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This study aimed to analyze a technology of hydrogen-rich gas from full-component oriented pyrolysis (FCOP) of biomass using energy, economic, and environmental life cycle assessment. Firstly, the study taked corn straw (CS) as the research object, the yield of hydrogen-rich gas and char produced by the oriented pyrolysis method are 78.26% and 20.35%, and the yield of biochar produced by activating char with phosphoric acid is 40%. Secondly, the system boundary of FCOP of biomass to produce hydrogen-rich gas and biochar was creatively designed, establishing the energy, environmental, and economic analysis comprehensive model. Various energy, economic, and environmental indicators were computed to facilitate process optimization for hydrogen-rich gas co-production biochar and explored the feasibility of the process. The results show that the stage of hydrogen-rich gas prepared by FCOP of biomass is an important factor affecting energy output and input, and has the highest standard pollutant emissions (92.11%). This process has low carbon emissions and GHG emissions, showing good sustainability and application prospects, which has important guiding significance for realizing cleaner production and solving the energy crisis. Thirdly, taking the large-scale system of producing hydrogen-rich gas co-production biochar, which processes 40,000 t of CS per year, as an example, the economic benefit analysis results were obtained, that is, IRR , NPV , and P m are 22%, 6.33 million yuan, and 7.3 years, respectively. Meanwhile, the key factors, including the initial investment, expenses of biomass and catalyst, and the sale income of hydrogen and biochar, which are the main factors affecting the economic efficiency of technology, and uncertainties were identified through sensitivity analysis. Finally, we put forward in the background of ecological civilization, the research focus and thinking for the development of hydrogen production technology from pyrolysis/gasification of biomass were proposed. The results obtained can be valuable in practical applications to enhance the sustainability and viability of hydrogen production in biomass conversion and utilization activities. The applied energy, economic, and environmental methodologies appear to be reliable and comprehensive tools for assessing the whole-life sustainability and viability of biofuel. [Display omitted] • Provides a detailed inventory for a hydrogen produced from pyrolysis of biomass. • An energy, environmental and economic model and indicators were established. • Anergy consumption, economic benefits and environmental emissions were studied. • Technology of hydrogen production has good feasibility and application prospects. • Enhance the sustainability and viability of hydrogen production from biomass. [ABSTRACT FROM AUTHOR]

[Display omitted] • Adding biomass and hydrothermal treatment (HTT) increased hydrochar heating value. • HTT of sludge alone had the lowest capital and operational expenditures. • HTT of sludge–cane bagasse led to the highest hydrochar energy recovery. • HTT of sludge–softwood sawdust led to the highest hydrochar revenue. • Saved sludge disposal cost was the most significant factor affecting the economics. Digested sludge is a waste stream from anaerobic digestion (AD) in wastewater treatment plants. Hydrothermal treatment (HTT) of sludge mixed with lignocellulosic biomass is an attractive approach to improve sludge dewaterability and generate value-added products. However, process economics has not been well understood. In this study, firstly, the effect of biomass type on the energy properties of hydrochars was studied. Secondly, two scenarios were simulated to evaluate the effects of biomass type on the economics (processing 50,000 tonnes of sludge per year) of HTT of digested sludge for solid fuel and soil amendment applications. The two HTT scenarios included sludge alone and sludge-biomass mixtures (four cases for four biomass feedstocks) at 180 °C for 60 min. In both scenarios, HTT liquids were returned to existing AD facilities for biomethane production to offset the energy cost of the HTT process. The results showed that the higher heating value significantly increased from 16.0–17.0 MJ kg−1 in the sludge alone case to 18.0–23.0 MJ kg−1 in sludge–biomass mixtures (except for rice husk). With the use of saved transport cost as a revenue source, HTT of sludge–biomass led to a net present value (NPV) range of AU$ 9.9–20.3 million (20 years) and an internal rate of return (IRR) range of 25.0 %–45.2 % for solid fuel application of resulting hydrochar compared to an NPV of AU$ 18.4 million and an IRR of 55.0 % from HTT of sludge alone scenario. HTT of sludge-biomass led to a NPV range of AU$ 4.5–14.5 million and an IRR range of 17.2 %–35.7 % for soil amendment application while the hydrochar from HTT of sludge alone was not recommended for soil application due to the high contents of heavy metals. This study provides useful and critical information for process scale-up and commercialization for integration into wastewater treatment plants. [ABSTRACT FROM AUTHOR]

Under the circumstances of serious environmental challenges and energy crises, it is of utmost importance to produce fuels and chemicals from renewable biomass and organic wastes. Biochar as a bioproduct from thermochemical conversion of biomass has attracted exponential research interest in recent years due to the abundance of its precursor (biomass resources) and its adaptability in different chemical reaction systems. Undoubtedly, it is essential to attain an in-depth understanding of the physiochemical properties and functionalization of biochar catalysts to further improve their catalytic activity, selectivity and stability in the reactions. However, until now, only a few reports are accessible on the use of biochar as a catalytic support material and/or a standalone catalyst in thermochemical biomass conversion to produce high-quality biofuels. Thus, the key objective of this review article is to summarize and discuss the latest progress in biochar production, modification, activation and functionalization by understanding its physical chemistry, composition and application in catalytic processes. This review article provides insights into the thermochemical and hydrothermal production of biochar as well as the engineering and process optimization aspects for value-added biofuel production and decarbonization. [Display omitted] • Effects of biomass composition and process conditions on biochar are reviewed. • Systematic discussion on biochar functionality as bio-based catalyst support is made. • Insights into the modification of biochar targeting optimal performance are shown. • Comparative analysis of biochar-based catalytic pyrolysis, gasification and liquefaction. • The significance of activation of biochar for enhanced functionality is justified. [ABSTRACT FROM AUTHOR]

This study aims to explore the effects of different Na-salt solutions on the behavior of biomass pyrolysis and gasification. The same molar number of Na was introduced via the impregnation method. The distinction was that pine wood impregnated with neutral NaCl and Na 2 SO 4 solutions was the Na in physical adsorption form, whereas the alkaline Na 2 CO 3 , CH 3 COONa, and NaOH solutions resulted in both carboxylate form and physical adsorption form. Thermogravimetric analysis results showed that impregnating alkaline Na solution was more potent than the neutral Na solution in reducing the thermal stability of pine wood structures. Results of pyrolysis and CO 2 -assisted gasification indicated that samples impregnated with the alkaline Na solutions obtained lower CO and higher CO 2 evolution than that from the neutral Na solution during pyrolysis. The Na in carboxylate form was more difficult to volatilize, and formed more Na-containing active catalytic structures, resulting in biochar that provided higher reactivity in gasification. However, different Na solutions on the biochar's gasification reactivity showed the order of NaCl-loaded sample < CH 3 COONa-loaded sample ∼ NaOH-loaded sample < Na 2 SO 4 -loaded sample < Na 2 CO 3 -loaded sample. This can be attributed to the combined effects of Na-containing active catalytic structures, along with the active surface salt complex formed by molten Na species and biochar. As for the overall energy efficiency of pine wood impregnated with different Na solutions, gasification of Na 2 CO 3 -loaded sample provided the highest maximum overall energy efficiency (49.2 %). The results presented here provide useful insights for practical application of using syngas for electricity generation. • Effect of different Na-salt solutions on the behavior of biomass pyrolysis and gasification. • TGA results showed more potency of alkaline Na in reducing thermal stability of pine wood structures. • Gasification reactivity in the order: NaCl < CH3COONa ∼ NaOH < Na2SO4 < Na2CO3-loaded sample. • Impregnating with alkaline Na solution showed lower CO and higher CO2 than neutral Na in pyrolysis. • Gasification of Na2CO3-loaded sample provided highest (49.2 %) overall energy efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni-Co/PWA was prepared, the tar yield was only 1.2 wt%, and the CH 4 carbon yield was 56.0 %. • DFT calculations show that the Co-Ni species reduce the adsorption energy of naphthalene. • The particle size was a main factor affecting the catalyst activity. • The reduction of C support would cause the deactivation of the catalyst. The metal-doped pine wood activated char (PWA) was used in the catalytic reforming of the pyrolysis vapor of pine sawdust in the H 2 atmosphere, to promote the removal of tar and methane-rich gas production. Ni-Co/PWA showed the best catalytic performance compared with Ni/PWA, Co/PWA, Fe/PWA, and Ni-Fe/PWA. The acquired tar yield was as low as 1.2 wt%, and the carbon yield of methane was 56.0 %. The characterization data of catalysts revealed that the NiCo active species in the catalyst was better dispersed and had a smaller particle size of 11.8 nm. Density functional theory (DFT) calculations showed that the introduction of Co reduced the adsorption energy of naphthalene on Ni/PWA catalysts. In addition, a synergistic effect of the H 2 atmosphere and the metal-doped PWA catalyst was observed by comparing the reaction products under H 2 and N 2 atmospheres. According to DFT calculations, H radical combines with naphthalene to release 104 kJ/mol of energy, promoting the decomposition of naphthalene. As a result, a high efficiency of Ni-Co/PWA in tar removal and methane generation was obtained. This study provides references for the efficient utilization of biomass energy. [ABSTRACT FROM AUTHOR]

