Wheat Straw Pellets Research Articles

Thermal decomposition of wheat straw pellets in a nitrogen environment: Characterization Using Thermogravimetric Analyzer

This experiment used a thermogravimetric (TG) analyzer within a nitrogen environment, investigating the thermal degradation patterns of wheat straw pellets (WSP) under temperatures ranging from 31 to 800°C and varying heating rates (5, 10, and 20 °C/min). Two pellet types were considered: T1 (100% wheat straw) and T2 (70% wheat straw, 10% sawdust, 10% bentonite clay, and 10% biochar). This study comprehensively analyzes WSP’s thermal degradation, emphasizing model selection, composition effects, heating rate, and temperature. Results highlighted higher volatile matter content and calorific value in WSP. Model-free methods were applied to analyze TG/DTG profiles, revealing three distinct zones in WSP thermal decomposition: drying, devolatilization, and carbonization. Devolatilization, especially its 1st and 2nd steps, was extensively examined, with a significant mass loss (approx. 65%) observed between 150 and 550°C. Higher heating rates induced a shift in thermogravimetric profiles to elevated temperatures. Maximum mass loss rates during devolatilization ranged from 4.41 to 16.28%/min for T1 and 4.0 to 15.9% for T2 pellets. Temperature significantly influenced mass loss and reaction rates, whereas heating rates had a negligible impact. Thermodynamic properties indicated equilibrium reactions during pyrolysis for both T1 and T2 pellets. Additionally, increasing heating rates correlated with an upward trend in the reactivity index. The findings contribute valuable knowledge for optimizing biomass utilization in combustion and pyrolysis processes.

Solid-to-gas phase transition kinetics of diverse potassium occurrence forms during biomass pellet combustion: Time-resolved detection and multi-step modeling

The solid-to-gas phase transition of potassium during biomass combustion significantly impacts ash-related issues in bioenergy systems, affecting operational efficiency and equipment longevity. However, the specific mechanisms and kinetics of this transition process remain inadequately understood. This work investigates the time-resolved transition of solid-phase potassium to the gas phase during the combustion of rice husk and wheat straw pellets, combining experimental measurements with theoretical modeling. Tunable diode laser absorption spectroscopy (TDLAS) was employed to measure atomic potassium concentrations 15 mm above burning pellets tray, where gas-phase equilibrium is approached. Key combustion characteristics including thermogravimetric profiles, spectral radiation, and temperature were simultaneously monitored. A novel multi-step model was developed to describe the transition of different forms of solid-phase potassium (organic, exchangeable, and inorganic) to the gas phase. This model integrates TDLAS measurements, observed combustion characteristics, and biomass physicochemical properties. Thermodynamic equilibrium calculations were used to estimate the atomic potassium fraction from total gaseous potassium. The results showed that the solid-to-gas phase transition of organic potassium synchronizes with volatiles release. In contrast, the maximum emission rates of inorganic and exchangeable potassium occurred at the onset of char combustion. The developed model agrees well with the online detection experiments and were further validated by offline ICP analysis of residual ash. While not directly simulating gas-solid interface reactions near the particle surface, this work lays groundwork for future multi-scale modeling of particle-laden flows and reactor-scale phenomena in biomass combustion systems.

Pyrolytic Pathway of Wheat Straw Pellet by the Thermogravimetric Analyzer

Pyrolytic Pathway of Wheat Straw Pellet by the Thermogravimetric Analyzer

Pyrolysis of wheat straw pellets in a pilot‐scale reactor: Effect of temperature and residence time

AbstractPyrolysis of two types of pellets (T1: 100% wheat straw, and T2: 70% wheat straw; 10% sawdust, 10% biochar, and 10% bentonite clay) was performed in a pilot‐scale reactor under a nitrogen environment at 20°C to 700°C. This was to investigate slow pyrolysis yields and gas composition as a function of temperature and residence time. The experimental data were obtained between 300°C and 600°C, with a residence time of 90 min, a nitrogen flow rate of 50 cm3/min, and a heating rate of 20°C/min. The results indicated that the maximum pyrolysis temperature is 605°C with a residence time of 55 min. The product analysis showed that the proportion of gas was higher than that of biochar and bio‐oil. The conversion efficiency increased with higher temperatures and varied between 66% and 76%. The results showed that carbon dioxide was the main component in the produced gas, and the maximum gas concentration was 63.6% at 300°C for T1. The higher temperature and longer residence time increased the syngas (CO + H2) composition for both T1 and T2 treatments. Nevertheless, the produced biochar had a high carbon content and retained a high calorific value, indicating slow pyrolysis is the ideal utilization route of wheat straw pellet biomass for biochar.

