train 3 (2 mg/g, 16 bottles) achieved 73.6% glucose conversion and 67 g/L total sugar. Compared to 5-day batch saccharification, to achieve the same glucose conversion, enzyme requirements were reduced by factors of 16.8, 8, and 20.5 for Trains 1, 2, and 3, respectively. Further improvements can be realized by changing the enzyme addition point and increasing the number of stages. [ABSTRACT FROM AUTHOR]

Research is focused on the utilisation of waste or residue biomass for bioenergy conversion. A promising conversion technology for the production of liquid biofuels from residue biomass is a process called Thermo-Catalytic Reforming (TCR ®​ ) which is a combination of prior thermal treatment of the biomass at mild temperatures (intermediate pyrolysis) followed by a second catalytic treatment step at elevated temperatures (reforming). This article focuses on the conversion of TCR ® liquids from digestate as a feedstock for subsequent hydrocarbon production. The generated bio-oil showed a lower heating value of 34.0 MJ kg − 1 with an oxygen content of 7.0% and a water content of 2.2%. The bio-oil was hydrodeoxygenated using an industrial NiMo–Al 2 O 3 catalyst at temperatures of 503 K–643 K and a pressure of 14 MPa. The hydrodeoxygenated bio-oil reached a lower heating value of 42.3 MJ kg −1 with an oxygen content below 0.8 mg kg −1 and water content of 30 ppm. Product yields and catalyst life give confidence that upgrading of the TCR ®​ bio-oil offers a suitable option to meet the high standards of common fuels. [ABSTRACT FROM AUTHOR]

The conversion of lignocellulosic biomass to ethanol involves three major unit operations such as pretreatment, hydrolysis and fermentation. Each unit operation involves processing of biomass with changes in its structure, and release of fermentable and other sugars and lignin degrading compounds. The evaluation of biomass conversion processes through material balance is fundamentally crucial in its commercialization. This gives an idea about the transfer of biomass from one phase to another and hence eventually of the efficiency of the total process. In the present study, material balance has been evaluated in each unit operations for sorghum biomass to ethanol conversion. An account of carbohydrates in the native as well as pretreated sorghum biomass, the release of fermentable sugars and the conversion of sugars to ethanol was maintained and analysed. Ethanol yield of 91.94 g per kg sorghum was achieved without any detoxification and washing of pretreated biomass after mild acid pretreatment followed by enzymatic hydrolysis and fermentation. [ABSTRACT FROM AUTHOR]

Literature values for glucose release from corn stover are highly variable which would likely result in tremendous variability in bio-refinery ethanol yield from corn stover feedstock. A relatively recent change in United States corn genetics is the inclusion of the Bacillus thuringiensis (Bt) trait, which now accounts for three-fourths of all US planted corn acreage. The objective of this study was to evaluate the effect of corn grain yield, inclusion of the Bt trait, and location environment on corn stover quality for subsequent ethanol conversion. Two hybrid pairs (each having a Bt and non-Bt near-isoline) were analyzed giving a total of 4 hybrids. In 2010 and 2011, field plots were located in Michigan at four latitudinal differing locations in four replicated plots at each location. Stover composition and enzymatic digestibility was analyzed and estimated ethanol yield (g g −1 ) was calculated based on hydrolyzable glucan and xylan levels. Analysis showed that there were no significant differences in total glucose or xylose levels nor in enzymatically hydrolyzable glucan and xylan concentrations between Bt corn stover and the non-Bt stover isolines. Regression analyses between corn grain yield (Mg ha −1 ) and corn stover ethanol yield (g g −1 ) showed an inverse relationship indicative of a photosynthate source-sink relationship. Nevertheless, the quantity of stover produced was found to be more critical than the quality of stover produced in maximizing potential stover ethanol yield on a land area basis. [ABSTRACT FROM AUTHOR]

