Paradigm Shift in Bioenergy: Addressing the System of Biomass Wastage and Environmental Pollution with Biomaterial Valorisation into Biochar

Life cycle perspective of bio-oil and biochar production from hardwood biomass; what is the optimum mix and what to do with it?

The accumulation of municipal solid wastes (MSW) and the negative implications of using fossil fuels are some of the current environmental issues in the Philippines. Hence, this study aimed to utilize MSW by converting it into biochar through pyrolysis and maximize biochar production for energy application. The effects of pyrolysis parameters such as temperature and holding time on biochar yield were initially determined using 2k factorial experiment. Results showed that both factors had negative effects on biochar yield wherein temperature had a relatively higher impact. For the optimization study, Response Surface Methodology (RSM) was performed to determine the optimum pyrolysis conditions for maximum biochar production. The optimum conditions were found to be 300°C and 20 min holding time resulting to maximum biochar yield of 69.64 % by wt. Biochar characteristics were evaluated in terms of higher heating value (HHV), proximate and elemental analyses to determine its suitability as alternative fuel. The HHV of biochar obtained at optimum conditions was about 15.82 MJ/kg which is higher compared to that of the raw MSW (14.42 MJ/kg) and biochar obtained at extreme conditions (13.03 MJ/kg). Moreover, the energy recovery at optimum conditions based on biochar yield was about 76.37% which was also higher compared to that of the biochar obtained at higher temperature and holding time which was about 32.75 %. Using van Krevelen diagram, MSW-derived biochar at the optimum conditions can be classified as lignite, while MSW-derived biochar at extreme conditions is comparable to anthracite coal.

Kinetic analysis of biochar formation during biomass pyrolysis

This work fashioned the conventional pyrolysis by introducing a microwave process to assess the feasibility of lemon myrtle waste (LMW) to produce biochar, bio-oil and biogas in the presence of catalyst. Microwave assisted pyrolysis (MAP) of LMW was established as a control before introducing five different catalysts in the Microwave Assisted Catalytic Pyrolysis (MACP) reaction. The catalyst includes CaO based catalyst (Dolomite and Eggshell (CES)) and Zeolite based catalyst (ZSM-5, HY-Zeolites and FCC). These catalysts were characterized using the X-Ray Diffraction (XRD) method, Brunauer-Emmet-Teller (BET) surface area, Particle Size Analyzer (PSA) and Scanning Electron Microscope (SEM) to determine their physical properties. These characterizations proved that all catalysts are suitable for the MACP reaction. The biochar, bio oil and biogas yield were determined using mass balance. Biochar quality was evaluated by its calorific value content while the bio-oil and biogas produced from the MACP was characterized using Gas Chromatography-Mass Spectrometry (GC–MS) and GC-Thermal Conductivity Detector (GC-TCD) analysis. The result shows that more than 95 % of MACP yield were biochar and biogas. MAP of LMW produced highest calorific value biochar at 21.72 MJ/kg. Dolomite catalyst produced the highest bio-oil yield of 2.27 % with the highest hydrocarbon content of 86.35 %. MACP of LMW proved that the bio-oil yield produced was increase by 0.7 % while hydrocarbon percentage was increased by 11.4 % in the presence of Dolomite catalyst. The feasibility of LMW to be used as solid fuel is successfully proven form this study.

The regression analysis of fast pyrolysis product yields and determination of product quality

The composition and pyrolysis characteristics of 60 types of biomass waste from the following six source categories were compared: agricultural residues, woody pruning waste from gardens and lawns, aquatic plant material from eutrophic water bodies, nutshells and fruit peels, livestock manure and residual sludge from municipal wastewater treatment. The yield and physicochemical characteristics of the biochar produced from these feedstocks at 350 °C, 500 °C and 650 °C were also examined. Results of correlation and canonical correspondence analysis between feedstock composition and biochar properties showed that feedstock type played an important role in controlling yield and properties of biochars. The yields of biochar dry ash‐free (daf.) basis were positively correlated with cellulose, lignin and lignin/cellulose content of feedstock; and ash content hampered the biochar production. Furthermore, the intensity of correlation between biochar yield and its feedstock composition was improved with pyrolysis temperature and degree of feedstock decomposition. The fixed carbon content in biochar was also negatively influenced by ash content of feedstock, and it increased with increasing pyrolysis temperature when the ash content was below 34.57% in feedstock and decreased when the ash content exceeded. The fixed carbon production in biochar per unit ash‐free mass (af.) was positively related to cellulose, lignin and lignin/cellulose content in feedstock, which were same with the yield of biochar (daf.). But on the contrary, the volatiles content in biochar (af.) had negative correlation with these organic constituents. For most feedstocks, the differences in the biochar characteristics among the biomass categories were greater than within any individual category. C/N, H/C and O/C atomic ratio and bulk density of biochar from different types of biomass were also compared. The results will provide guidance for the reutilization of biomass wastes and production of biochar with specified properties for soil amendment applications.

