Highest Biochar Yield Research Articles

Assessment of biochar quality and agronomic efficiency produced from rice-husk and saw-dust at different temperature regimes

Declining soil fertility and the limited use of sustainable soil organic amendments has resulted in reduced crop productivity in Nepal. This study assessed biochar produced from rice husk and sawdust at three different pyrolysis temperatures (200°C, 400°C, and 600°C), characterized their properties and applied them as soil amendments to test their agronomic effect on kidney bean production. The highest biochar yields were achieved at lower pyrolysis temperatures (200°C) for both rice husk (40%) and sawdust (38.4%). Ash content was significantly higher in rice husk (33.6%) compared to sawdust biochar (5.8%) across all temperatures. Sawdust biochar had higher volatile matter (91%) than in rice husk biochar (61.5%). The fixed carbon content was greater at 200°C and 400°C for both rice husk and sawdust biochar. FT-IR result showed significant loss of aromatic groups with increasing temperature. Biochar from all three temperatures was then used in a pot experiment to grow kidney beans and assess their agronomic effects. Seven treatments were used: control (CK), rice husk biochar at 200°C (RH200), 400°C (RH400), and 600°C (RH600), sawdust at 200°C (SD200), 400°C (SD400), and 600°C (SD600) following a completely randomized design with 3 replications per treatment. Cattle manure was applied uniformly (25 t ha-1) across all treatments, including the control. Over 50 days, SD400 resulted in the tallest plants, SD600 produced the thickest stem and RH600 had the highest number of leaves. Biochar applications showed significantly higher fruit weight and counts, which was on average 24 % higher than the control, with no significant differences between rice husk and saw dust biochar at three different temperatures. The study suggests that high quality biochar can be produced from both rice husk and saw dust and its application boost legume yields, which is crucial for enhancing country’s nutritional and food security.

Hydrothermal Co-Liquefaction of Sugarcane Bagasse and Residual Cooking Soybean Oil for Bio-Crude Production

Hydrothermal co-liquefaction (co-HTL) is a process involving two sources of biomasses aiming at bio-crude production. Since there is a lack of studies performed with sugarcane bagasse and residual soybean oil, this study investigated different conditions for the co-HTL of these biomasses, with and without the presence of ethanol as a co-solvent to maximize the bio-crude yield. All co-HTL reactions were carried out in a 300 mL Parr® reactor at temperatures ranging from 200 to 300 °C. After the reaction, a vacuum filtration was performed to separate the bio-char, later washed with ethanol to extract heavy bio-crude, while the liquid-phase was mixed with dichloromethane to recover light bio-crude. Bio-crude yields of around 95 wt.% were obtained at 300 °C using ethanol and water as solvents. The highest bio-char yield (16.6 wt.%) was achieved when using only sugarcane bagasse as the substrate, without the presence of soybean oil. Bio-crude samples obtained at higher temperatures (280 °C and 300 °C) using ethanol as a hydrogen donor presented higher contents of both free fatty acids and fatty acid ethyl esters. This work presents a promising process to produce high-quality bio-crude using an abundant feedstock (sugarcane bagasse) in the presence of a lipid source which could cause environmental problems if poorly handled.

Prospective of biochar material production and process optimization using co-pyrolysis approach-A mini-review

This mini-review explores the perspective of biochar material production using the co-pyrolysis approach, which involves the thermal decomposition of biomass and other carbonaceous materials in the absence of oxygen at low temperatures (300-500°C). The study investigates the co-pyrolysis of biomass with different materials such as plastics, tires, municipal solid waste, and other organic waste to produce a high biochar yield. The review focuses on the benefits of co-pyrolysis, including higher yield and better quality of biochar, as well as reduced environmental impact by using different waste materials as feedstock. The review also highlights co-pyrolysis challenges, such as process optimization, feedstock preparation, and product characterization. The study concludes that co-pyrolysis of biomass with different materials can be a promising approach for producing high-quality biochar with multiple applications. However, more research is needed to optimize the co-pyrolysis process and evaluate the economic feasibility of biochar production using a computation approach.

