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This study investigated the combustion behavior and evolved greenhouse gases of coal, Scenedesmus microalgae, and coal-Scenedesmus microalgae blends (Coalgae® 5–20%) in air using a thermogravimetric analyzer (TG)-mass spectrometer (MS). Coalgae® refers to a blend of coal fines and microalgae biomass. TG-DTG curves of coal and microalgae confirmed t...
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... kinetic parameters obtained showed changes in the activation energies, when rates derived for the blends were compared to that of coal. The first-order devolatilization rate and activation energy and Arrhenius parameters are presented in Table 5. The activation energy calculated for the coal peak combustion was 161.3 kJ/mol, while a significant decrease of ~2 kJ/mol was observed when 5% by mass Scenedesmus microalgae (Coalgae® 5%) was added to coal. ...Citations
... Mass spectrometry was used to detect the composition and content of the gaseous products released during the combustion of bio-heavy oil and coal blended with bio-heavy oil (coal : bio-heavy oil = 1 : 1), including the mass spectral curves of CO (m/z = 28), NO (m/z = 30), O 2 (m/z = 32), CO 2 (m/z = 44), NO 2 (m/ z = 46), and SO 2 (m/z = 64). 41 As shown in Fig. 6, the amount of gaseous pollutants in bio-heavy oil aer combustion is in the order of CO > CO 2 > NO > SO 2 z NO 2 . The peak of CO 2 is signicantly higher than that of the other gases, mainly because of the precipitation of organic matter and coke combustion in the air. ...
Excessive carbon-dioxide emissions drive global climate change and environmental challenges. Integrating renewable biomass fuels with coal in power units is crucial for achieving low-carbon emission reductions. Coal blending with bio-heavy oil enhances the combustion calorific value of the fuel, improves combustion characteristics, and decreases pollutant emissions. This study found that bio-heavy oil with low sulfur (0.073%), low nitrogen (0.18%), low ash, and high oxygen (11.005%) content exhibits excellent fuel performance, which can be attributed to the abundant oxygen-containing functional groups (such as C 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 O) in the alcohols, aldehydes, and ketones present in bio-heavy oil. Additionally, the residual moisture in coal-blended bio-heavy oil reduces the fuel's calorific value. The calorific value increases with a higher proportion of blended bio-heavy oil (28.1, 28.9, 32.1, 34.7, 40.6 MJ kg⁻¹). Experiments on combustion flame shooting reveal that the combustion time of bio-heavy oils is significantly shorter than that of coal. As the proportion of blended bio-heavy oil increases, the flame height increases. Coal blending with bio-heavy oil involves three stages: water evaporation, volatile-matter decomposition, fixed-carbon combustion and mineral decomposition. This advances the combustion process and improves coal's ignition performance. Furthermore, the amount of gaseous pollutants (sulfur dioxide and nitrogen dioxide) in coal mixed with bio-heavy oil is relatively low, which is in alignment with the green environmental protection guidelines. The blending of coal with biomass fuel holds significant practical and strategic importance for developing high-efficiency, low-carbon, coal power units.
... 8 Coal as a fossil fuel is known to be one of the principal energy sources for energy production in many industrialized and developing countries of the world due to escalating energy demands. 9,10 However, coal usage has implications such as air pollution, which causes various health and environmental challenges, and the rapid global energy consumption of coal, which contributes to its depletion. These difficulties sparked an exploration of renewable, sustainable, environmentally friendly, and clean energy alternatives. ...
Copyrolysis, being an active area of research due to its synergistic impact in utilizing diverse fuel resources, including waste materials, like, peach stone (PS), has been the focal point for this study. PS, produced in vast quantities annually and typically intended for landscaping or insulation purposes, is being studied in combination with low‐grade bituminous coal for energy utilization focusing on thermokinetics and synergistic aspects. Coal‐peach stone (C‐PS) blends were formulated at different ratios and subjected to comprehensive characterization techniques, including ultimate analysis (CHN‐S), gross calorific value (GCV), Fourier transform infrared spectroscopy, and thermogravimetric analyzer (TGA). The ultimate analysis revealed an enhancement in carbon and hydrogen content from 45.38% to 68.08% and from 3.89% to 6.96%, respectively. Additionally, a reduction in sulfur and nitrogen content from 0.54% to 0.11% and from 1.16% to 0.42%, respectively, was observed with an increase in the ratio of PS in the C‐PS blends. The GCV of C‐PS blends ranged from 20.75 to 26.01 MJ kg ⁻¹ . The pyrolysis conditions simulated in TGA are pivotal for evaluating thermokinetics and synergistic effects. The 60C:40PS blend shows a positive synergy index (SI) value of 0.0203% concerning total mass loss ( ML T ) indicating a favorable condition for bio‐oil generation. Coats–Redfern model‐fitting method reveals that the activation energy ( Ea ) of C‐PS blends increases in Section II with the addition of PS, and conversely, it decreases in Section III. The Ea for 100PS and 100C was 106.76 and 45.85 kJ mol ⁻¹ through (D3) and (F1), respectively, which was improved through the optimal blend 60C:40PS with an Ea of 94.56 and 27.58 kJ mol ⁻¹ through (D3) and (F2), respectively. The values obtained from linear regression prove that the kinetic models are effective while the thermodynamic analysis indicates that the pyrolytic behavior of C‐PS blends is characterized as endothermic, nonspontaneous, and capable of achieving thermodynamic equilibrium more rapidly.