Catha edulis (Khat) waste (KW) is one of the challenging waste managements in Ethiopian urban areas. While biochar from other biomass sources has been studied, the effect of pyrolysis conditions on Catha edulis waste-based biochar yield and quality remains unexplored. Therefore, this study aims to optimize the biochar production process from Catha edulis waste for high yield and desirable characteristics. The KW and biochar were characterized using FTIR, BET, proximate analysis and other key parameters. The results indicated that KW possesses favorable properties for thermochemical conversion, with low ash content (4.35% wt. dry basis) and significant organic constituents (46.89% cellulose, 28.53% lignin, 19.62% hemicellulose, 4.96% extractives). The effect of pyrolysis process variables embracing reaction temperature, reaction time, and particle size on biochar yield and quality was optimized using response surface methodology (RSM) coupled with central composite design (CCD). The biochar was desirably characterized by a pH of 8.96, fixed carbon of 60.08%, ash content of 10.55%, and a yield of 45.12% at the optimum production processes of 390 °C, 44 min, and 0.7 mm particle size. Moreover, the study found that pyrolysis temperature was the most influential factor across all responses (yield and quality). Consequently, the biochar (yield and quality) was significantly (p < 0.05) influenced by pyrolysis temperature. In conclusion, the study inferred that KW holds substantial potential for biochar production with remarkable soil amendment characteristics.Graphical

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.

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.

Renewable energy and alternative fuel technologies.

Many analytical solution methods are incapable of dealing with modern power system planning, operation and control problems due to various uncertainties involved in the system. Generation output from most of renewable energy (RE) sources is uncertain which varies with time. Therefore, appropriate solution methods need to be considered in light of the uncertainty of RE generation. In this paper, a generation duration curve approach has been presented in order to handle the uncertainty of RE generation output while solving a combined dispatch problem of fossil fuel (FF) units and RE sources. A cost minimisation scheduling problem of FF units along with forecasted quantities of RE sources is formulated and solved considering the probability of meeting or exceeding anticipated shortfalls of RE outputs. Due to the complexity of the problem a genetic algorithm (GA) based solution approach is considered for solving the problem. A test problem with five FF units and three RE sources is formulated and solved under various considerations. It is demonstrated that the combined operation of FF units with RE sources gives better results, which can also manage uncertainty associated with RE generation outputs.

The depletion of fossil fuels is a major concern for the world because of the demand for energy that has increased rapidly with population growth and urbanization. For sustainable development, energy producing industries are trying to find suitable substitutes for petroleum fuel that are environmentally friendly and economically feasible. Biomass ,such as bio-oil and biochar production, could be a possible alternative energy source. Production of biochar and bio-oil from chicken manure(CM) by the pyrolysis process could be a robust approach for organic waste recycling. In this work, experiments were conducted to examine the effect of pyrolysis temperature on the quality of chicken manure biochar (CMB) and to identify the optimal pyrolysis temperature for the conversion of CM into biochar. As the maximum pyrolysis temperature gradually increased from 350 to 650OC, the biochar yield, total nitrogen content in biochar, organic carbon (OC) content, and cation exchange capacity (CEC) of the produced biochar decreased ,while the pH value, ash content and BET surface area of the biochar increased. The generated biochar showed yields of 44.87�61.15% reported to raw material mass, organic carbon of 320�370 g/kg, pH value of 9.4�11.7, BET surface area of 2.65�6.35 m2/g and CEC of 50.21� 31.45 cmolc/kg. The maximum transformation of organic carbon from CM to biochar occurred at 550 OC, however 80.5% of N contained in CM was lost to volatile compounds at this temperature. To produce CMB for use as fertilizer, a temperature value of 350 OC should be selected in pyrolysis process while for environmental applications, 550OC is a suitable temperature value. The obtained results suggest that chicken manure could be used as potential feedstocks for slow pyrolysis process to produce high-value products useful as energy resources.