Enhanced phosphorus and potassium recovery through co-pyrolysis of nutrient-rich biomass feedstocks for engineered biochar production

Engineered biochars were produced via slow pyrolysis at 600 °C for 1 h from selected carbon-rich (diyar wood, sawdust, cotton stalk, sunflower straw, and banana stem) and nutrient-rich (eggshell, chicken bone, chicken manure, and sewage sludge) biomass residues with enhanced P and K recovery. Separate pyrolysis of both category feedstocks and co-pyrolysis of selected carbon-rich and nutrient-rich feedstocks mixed at 3:1 ratio was conducted. Higher biochar yield (41 %) was achieved in the co-pyrolysis of sewage sludge and sunflower stalk compared to average (38.5 %) of their separate pyrolysis. Moreover, increased K recovery (5.3 % to 19.5 %) and increased P recovery (1.8 % to 25.5 %) was achieved in biochar through co-pyrolysis of nutrient-rich and selected carbon-rich feed stocks compared with their separate pyrolysis. The chicken bone and sewage sludge can be ideal feedstocks for enhanced P and K recovery through their co-pyrolysis with carbon rich biomass such as banana stem or sunflower stalk.

Co-pyrolysis of sewage sludge and sawdust: Synergistic effects of product yield and synthetic gas calorific value

Co-pyrolysis of sludge and sawdust, which are two renewable and abundant biomass resources, offers a promising environmental-friendly way to produce valuable energy products. In this study, the synergistic effect between sludge and sawdust was quantified by fixed bed reactor and thermogravimetric experiments. The product yield and product quality were also studied. The results showed that both temperature and sawdust addition significantly affected the distribution of co-pyrolysis products. Biochar yield decreased with increasing temperature, with the highest yield at 700 °C. With the addition of sawdust, the yield of biochar first increased and then decreased. The highest biochar yield was 58.1 wt% after adding 10 wt% sawdust. The yield of bio-oil initially decreases and then increases with temperature. With the addition of sawdust, the yield of bio-oil first decreased and then increased. The process condition of a temperature of 700 °C–800 °C and a sawdust addition ratio of less than 30 wt% is more favorable for the production of bio-oil. Increasing temperature and the addition of sawdust boosteded syngas production and calorific value. When the sawdust ratio was 10 wt%, it exhibited the most pronounced influence on gas yield and demonstrated less susceptibility to temperature variations. The most obvious increase in the calorific value of syngas was observed at 700 °C and 10 wt% sawdust ratio. Taking into account the product yield and product quality, the optimum conditions for co-pyrolysis were determined to be 750 °C and a sawdust ratio of 10 wt%.

Production of Biofuel by Catalytic and Non-Catalyst Pyrolysis of Plantain Stalk

The depletion of global fossil fuel reserves and environmental concerns associated with its production are driving the shift towards biomass as a renewable energy source, which can be converted into biofuels and biogas for diverse energy applications. Hence, we conducted pyrolysis experiments on plantain stalk samples to examine the impact of pyrolysis temperature and heating rate on product yields and their chemical compositions. Optimal conditions for maximum bio-oil yield (22%) were identified at a torrefaction pre-treatment temperature of 300℃. The highest biochar yield (16.88%) was achieved at 300℃, while the highest biogas yield (61.85%) was observed at 150℃. Detailed elemental, proximate, and ultimate analyses of the bio-oil were performed, and its chemical composition was analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). The chromatographic and spectroscopic studies confirmed that bio-oil derived from plantain stalk is a promising renewable fuel and chemical feedstock, indicating its potential in sustainable energy applications.

Minimizing the total petroleum hydrocarbon contaminants in biochar derived from agricultural byproducts

The use of agricultural byproducts as feedstocks for the synthesis of biochar might result in the release of total petroleum hydrocarbons (TPHs) because of the presence of various plastic residues, such as plastic film mulch, gloves, and poles. TPH has been considered a critical health concern for humans worldwide. The aim of the present study was to evaluate the effect of different pyrolysis temperatures and durations on reducing the TPH concentration while synthesizing biochar using agricultural byproducts as feedstock materials. Agricultural byproducts, comprising sawdust and plastic films, were pyrolyzed as feedstocks at temperatures of 400, 500, 600, and 700 °C for durations of 0.5, 1, 2 and 3 h, respectively. Pyrolyzing the feedstock at 500 °C for 1 h and at 600 °C for 0.5 h significantly reduced the TPH concentration in the biochar by 98 and 91 %, respectively, compared to that at 400 °C for 0.5 h. The highest biochar yield was obtained at the lowest pyrolysis temperature (400 °C) and the shortest pyrolysis duration (0.5 h), with a subsequent steady decrease as the temperature and duration increased. These findings underscore the importance of understanding pyrolysis conditions for producing low-cost but high-quality biochar with reduced TPH contaminants and increased biochar yield. This research offers valuable insights for developing sustainable strategies for minimizing the health risks of TPH and utilizing biochar for environmental benefits.