Influence of natural organic matter on the aggregation dynamics of biochar colloids derived from various feedstocks

Abundant biochar colloids (BCs) produced from a wide range of feedstocks, resulting from forest fires, agricultural production, and environmental restoration, exhibit varying aggregation behaviors influenced by feedstock type and natural organic matter. However, the impact of natural organic matter on the colloidal stability of BCs derived from different feedstocks remains poorly understood. In this study, six selected biochars were derived from various feedstocks as follows: sewage sludge (SS), rice husk (RH), oil seed rape straw pellets (OSR), wheat straw pellets (WS), miscanthus straw pellets (MS) and softwood pellets (SW). The colloidal stability of BCs, with the exogenous addition of organic matter, was further determined. The order of critical coagulation concentrations (CCCs) of BCs with the presence of humic acid (HA) was as follows: RH (989.48 mM) < MS (1084.69 mM) < SS (1149.76 mM) < WS (1338.99 mM) < OSR (2402.98 mM) < SW (3151.32 mM). This order was significantly positively correlated with the specific surface area and negatively correlated with the ash content of the bulk biochar. Compared to HA, bovine serum albumin (BSA) more effectively inhibited the aggregation behavior of BCs due to steric hindrance. The initial aggregation rate constant (k) of BCs at 3000 mM NaCl was as follows: MS (0.238 nm/s) > OSR (0.142 nm/s) > WS (0.128 nm/s) > SS (0.126 nm/s) > RH (0.118 nm/s) > SW (0.112 nm/s). The stabilizing effects of BSA on biochar colloids were independent of the physicochemical properties of bulk biochar. In the presence of BSA, a thin layer of protein corona significantly enhanced the stability of biochar colloids, particularly the BCs derived from MS. Our results underscore the importance of considering feedstock resources and natural organic matter type when assessing the aggregation and potential risks of BCs in aquatic systems.

Comparative study of the thermo‐catalytic reforming of agricultural and forest residue and advanced characterization of final products in a cold climate

AbstractGlobal agricultural and forest residues hold promise for renewable fuel production through thermo‐catalytic reforming (TCR). Limited data exists on TCR outcomes for regions known for cold conditions like Canada. This study used a 2 kg h−1 TCR unit for the intermediate pyrolysis/reforming of agricultural (wheat straw pellet, WSP) and forest (softwood pellet, SWP) residues. Maximum bio‐oil yields were 8.43% for wheat straw pellets and 7.99% for softwood pellets at 400 and 500°C reactor and reformer temperatures. Feedstock, bio‐oil, and biochar properties were analyzed through proximate and ultimate analysis. At 550°C reactor and 700°C reforming temperatures, 70.73% of the wheat straw pellet‐based gas yield contained 36.11 vol.% H2 and 11.08 vol.% CH4, giving a higher heating value (HHV) of 12.54 MJ kg−1. A high concentration of CH4 (22.02 vol.%) in the softwood pellet‐based gas gave an HHV of 17.94 MJ kg−1. The low viscosity (3.9 mPa · s−1) and total acid number (7.3 mg KOH g−1) wheat straw pellet‐based bio‐oil had an O/C molar ratio of 0.09 and an HHV of 35.80 MJ kg−1. The 400/600°C reactor/reformer temperatures gave the lowest area percentage of mono‐aromatic (16 vol.%) and polycyclic aromatic (11.20 vol.%) compounds in the softwood pellet bio‐oil. The O/C molar ratio (0.5–0.6) in softwood pellet biochar elevated the higher heating value from 32.37 to 34.57 MJ kg−1. The study results guide optimal TCR unit operation in cold climates like Canada with local feedstocks, emphasizing its notable hydrogen production over bio‐oil and biochar.