Alkali metals inherent in black liquor (BL) have strong catalytic activity during gasification. A catalytic co-gasification process based on BL with pyrolysis oil (PO) has the potential to be a part of efficient and fuel-flexible biofuel production systems. The objective of the paper is to investigate how adding PO into BL alters fuel conversion under gasification conditions. First, the conversion times of single fuel droplet were observed in a flat flame burner under different conditions. Fuel conversion times of PO/BL mixtures were significantly lower than PO and comparable to BL. Initial droplet size (300–1500 μm) was the main variable affecting devolatilization, indicating control by external heat transfer. Char oxidation was affected by droplet size and the surrounding gas composition. Then, the intrinsic reactivity of char gasification was measured in an isothermal thermogravimetric analyser at T = 993–1133 K under the flow of CO 2 –N 2 mixtures. All the BL-based samples (100% BL, 20% PO/80% BL, and 30% PO/70% BL on mass basis) showed very high char conversion. Conversion rate of char gasification for PO/BL mixtures was comparable to that of pure BL although the fraction of alkali metal in char decreased because of mixing. The reactivities of BL and BL/PO chars were higher than the literature values for solid biomass and coal chars by several orders of magnitude. The combined results suggest that fuel mixtures containing up to 30% of PO on mass basis may be feasible in existing BL gasification technology. [ABSTRACT FROM AUTHOR]

Complete conversion of glycogen to glucose is achieved by using H 3 PW 12 O 40 ·nH 2 O (HPW) and H 4 SiW 12 O 40 ·nH 2 O (HSiW) as catalysts for the hydrolysis under optimized hydrothermal conditions (mass fraction of catalyst 2.4%, 373 K and 2 h reaction time). The reusability of the catalyst (HPW) was demonstrated. In addition to carrying out the glycogen hydrolysis in an autoclave, other novel methods such as microwave irradiation and sonication have also been investigated. At higher mass fraction of the heteropoly acids (10.5%), glycogen could be completely converted to glucose under microwave irradiation. Sonication of an aqueous solution of glycogen in the presence of HPW and HSiW also yielded glucose. Thus, heteropoly acids are efficient, environmentally friendly and reusable catalysts for the conversion of glycogen to glucose. [ABSTRACT FROM AUTHOR]

The presence of contaminants considerably restricts the application of sewage sludge for the fertilisation and reclamation of soils. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment and vary widely in sewage sludge depending on the input of industrial effluents. The objective of the study was the investigation whether the pyrolysis affect (reduces or adds) the total quantity of PAHs in sewage sludge-derived biochars and whether the pyrolysis changes the PAHs spectrum in terms of relative contributions of more hazardous components. Additionally, the trace metal content was determined before and after pyrolysis as well as the ecotoxicological parameters test towards plant ( Lepidium sativum ), bacteria ( Vibrio fischeri ) and crustacean ( Daphnia magna ). Sewage sludges conversion to biochar significantly reduced the content of PAHs (from 8- to 25-fold depending on pyrolysis temperature and kind of sludge). The exception was the content of naphthalene. Naphthalene was predominant in sewage sludge-derived biochars. However the concentration of the most hazardous 5- and 6-rings PAHs in sewage sludge-derived biochars was much lower compared to sewage sludge. The pyrolysis of sewage sludges caused also a significant reduction of their toxicity towards the test organisms. Only in the case of crustacean it was observed that the extracts from some biochars, obtained at higher temperatures (600 °C and 700 °C) were more toxic to D. magna than extracts from sewage sludge. In turn, after pyrolysis an increase was noted for trace metals content (Pb, Cd, Zn, Cu, Ni and Cr). [ABSTRACT FROM AUTHOR]