Influences of Mg-activation on sugarcane bagasse biochar characteristics and its PNP removing potentials from contaminated water

Biochar as a substitute eco-friendly and low-cost adsorbent is introduced for removing p-nitrophenol (PNP) one of the most important chemical contaminant that recognized as the main metabolite in many pesticides and an intermediate compound in many industries. Physicochemical characteristics of sugarcane bagasse biochar (SCBB) and its Mg-activation (ASCBB) generated at 500 °C for 30 min were investigate. Batch kinetic experiment was conducted (200 mg L−1 PNP) to evaluate sorption efficiency of both tested biochars. To study the reaction behavior of PNP adsorption on ASCBB, solution pH and isotherm experiment of different concentrations and dosages were as investigated. The results show that ASCBB had a higher biochar yield, ash content, pH, molar ratios (H/C and O/C), surface area, pore volume, mean pore diameter, and specific and thick wall structure than SCBB. The efficiency of ASCBB to remove PNP was higher than SCBB which reached 51.98% in the first 1 min., and pH 7 achieved the optimum adsorption. Pseudo-second-order model examination exhibited well fitted to explain the adsorption results depending on R2 value (1.00). The adsorption isotherm results were well described by the Elovich and Freundlich models depending on the R2, qm and n values, which means the formation of a multilayer of PNP on the ASCBB surface through the chemisorption reaction. The calculated qm (144.93 mg g−1) of 1g L−1 was relatively close with experimental value (142.03 mg g−1). The PNP adsorption mechanism on both biochar types was electrostatic attraction, hydrogen bonding, and π-π stacking interactions, which were confirmed by studying the surface reactions before and after adsorption. Overall, the current study provided a successful waste biomass-derived biochar as a conducive alternative eco-sorbent to eliminate p-nitrophenol from wastewater.

Optimization of biochar production from greywater grown polyculture microalgae using microwave pyrolysis

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.

Analysis of rice husk biochar characteristics under different pyrolysis temperature

Rice is the main food for Indonesian. In production, it produces rice husk in huge amounts as waste. Rice husks have tough fibers, so their natural decomposing takes a long time. One strategy to take advantage of and add value to rice husk waste is to convert it into biochar. Biochar is a material that produced by a pyrolysis process of organic material, which is beneficial for the soil. The quality of biochar is influenced by pyrolysis temperature. This research aimed to analyze the biochar characteristics under various pyrolysis temperatures. The results showed that increasing the pyrolysis temperature will increase the element concentration of SiO2 (ash fraction). On the other hand, increasing the pyrolysis temperature decreases the biochar yield, calorific value, carbon and hydrogen content, and K2O, CaO, P2O5, MnO, and TiO2 concentration. The dominant elemental content of biochar (ash fraction) is SiO2 with a concentration of 85.35–89.47%. Biochar yield was 37.4–68.18%. The carbon, hydrogen, and nitrogen content ranged from 31.77–38.11; 1.67–3.61; and 0.63–0.73%, respectively. The calorific value of the biochar ranged from 14.48 to 11.61 MJ/Kg. The highest biochar yield, with the highest carbon, hydrogen, and calorific value content, was obtained using the lowest pyrolysis temperature of 250 °C. Fourier transform infrared (FTIR) analysis showed that the functional groups in the biochars were O-H, C=O, and C-OH. Following the X-Ray diffraction (XRD) analysis result, the amorphous biochar of rice husk decreases with increasing pyrolysis temperature and vice versa. The rice husk biochar has excellent potential to produce silicate crystals.