Effect of Biomass Torrefaction on the Syngas Quality Produced by Chemical Looping Gasification at 20 kWth Scale.

The innovative Biomass Chemical Looping Gasification (BCLG) process uses two reactors (fuel and air reactors) to generate nitrogen-free syngas with low tar content under autothermal conditions. A solid oxygen carrier supplies the oxygen for partial oxidation of the fuel. This study investigated the BCLG process, conducted over 25 h of continuous operation at 20 kWth scale, using ilmenite as the oxygen carrier and wheat straw pellets as fuel (WSP). The effect of using torrefied wheat straw pellets (T-WSP) on the syngas quality was assessed. In addition, the impact of several operational variables on the overall process performance and syngas yield was analyzed. The primary factors influencing the syngas yield were the char conversion through gasification and the oxygen-to-fuel ratio. Higher temperatures, extended residence times of solids in the fuel reactor, and using a secondary gasifier led to increased char conversion, enhancing H2 and CO production. Optimizing the air reactor design could enhance the CO2 capture potential by inhibiting the combustion of bypassed char. While char conversion and syngas yield with T-WSP were lower than those with WSP at temperatures below 900 °C, T-WSP achieved a higher syngas yield under conditions favoring high char conversion. The presence of CH4 and light hydrocarbons showed minimal sensitivity to operating conditions variation, limiting the theoretical syngas yield. Overall, the CLG unit operated smoothly without any agglomeration issues.

Effects of pelletization on biomethane production from wheat straw

ABSTRACT The high lignin content and low bulk density of wheat straw pose challenges for biogas production. To overcome these hurdles, pretreatment and biomass pelletization have emerged as viable options. Thus, this research aims to reduce the recalcitrant nature of WS by employing various thermal pretreatment techniques and identifying the optimum parameters (temperature and time). To prepare pellets, a mixture comprising wheat straw (subjected to the best pretreatment) and cow manure pellets (WCP) at varying substrate and binder (Svs/Bvs) ratios ranging from 0.5 to 2.5 were used. Parameters such as density, water absorption, and drop shattering were evaluated to evaluate the physical characteristics of produced WCP. Additionally, the biomethane yield test of WCP (exhibiting the most favourable physical characteristics) was performed with various total solids (TS) concentrations from 4 to 12%. The WS demonstrated the highest sCOD solubilisation of 9066 mg/L when subjected to a hot air oven pretreatment (90 min at 110°C). The physical qualities of WCP were found to be dependent on the Svs/Bvs ratio (with the optimal ratio being 2.0). It was also observed that a TS content of 6% yielded the highest biomethane production (253.85 mL/g-VSconsumed). In summary, this study’s conclusion waves the path of management of wheat straw and cow dung while simultaneously generating bioenergy.

CFDs Modeling and Simulation of Wheat Straw Pellet Combustion in a 10 kW Fixed-Bed Downdraft Reactor

This research paper presents a comprehensive study on the combustion of wheat straw pellets in a 10 kW fixed-bed reactor through a Computational Fluid Dynamics (CFDs) simulation and experimental validation. The developed 2D CFDs model in ANSYS meshing simulates the combustion process in ANSYS Fluent software 2021 R2. The investigation evaluates key parameters such as equivalence ratio, heating value, and temperature distribution within the reactor to enhance gas production efficiency. The simulated results, including combustion temperature and produced gases (CO2, CO, CH4), demonstrate a significant agreement with experimental combustion data. The impact of the equivalence ratio on the conversion efficiency and lower heating value (LHV) is systematically explored, revealing that an equivalence ratio of 0.35 is optimal for maximum gas production efficiency. The resulting producer gas composition at this optimum condition includes CO (~27.67%), CH4 (~3.29%), CO2 (~11.09%), H2 (~11.09%), and N2 (~51%). The findings contribute valuable insights into improving the efficiency of fixed-bed reactors, offering essential information on performance parameters for sustainable and optimized combustion.

Comparative removal of pharmaceuticals in aqueous phase by agricultural waste-based biochars.