• Microwave co-torrefaction (MCT) of Saccharum bagasse has high potential for producing high quality renewable biochar. • The HHV of biochar increased to 16–25 MJ/kg after MCT. • Satisfactory energy efficiency can be suitable for sustainable reuse. • An environmental perspective with 77% less CO 2 emissions than burning bituminous coal. An efficient technology for producing renewable energy is urgently being developed due to the limited non-renewable resources, while disposing of biowaste and achieving zero-waste generation. To achieve the goals, this work explored the yielding of biochar as renewable energy by simultaneously recycling Saccharum bagasse (SB) and waste cooking oil (WCO) via microwave co-torrefaction (MCT). Influencing factors, including different torrefaction temperature (200–300 °C), reaction time (10–30 min), and WCO blending ratios (0%–15%), were systematically assessed using the box-behnken design (BBD) method. Results showed that the reaction temperature had a dominant impact on the biochar of higher-heating-value (HHV), followed by the WCO blending ratio. The HHV of the optimal biochar (24.7 MJ/kg), produced through MCT of SB at 300 °C for 26 min and blended with 15% WCO, was only marginally higher by 0.9% than the second highest HHV of the B12 biochar (24.5 MJ/kg), produced through MCT of SB at 300 °C for 20 min and blended with 15% WCO. Therefore, the B12 biochar was selected as the best condition in terms of energy efficiency. The B12 biochar exhibited superior energy density of 1.5, energy yield of 98.0%, fixed carbon content (17.5%), and thermal stability compared with the raw SB. The O/C and H/C ratios of the B12 biofuel were proximate to those of lignite. In contrast to bituminous coal, a 76.7% lower greenhouse gas (GHG) emissions and a satisfactory energy return on investment (EROI = 6.3) were achieved for the B12 biochar. Overall, the MCT of SB and WCO has a high potential in practical application for producing biochar with high HHV and energy density, good thermal stability, superior EROI, and low GHG emissions for providing green and renewable energy. [ABSTRACT FROM AUTHOR]

The study explores the synthesis and utilization of biochar (BC) and multi-layer MXene to MXene/biochar (MB) composites for wastewater treatment. Simultaneously, it also investigates their energy generation potential through biomass and soil property assessments. The integrated column and batch treatments have shown significant results, elevating total dissolved solids from 63.7 to 125.5 mg L−1 with column treatment, while reducing them to 6.37 % and 1.35 % with BC and MB treatment, respectively. BC with high carbon content, demonstrated increased hydrophobicity, which was amplified by the integration of MXene, thereby enhancing its potential for advanced wastewater treatment. Treated wastewater exhibited elevated nutrient concentrations (Ca, Cu, Fe, K, Na, and NH 4 +), promoting the growth of Pennisetum purpureum. WW_B shows promising energy potential, with a higher heating value of 25.03 MJ kg−1 and a lower heating value of 23.57 MJ kg−1. They demonstrated high volatile matter exceeding 70.9 wt %, and a fixed carbon from 10.02 to 27.53 wt %, signifying their potential for efficient conversion and bio-oil yield during pyrolysis. The ultimate analysis emphasized significant carbon, with oxygen content ranging from 43.42 to 47.78 wt %., influencing combustion characteristics. MT_B exhibited its suitability for energy production through thermochemical conversion, underlined by its high flammability and low volatile ignition values. In the absence of BC, the E a ranged from 24.77 to 77.88 kJ mol−1 in wastewater and from 21.67 to 69.6 kJ mol−1 in MB treated wastewater. Meanwhile, when soil contained BC and was irrigated with wastewater, the E a varied from 24.66 to 80.91 kJ mol−1. In the case of MB treated wastewater, it ranged from 25.01 to 75.79 kJ mol−1. The research thereby affirms the potential of MB composites to advance water and energy sustainability setting us for broader nexus-based applications. [Display omitted] • Wastewater reclamation within the context of sustainable energy generation was studied. • Pennisetum purpureum exhibited promising bioenergy production potential using MT_B. • Crops, with WW_B having even higher VM, exhibited high VM exceeding 70.9 %. • WW_B's high HHV (25.03 MJ kg − 1 ) and LHV (23.57 MJ kg − 1 ) indicate promising energy potential for thermochemical conversion. [ABSTRACT FROM AUTHOR]

A novel magnetic carbon-based catalyst was prepared from solid waste (reed straw and electric furnace dust) by coprecipitation and high temperature pyrolysis with excellent application potential. Single factor and response surface experiments were used to optimize the catalyst preparation process (mass ratio of reed straw/electric furnace dust of 5:1 at 500 °C in 4 h) and biodiesel production, respectively, with results of 99.89 wt% biodiesel yield in the first cycle (93.61 wt% after 11 cycles) obtained at 74.15 °C in 4.16 h with a 14.06:1 M ratio of methanol/oil and 7.75 wt% catalyst. The life cycle assessment of magnetic carbon-based catalysts for biodiesel production suggested that the soybean oil extraction stage had the greatest impact on the environment, mainly from the use of soybeans and electricity. Solid waste as raw material to prepare catalysts for biomass energy conversion was proven to be a good strategy for energy conservation and emission reduction. This study provides guidance sustainable biomass energy conversion with low cost, low energy consumption, and minimal negative environmental impact. [Display omitted] [ABSTRACT FROM AUTHOR]

Co-feed pyrolysis is a thermochemical conversion process that entails the simultaneous or sequential decomposition of various feedstock in an oxygen-free environment, concurrently improving the quality of the end products. The technique is widely used to produce a range of valuable products, including biofuels, chemicals and biochar, capitalizing on the synergies between various feedstock. The current study focuses on the synergistic effects of co-feed pyrolysis of Erythrina indica (EI) and Azadirachta indica (AI) biomass at different co-feed ratios (EI:AI) of 1:4, 1:3, 1:2, 1:1, 2:1, 3:1 and 4:1 on weight basis. The reactions were carried out at a temperature of 600 °C under a pressure of 1 bar using nitrogen as inert atmosphere. The bio-oil yield produced through the co-feed pyrolysis reactions ranged from 29.51 to 32.40 % by weight, while the biochar and non-condensable gases yields ranged from 38.25 to 42.48 % and 26.90 to 30.73 % by weight, respectively. Positive synergistic effects of co-feed pyrolysis led to a notable enhancement in physicochemical properties of the fuel phase, especially by virtue of calorific value, density and presence of low mol. wt. components when compared to their individual counterparts. Specifically, the fuel phase obtained at 1:1 co-feed ratio exhibited the peak calorific value of 36.80 MJ/kg along with lowest density of 0.82 g/ml and pH of 3.58 which is the pinnacle accomplishment of this work; and comparable with commercial gasoline. Gas chromatography and mass spectroscopy of biofuels revealed alkanes, alkenes, alcohols, aromatics, esters, nitro compounds and organosilicons as their main compounds. Specific compounds, including cyclopentane, methyl-, 1-cyclohexyl-2-propen-1-ol and 1-pentene, 3-methyl, are the most significant compounds at co-feed ratio of 1:1. Biochar produced at co-feed ratio of 1:1 also depicted excellent physiochemical properties with the highest elemental carbon of 79.23 wt % and lowest oxygen and hydrogen contents of 18.49 wt % and 2.28 wt %, respectively with a maximum calorific value of 29.23 MJ/kg; which can be utilized as solid fuels. The biochar produced from the co-feed pyrolysis reactions also possesses highly porous structure which can be useful as a soil conditioner, carbon sequestration water filtration or wastewater treatment. Additionally, non-condensable gases composed of 7.45 vol % hydrogen, 34.26 vol % carbon monoxide, 21.32 vol % methane and 36.97 vol % carbon dioxide when co-feed ratio is 1:1. [Display omitted] • E. indica & A. indica co-feed pyrolysis at 1:4, 1:3, 1:2, 1:1, 2:1, 3:1 & 4:1 ratio. • Synergistic effect notably enhanced the physiochemical properties of py-products. • Peak HHV of 36.80 MJ/kg and least density of 0.82 g/ml achieved at 1:1 ratio. • Biochar at 1:1 yielded maximum C content of 79.23 wt% & HHV of 29.23 MJ/kg. • Py-gases at 1:1 ratio composes of 7.45 % H 2 , 34.26 % CO, 21.32 % CH 4 & 36.97 % CO 2. [ABSTRACT FROM AUTHOR]

• Innovative integration of slow and fast pyrolysis within drop-in biofuel production. • Biochar co-production leads to carbon sequestration and high GHG emission savings. • Tuning biomass flows, significant reductions of fossil-based inputs are achieved. • Improved scenarios at higher RES share to further reduce GHG emissions are proposed. • The proposed methodology establishes a foundation for innovative BECCS solutions. Biochar has an enormous potential to store carbon in the long-term. Differently than BioEnergy Carbon Capture and Storage (BECCS) technologies, biochar incorporates biogenic carbon in a solid form that offers multiple benefits as carbon sink, soil improver or for advanced materials production. The present study proposes an innovative approach, where carbon sequestration through biochar is obtained through the integration of slow pyrolysis with fast pyrolysis in decentralised biorefining systems, and then converted producing drop-in fuels from pyrolysis oil hydrotreating or gasification and Fischer-Tropsch (FT) synthesis. The scope is either to achieve negative GHG emissions assigned to advanced biofuels, or to export the generated carbon credit for the carbon markets (i.e. outside the biofuels carbon intensity). The innovative concept entails process integration and optimisation for the different stages of biomass drying, conversion and upgrading into biofuels in a way to reduce fossil-based inputs, applying a full value chain approach. Methodological choices for the assumptions on life cycle emissions calculation are discussed, evaluating the environmental performances by comparing the new concept to traditional biofuels value chains. Using a tailored lifecycle accounting methodology, this paper demonstrates that high GHG emissions savings can be achieved. The improved scenario shows how the carbon sequestration with biochar further reduces the carbon intensity up to –4.2 gCO 2 e MJ−1 for pyrolysis oil-based fuels, and to −20.2 gCO 2 e MJ−1 for FT-based fuels: this demonstrated that carbon negative sustainable biofuels can be obtained. The study demonstrates that an integrated biorefinery of 100 MW capacity can deliver additional 13.3 and 6.8 ktons of CO 2 e of GHG savings of per year, from drop-in fuels made of hydrotreated pyrolysis oil and FT synthesis, respectively. [ABSTRACT FROM AUTHOR]

A comprehensive comparison is conducted to explore the conversion performance of torrefaction and hydrothermal carbonization of high-moisture microalga for producing solid biofuel with low expense and environmental impact. The results suggest that when their solid yields are close, the hydrochar has higher HHV (higher heating value) (21.10–25.39 MJ kg−1) and energy yield (72.48–92.29%) than the biochar. The graphitization degrees of the biochar and hydrochar are 1.298–3.107 and 2.193–3.049, respectively. Considering fuel grade, the biochar is in biomass and peat zones, but the hydrochar is only in the biomass zone. The biochar's elemental valence transformation and graphitization degree are better than hydrochar's. The pyrolysis and combustion characteristics of the hydrochar are better than those of the biochar when considering the thermodegradation data, leading to a lower expense and environmental impact. The results are conducive to efficiently figuring out a solution with a comparative advantage for microalgal thermochemical conversion. The hydrothermal carbonization conditions at 160 °C for 2 h are the best operation for microalgal solid biofuel production. [Display omitted] [ABSTRACT FROM AUTHOR]