Conversion of biomass to biochar using top‐lit updraft technology: a review

AbstractThe demand for biochar has increased over time due to its wide range of applications in various industries. Biochar, which is the solid product of the thermochemical conversion of biomass, has been synthesized using different reactor‐based technologies. One such technology is top‐lit updraft (TLUD) technology. This study is a review of published literature that discusses trends in the utilization of the TLUD technology, focusing on biochar production. This study also evaluated the principles of TLUD technology. The properties and applications of TLUD‐based biochar were also discussed. In comparison with other technologies, TLUD technology is characterized by higher thermal efficiency, simplicity of starting the fuel, low smoke emission, and high biochar yield. It was observed that the use of TLUD technology resulted in the production of high‐quality biochar with a variety of characteristics, which has been utilized as an adsorbent for wastewater treatment, in the agricultural sector to increase soil nutrients, and as a solid fuel. The concept of semi‐batch‐fed TLUD technology was also introduced in this study to enhance the efficiency and output of the batch‐fed TLUD configuration that has been in use. Some knowledge gaps in the study could be addressed by future studies on the use of this technology. © 2023 Society of Industrial Chemistry and John Wiley & Sons Ltd.

Value-added biochar production from microwave pyrolysis of peanut shell

Abstract In order to seek efficient resource utilization, the carbonization of agricultural and forestry wastes through microwave pyrolysis technology is an important research hotspot to develop value-added products. The main objective is to produce value-added biochar through microwave pyrolysis of peanut shell in this study. The product yields, functional groups, and biochar HHVs caused by pyrolysis temperature (400, 450, 500, 550, and 600 °C), microwave power (350, 450, 550, 650, and 750 W), and residence time (10, 20, 30, 40, and 50 min) were investigated, and the energy recovery efficiencies were evaluated. It was obtained that the biochar yield declined monotonously within the range of 45.3–86.0 wt% with the enhancement of pyrolysis temperature, microwave power, or residence time. The pyrolysis temperature of 400 °C, microwave power of 350 W, and residence time of 10 min generated the maximum biochar yield (86.0 wt%). The value-added biochar was obtained with high HHV (20.15–31.02 MJ/kg) and abundant oxygen-contained functional groups (C–O bonds and C=O bonds). The maximum energy recovery efficiency during the whole process reached 97.96%. The results indicated that the peanut shell could reach high biochar yield through microwave pyrolysis, and potentially be transformed into value-added products with high energy recovery efficiency.

Component Properties and Heavy Metal Accumulation Characteristics of Contaminated Rice Straw Biochar During Oxygen-controlled Pyrolysis

Pyrolysis is an important technology to achieve the harmlessness and recycling of contaminated biomass. In this study, the effects of oxygen-controlled atmosphere on the component properties and heavy metal accumulation characteristics of contaminated rice straw biochar were studied. The results showed that low-oxygen pyrolysis could effectively produce biochar using contaminated rice straw and improve the stability of heavy metals in biochar. Under the nitrogen atmosphere, the yield of rice straw biochar was 29.4%-34.9%. The aromatization index (SUVA254) of dissolved organic matter (DOM) increased first and then decreased with the increase in pyrolysis temperature, whereas the fluorescent components were mainly humic-like acid substances. Meanwhile, Ca mainly existed in the form of CaCO3 in biochar. Compared with the pure nitrogen condition, the biochar yield was reduced by 5.6%-13.5% and 14.9%-15.7% under the pyrolysis atmosphere containing 10% and 20% oxygen content, respectively. Ca existed in the form of CaO in biochar, which increased the pH value of the biochar by more than 0.5 units. The oxygen of the pyrolysis atmosphere accelerated the degradation of the lignin component, resulting in the gradual decrease in SUVA254 of DOM. With the increase in oxygen content in the pyrolysis atmosphere, humic-like acid substances in DOM were transformed into fulvic-like acid substances. Under the conditions of 400℃ and a 10% oxygen-containing atmosphere, the exchangeable fractions of Cu, Cd, Pb, Ni, and As in biochar were decreased by 5.2%, 3.7%, 1.7%, 0.8%, and 0.7%, respectively, indicating that heavy metals are transformed into more stable states. The results suggested that the higher biochar yield and heavy metal stability could be obtained by introducing a proper amount of nitrogen into the air (controlling the oxygen content of approximately 10%) for pyrolysis treatment of contaminated rice straw, providing an economic and feasible technology for the achievement of harmlessness and recovery of contaminated rice straw.