The intensification of pharmaceutical use globally has led to an increase in the number of water bodies contaminated by drugs, and an effective strategy must be developed to address this issue. In this work, several biochars produced from Miscanthus straw pellets (MSP550, MSP700) and wheat straw pellets (WSP550, WSP700) at 550 and 700°C, respectively, were selected as adsorbents for removing various pharmaceuticals, such as pemetrexed (PEME), sulfaclozine (SCL), and terbutaline (TBL), from the aqueous phase. The biochar characterizations (physicochemical properties, textural properties, morphological structures, and zeta potentials) and adsorptive conditions (contact times, temperatures, and pH effect) were investigated. The infrared and Raman spectra of biochars before and after pharmaceutical adsorption, as well as quantum chemical computations, were carried out to explore the adsorption mechanisms. The results showed that the general adsorption abilities of biochars for pharmaceuticals were in the order of WSP700 > MSP700 > MSP550 > WSP550. Both the higher drug concentration and higher temperature improved biochar adsorption. By decreasing the pH, the adsorption amounts increased for PEME and SCL. However, TBL exhibited the best adsorption at pH7, whereas a weakening of affinity occurred at lower or higher pH values. Electrostatic interactions and hydrogen bonding were the main adsorptive mechanisms between all biochars and pharmaceuticals. π-π interactions played a role in the adsorption process of low-temperature-prepared biochars (MSP550 and WSP550). This work can provide new insights into the control of pharmaceuticals from water with low-cost adsorbents. PRACTITIONER POINTS: Use of biochars for pharmaceuticals removal from aqueous phase. Characterization of biochars : physical and chemical properties, textural and surface properties. Simulation calculation for characterization of pharmaceuticals. Kinetic studies of pharmaceuticals adsorption on biochars. DRIFTS and Raman analysis for the understanding of adsorption process.

4D structural changes and pore network model of biomass during pyrolysis

Biochar is an engineered carbon-rich substance used for soil improvement, environmental management, and other diverse applications. To date, the understanding of how biomass affects biochar microstructure has been limited due to the complexity of analysis involved in tracing the changes in the physical structure of biomass as it undergoes thermochemical conversion. In this study, we used synchrotron x-ray micro-tomography to visualize changes in the internal structure of biochar from diverse feedstock (miscanthus straw pellets, wheat straw pellets, oilseed rape straw pellets, and rice husk) during pyrolysis by collecting a sequence of 3D scans at 50 °C intervals during progressive heating from 50 °C to 800 °C. The results show a strong dependence of biochar porosity on feedstock as well as pyrolysis temperature, with observed porosity in the range of 7.41–60.56%. Our results show that the porosity, total surface area, pore volume, and equivalent diameter of the largest pore increases with increasing pyrolysis temperature up to about 550 °C. The most dramatic development of pore structure occurred in the temperature range of 350–450 °C. This understanding is pivotal for optimizing biochar’s properties for specific applications in soil improvement, environmental management, and beyond. By elucidating the nuanced variations in biochar’s physical characteristics across different production temperatures and feedstocks, this research advances the practical application of biochar, offering significant benefits in agricultural, environmental, and engineering contexts.

Use of coffee husks – comparison of pellet bedding quality, performance features, and some welfare indicators of broiler chickens

BackgroundThe study aimed to evaluate the influence of wheat straw and different coffee husk (CHs) levels in pellet bedding on its quality, broiler chickens’ performance, meat quality, and welfare indicators. In total, 200 Ross 308 chickens were divided into 4 groups: C – control with wheat straw pellet; CH10 – pellet with 10% CHs, CH25 – pellet with 25% CHs, and CH50 – pellet with 50% CHs. During 42 days of rearing, each bedding's physicochemical features were analyzed. The production results were controlled, and the footpad dermatitis, hock burns, and feather quality were assessed. From chosen birds, carcass composition was analyzed, as well as the qualitative features (color, water-holding capacity, drip loss) and breaking bone strength.ResultsThe bedding material and rearing days influenced the content of dry matter, crude fiber, nitrogen, phosphorus, potassium, NDF, ADF, and pH. The results were inconclusive. The increasing trends in nitrogen, phosphorus, and potassium content were noticed at the end of rearing. Strong coefficient determination in bedding features was found (0.580 – 0.986). The pellet with CHs had no adverse effect on the growth performance of broilers. In the CH50 group, a lower fat percentage was found. A beneficial effect on water-holding capacity was noticed in leg muscles from CH10 and pectoral muscles from CH25. A significant decrease was found in footpad dermatitis incidence in groups CH25 and CH50.ConclusionsIt can be concluded that CHs reuse in broilers as the pellet bedding material is possible due to the beneficial effect on some meat quality features and no adverse effect on the performance of broiler chickens. The positive impact on lower foot pad dermatitis incidence indicated the possibility of using CHs in pellet bedding.