The conversion of glucose into a potential platform chemical for fuels and plastics, 5-hydroxymethylfurfural (HMF), has been studied using B(OH) 3 as a promoter in different solvents, namely molten mixtures made of choline salts and carboxylic acids, with the aim of developing an inexpensive and less harmful alternative to Cr/ionic liquid systems. Choline chloride-based molten mixtures afforded poor yields of HMF, whereas the yields were improved by replacing choline chloride with choline dihydrogen citrate. The combination of choline dihydrogen citrate and glycolic acid was the best choice, providing an HMF yield of ∼60% at 140 °C within 4 h by adding a small volume of water as a co-solvent. [ABSTRACT FROM AUTHOR]

Tar removal in biomass gasification systems is one of the key challenges to overcome for the successful commercialization of this technology. This study focused on tar conversion over the active char particle besides the simultaneous carbon conversion of the char particle. In the presented model, the char particle was assumed a sphere surrounded by a gas film in a bulk gas composition of naphthalene, nitrogen, steam, hydrogen, carbon monoxide, carbon dioxide and methane. The model treated the heterogeneous gasification reaction kinetics, external and internal mass transfer and changing particle properties during gasification. In addition, the effect of different parameters on naphthalene and carbon conversion was investigated. The investigated parameters were particle size, temperature and time on stream. The gas and solid mass balance equations besides the energy balance equation were solved in the radial direction using a set of initial and boundary conditions. The model results show that the naphthalene and carbon conversion reactions were kinetically limited at the reference conditions of 850 °C bulk gas temperature and 600 μm char particle size. Further, the model calculations show that isothermal char particle can be assumed up to a bulk temperature of about 1160 °C. The variation of the physical properties and pore structure of the char particle with carbon conversion affects the active surface area of the particle. Finally, the results of the single particle model will be extended to a fixed bed reactor model and will be validated with experiments. [ABSTRACT FROM AUTHOR]

The methanolysis of jojoba oil has been studied in the presence of tin powder, dibutyltin diacetate (C 4 H 9 ) 2 Sn(OOCCH 3 ) 2 , dioctyltin diacetate (C 8 H 17 ) 2 Sn(OOCCH 3 ) 2 , dibutyltin oxide (C 4 H 9 ) 2 SnO, dioctyltin oxide (C 8 H 17 ) 2 SnO, diphenyltin oxide (C 6 H 5 ) 2 SnO, dibutyltin chloride dihydroxide (C 4 H 9 ) 2 Sn(OH) 2 Cl, butyltinhydroxide hydrate (C 4 H 9 )Sn(=O)OH. x H 2 O, Ni nanoparticles and Pd nanoparticles act as catalysts. Among these, 1 weight % of dibutyltin diacetate shows the maximum conversion. Then, methanolysis of sunflower oil, neem oil, rocket seed oil and linseed oil into methyl esters studied in the presence of 1% dibutyltin diacetate as a catalyst and was compared their percentage conversions. The experimental yield for the conversion of jojoba oil, sunflower oil, neem oil, rocket seed oil and linseed oil into biodiesel was found to be 71%, 51%, 50.78%, 40.90% and 39.66%, respectively. The experimental yield of the conversion of jojoba oil into methyl esters was found to be increased up to 96% by increasing reaction time, without emulsion formation. The synthesis of jojoba seed oil biodiesel (JSOB), soybean oil biodiesel (SOB), neem oil biodiesel (NOB), rocket seed oil biodiesel (RSOB) and linseed oil biodiesel (LSOB) was confirmed by NMR ( 1 H & 13 C) and FT-IR analyses of biodiesel. [ABSTRACT FROM AUTHOR]

Wheat straw has a vast potential as feedstock for biofuel production in China. However, little information is available regarding variation in cell wall composition and enzymatic digestibility of wheat straw. This study investigated cell wall compositions and biomass digestibility of the straw of 115 wheat accessions from central China using a 1% NaOH pretreatment and mixed enzymatic hydrolysis. Significant variation in cell wall composition and sugar release was observed, with a coefficient variation (CV) ranging from 4.7% to 21.2%. Cellulose, hemicelluloses, alkali detergent hemicelluloses (ADH), and acid insoluble lignin (AIL) positively correlated with each other, and they all negatively correlated with acid soluble lignin (ASL). Hexose yields had a negative correlation with ADH and AIL, and positive correlation with ASL. No apparent undesirable correlation was found between sugar release and grain yield, thus yield and biomass convertibility can be potentially improved simultaneously. Furthermore, the features of the cell wall constitutions were compared with other plants and their implication in determining the best possible conversion strategy was discussed. This initial study is essential to understand the cell wall composition of wheat straw and to explore the potential of wheat straw as feedstock for biofuel production. [ABSTRACT FROM AUTHOR]