A novel method for preparation of graphene-containing biochar and application to supercapacitors

New carbon-based materials have drawn tremendous attention in several technological applications. Here, the synthesis of graphene-containing biochar was prepared through carbonation and activation processes, using pre-oxidized magnolia flowers. In particular, the activation method was conducted in copper foil under high pressure, which led to the high biochar yield and excellent electrical conductivity of biochar for graphene-containing hybrid. Furthermore, heteroatoms (including nitrogen and oxygen) were successfully doped into the biochar. As a result, the hybrid demonstrated excellent electrical properties, at high nitrogen (1.02 %) and oxygen levels (14.80 %). The as-prepared biochar was used to produce an all solid state symmetric superconductor with a capacitance of 261.8 F g-1 at a specific current of 0.5 A g-1 , and energy density of 6.9 Wh kg-1 at powder density of 20 kW kg-1 .The enhanced electrochemical performance was attributed to the positive effect of synergy between highly conductive graphene-containing biochar and heteroatoms doping

Energy recovery from sugarcane bagasse under varying microwave-assisted pyrolysis conditions

Waste management and utilization of waste is a major global issue. This study investigated the influential parameters on the energy recovery from the sugarcane bagasse breakdown under microwave pyrolysis conditions. The by-product yield is optimised from 45 different combinations of microwave power, reaction time and microwave susceptor. The surface methodology, energy efficiency and byproduct quality were studied. Low power, less microwave susceptor and longer residence time are the desirable conditions for high biochar yield due to the gradual thermal decomposition of the biomass and low heating rates. The highest bio-oil yield was obtained from higher microwave power and lower residence time. The excess pyrolysis temperature generated by the higher microwave power and higher microwave susceptor addition produces higher temperatures beyond the optimal condition for bio-oil production. This phenomenon is relative to the self-gasification of the biochar during the high pyrolysis power, contributing to the formation of H2, CO and CH4.

Valorization of Different Fractions from Butiá Pomace by Pyrolysis: H2 Generation and Use of the Biochars for CO2 Capture.

This work valorizes butiá pomace (Butia capitata) using pyrolysis to prepare CO2 adsorbents. Different fractions of the pomace, like fibers, endocarps, almonds, and deoiled almonds, were characterized and later pyrolyzed at 700 °C. Gas, bio-oil, and biochar fractions were collected and characterized. The results revealed that biochar, bio-oil, and gas yields depended on the type of pomace fraction (fibers, endocarps, almonds, and deoiled almonds). The higher biochar yield was obtained by endocarps (31.9%wt.). Furthermore, the gas fraction generated at 700 °C presented an H2 content higher than 80%vol regardless of the butiá fraction used as raw material. The biochars presented specific surface areas reaching 220.4 m2 g-1. Additionally, the endocarp-derived biochar presented a CO2 adsorption capacity of 66.43 mg g-1 at 25 °C and 1 bar, showing that this material could be an effective adsorbent to capture this greenhouse gas. Moreover, this capacity was maintained for 5 cycles. Biochars produced from butiá precursors without activation resulted in a higher surface area and better performance than some activated carbons reported in the literature. The results highlighted that pyrolysis could provide a green solution for butiá agro-industrial wastes, generating H2 and an adsorbent for CO2.

Towards local circular economy through Opuntia Ficus Indica cladodes conversion into renewable biofuels and biochars: Product distribution and kinetic modelling

Opuntia Ficus Indica (OFI) cladodes slow pyrolysis was conducted in a fixed-bed reactor at various temperature (500–600–700 °C) and residence time (30–60–120 min) with a constant heating rate (10 °C min−1). The highest biochar yield (40.08%) was obtained at 500°C and 30 min whereas more liquid (35.03%) and gaseous (31.08%) products were produced at 700 °C and 120 min. The produced biochar is an alkaline carbon rich with minerals and nutrient (N, P, K, Ca, Mg) that could be applied in agriculture to balance acidic soil. The obtained bio-oil and syngas could be used as green biofuels. The kinetic study using Vyazovkin and FWO indicates an activation energy (Eα) values of 36.05–224.41 and 47.87–242.36 kJ mol−1 respectively, with a good prediction (R2 ≥ 0.9). This integrated approach of local OFI biomass conversion into biofuels and bio-based materials is an opportunity for the implementation of a local circular economy in Tunisia.