Kinetic mechanism of wheat straw pellets combustion process with a thermogravimetric analyser

In this study, the combustion characteristics of two wheat straw pellets (WSP) (T1: 100% wheat straw and T5: 70% wheat straw; 10% sawdust, 10% biochar; 10% bentonite clay) were performed at a heating rate 20 °C/min under a temperature from 25 to 1200 °C in air atmosphere. A thermogravimetric analyser (TGA) was used to investigate the activation energy (Eα), pre-exponential factor (A), and thermodynamic parameters. The DTG/TG profile of WSP was evaluated by model-free and model-based methods and found the model-based method was suitable for WSP thermal characterisation. The result demonstrates that the thermal decomposition occurred in four stages, comprising four consecutive reaction steps. A→B→C→D→E→F. Further, the model-based techniques were best fitted with kinetic reaction models like Cn (nth-order reaction with auto-catalyst), Fn (reaction of nth order), F2 (second-order phase interfacial reaction) and D3 (diffusion control). The average Eα for Fn, Cn, D3 and F2 models were 164.723, 189.782, 273.88, and 45.0 kJ/mol, respectively, for the T1 pellets. Alternatively, for T5 pellets, the A was 1.17E+2, 1.76E+16, 5.5E+23, and 1.1E+3 (1/s) for F2, D3, Cn and Fn models. Overall, the thermodynamic properties showed that WSP thermokinetic reactions were complex and multi-point equilibrium, indicating a potentiality as a bioenergy feedstock.

Kinetics and modeling of Pb (II) adsorption in pellet biochar based on micro-computed tomography characterization

Biochar, a cost-effective adsorbent for the removal of heavy metals from aqueous solutions, has gained increasing attention. In this study, an advanced micro-computed tomography (micro-CT) system was used to investigate the adsorption kinetics by direct localization and visualization of Pb (II) on wheat straw pellet biochar. The normalized digital images indicating the dynamic changes of Pb (II) adsorption on biochar samples at different initial Pb (II) concentrations of 100, 200, 300, and 400 mg/L and adsorption times were obtained. It was found that image grayscale (GS) changes over adsorption time (t) followed the power function, GSe/GSt=2.45∗t-0.27. Based on this finding, modified pseudo-first-order (PFO) and pseudo-second-order (PSO) models incorporated with time-dependent kinetic constants kPFOt=KPFO∗GSe/GSt and kPSOt=KPSO∗GSe/GSt were proposed, resulting in a better interpretation of the adsorption mechanism. The micro-CT-guided novel approach demonstrated visual evidence-based superiority and should prove valuable to the existing body of research in related fields.

Technoeconomic and Environmental Assessment of Biomass Chemical Looping Gasification for Advanced Biofuel Production

Chemical looping gasification is a promising biomass conversion technology that could produce sustainable liquid transportation fuels on a large scale to reduce fossil fuel dependency. The current paper examines the technical, economic, and environmental performance of a biomass-to-liquid (BtL) process based on chemical looping gasification and Fischer-Tropsch synthesis. Two biomass feedstocks, i.e., pine forest residues and wheat straw, are selected for assessing the complete BtL production chain. The results of process simulations showed that both biomass types are suitable gasification feedstocks, with an overall energy efficiency of 53% and 52% for pine residues and wheat straw, respectively. The economic results show that the breakeven selling prices (BESP) are €816 and €781 per m3 for the pine forest residues and wheat straw pellets, respectively. However, if low-grade excess heat valorisation and CO2 credits are considered, the BESPs could meet or become lower than the target value of €700 per m3, making the BtL plant competitive with other biofuel plants. The CO2 avoidance cost is estimated at €74.4/tCO2 for pine residues and €61.3/tCO2 for wheat straw, when replacing fossil fuels. The results of the life cycle assessment study showed that the produced biofuels fulfil the requirements of the EU Renewable Energy Directive II, achieving the reduction in greenhouse gases emissions of up to 79% without carbon capture and storage (CCS) and up to 264% with CCS compared to fossil fuels.