Solar energy and biomass produce energy, which is sustainable and does not harm our environment. This characteristic of the two-energy feedstock is harnessed using the pyrolysis method to produce liquid and gaseous fuel that is transportable while bio-char regarded as a by-product has found usefulness in soil amendments. Solar-biomass pyrolysis technology combines these two low-density energy feedstock to produce high energy density fuel. The effectiveness of this process depends not only on the feedstock or reaction dynamics but also on the solar-thermal systems and reactor configuration. This review addressed the benefits of solar-biomass pyrolysis, available optical concentrating device, conceptual heating modes, the existing configuration of solar-thermal and reactor orientations, and some basic model equations applied in solar biomass pyrolysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • The maximum biogas generation (54.33 %) was attained at 4 g/L magnetic bone biochar. • Volatile solids removal (89.02 %) was achieved at 4 g/L magnetic bone biochar. • Ruminofilibacter abundance was increased in all biochar treated reactors. • Methanosarcina was abundant archaea in magnetic biochar added digesters. This study showed the effects of prepared chicken bone-derived biochar (CB) and magnetic chicken bone-derived biochar (MCB) at various ratio (2–12 g/L) on anaerobic co-digestion (AcoD) of corn straw (CS) and cow dung (CD). The physiochemical characterization of CB, MCB, and lignocellulosic biomass (including CS and CD) was analyzed. Biogas production, kinetics, total solid (TS), volatile solid (VS) removal, and microbial communities were studied. Addition of 4 g/L MCB enhanced the biogas production by 54.33 % along with 75.82 % TS and 89.02 % VS removal. Ruminiclostridium was enhanced by 81.25 % in MCB 4 g/L treated reactor, which degrade cellulose and hemi-cellulose fibers. Methanosarcina involved in the biogas production through hydrogenotrophic and acetoclastic pathways was enriched by 43–61 % in the MCB treated reactors compared to control group. The improvement of biogas production from the lignocellulosic biomass can be improved by the addition of MCB due to facilitation of direct interspecies electron transfer among the microbes in anaerobic digestion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Efficient co-valorization of waste cooking oil into biofuel and carbon nanotubes. • Natural biochar shows excellent deoxygenation performance and good stability. • Correlation between AAEM in biochar and selectivity of A&E and HCs in bio-oil. • Potential for obtained biofuel to serve as a precursor for jet fuel. • Feasibility and profitability of integrated production process demonstrated. Valorizing renewable precursors into high-quality biofuel and functional carbon nanomaterials can considerably improve the economic viability. Here, we propose a process for integrated production of high-quality biofuel and carbon nanotubes from waste cooking oil via catalytic pyrolysis coupling with chemical vapor deposition (CVD) technology. The natural biochar catalyst demonstrates excellent deoxygenation performance and good stability in catalytic pyrolysis process. The alkali/alkaline earth metal species (AAEMs) content in biochar catalysts has a strong correlation with the selectivity of esters and hydrocarbons in bio-oil. The biofuel obtained under optimal conditions exhibited potential as a precursor for jet fuel. The CVD process convert pyrolysis gas into carbon nanotubes with yield of 2.13%. The technical–economic analysis demonstrated the feasibility of the integrated process, projecting profitability and substantial total profit over a ten-year period. Overall, this study improves the economic viability of the waste cooking oil pyrolysis process and supports its wider commercial application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Optimized biochar with an HHV and energy yield of 23.83 MJ kg−1 and 82.11 % • Optimization promoted biochar quality while reducing emissions and energy requirements. • Pequi seed biofuel: CO 2 reduction by 188.65 kg CO2 eq, replacing diesel fuel. • Circular economy frame shows the environmental benefits of pequi seed as biofuel. • Stoichiometry diagram of pequi seeds thermochemical conversion routes. Food loss and waste, about 30% of human-consumable food production, pose challenges to safety, the economy, and the environment. A significant portion includes discarded fruit parts, notably seeds. Pequi fruit seeds contribute to agro-industrial waste due to their intricate structure and thorns, raising environmental concerns. Prior research shows promise in utilizing pequi seeds (PS) for bioenergy through pyrolysis and gasification, but comprehensive torrefaction optimization investigation is lacking. Furthermore, PS contains 40–50% extractives, constituting a potential feedstock for biodiesel and enhanced biorefinery value. Despite literature on extractive valuation, studies often neglect residual biomass and biorefinery integration. This study fills the gap by evaluating the torrefaction of post-extraction residual biomass (PSW) and comparing it to PS. Using Response Surface Methodology (RSM), torrefaction conditions are optimized, evaluating Soxhlet extraction impact on raw (PS) and de-oiled pequi seeds (PSW) across scenarios: prioritizing biochar quality (S 1) and simultaneously evaluating biochar quality, energy requirements, and potential CO 2 retention (S 2). Biochar parameters include solid yield, bulk density, proximate, ultimate, and energetic properties. Torrefied pequi seeds show superior biofuel properties, with up to 21% HHV enhancement for PSW, including increased energy content and substantial CO 2 emission reductions compared to fossil fuels. RSM provides statistically significant models (reduced quadratic, reduced cubic, and reduced 2FI), with R2 > 0.9762 for the assessed biochar outcomes. The study identifies PS torrefaction at 274 °C and 42 min as optimum in S 1 , resulting in biochar (CH 1.30 O 0.33) with a 76.18% energy yield and HHV of 24.11 MJ kg−1. In S 2 , PS is also optimal, with ideal torrefaction at 265 °C and 31 min, providing biochar (CH 1.39 O 0.36) with an 82.11% energy yield, HHV of 23.83 MJ kg−1, and a 188.65 kg CO 2 eq (by substituting diesel as fuel). The results allowed the development of a pioneering stoichiometry diagram that provides a thorough understanding of the biofuels derived from pequi seed residues. This contribution significantly advances the insights of thermochemical conversion pathways, aimed at maximizing bioenergy yield and fostering environmental benefits within the context of a circular economy framework. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) is a process for enhancing energy content of biomass through deoxygenation reactions, effectiveness of which depends on composition of biomass. Thermal pretreatment could induce structural change of biomass and thus affects the chemical inertness/reactivity in HTC. This was investigated herein by HTC of the pine needles, thermally treated at 250 or 350 °C with/without presence of 11.5% O 2 , at 250 °C for 10 h. The results showed that pretreatment at 250 °C could increase overall yield of hydrochar in subsequent HTC, due to the enhanced aromatization and the resistance towards fragmentation in HTC. Nonetheless, the HTC worked on biochar formed at 250 °C, facilitating deoxygenation to remarkably decrease O/C ratio. In comparison, the pretreatment at 350 °C removed substantial amount of volatile fractions, significantly increasing chemical inertness of resulting char-350 during the followed HTC. Oxygen presence induced oxidation reactions in pretreatment, forming more bio-oil/gases and making resulting hydrochar more hydrophilic. Especially, oxidation at 250 °C formed more aliphatic structures that could be easier removed during followed HTC, enhancing thermal stability of resulting hydrochar. Although a portion of cellulose retained in the biochar obtained from pretreatment at 250 °C, the elimination of aliphatics suppressed formation of spheric structures of hydrochar, while retained original fibrous structures from pine needles. [Display omitted] • Pine needle pretreated at 250°C is more inert in HTC, generating more hydrochar. • HTC barely works the sample pretreated at 350°C, due to removing most of volatiles. • Pretreatment at 250°C retains cellulose crystals, which are removed at 350°C. • O2-pretreatment makes hydrochar thermally more stable via removing more aliphatics. • Pretreatment at even 250°C suppresses formation of hydrochar of spheric structures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Higher heating value of biochar was predicted using machine learning method. • Ultimate-XGBR model gave best prediction (R2 = 0.94, RMSE = 1.02). • SHAP and PDP were introduced for model interpretation. • Lig and HHV-R had strong positive correlations with HHV-BC. • An easy-to-use graphical user interface was developed for HHV-BC prediction. The higher heating value of biochar is an important parameter for the utilization of biomass energy. In this work, extreme gradient boosting regression and artificial neural network were used to predict it based on the characteristics of biomass and pyrolysis conditions. Besides, empirical correlations were developed for comparison. Results showed that the extreme gradient boosting regression models showed better performance (R2 = 0.83–0.94). The shapley additive explanations and partial dependence plot indicated that lignin content and higher heating value of raw material were highly positively correlated with higher heating value of biochar, and found the better conditions such as pyrolysis temperature (>550 °C), lignin content (>40 wt%) for high-higher heating value biochar preparation. What's more, a program that predicted higher heating value of biochar was developed through PySimpleGUI library. It offered a new optimization idea for the directional preparation process of biochar. [ABSTRACT FROM AUTHOR]

Interaction between AAEMs and added metals in biomass has been reflected in the form of "auxiliary agents", ignoring the influence of self-contained AAEMs and the migration and transformation of biomass on the added transition metals. The fast/slow pyrolysis experiments of biomass containing Ni and K were conducted in the fixed bed reactor, and the interaction mechanism between self-contained K and added Ni was simulated using DFT. The results show that Ni is mainly distributed on the surface of the solid carbon matrix through adsorption and aggregated into nickel crystal particles. K accumulates inside the carbon matrix as C–K or C–O–K. K enhances the catalytic activity of Ni by enhancing the binding ability of Ni and biochar (increased to 354.89 kJ/mol), electron inversion and deficient oxygen. This study provides new insights into the design of biomass catalysts and the utilization of biomass energy. [Display omitted] [ABSTRACT FROM AUTHOR]