Due to concerns about the sustainability of the energy sector, conversion of biomass to energy is increasing its hold globally. Life Cycle Impact Assessment (LCIA) is being adopted as an analytical tool to assess the environmental impacts in the entire cycle of biomass production and conversions to different products. This study deals with the LCIA of straw conversion to district heat in a Combined Heat and Power (CHP) plant and in a district heating boiler (producing heat only). Environmental impact categories are Global Warming Potential (GWP), Acidification Potential (AP), aquatic and terrestrial Eutrophication Potential (EP) and Non-Renewable Energy (NRE) use. In the case of CHP, the co-produced electricity is assumed to displace the marginal Danish electricity mix. The current study showed that straw fired in the CHP plant would lead to a GWP of −187 g CO2-eq, AP 0.01 m2 UES (un-protected ecosystem), aquatic EP 0.16 g NO3-eq, terrestrial EP 0.008 m2 UES, and NRE use −0.14 MJ-primary per 1 MJ heat production. Straw conversion to heat in the CHP plant showed better environmental performances compared to the district heating boiler. Furthermore, removing straw from the field is related to the consequence e.g. decline in soil carbon sequestration, limiting soil nutrient availability, and when compared with natural gas the conversion of straw to heat would lead to a higher aquatic and terrestrial EP and AP. The study also outlays spaces for the detail sustainability assessment of straw conversion in a biorefinery and compare with the current study. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes and tests novel supply chain designs for bioenergy and biobased products that result in logistical costs savings of 2–38%. The proposed supply chain design reduces the costs of: (1) purchasing logistical harvesting equipment; (2) operating logistical harvesting equipment; and (3) holding feedstock inventory, by using a multitude of crop types as feedstock, instead of just one, as is common in research and practice today. In so doing, this research challenges the prevalent assumption that monocultures, despite their known environmental concerns, are preferable from a costs perspective. Simulation/optimization is used to test supply chain designs, and then to find the environmental conditions where these new supply chain designs could be most profitably implemented. [Copyright &y& Elsevier]

Supercritical water oxidation (SCWO) is an effective, promising technology for destroying almost all kinds of organic waste with the advantage of high removal efficiency and low residence time, and without producing pollutant byproduct. The chemical energy of organic pollutants can be considered as an emerging renewable energy source. As a high-temperature and pressure process, an immense energy demand is required in the pressurization and preheating sections. On the other side, the reactor effluent has a great potential for energy recovery because of the great amount of heat released during the SCWO reaction combined with the previous energy input. Thus, SCWO is not only an organic waste treatment process but also an energy conversion and utilization system. The application of SCWO has been extended to the clean, efficient utilization of low-quality fuels such as high-sulfur coal, heavy oils, and biomass instead of conventional combustion, hydrothermal spallation drilling in geothermal energy production, and heavy oil recovery. However, energy consumption cost is still rather high in the actual process due to insufficient equipment performance, unreasonable energy system integration, and selection of an anti-corrosion and salt plugging reactor. Thus, a systematic, in-depth analysis on energy conversion and utilization in SCWO is conducted for the first time in the paper. The mechanism of exergy destruction analyses indicates that reducing enthalpy change and energy level difference are critical to reducing energy consumption. Suggestions on improving energy efficiency are proposed in the preheating stage, chemical exergy release, and reactor design. [Display omitted] • Energy conversion and utilization in each stage of an SCWO system are analyzed. • Research methods and evaluation parameters for energy utilization are summarized. • Main factors affecting energy efficiency are summarized and analyzed. • The mechanism of exergy destruction is analyzed to reduce energy consumption. • Suggestions on improving energy efficiency are proposed. [ABSTRACT FROM AUTHOR]