Effect of different water contents in the substrate on cultivation of Pleurotus ostreatus Jacq. P. Kumm

ABSTRACT Pleurotus ostreatus is a widely cultivated and investigated mushroom for its economical and ecological values and medicinal properties. P. ostreatus can be cultivated on different lignocellulosic substrates (oak sawdust, wheat straw, corn cobs and many more). Optimal growth is influenced not only by the composition of the substrate but also by the amount of water in it. In our study, P. ostreatus was cultivated on wheat straw pellets with different water contents (60%, 65%, 70% and 75%). Mycelium growth, biological efficiency (BE), moisture of substrate, pH, enzymatic activities and relationships were the parameters that were evaluated. Based on the results, the optimum initial substrate water content for mycelial growth and BE of the substrate ranged between 65% and 75%. On the other hand, the highest enzymatic activities of hydrolytic and ligninolytic enzymes (Mn-dependent peroxidase, 1,4-β-glucosidase and cellobiohydrolase) were determined for substrates with 75% of water content.

Ozonation-pelleting of nitrogen-enriched wheat straw: Towards improved pellet properties, enhanced digestibility, and reduced methane emissions

The livestock industry needs to use crop straws that are highly digestible to improve feed productivity and reduce ruminal methane emissions. Hence, this study aimed to use the ozonation and pelleting processes to enhance the digestibility and reduce the ruminal methane emissions of wheat straw enriched with two nitrogen sources (i.e., urea and heat-processed broiler litter). Various analyses were conducted on the pellets, including digestibility indicators, mechanical properties, surface chemistry functionalization, chemical-spectral-structural features, and energy requirements. For comparison, loose forms of the samples were also analyzed. The nitrogen-enriched ozonated wheat straw pellets had 43.06 % lower lignin, 28.30 % higher gas production for 24 h, 12.28 % higher metabolizable energy, 13.78 % higher in vitro organic matter digestibility for 24 h, and 28.81 % higher short-chain fatty acid content than the nitrogen-enriched loose sample. The reduction of methane emissions by rumen microorganisms of nitrogen-enriched wheat straw by ozonation, pelleting, and ozonation-pelleting totaled 89.15 %, 23.35 %, and 66.98 %, respectively. The ozonation process resulted in a 64 % increase in the particle density, a 5.5-time increase in the tensile strength, and a 75 % increase in the crushing energy of nitrogen-enriched wheat straw. In addition, ozone treatment could also reduce the specific and thermal energy consumption required in the pelleting process by 15.10 % and 7.61 %, respectively.

Biochar Amendment Increases C and N Retention in the Soil–Plant Systems: Its Implications in Enhancing Plant Growth and Water-Use Efficiency Under Reduced Irrigation Regimes of Maize (Zea mays L.)

Biochar influences soil biophysicochemical processes and nutrient availability, yet the effects of different biochar and soil water dynamics on carbon (C) and nitrogen (N) retention in the soil–plant systems remain unknown. Maize plants were grown in split-root pots filled with clay loam soil amended with wheat straw pellet biochar (WSP) and softwood pellet biochar (SWP) at 2% (w/w) and were either irrigated daily to 90% of water-holding capacity (FI) or irrigated with 70% volume of water used for FI to the whole root-zone (DI) or alternately to half root-zone (PRD) from the fourth leaf to grain-filling stage. Compared to the unamended controls, biochar amendment enhanced plant biomass and water-use efficiency, particularly when combined with PRD. Although the WSP amendment tended to decrease soil net N mineralization rate, it significantly increased C and N retention in the soil–plant systems. Compared to DI, PRD significantly increased soil respiration rate while lowering soil total organic C content. Moreover, PRD increased soil inorganic N content, which might be related to increased mineralization of soil organic C (SOC) and soil organic N (SON). Such effects might implicate that PRD outperformed DI in enhancing the mineralization of soil organic matter. Although PRD alone might not be a sustainable irrigation method because of greater C and N losses, biochar addition could alleviate these undesirable effects via depressing SOC and SON mineralization. Biochar amendment, especially WSP combined with PRD, could be a promising practice to increase maize growth and water-use efficiency while sustaining C and N retention in the soil–plant systems.