Biomass to biochar through pyrolysis is promising for carbon-negative biomass energy. Potassium could enhance biochar formation whereas the difference among potassium agents has not been understood. Herein, 13 potassium agents were adopted, and the product compositions and carbon distributions of slow and intermediate pyrolysis were investigated. Results show that neutral agents have a weak influence on the products, while high-basicity agents enhance biochar formation, decrease organics yields, and promote H 2 generation (9–144 cm3/g) and phenols selectivity (64–79 area%). Especially, due to the anion properties, borate and phosphates deviate from the basicity tendency; acetate contributes to increasing acetic acid selectivity (up to 43 area%) while oxidizing agents promote CO 2 and H 2 O yields. Potassium performs obvious enhancement of biochar carbon sequestration, increasing by 2–49 % for intermediate pyrolysis and -8–51 % for slow pyrolysis with biochar carbon retention reaching 55 % and 77 %, respectively. Meanwhile, the thermally unstable phases of biochar were also generated. General correlation analysis indicates that CO yields and phenols selectivity highly relate to biochar carbon retention. This study sheds light on the key role of acid-base properties and anion properties, and provides insight into AAEM-catalytic biomass pyrolysis. [Display omitted] • Acid-base properties of additives have essential influence on pyrolysis products. • Anion properties such as cross-linking cause differences in specific products. • Slow pyrolysis benefits biochar carbon sequestration and phenols selectivity. • Promotion of cross-linking by potassium lowers biochar thermal stability. • Key roles of potassium in cross-linking and polycondensation are revealed. [ABSTRACT FROM AUTHOR]

Enormous annual sewage sludge (SS) volumes pose global environmental challenges owing to contamination and significant greenhouse gas emissions. Here, we investigated the economic viability of co-pyrolyzing SS and biomass waste to produce biofuels (bio-oil and gas) and biochar. Net present worth (NPW) analysis, the sale product break-even price, and sludge handling price (SHP) were used to determine the profitability of co-pyrolysis compared with SS pyrolysis alone and conventional treatment methods. In this study, the sale prices of biochar based on quality (i.e., stability, carbon sequestration effectiveness, and heavy metal content) were estimated to be 2.24, 1.44, and 0.98 CAD/kg for high-, medium-, and low-grade biochar. The bio-oil prices, estimated based on the higher heating values of bio-oil and diesel, ranged from 0.80 to 1.22 CAD/kg. Sawdust (SD) and wheat straw (WS) were the chosen co-pyrolysis feedstocks, with four mixing ratios (20, 40, 60, and 80 wt%). Economically, SD (40 wt% mixing ratio) co-pyrolysis achieved the best performance, with a maximum NPW of 8.71 million CAD. SD single and co-pyrolysis were the only profitable scenarios. Moreover, SS single pyrolysis and WS co-pyrolysis exhibited higher profitability than conventional SS treatment methods, with SHPs of 65 and 40 CAD/1000 kg dry sludge, respectively. Sensitivity analysis highlighted the dependence of economic performance on biochar and bio-oil market value. This study offers the first economic analysis of this approach and enhances our understanding of the potential of co-pyrolysis for biofuel and biochar production, providing innovative solutions for the environmental challenges of SS disposal. [Display omitted] • Cost, operating expenses, and energy recovery of a pyrolysis plant were evaluated. • Co-pyrolyzing SS with sawdust SS showed the highest NPW of 8.71 million CAD. • All single and co-pyrolysis cases showed higher revenue than SS disposal methods. • Economic feasibility was dependent on bio-oil and biochar quality and sales price. [ABSTRACT FROM AUTHOR]

• Biochar was prepared by pyrolyzing peanut shells in molten KCl and heat-treatment. • PS-800-1000 displays better oxygen reduction catalytic activity than other biochar. • PS-800-1000 has superior specific capacitance to all peanut shell-derived biochar. • PS-800-1000-based zinc-air battery displays outstanding performances. The use of activated biochar-based electrode derived from waste biomass in energy technologies, such as metal-air batteries and supercapacitors, is an important strategy for realizing energy and environmental sustainability in the future. Herein, peanut shells (waste biomass) were employed to prepare activated biochar materials by pyrolysis in molten KCl and heat-treatment. The effective dispersion and corrosion effects of molten salt for the pyrolysis products during pyrolysis obviously increase defects and specific surface area of the activated biochar materials. The prepared activated biochar material (PS-800-1000) by pyrolysis in molten KCl at 800 °C and heat-treatment at 1000 °C exhibits excellent catalytic activity with half-wave potential of 0.84 V vs. RHE, comparable to commercial Pt/C for oxygen reduction reaction (ORR) in 0.1 M KOH and outstanding supercapacitance performance in 6 M KOH with high specific capacitance (355 F g−1 at 0.5 A g−1), which exceeds all reported biochar derived from peanut shells. The PS-800-1000-based zinc-air battery (ZAB) displays higher peak power density (141 mW cm−2), specific capacity (767 mAh g Zn -1) and cycling stability than Pt/C-based ZAB. The activated biochar prepared by pyrolysis in molten KCl and heat-treatment method from peanut shells can be a promising candidate for replacing precious metals in energy conversion/storage devices. [ABSTRACT FROM AUTHOR]

A lab scale gasifier was built to perform the gasification experiment. The effects of temperature and steam flow on the process were investigated, and the effects of the addition of blast furnace gas ash (BFGA) on product composition, the value of H 2 /(CO + CO 2), the lower heating value (LHV) of product gas, and productivity are summarized. The experimental results clearly indicate that the addition of BFGA in the steam gasification of corn straw pellets effectively enhances the ability of the downdraft gasifier to produce hydrogen-rich gas. Compared with the non-catalytic gasification process, the addition of BFGA promotes the formation of H 2 , inhibits the generation of methane, CH 4 , and other hydrocarbon gases, C n H m , and increases the H 2 /(CO + CO 2) ratio. Unlike the process without the BFGA, the LHV of the product gas with BFGA increases with increasing temperature. When the water vapor volume was 0.75 kg/h, the gas production rate was the same at 850 °C with BFGA and at 950 °C without ash gas. The addition of BFGA clearly leads to a significant improvement in the ability of gasifiers to produce hydrogen-rich gas. • The blast furnace gas ash improves the capacity of gasifier. • The catalytic reforming of the char layer is intensified, and H 2 content is improved. • Temperature and S/B have a stronger influence on product gas characteristics. [ABSTRACT FROM AUTHOR]

New analytical laboratory tools for qualitative analysis of alternative and renewable solid biofuels have been developed. The primary target of this research was to develop and then validate a rapid method for semi-quantitative and qualitative analyses of the second-generation solid biofuels. X-ray fluorescence spectroscopy (XRF) was used in combination with a two-step, multivariate modelling procedure. First, soft independent modelling of class analogies (SIMCA) and classification and regression trees (C&RT) were applied to develop and validate the classifier, which enabled different biomass origins (agrarian biomass, forest biomass and furniture waste) and different possible sources of contamination (plastic, fossil fuels and lignin-cellulose after biomass acid hydrolysis) to be distinguished. Next, the model attempted to predict the concentration of individual components using partial least-squares regression (PLSR) models. In our study, we compared C&RT and SIMCA, and the classification models (algorithms) constructed by the C&RT method were characterised as having better properties than those based on SIMCA. The C&RT classification algorithm was able to predict the origin of biomass sources with a non-error rate greater than 95%. For predictions of the addition type, the non-error rate was greater than 91%. The developed methods can rapidly and adequately determine (qualitatively) the origin of biofuels and indicate possible sources of contamination. • XRF spectroscopy as tool to monitoring of the renewable solid biofuels origin. • C&RT classification model distinguishing between investigated chars type. • Quantitative PLS models for determination of the main additions concentration. • Developed method demonstrated suitable for routine use. [ABSTRACT FROM AUTHOR]

N 2 O emissions resulting from the application of nitrogen (N) fertilizers and vinasse represent the main sources of greenhouse gases (GHG) emissions in sugar-energy sector. Conversely, the application of biochar in soils has been worldwide recognized as an strategy to mitigate N 2 O emissions, although little is known about their effects on soils under energy cane production. The study aimed to evaluate the effects of biochar addition as a strategy to mitigate soil N 2 O emissions in soil under energy cane cultivation, as well as to quantify the abundance of N 2 O-producing and N 2 O-reducing microbial guilds. A greenhouse experiment was conducted in a completely randomized design, with five treatments and four replications. The treatments were: i) no N fertilization (control); ii) N fertilization; iii) N fertilization plus vinasse; iv) N fertilization plus biochar; v) N fertilization plus vinasse plus biochar. All treatments (except control) were balanced to receive the same amount of nutrients. Biochar was added at a rate of 5 g kg−1 of soil. Soil N 2 O emissions were quantified by static chambers for 78 days, and soil sampling were performed to determine chemical and microbiological attributes, including functional genes of the nitrogen cycle (AOA, AOB, nir K, nir S, nos ZI and nos ZII) by real-time PCR. Results indicated that vinasse addition increased N 2 O emissions. Conversely, the application of biochar reduced N 2 O emissions associated with the application of N fertilizer (56 %) and N fertilizer + vinasse (41 %). The high N 2 O emissions observed in vinasse treatment were directly correlated with nitrifier microorganisms (AOB and AOA), indicating that nitrification should be the main pathway of N 2 O emissions in this treatment. The production of energy cane biomass was similar between N fertilizer treatments. High N 2 O emission intensities (mg N 2 O g biomass−1) were obtained in treatments with vinasse application. This study concluded that biochar is an effficient strategy to mitigate N 2 O emissions, providing the first insights into how biochar affects the microbial community associated with N 2 O emissions from soil under energy cane cultivation. [Display omitted] • Organic residues are important drivers of N 2 O emissions in agricultural soils. • The application of vinasse increased N 2 O emissions by 86 %. • Highest N 2 O emissions correlated with nitrifier microorganisms (AOB, and AOA). • The addition of biochar reduced N 2 O emissions by rates ranging from 41 % to 54 %. • Energy cane biomass was not affected by N fertilization methods. [ABSTRACT FROM AUTHOR]