An alternative fuel production from sawdust through batch-type pyrolysis reactor: Fuel properties and thermodynamic analysis

This paper deals with the experimental investigations and thermodynamic studies carried out for five distinct temperatures ranging from 300 to 500 ℃ with a heating rate of 10 ℃/min. This work aims to study the influence of pyrolysis temperature on product (biochar, bio-oil, syngas) yield, its physicochemical properties and energy yield. The experiments were conducted in a batch-type vacuum pyrolysis reactor with sawdust as a feedstock. Findings show that biochar yield declined with temperature rise, whereas bio-oil and syngas yield increased. A higher yield of bio-oil (40.67%) was obtained at 450 ℃; after that it was declined. However, a higher biochar yield (60.67%) was attained at 300 ℃. Syngas generated at 500 ℃ had a higher product yield (24%) and energy output (147.05 kJ). Although, total energy output was found to be higher at 500 ℃ (634.71 kJ). This research also included thermodynamic studies such as mass, energy, exergy analysis, and sustainability analysis and found good agreement between input and output parameters. The study's main conclusion is that higher pyrolysis temperatures (450–500 ℃) offer better results in terms of higher product and energy yield for sawdust feedstock.

PRODUCTION AND PHYSIO-CHEMICAL CHARACTERIZATION OF BIOCHAR OBTAINED FROM COFFEE PROCESSING WASTES AND CROP RESIDUES OF COFFEE PLANTATION

Biochar is a pyrogenous organic material obtained mostly from various plant based waste biomass through pyrolysis process. The production of biochar from various plant based waste biomass is a part of the modern agenda to recycle bio-wastes and its application in agriculture is reported to improve the soil health in several ways. The other potential benefit of biochar include pollution remediation due to its high cation exchange capacity and specific surface area. In the present study, production and physico-chemical characterization of biochars obtained from coffee processing waste biomass (cherry husk and parchment husk) and crop residues from coffee plantation (diseased uprooted coffee stem and pepper stem waste) were attempted following standard methodologies. The statistical analysis of the data on biochar yield and physico-chemical parameters (moisture, pH, fixed carbon level, ash and volatile matter) of the biochar produced in the present study indicated that among the four waste biomass studied, significantly (p=0.05) highest biochar yield (40.53%) and fixed carbon level (54.53%) were recorded in cherry husk waste biomass. While, biochar obtained from pepper stem waste showed significantly (p=0.05) highest pH level (10.85%) and lowest moisture level (3.59%). Significantly (p=0.05) highest volatile matter (66.3%) and ash (18.13%) contents were observed in the biochars obtained from pepper stem waste and cherry husk, respectively. These data indicated that biochar yield and physico-chemical parameters of the biochar primarily depends on the chemical nature of waste biomass or crop residues. Therefore, screening of biochar obtained from various waste biomass or crop residues is pre-requisite for assessing its agronomical and environmental potentials. The results of the present study has provided baseline information of biochars obtained from various coffee processing waste biomass as well as crop residues from coffee plantation.

Production and Characterization of Biochar from Almond Shells

Biomass from specialty crops, including almonds, walnuts, and numerous others, serves as an important resource for energy and materials as agricultural systems evolve towards greater sustainability and circularity in management and operations. Biochar was produced from almond shells in a laboratory furnace at temperatures between 300 and 750 °C for residence times of 30 and 90 min with moisture contents of 5% to 15% wet basis. Response surface methodology was used to optimize the biochar yield. Feedstock and product temperatures were continuously monitored throughout the experiments. In addition, larger batches of biochar were also produced in a fixed-bed pilot-scale pyrolyzer. The yield of biochar was determined as a weight fraction of the amount of oven-dry almond shells used in each experiment. Physical and chemical characteristics of biochars were evaluated. Pyrolysis temperature and time were found to be the significant parameters affecting the biochar yield, with second-order regression models derived to fit yield results. As anticipated, highest biochar yields (65%) were obtained at a pyrolysis temperature of 300 °C and a pyrolysis time of 30 min due to the limited volatilization at this short residence at low temperature affecting torrefaction of the feedstock. The average biochar yield from the fixed-bed pilot-scale experiments was 39.5% and more closely aligned with the fixed carbon from standard proximate analyses. Higher pyrolysis temperatures resulted in higher C:N ratio and pH with the highest C:N ratio of 19:1 and pH of 10.0 obtained at a pyrolysis temperature of 750 °C for 90 min. Particle density increased with the increase of pyrolysis temperature. Results of this study can aid in predicting biochar yields from almond shells under different pyrolysis conditions and determining the amount of biochar required for different applications.