Effect of biochar addition and reduced irrigation regimes on growth, physiology and water use efficiency of cotton plants under salt stress

To alleviate the salinity and drought stresses faced in agricultural production, and to improve crop water use efficiency (WUE) in drought-prone regions, novel management strategies are needed. The combination of biochar amendment and reduced irrigation regimes could mitigate the negative effects of salinity and drought stresses and improve WUE of cotton plants. A split-root pot trial was performed in order to investigate the effects of two biochar amendments [wheat straw pellets biochar (WSP) and soft wood pellets biochar (SWP)] combined with three irrigation schemes [full irrigation (FI), deficit irrigation (DI), and partial root-zone drying irrigation (PRD)] on the growth, physiology and WUE of cotton plants under two salinity levels [0 mM NaCl (S0) and 200 mM NaCl (S1)]. The results showed that salt stress depressed plant growth and physiology, and reduced seed cotton yield and lint yield by 19.33–47.22% and 40.43–58.81%, respectively. However, the biochar amendment alleviated salt stress and increased plant dry biomass allocation ratio by 3.85%–12.54%, 5.07%–14.39% and 9.78%–46.62% in boll, seed cotton and lint cotton under S1, respectively, and also increased lint ginning out turn (GOT), harvest index (HI), WUE at plant and yield level (WUEp and WUEy) by 0.21%–28.69%, 5.07%–14.39%, −0.30%–15.71% and 5.83%–32.44%, respectively. Moreover, WSP was superior to SWP in terms of improving plant growth and yield. PRD showed better growth and physiological effects than DI, especially WUEp and WUEy were 6.88%–13.73% and 9.16%–22.78% greater under PRD than under DI. The combined application of biochar and PRD counteracted the decrease in WUE caused by biochar application alone under S0. Collectively, WSP combined with PRD could be a promising strategy in sustainable cotton production under drought and salinity stress.

The Apeli: An Affordable, Low-Emission and Fuel-Flexible Tier 4 Advanced Biomass Cookstove

Based on the decision of representatives from the West African region and feedback from locals in Togo, an advanced continuous-feed, forced-draft, biomass cookstove named “Apeli” was developed. The stove was tested in modified ISO measurements based on the ISO 19867-1:2018 standard. This included a long shutdown operation using wood pellets and short shutdown operations using wood pellets, bamboo pellets, wheat straw pellets and palm kernel shells. Due to the fast shutdown capability, the short shutdown was chosen for more realistic results using this stove type. For cold start and long shutdown operation using wood pellets, the thermal efficiency is determined as 44.1% at a 1116 W power output by emitting 0.272 g CO and 17.2 mg PM 2.5 per MJd at high load. At low load, the efficiency is 38.0% at a 526 W power output by emitting 1.1 g CO and 45.1 mg PM 2.5 per MJd. Due to a misinterpretation of the standard, the burnout duration of the tests with long shutdown is approx. 1.5 min shorter than required. Using a worst-case approximation, values for a theoretical ISO-conforming measurement were calculated and rated according to the ISO 19867-3:2018 standard. The results showed that the Apeli would correspond to Tier 4 for efficiency and PM 2.5 as well as Tier 5 for CO in high-power operation using wood pellets. The use of alternative fuels is possible, but can lead to higher emissions compared to the use of wood pellets. With regard to possibly using the biochar produced in the process for soil application, it has been demonstrated that the PAH content ensures European BioChar-Agro-Organic limitations. The first results of a field test in Togo have shown that operating and feeding the stove by the target group is easy. The required permanent presence of the user during cooking with this stove seems to have a limited influence on acceptance, which seems to primarily depend on the age of the user. Moreover, it can be concluded that the Apeli has good potential to be mass-produced locally at low costs with a reliable supply of spare parts. This can contribute not only to improving clean cooking, but also to fighting air pollution and deforestation caused by solid fuel burning due to the reduced consumption of resources in the form of fuel, especially wood.