As the most promising anode material for ultra-high specific capacity lithium-ion batteries, Si has been hindered from widespread use by large volume effects and limited electrical conductivity during cycling. In this study, NiO nanoflowers were coated onto the exterior of Si NPs by hydrothermal method. Si@NiO was then mixed and annealed with natural biomass gel extracted from moldy wheat to produce Si@NiO@Biochar ternary composites, which were prepared. Si NPs are the source of high specific capacity of anode materials. The carbon layer minimizes the electrode bulk effect and enhances cycling stability, while the NiO flowers expand the lithium-ion transport channel and reduce Si NPs bulk effect. Furthermore, the N element from wheat protein in the carbon layer enhances the electrical conductivity of the material. After 100 cycles at 0.1 A g−1 and 1000 cycles at 1 A g−1, the capacity of the electrode rose to 952.12 mAh g−1 and 1098.05 mAh g−1, respectively. The Si@NiO@Biochar material showed remarkable electrochemical stability at various current densities and the thickness grew by just 27.97% after 500 cycles. It can also be utilized in lithium-sulfur batteries because of its microporous structure and capacity to transport sulfur. The reversible capacity was 388.21 mAh g−1 after 70 cycles at 1 C. Biomass carbon from biomass gels coated on Si@NiO reduces biomass energy waste. This research is a significant step for commercializing Si anode materials and providing an eco-friendly new method for storing energy. [Display omitted] • Nitrogen-doped biochar is made from the recycling of mouldy wheat. • The simple preparation process and excellent results. • The volume expansion of the silicon is well limited. • The composite has low internal resistance and high cycle life. • It can be used in two scenarios: lithium batteries and lithium- sulfur batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Greywater derived microalgae used to produce biochar via microwave pyrolysis. • Biochar has high heating value of 28.3 MJ/Kg, comparable to coal. • BET surface area and pore volume of biochar is 121.3 m2/g and 0.3 cc/g. • Fixed carbon and carbon content of biochar increased by 193.6% and 42.3%. • The biofuel production process had a net energy balance of + 11.32 MJ/Kg. Biochar was produced from polyculture microalgae cultivated in greywater using microwave pyrolysis. The highest biochar yield and fixed carbon content of 49.9% and 68.7% were obtained at microwave power (P) of 800 W and reaction time (T) of 8.6 min. The developed quadratic models, 166.96 – 0.23P – 3.87 T – 3.49 x10-3PT + 1.73 x10-4P2 + 0.13 T2 and – 73.79 + 0.29P + 1.86 T – 1.80 x10-4P2 could predict biochar yield and fixed carbon content respectively with errors of 6.2 and 7.9%. The volatile matter (VM), fixed carbon (FC), and high heating value (HHV) of the biomass were 69.2%. 23.4% and 17.6 MJ/Kg, respectively. VM, FC, and HHV for biochar obtained at optimum conditions were 20.2%, 68.7%, and 28.3 MJ/Kg, respectively. The process had a net positive energy balance of 11.32 MJ/Kg and energy efficiency of 1.76. This study paves the way for biochar production from greywater-grown microalgae, contributing to waste valorization and energy sustainability. [ABSTRACT FROM AUTHOR]

Grass silage and cattle slurry are the most abundant feedstocks for biogas in an Irish context. This work describes how to optimize their biomethane yield. Hydrolysis and biomethane yields from co-digestion of grass silage and slurry were enhanced in a biochar-supplemented two-stage digestion process. Biochar addition at the optimal dosage of 10 g/L in batch two-stage digesters led to the highest methane yield of 253 L per kilogram (kg) volatile solid (VS), which was 24% higher than that from two-stage digesters without biochar supplementation. For a batch single-stage digester, the biomethane yields were lower than the two-stage but 10 g/L biochar addition led to an increase to 218 L/kg VS as compared to 198 L/kg VS for the group without biochar supplementation. Volatile fatty acid accumulation increased with the enhancement of biomethane production in the biochar-supplemented two-stage reactors. The addition of biochar in single-stage and two-stage anaerobic digesters presented positive effects on the electrochemical properties of the digester contents, reflected by the increased charge storage capacity, reduced solution resistance and improved digester content conductivity. The methane yields in two-stage anaerobic digestion were shown to be strongly correlated (R2 = 0.92) with the concentration of extracellular polymeric substances. This evidenced that the interlaced conductive network established by extracellular polymeric substances and biochar was essential for direct interspecies electron transfer and biomethane production. This study demonstrated that biochar-supplemented two-stage anaerobic digestion is an optimal route for energy recovery from grass silage and cattle slurry. [Display omitted] • Co-digestion of on-farm feedstock was enhanced in a two-stage process with biochar. • Biochar at 10 g/L in two-stage digestion maximized CH 4 yield at 253 L/kg VS. • Biochar at 10 g/L in single-stage digestion achieved a CH 4 yield of 218 L/kg VS. • Biochar improved sludge conductivity to facilitate interspecies electron transfer. • CH 4 yield highly correlated with extracellular polymeric substances concentration. [ABSTRACT FROM AUTHOR]

Involving biomass in the energy sector is a way to replace fossil fuels with renewable and CO 2 -neutral raw materials, reducing the negative impact on the environment. The energy application of agro-industrial waste is of particular interest, allowing one not only to obtain biofuel, but also to utilize by-products. The present work considers pine nut shells from a candy factory in relation to microwave processing into solid and gaseous fuels. The aim is to study the features of pine nut shells microwave pyrolysis, including the initiation mechanism and process behaviour, as well as the composition and characteristics of the resulting products. The study included experimentation in combination with application of high-speed video recording of the process and gas analysis, study of dielectric characteristics of raw materials, proximate and ultimate analysis of the obtained solid and gaseous products. At microwave pyrolysis, the conversion degree into liquid and gaseous products (76.9%) is much higher than, for example, at slow fixed bed pyrolysis (65.5%). The radiation absorption by the sample is nonlinear throughout the process and increases during the organic part degradation with the appearance of liquid and gaseous products. The gas obtained at microwave processing has a low ballast (share of CO 2 =3.5%) and a high hydrogen content (share of H 2 =19.3%) that results in a high heat of combustion (21.8 MJ·m−3), which is probably connected with interaction of pyrogenetic water and fuel carbon during plasma-chemical reactions. • Microwave pyrolysis of pine nut shells is caused by electric discharges. • Microwave radiation absorption by pine nut by shells is nonlinear over process time. • Microwave radiation absorption grows with increasing the yield of volatile products. • Interaction of pyrogenetic water and carbonaceous residue leads to high H 2 content. • Pyrolysis gas has a high heat of combustion (21.8 MJ·m–3) and low CO 2 content (< 3.5%). [ABSTRACT FROM AUTHOR]

Fossil fuels-related environmental issues, such as global climate change and soil and water acidification, are driving countries to develop biomass energy sources. As a second-generation biofuel with a significant spatiotemporal availability for global consumption, Ganoderma lucidum (GL) calls for the characterization and multi-objective optimization of its pyrolytic performance and byproducts. The GL pyrolysis was divided into three stages, with the main stage occurring between 205 and 630 °C. The activation energy for the main stage was estimated at 221.23 kJ/mol and 222.83 kJ/mol according to the FWO and KAS methods, respectively. The primary volatile products of the GL pyrolysis between 200 and 600 °C included H 2 O, CH 4 , CO 2 , CO, C O, C-O(H), C C, and NH 3. The multi-objective optimization indicated that the GL pyrolysis between 650 and 750 oC jointly led to maximum energy yield and minimum gas emission. Biochar produced from GL (GLB) between 400 and 600 °C enhanced its aromaticity and stabilized the functional groups in the carbon structure. GLB obtained exhibited an increased number of porous structures and decreased aromaticity. These results provide a theoretical and practical basis for enhancing and volarizing the comprehensive circularity of GL biomass. [Display omitted] • The pyrolysis behavior of GL was characterized through thermogravimetric analysis. • The activation energy for the main stage was based on the FWO and KAS methods. • The gaseous products and emission patterns were identified and quantified. • The production and properties of GL-derived biochar were explored. • A multi-objective optimization of energy yield and gas emissions was employed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The multistage utilization of P-doped biochar from soybean straw is developed. • The maximum sulfadiazine adsorption amount of P-doped biochar is 252.24 mg·g−1. • The HHV of P-doped biochar is 24 MJ.kg -1, which can be a coal alternative. • P-doped biochar ash is rich in K and P for fertilization application. • The optimal choice of P-doped biochar acquires comprehensive analysis. Biochar is of great importance to realizing solid biowastes reduction and environmental remediation. Modifying biochar for better performance is also of great concern to achieve property improvement. P-doped biochar from soybean straw is prepared for multistage utilization to realize water pollutant removal and biofuel usage. The results suggest that the prepared biochar is adequate for sulfadiazine adsorption and has stable performance under coexisting ions and aquatic pH. Furthermore, the higher heating value of the biochar is close to coal and thus can be an alternative to fossil fuel. The maximum sulfadiazine adsorption amount of P-doped biochar is 252.24 mg·g-1, and the P-doped biochar HHV is 24 MJ·kg−1 which can be an alternative to coal. The greenhouse gas and pollutant emission potential are also considered to explore the environmental impact of P-doped biochar production and usage. Overall, the optimal ratio of soybean straw: K 3 PO 4 is 3:1. [ABSTRACT FROM AUTHOR]