The global increase in agri-food production results in a consequential societal requirement to better manage the unavoidable and copious agri-food waste (AFW) generated throughout the agri-food chain. Currently, attaining a zero AFW status is not feasible due to the inefficiencies in the agri-food chain. However, technologies to recover energy (electricity, heat, biofuel) and value-added biomaterials from AFW exist, and their effective adoption offers significant environmental and economic benefits. However, implementing efficient utilisation and valorisation of AFW at the scale needed is a non-trivial engineering challenge that must accomplish optimised energy yield (and conversion efficiencies) without environmental harm from fugitive emissions and discharge of secondary pollutants. Despite advances in standalone conversion technologies (SCTs), including thermal (incineration), biochemical (fermentation/anaerobic digestion), and thermochemical (pyrolysis, gasification and hydrothermal processes), there are still unresolved challenges (e.g., selectivity, low conversion efficiency, downstream upgrading of energy carriers), exacerbated by the accompanying production of polluting intermediates and by-products that scale with the process; potentially significant sources of GHG emissions and environmental risk if discharged untreated. Integrated conversion technologies (ICTs), that combine SCTs have been proposed as an approach that processes intermediates and by-products for further energy recovery at source. Effective implementation has the potential to enhance conversion efficiencies, energy carriers' diversification and yield. This critical appraisal of SCTs, advances in SCTs exploitation as ICTs, and developmental challenges describes the opportunities for efficient utilisation of AFW. The resultant characterisation of barriers to adopting efficient conversion technologies for AFW exploitation also aligns with growing country-level assessments of AFW bioenergy potentials and the next generation of clean energy policy priorities. • Complete agri-food waste (AFW) valorisation requires innovative approaches. • Standalone conversion technologies by-products have up to 50% residual energy. • Integrated conversion technologies enhance energy yield & conversion efficiencies. • HTC-AD integrations are most favourable for AFW; up to 91% efficiency is feasible. • Optimisation studies are critical to facilitate ICTs scale-up & commercialisation. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) provide an efficient way to utilize energy from biomass while it offer advantages such as pollution avoidance, high energy conversion efficiency, and flexibility for a wide range of applications. MFCs have gained much attention and are considered as current research hotspot in bioenergy. To further improve the reaction area, microbial compatibility, and to increase the power generation efficiency in the design and manufacturing of a small-scale MFC, the use of 3D printing technology and the employment of a high-efficiency mixing area are proposed in this work. Carbon cloth is employed as the electrode substrate of the MFC. Moreover, the carbon nanotubes and graphene dispersions are used to modify the carbon electrode plates. The results show that the graphene modified carbon cloth electrode MFC has a maximum power density of 199.24 mW m−2 at a current density of 1.52 A m−2. While the unmodified carbon cloth electrode MFC has a current density of 0.63 A m−2. This indicates that the graphene modified carbon cloth electrode MFC achieved a maximum power density of about 232% compared with the unmodified carbon cloth electrode MFC. The lowest internal resistance obtained was 0.66 kΩ when the electron transfer medium was accounted. This indicated a low anode impedance which is desired in MFC systems. Result revealed that the graphene modified carbon cloth electrode is the best electrode material based on the enhanced power density and lowered internal resistance. The results of the work aims to provide insight in the improvement of the MFC electrode modification technology. • The study aims to improve the power generation efficiency of MFCs. • Carbon cloth is employed as an electrode substrate. • A designed mixer is introduced to enhance the reaction rate in the MFCs. • Results have shown a maximum power density of 0.633 A m−2. • Carbon cloth and graphene are the best choices as plate materials. [ABSTRACT FROM AUTHOR]