Anaerobic digestion, which is the process by which bacteria breakdown organic matter to produce biogas (renewable energy source) and digestate (biofertiliser) in the absence of oxygen, proves to be the ideal concept not only for sustainable energy provision but also for effective organic waste management. However, the production amount of biogas to keep up with the global demand is limited by the underperformance in the system implementing the AD process. This underperformance is due to the difficulty in obtaining and maintaining the optimal operating parameters/states for anaerobic bacteria to thrive with regards to attaining a specific critical population number, which results in maximising the biogas production. This problem continues to exist as a result of insufficient knowledge of the interactions between the operating parameters and bacterial community. In addition, the lack of sufficient knowledge of the composition of bacterial groups that varies with changes in the operating parameters such as temperature, substrate and retention time. Without sufficient knowledge of the overall impact of the physico-environmental operating parameters on anaerobic bacterial growth and composition, significant improvement of biogas production may be difficult to attain. In order to mitigate this problem, this study has presented a nonlinear multi-parameter system modelling of mesophilic AD. It utilised raw data sets generated from laboratory experimentation of the influence of four operating parameters, temperature, pH, mixing speed and pressure on biogas and methane production, signifying that this is a multiple input single output (MISO) system. Due to the nonlinear characteristics of the data, the nonlinear black-box modelling technique is applied. The modelling is performed in MATLAB through System Identification approach. Two nonlinear model structures, autoregressive with exogenous input (NARX) and Hammerstein-Wiener (NLHW) with different nonlinearity estimators and model orders are chosen by trial and error and utilised to estimate the models. The performance of the models is determined by comparing the simulated outputs of the estimated models and the output in the validation data. The approach is used to validate the estimated models by checking how well the simulated output of the models fits the measured output. The best models for biogas and methane production are chosen by comparing the outputs of the best NARX and NLHW models (each for biogas and methane production), and the validation data, as well as utilising the Akaike information criterion to measure the quality of each model relative to each of the other models. The NLHW models mhw2 and mhws2 are chosen for biogas and methane production, respectively. The identified NLHW models mhw2 and mhws2 represent the behaviour of the production of biogas and methane, respectively, from mesophilic AD. Among all the candidate models studied, the nonlinear models provide a superior reproduction of the experimental data over the whole analysed period. Furthermore,…

The efficient and sustainable disposal or value addition of waste plastic has of major importance. Recent studies on the char produced via pyrolysis have demonstrated that it is a valuable additive with multiple applications ranging from soil and water amendment, improving agricultural yield, supercapacitors, fuel cells, and in support/catalysts, sustainable chemistry, and carbon sequestration. Thus, it is essential to ensure the quality and efficacy of biochar produced from any combination of feedstock and process to ensure maximum benefits. However, very few studies have focussed on techniques or process parameters to optimize biochar yield. This study aims to review pyrolysis techniques, reactor types, and pyrolysis parameters to identify the process parameters that could enhance the generation of biochar from co-pyrolysis of plastic and biomass feedstock. This review discusses biochar production techniques, the mechanism of pyrolysis technology, pyrolysis types, and the reactor types. This is followed by a review of the factors that can be used to optimize biochar production. Accordingly, the review identified temperature, heating rate, reactor bed height and type, residence time, pressure, feedstock type and blending ratio of feedstock as the determinants that had the highest influence on the yield, stability, and carbon content of biochar. Most importantly, the technology readiness level (TRL) of biomass pyrolysis, plastic pyrolysis and co-pyrolysis of biomass and plastic is discussed. The review necessitates further studies on these parameters to ascertain the accuracy of optimization that can be achieved by configuring pyrolysis processes to biochar production.

The world currently obtains its energy from the fossil fuels such as oil, natural gas and coal. However, the international crisis in the Middle East, rapid depletion of fossil fuel reserves as well as climate change have driven the world towards renewable energy sources which are abundant, untapped and environmentally friendly. Indonesia has abundant biomass resources generated from the agricultural industry particularly the large commodity, palm oil (Elaeis guiinensis Jacq.). The aims of the research were to (i) characterize palm oil mill effluent which will be used as source of biogas production, (ii) know the biotic and abiotic factors which effect POME substrate for biogas production by anaerobic digestion in bulk system. The results show that POME sludge generated from PT Pinago Utama mill is viscous, brown or grey and has an average total solid (TS) content of, 26.5-45.4, BOD is 23.5-29.3, COD is 49.0-63.6 and SS is 17.1-35.9 g/L, respectively. This substrate is a potential source of environmental pollutants. The biotic factors were kind and concentration of the inoculums, i.e. seed sludge of anaerobic lagoon II and 20% (w/v) respectively. Both physical and chemical factors such as pre-treated POME pH, pH neutralizer matter Ca (OH)2, temperature ≥40oC, agitation effect to increase biogas production, but in both coagulant concentration, FeCl2 were not.© 2008 Jurusan Biologi FMIPA UNS SurakartaKey words: characteristic of POME, biogas production, biotic and abiotic factors, batch system, laboratory scale