• Effect of leakage of CO2 stored using negative emissions has been investigated. • The effect of leakage rate on the future atmospheric carbon stock has been shown. • Unless leakage is rapid it will not compromise the benefits of negative emissions. With present emissions the global CO 2 budget associated with a maximum temperature increase of about 1.5–2 °C will likely be spent within a few decades, Thus, it will be very difficult or perhaps even impossible to meet the climate targets agreed upon in Paris only by decreasing emissions of greenhouse gases. Scenarios presented in the IPCC reports accommodate for this by introducing so-called negative CO 2 emissions. The idea is that the cumulative CO 2 emission budget will be exceeded, but that massive negative emissions, especially during the latter part of the century, will remove the surplus of CO 2 in the atmosphere. A number of different Negative Emissions Technologies (NETs) have been proposed, including Biomass Energy with Carbon Capture and Storage (BECCS), afforestation/reforestation, altered agricultural practices, biochar production, enhanced weathering and direct air captured. However, many of the options proposed could be associated with carbon leakage which could compromise the purpose of negative emissions, e.g. storage in of carbon in growing/dead biomass that leaks to the atmosphere. Furthermore, it may be difficult to safely assess the long-term leakage rates. To reach the large negative emissions needed it is expected to require a mix of approaches having different expected retention times, and different safety in terms of leakage rates. Could the risk of leakage mean that we are just delaying the problem and transferring the problem to coming generations? The short answer to this is that it all depends on the leakage rates. Different leakage rates and mixes of leakage rates are investigated in the paper. For the case of a mixture of leakage time scales of 300, 1000 and 10,000 years and assuming that 80% or more was permanently stored, the contribution to the atmospheric stock was small, peaking at about 3 ppm CO 2. It was concluded that leakage would not significantly compromise the benefits of negative emissions unless leakage is substantial and rapid. To quantify what could be meant by substantial and rapid, an example would be if 100% of the CO 2 stored would leak out at a rate of the order of 1%/year. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Three types of biochar can efficiently activate hydrogen peroxide. • Biochar/H 2 O 2 systems exhibited high tetracycline degradation efficiency. • Catalytic property of biochar depends on the amounts of PFRs. • Biomass types and its compositions were crucial for the formation of PFRs. • Electron transfer pathways could be the catalytic mechanisms of biochar. Abstract Biochar, a green material that possesses high catalytic potential due to its persistent free radicals (PFRs), has attracted increasing attention in the removal of refractory pollutants from water. The influences of biomass types (bamboo, corn stalk, and pig manure) and its compositions (metals and phenolic compounds) on the formation of PFRs in biochar were investigated by electron paramagnetic resonance (EPR). It was found that the amounts of PFRs in biochar would decrease sharply with the decrease of the initial metals and phenolic compounds existed in biomass, and the effect of metals contents on PFRs formation was much greater than that of phenolic compounds contents. This finding was supported by the results obtained from elemental analysis and molar H/C analysis of three types of biochar, which suggested that pig-manure biochar (PM500) had the highest concentrations of PFRs of 14.13 × 1018 spins·g−1 due to the high content of metals and phenolic compounds in pig manure. The EPR trapping experiment and Linear sweep voltammetry (LSV) measurements in biochar/H 2 O 2 systems showed that OH was the dominant reactive radical and electrons transfer pathways might be responsible for the activation of H 2 O 2 by biochar. Possible degradation pathways of the tetracycline in biochar/H 2 O 2 systems were also proposed. Besides, high degradation efficiency and good stability were observed in real wastewater application of the PM500/H 2 O 2 system. These findings would provide a clearer insight into the formation mechanisms of PFRs in biochar, and also present a better strategy for biochar preparation and application in Fenton-like system. [ABSTRACT FROM AUTHOR]

Abstract Present work demonstrates the pyrolysis of sagwan sawdust for the production of bio-oil and biochar. Thermal degradation characteristics of sawdust by thermo-gravimetric analyzer revealed different zones of degradation. The effects of temperature, nitrogen flow rate and packed bed height were observed and optimized using response surface methodology with Box-Behnken design. For both cases, the quadratic model proved non-linear behaviour of the model response. Co-efficient of determination (R2) value for bio-oil and biochar yield was 0.9905 and 0.9975, respectively justifying excellent fitting of the model. Optimum yield (bio-oil and biochar) were obtained as 48.7083 and 25.5627 wt. %, respectively at the temperature of 640 °C, packed bed height of 8 cm and nitrogen flow rate of 180 mL/min. Presence of various organic compounds and chemicals were confirmed by GC-MS, FTIR analysis and physicochemical analysis described the fuel characteristics. Also, biochar was characterized by proximate and ultimate analysis, HHV, BET, FTIR and SEM-EDX. The above results revealed the utility of bio-oil as engine fuel or source of valuable chemicals. The HHV, porous nature of biochar along with high BET surface area and valuable nutrients indicates its utility as solid fuel, as an adsorbent or in soil amendment. Highlights • Optimization of pyrolysis process variables was done using response surface methodology (RSM). • Characterization for pyrolysis products was assessed by using advanced analytical techniques. • Bio-oil contained various chemicals and can be used as an alternative fuel after upgradation. • Biochar can be used as biocatalyst in process industry or may be as good adsorbent. [ABSTRACT FROM AUTHOR]

Abstract Non-edible Jatropha seed used for biodiesel production has increased due to its high-oil contents in kernel and potential to reduce greenhouse gas emission. High demand for biodiesel generates a large volume of waste. In this study, de-oiled Jatropha seed kernel was torrefied at 200 °C, 250 °C and 300 °C, holding time of 15, 30, 45 and 60 min and particle sizes of 0.5–1.0 and 1.0–2.0 mm to produce solid fuel. Torrefaction performance was highly affected by torrefaction temperature compared with holding time. The enhancement factor of HHV increased up to 1.243 after torrefaction at 300 °C and 60 min with particle size of 0.5–1.0 mm. The large particle size reduces the diffusion rate of torrefaction vapour through internal pores, thereby producing high solid yield and low enhancement in HHV. The analysis of torrefaction severity index shows that HHV increase is highly dependent on the weight loss, thereby directly decreasing the total energy in biochar. Scanning electron microscopy image clearly illustrated that the microparticles on the surface were destroyed to increase the porous structure of the biochar with increasing torrefaction temperature. Severe torrefaction with particle size of 0.5–1.0 mm was an effective approach to increase the energy content of biochar. Graphical abstract Highlights • De-oiled seed kernel was converted to biochar as solid fuel via torrefaction. • Particle size (0.5–1.0 mm) shows better torrefaction performance as solid fuel. • The HHV of torrefied biomass increase from 23.08 to 28.69 MJ/kg. • Energy yield of 97% was achieved with HHV enhancement of 19% at 250 °C. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Tobacco has high phytoextraction potential for moderate Cd-contaminated soils. • Various disposals of metal-enriched tobacco biomass are carried out. • Crude protein and nicotine could be separated and recovered. • Low-temperature biochar (300 °C) is a better choice to retain Cd and nutrients and recover them. • Extraction of K from stem biochar without excess metals can be obtained. Abstract Successful phytoextraction produces a large quantity of contaminated biomass, which will cause secondary pollution unless properly treated. This study investigated the disposal of contaminated tobacco biomass after phytoextraction. We detected significantly high Cadmium concentrations in tobacco, especially in their stems and leaves. From the latter, nearly all the Cd and nicotine were removed by extractions with 0.5% HCl + 70% ethanol, and the nicotine completely recovered via steam distillation, whereas the protein content remained unaffected in the leaves, thus making them safe for use as animal feed. The highest biochar yield was 47%, obtained after slow pyrolysis at 300 °C. In this case, the biochar contained the highest amount of nutrients and metals. From stem biochar, 87% of Cd and a large amount K along with several other elements were extracted by deionized water at pH 1. After acid-extraction, metals were formed precipitation and then separated from the K-enriched solution when the pH was adjusted to 11 by using drops of 40% KOH. Therefore, with improved technology to remove metals and recover nutrients and nicotine from biomass, tobacco is an ideal candidate as profit yielding crop for use in phytoextraction while also providing renewable resources. [ABSTRACT FROM AUTHOR]

Highlights • Economic feasibility of portable systems to utilize forest residues was investigated. • Forest residues were processed into raw and torrefied briquettes and biochar. • Minimum selling price (MSP) of biochar was estimated to $1044/ODMT. • MSP of raw and torrefied-briquettes were $162 and $274/ODMT respectively. • MSPs could be reduced by at least 50% with improved portable systems. Abstract Wildfires are getting extreme and more frequent because of increased fuel loads in the forest and extended dry conditions. Prevention of wildfire by fuel treatment methods will generate forest residues in large volumes, which in addition to available logging residues, can be used to produce biofuels and bioproducts. In this study, the techno-economic assessment of three portable systems to produce woodchips briquettes (WCB), torrefied-woodchips briquettes (TWCB) and biochar from forest residues were evaluated using pilot-scale experimental data. A discounted cash flow rate of return method was used to estimate minimum selling prices (MSPs) for each product, to conduct sensitivity analyses, and to identify potential cost-reduction strategies. Using a before-finance-and-tax 16.5% nominal required return on investment, and a mean transport distance of 200 km, the estimated delivered MSPs per oven-dry metric ton (ODMT) of WCB, TWCB, and biochar were $162, $274, and $1044 respectively. The capital investment (16–30%), labor cost (23–28%), and feedstock cost (10–13%) without stumpage cost were the major factors influencing the MSP of solid biofuels and biochar. However, the MSPs of WCB, TWCB, and biochar could be reduced to $65, $145, and $470/ODMT respectively with technologically improved portable systems. In addition, the MSPs of solid biofuels and biochar could be further reduced by renewable energy and carbon credits, if the greenhouse gas (GHG) reduction potentials are quantified and remunerated. In conclusion, portable systems could be economically feasible to use forest residues and make useful products at current market prices while simultaneously reducing potential wildfires and GHG emissions. [ABSTRACT FROM AUTHOR]

Abstract This work investigated the optimization of process parameters in the upgrading of the oil extracted from Scenedesmus obliquus microalgae using a novel nickel-impregnated biochar catalyst. The effects of temperature, dodecane-to-oil mass ratio and pressure on the upgraded liquid-phase biofuel yield were evaluated and optimized by central composite design of the response surface methodology (RSM). The model equation generated from RSM showed that dodecane-to-oil mass ratio and pressure, as well as the quadratic effects of all the three factors, were significant model terms in predicting the yield of upgraded liquid-phase biofuel. Maximum liquid biofuel yield was attained at 246.89 °C, 3.72 (w/w) dodecane-to-oil mass ratio, 3.84 MPa hydrogen pressure and 6 h processing time. Validation runs resulted in an upgraded biofuel yield of 69.4%, which was in close agreement with predicted values generated by RSM. The upgraded biofuel comprised of 100% green liquid hydrocarbons containing 94% alkanes and 6% alkenes. Its main fuel properties, such as heating value (43.78 MJ kg−1), elemental composition, density, and viscosity, exceeded those of the fatty acid methyl ester standard and were found comparable to those of petroleum diesel. More importantly, the results of the ultimate analysis and confirmed by the findings from Fourier transform infrared and gas chromatography – mass spectroscopy analyses, showed significantly low oxygen and nitrogen content and absence of sulfur in the upgraded biofuel. Graphical abstract Image Highlights • Novel catalyst was synthesized from rice hull biochar. • The catalyst was used to upgrade Scenedesmus obliquus oil to high-quality biofuel. • Response surface methodology was used to optimize biofuel yield. • High optimum biofuel yield at 69.4 wt. % was obtained. • The biofuel consisted of 100% green liquid hydrocarbons and HHV of 43.78 MJ kg−1. [ABSTRACT FROM AUTHOR]

Abstract The combination of pyrolysis and CO 2 gasification was studied to synergistically improve the syngas yield and biochar quality. The subsequent 60-min CO 2 gasification at 800 °C after pyrolysis increased the syngas yield from 23.4% to 40.7% while decreasing the yields of biochar and bio-oil from 27.3% to 17.1% and from 49.3% to 42.2%, respectively. The BET area of the biochar obtained by the subsequent 60-min CO 2 gasification at 800 °C was 384.5 m2/g, compared to 6.8 m2/g for the biochar obtained by the 60-min pyrolysis at 800 °C, and 1.4 m2/g for the raw biomass. The biochar obtained above 500 °C was virtually amorphous. Highlights • CO 2 gasification was used to improve the yield of syngas and the quality of biochar. • 60-min CO 2 gasification at 800 °C further increased syngas yield from 23.4% to 40.7%. • CO 2 gasification above 300 °C significantly increased biochar porosity and BET area. • The degree of biochar aromaticity increased with temperature. • Biochar obtained above 500 °C was virtually amorphous. [ABSTRACT FROM AUTHOR]

Abstract The study related to the effects of rice husk biochar (RHB) application on soil microbial aspects and paddy productivity in field condition is scare. Therefore, present study provides fresh insight into the effects of RHB on rice production in field conditions, with some updated information on soil microbial aspects. To study the impact of RHB and CSR-BIO (commercialized bio-formulation), on soil physico-chemical properties, soil microbial biomass (SMB) quantity and paddy productivity, four treatments were set up: control, RHB, CSR-BIO and RHB + CSR-BIO. The RHB with CSR-BIO both the amendments were applied at a rate of 10 t ha−1. Across treatments, the water holding capacity, total -C, -N, -P concentrations and soil moisture content were statistically higher in RHB and CSR-BIO treated soils over the control. The highest SMB-C, -N and -P (408.66 ± 0.57, 83.33 ± 2.08 and 25.66 ± 1.52 μg g−1 dry soil, respectively) was recorded in RHB + CSR-BIO treated soil. Across the sampling dates, SMB-C, -N, -P and inorganic-N (ammonium- and nitrate-N) concentrations were minimum on 35 day after transplantation (DAT) (tillering stage-active growth period), and maximum on 105 DAT (maturity stage). The paddy plant growth variables (panicle length, tiller number, rice grain and paddy straw yields) were found higher in treated plots compared to untreated (control) plots, and varied significantly (P ≤ 0.001) due to treatments. Among the various selected paddy agronomic variables, the application of RHB and CSR-BIO treatment was more pronounced to the yield of rice grains. Results indicate that an increase in the quantity of SMB due to RHB + CSR-BIO addition, improves the soil nutrient status and hence, paddy productivity in nutrient poor agriculture soils. It is suggested that RHB generation from rice husk biochar could be a sustainable crop residues waste management option to enhance the nutrient status, microbial biomass and paddy productivity of disturbed agriculture soils. Highlights • Impact of rice husk biochar (RHB) on soil microbial aspects and paddy productivity is described. • The RHB is a potential amendment for nutrient poor soils. • The RHB application significantly increases the soil total N, C and P. • Addition of RHB improves soil available inorganic-N nutrients to paddy crop. [ABSTRACT FROM AUTHOR]

Highlights • Uncertainty in market prices drives financial outcomes. • Monte Carlo simulation allows uncertainty to be quantified. • Biochar-only production offers a potentially profitable venture. • Biofuel-biochar coproduction requires RINs to achieve financial success. Abstract A comparative techno-economic analysis of two different thermochemical biomass conversion pathways was conducted to examine the effects of fuel price and other variables on project financial performance. Monte Carlo simulation was used to quantify the effects of uncertainty and volatility of ten critical variables: biofuel, biochar and feedstock prices, discount rate, capital investment, labor cost, loan terms, feedstock drying, and biofuel and biochar conversion rates. Market prices for biofuel and biochar have the largest impact on net present value (NPV) of any variable considered, due in part to the high levels of uncertainty associated with future prices of both. Across the ranges of input values for these variables in simulation analysis, hearth-based pyrolysis biochar production had the highest likelihood of profitability with a mean NPV of $41.5 million and only 20% of outcomes resulting in a net loss, while 68% of outcomes for auger-based biochar-biofuel coproduction represented a financial loss, including a mean NPV of -$24.2 million. However, when additional revenue from Renewable Identification Numbers (RINs) credits generated by biofuel production is considered, financial outcomes of biochar-biofuel coproduction improve to 50% likelihood of experiencing a net loss. Findings of the very strong impact of market prices on financial outcomes, relative to other important technical and economic variables, can inform effective targeting of future renewable energy policy, as well as the design of future techno-economic analyses, which do not currently focus on the effect of market prices on profitability. [ABSTRACT FROM AUTHOR]

Abstract Biomass derived biochar is a stable carbon-rich product with potential for soil amendment. Introduced into the natural environment, biochar will naturally experience 'ageing' processes that are liable to change its physicochemical properties and the mobility of sorbed pollutants over the longer term. To elucidate the reciprocal effects of biochar ageing and heavy metal adsorption on the affinity of biochar for organic pollutants, we systematically assessed the adsorption of diethyl phthalate (DEP), representative of phthalic acid esters (PAEs), to fresh and aged biochars with and without coexistence of Cd2+. Long-term oxidative ageing was simulated using 5% H 2 O 2 and applied to biochar samples made from corn cob, maize straw and wheat straw made by pyrolysis at both 450 °C and 650 °C. Our results showed that biochar made at lower temperature (450 °C) and from straw exhibited the higher adsorption capacity, owing to their greater polarity and abundance of O-containing functional groups. The adsorption of DEP onto fresh biochars was found to be driven by van der Waals force and H-bonding. Biochar made at the higher temperature (650 °C) displayed higher carbon stability than that produced at lower pyrolysis temperature. Oxidized biochar showed lower adsorption capacity than fresh biochar owing to the formation of three-dimensional water clusters on biochar surface, which blocked accessible sites and decreased the H-bonding effect between DEP and biochars. The coexistence of Cd2+ suppressed the sorption of DEP, via competition for the same electron-rich sites. This indicates that cation/π-π EDA interactions are the primary mechanism for PAE and Cd2+ stabilization on biochar. Our study sheds light on the mechanism of organic pollutant sorption by biochar, as well as the potential susceptibilities of this sorption to ageing effects in the natural environment. Graphical abstract Image 1 Highlights • The oxidative ageing and coexisting Cd2+ decreased adsorption capacity of DEP on biochars. • Lower temperature straw biochar has high adsorption capacity driven by van der Waals force and H-bonding. • Formation of three dimensional water clusters on oxidized biochar surface suppressed H-bonding adsorption of DEP. • Coexisting Cd2+ suppressed the adsorption of DEP via competition for the same electron-rich sites on biochar surfaces. • Cation/π -π EDA interactions between Cd2+, PAEs and biochars were the primary mechanism of DEP stabilization. Our results show that ageing increases the affinity of biochar for PAEs but decreases the differences between them. Sorption of PAEs will always be diminished by coexistence and sorption of heavy metals. [ABSTRACT FROM AUTHOR]

Currently, the information about the sorption of tetracycline (TC) on animal manure derived biochar was rare although plant residue derived biochar showed high sorption of TC). Therefore, this study explored the sorption of TC on swine manure derived biochar, and compared with rice straw derived biochar simultaneously. Also, H 3 PO 4 was adopted to modify both types of biochar. The sorption kinetic and isotherm data showed H 3 PO 4 modification enhanced the sorption of TC on both types of biochar (especially swine-manure-biochar), and indicated the chemisorptions including H-bonding and π-π electron donor acceptor interaction might be the primary mechanism. Moreover, the strengthened electrostatic attraction between TC and biochars might largely explain the enhanced sorption capacity of TC along with pH increasing from 5.0 to 9.0. At the same conditions, swine manure derived biochar demonstrated lower sorption capacity of TC than rice straw biochar, but still could be good material for the sorption of TC. [ABSTRACT FROM AUTHOR]

This overview addresses the formation of solid trash and the various forms of waste from a variety of industries, which environmentalists have embraced. The paper investigates the negative effects on the environment caused by unsustainable management of municipal solid trash as well as the opportunities presented by the formal system. This examination looks at the origins of solid waste as well as the typical treatment methods. Pyrolysis methods, feedstock pyrolysis, and lignocellulosic biomass pyrolysis were highlighted. Explain in detail the various thermochemical processes that take place during the pyrolysis of biomass. Due to its carbon content, low cost, accessibility, ubiquitousness, renewable nature, and environmental friendliness, biomass waste is a unique biochar precursor. This study looks at the different types of biomass waste that are available for treating wastewater. This study discussed a wide variety of reactors. Adsorption is the standard method that is used the most frequently to remove hazardous organic, dye, and inorganic pollutants from wastewater. These pollutants cause damage to the environment and water supplies, thus it is important to remove them. Adsorption is both simple and inexpensive to utilize. Temperature-dependent conversions explain the kinetic theories of biomaterial biochemical degradation. This article presents a review that explains how pyrolytic breakdown char materials can be used to reduce pollution and improve environmental management. [Display omitted] • Sources, synthesis and modification techniques of biochar are discussed. • Conversion of biomass into energy is more effective after being torrefied. • Appraisals on the activation energies during biochar preparation are made. • Torrefied biomass has environmental applications which are critically surveyed. [ABSTRACT FROM AUTHOR]

On-farm feedstocks such as grass silage and cattle slurry present recalcitrant characteristics that can limit microbial conversion in biofuel production. Introducing a biochar supplement in two-stage anaerobic digestion may facilitate feedstock hydrolysis and improve energy yields in biohydrogen and biomethane production. The biomethane potentials were first investigated in batch trials without biochar supplement; results indicated a biomethane yield of 230 L per kilogram (kg) volatile solid (VS) in single-stage digestion and 275 L/kg VS in two-stage digestion. In continuous trials, operated at an organic loading rate of 4.0 g VS/L/d, the second-stage digester in two-stage digestion showed a methane yield of 237 L/kg VS with 10 g/L biochar addition; this was 7% higher than the second-stage digester without biochar addition. At the same loading rate of 4.0 g VS/L/d, the biomethane yield in continuous single-stage digestion with 10 g/L biochar addition was 212 L/kg VS; this was 3% higher than the single-stage digester without biochar addition. Biochar was found to enhance the hydrolysis of recalcitrant solid components in the hydrogen-producing phase, promote biomethane production in methanogenesis, and stabilize the digestion process. The highest energy yield of 8.5 MJ hydrogen and methane per kg VS was achieved in the two-stage digestion with 10 g/L biochar addition at a loading rate of 4.0 g VS/L/d. The results demonstrated that the application of a biochar supplement could effectively enhance gaseous biofuel production in two-stage anaerobic digestion. [Display omitted] • Co-digestion of silage and cattle slurry was compared in single and two stage. • Biochar enhanced hydrolysis and acidification in continuous two-stage process. • 10 g/L biochar enhanced CH 4 production and stabilized continuous digestion process. • Two-stage digestion increased H 2 and CH 4 production as compared to single stage. • The highest energy yield was 8.5 MJ/kg VS at 4.0 g VS/L/d in second-stage digestion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oxidative torrefaction is more efficient for upgrading biochar. • The maximum relative mass loss of oxidatively torrefied biochar is much higher. • The relative elemental C content of oxidatively torrefied biochar is higher. • Increasing temperature gradually decreases biochar's carbide carbon proportion. • Strong linear distributions between TSI versus elemental C and O exhibit. This study performs the comparative advantage analysis of oxidative torrefaction of corn stalks to investigate the advantages of oxidative torrefaction for biochar fuel property upgrading. The obtained results indicate that oxidative torrefaction is more efficient in realizing mass loss and energy density improvement, as well as elemental carbon accumulation and surface functional groups removal, and thus leads to a better fuel property. The maximum values of relative mass loss, higher heating value, enhancement factor, and energy yield are 3.00, 1.10, 1.03, and 0.87, respectively. The relative elemental carbon, hydrogen, and oxygen content ranges are 1.30–3.10, 1.50–3.30, and 2.00–6.80, respectively. In addition, an excellent linear distribution is obtained between the comprehensive pyrolysis index and torrefaction severity index, with elemental carbon and oxygen component variation stemming from pyrolysis performance correlating to the elemental component and valance. [ABSTRACT FROM AUTHOR]

This work investigates the feasibility of extracting biofuels from general wastes, with significant non-recyclable and inorganic components, through the novel thermo-catalytic reforming (TCR®) technology. Two forms of general waste (Up-Sieve Material and Grey Compost) supplied by Risorse Ambiente Palermo (RAP) are studied. Each feedstock is shredded, pelletised and characterised. Analyses of the feedstock materials show the Up-Sieve Material has a higher heating value (HHV) of 17.6 MJ kg−1 with an ash content of 19.60% (by weight), while the Grey Compost has a HHV of 11.5 MJ kg−1 and an ash content of 40.16%. The results of the TCR® experiments on both feedstock materials show they can be thermochemically converted into energy carriers in significant quantities. The characterisation results of the oil and char from the Up-Sieve Material show they have HHVs of 38.2 MJ kg−1 and 13.6 MJ kg−1 respectively, while the oil and char from the Grey compost have HHVs of 37.0 MJ kg−1 and 5.7 MJ kg−1 respectively. In addition, the biogases produced from both feedstock materials are rich in hydrogen (up to 30% by volume each). Hence, apart from the chars and the reaction product water, the products can be further processed into biofuels due to their fuel-grade properties. Therefore, the successful extraction of biofuels from general waste is an important step in renewable energy harnessing, waste management and environmental protection. • Thermo-catalytic reforming involves intermediate pyrolysis and catalytic reforming • General waste converted to biofuels using this technology • Two types of general waste studied: up-sieve material and grey compost • Both produce biochars with high ash contents and biooils with high heating values • Both produce biogases with high hydrogen fractions, compared to gasification and pyrolysis [ABSTRACT FROM AUTHOR]

[Display omitted] • Operating temperature and time have significance on all considered responses based on ANOVA. • O 2 concentration only affects the higher heating value and high-temperature degradation. • Oxidative torrefaction of microalgae is recommended to be conducted at 200 °C, 10.6 min, and 12% O 2. • The energy yield obtained under this condition is 98.73%, with an enhancement factor of 1.08. • Oxidatively torrefied chars are more reactive under an air environment than their inert counterpart. Microalgae are currently not viable as solid biofuels owing to their poor raw fuel properties. Torrefaction under oxidative media offers a cost-effective and energy-efficient process to address these drawbacks. A design of experiment was conducted using central composite design with three factors: temperature (200, 250, and 300 °C), time (10, 35, and 60 min), and O 2 concentration (3, 12, and 21 vol%). The responses were solid yield, energy yield, higher heating value, and onset temperatures at 50% and 90% carbon conversion determined from thermogravimetric analysis. Temperature and time significantly affected all responses, while O 2 concentration only affected higher heating value, energy yield and thermodegradation temperature at 90% conversion. Oxidative torrefaction of microalgae is recommended to be conducted at 200 °C, 10.6 min, 12% O 2 where the energy yield and enhancement factor are 98.73% and 1.08, respectively. It is also more reactive under an air environment compared to inert torrefaction conditions. [ABSTRACT FROM AUTHOR]

Highlights • Blending bituminous coal showed a pronounced effect on biochar. • Quadratic model was recommended for the prediction of biochar yield. • Elemental distribution of biochar could be adjusted by co-pyrolysis under suitable induction conditions. • Response surface methodology was introduced to investigate the physicochemical properties of biochar. • Induction conditions contributed to the transformation of small aromatic ring of biochar to large aromatic ring. Abstract In this study, biochar was produced by co-pyrolysis of bio-oil distillation residue and bituminous coal under different induction temperature and gas flow rate in a tube furnace. Central composite design was introduced to explore the combined effects of experimental conditions on biochar. The physicochemical properties of biochar from different induction conditions were comprehensively evaluated by elemental analysis, Fourier transform infrared spectrometry (FTIR) and Raman spectroscopy based on response surface methodology. The results showed that bituminous coal was beneficial to the increase in biochar yield, whereas temperature had the opposite effect and the effect of gas flow rate was not obvious. Moreover, C/O ratio increased with the increase of pyrolysis temperature and bio-oil distillation residue in feedstocks, while C/H ratio increased only with increasing temperature. Gas flow rate had a more pronounced descent effect on C/H compared with C/O. In addition, induction conditions caused a relative weakening of C C stretching vibration and the relative enrichment of C H in biochar. Bituminous coal, temperature and gas flow rate all contributed to the conversion of small aromatic rings of biochar to large aromatic rings during the co-pyrolysis process. [ABSTRACT FROM AUTHOR]

The effect of three operating parameters (peak temperature, pressure, and pyrolysis atmosphere) during the slow pyrolysis of three biomass sources (corn stover, vine shoots, and two-phase olive mill waste) was extensively analyzed. A 2-level full factorial design of experiments was adopted to assess the effect of the above-mentioned factors on the potential stability of biochar as well as the yields of the main pyrolysis products. To evaluate the effect of the biomass feedstock, the design was divided into three blocks (one per biomass feedstock). Results from the statistical analyses indicated that the properties of biochar related to its potential stability were mainly affected by the peak temperature and, to a lesser extent, the biomass feedstock. A significant increase in the yield of produced gas was observed when pressure was raised. This increase in the total gas yield was in part due to a higher release of CO, CH 4 , and H 2 . Using a pyrolysis atmosphere of CO 2 (instead of N 2 ) did not result in any remarkable change in neither the distribution of the pyrolysis products nor the potential stability of biochar. However, when CO 2 was used as carrier gas, a significant increase in the yield of CO, at the expense of produced CO 2 , was observed. The findings reported herein suggest that processing biomass through pressurized slow pyrolysis under CO 2 atmosphere is interesting to simultaneously obtain two valuable products: a biochar with an appropriate carbon sequestration potential, and a produced gas with an appropriate composition for energy recovery purposes. [ABSTRACT FROM AUTHOR]

This study investigates the effect of feedstock drying on the emissions of polycyclic aromatic hydrocarbons (PAHs) associated with the particulate matter (PM) produced during the co-generation of biochar and bioenergy. Raw pyrolysis volatile mixtures were generated from the pyrolysis of rice husk at 400, 500, 600, 700, and 800 °C using a laboratory-scale continuous pyrolysis-combustion system and combusted at 850 °C. PM samples from the combustion were collected and analysed for 15 priority PAH species with a gas chromatography/mass spectrometer (GC/MS). It was found that the utilization of the as received (AR) rice husk resulted in significantly greater energy-based yields of PM 10 (1.2 times at 400 °C and 1.6 times at 800 °C) than the dried rice husk. The majority of the increase was of the PM 2.1-10 size fraction. The PM-bound PAH concentration was found to be 2.1 and 2.8 times higher for the AR rice husk at 400 and 800 °C, respectively. This resulted in a significant increase in the energy-based yield of PAHs over the entire volatile production temperature range for the AR rice husk. Nevertheless, the majority of the PM-bound PAH species generated from the AR rice husk consisted of 2 and 3 ring PAHs (naphthalene, acenapthylene, and acenaphthene) with relatively low toxicity. The concentration of 4, 5, and 6 ring PAHs was generally lower than that generated from the dried rice husk. This resulted in the benzo( a )pyrene-equivalent toxicity of the PM generated from the AR rice husk being lower than the dried counterpart. [ABSTRACT FROM AUTHOR]