... The high ash contents were related to the origin of the microalgae polyculture, i.e. from a wastewater pond, which resulted in nutrient-rich chars. As a comparison, extensive literature has reported on the ash content of biochar derived from these single microalgal strains, namely, Scenedesmus (5.9 wt%) (Magida et al., 2021), Coelastrum (2.7 wt%) (Zheng et al., 2017), and Chlorella (2.1-6.0 wt%) (Binda et al., 2020), which were all significantly lower than the microalgae polyculture in this work (15.8 wt%). As a result, these high ash char products has a number of potential applications such as soil amendment, adsorption agent, and catalyst (Sun et al., 2021). ...
Microalgae, originating from a tertiary treatment of municipal wastewater, is considered a sustainable feedstock for producing biochar and hydrochar, offering great potential for agricultural use due to nutrient content and carbon storage ability. However, there are risks related to contamination and these need to be carefully assessed to ensure safe use of material from wastewater microalgae. Therefore, this study compared the properties and phototoxicity of biochar and hydrochar produced via pyrolysis and hydrothermal carbonisation (HTC) of microalgae under different temperatures and residence times. While biochar promoted germination and seedling growth by up to 11.0% and 70.0%, respectively, raw hydrochar showed strong phytotoxicity, due to the high content of volatile matter. Two post-treatments, dichloromethane (DCM) washing and further pyrolysis, proved to be effective methods for mitigating phytotoxicity of hydrochar. Additionally, biochar had 35.8-38.6% fixed carbon, resulting in higher carbon sequestration potential compared to hydrochar.
... Previously, some characteristic bands for lipids (1480-1350 cm −1 , 1770-1710 cm −1 , and 3025-2800 cm −1 ) are identified in the FTIR spectra of microalgae, Nannochloropsis oceania [54]. In assertive agreement with this study, the appearance of a sharp peak at 1350 cm −1 (assigned for lipid content) in FTIR spectra of microalgae and MBCCs indicates a significant influence of microalgae content in MBCCs [55]. Major structural features between MBCCs and coal are identical (Fig. 6). ...
Towards blended solid fuel processing technologies, the present study is first attempt to utilize de-oiled microalgae, Chlorella pyrenoidosa NCIM2738, as a binder to densify low-rank coal waste to formulate upgraded biomass-blended coal composites. The de-oiled biomass has shown similar gross calorific value (18.62 MJ/kg), sulfur content (1.45%), and low ash content (18%) in comparison to coal. Fuel characteristics of biomass-blended coal composites of 20:80 ratio showed gross calorific value (19.0 MJ/kg), fuel ratio (1.85), and low sulfur content (< 1%). The multi-objective optimization strategy is used to optimize the molding pressure, average particle size, and binder ratio for maximization of the mechanical performance indicators such as compressive strength and drop strength of biomass-blended coal composites. The maximum compressive strength and drop strength of blended composites at multi-objective optimized conditions after model validation (R² > 0.99) are observed to be 14.6 MPa and 97.8%, respectively. Fourier transform infrared analysis is used to evaluate structural variation during coal-microalgae interaction. Thermogravimetric analysis, derivative thermogravimetric, and differential thermal analysis (TGA-DTG-DTA) are conducted to determine characteristic temperature points and heat involvement during combustion. TGA-DTG-DTA showed remarkable shifting of ignition point from 335 °C (parent coal) to 301–299 °C (blended coal composites), extended burnout temperature (47–82 °C higher than parent coal), and excessive exothermic heat involvement (3305–3363 μVs/mg) during composite combustion. Levenberg-Marquardt algorithm–based artificial neural network model was applied to validate the thermal analysis of coal, microalgae, and blended composites, which offers an excellent tool for studying thermochemical conversions. An in-depth investigation of mechanical-thermal aspect of the coal-biomass energy system will provide new possibilities to select microalgae as binder with optimized binder ratios which can apply in coal-based power plants as sustainable and affordable fuels.
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... The results corresponding to the sixth run has a peak that appears as a shoulder to the left of the prominent degradation peak in the DTG curve. This shoulder can be related to the loss of high volatile compounds [43,44] such as the phycocyanin inside Spirulina platensis. It is also evident that a further increase of the temperature on the biomass up to 530 • C during pyrolysis leads to faster weight loss. ...
In this study, the Spirulina platenesis growth and carbohydrates, proteins, lipids, and chlorophyll production were investigated by using synthetic wastewater via a mixture experimental design using carbon–nitrogen–phosphorus (C:N:P) relation according to the mixing obtained in the experimental space. In addition, a scale-up in the growth of microalgal biomass in a tubular column photobioreactor was carried out. The activation energy was determined by thermogravimetric analysis from the Spirulina platenesis biomass obtained from the experimental design. Also, kinetic growth analysis and thermal hydrolysis of Spirulina platensis biomass were performed for the experimental case where the carbohydrate concentrations were the highest. The stress induced by phosphorus limitation in the synthetic wastewater enhanced intracellular carbohydrates production. It achieves a maximum concentration of 859.59 ± 80.87 mg/L (60.11% w/w) on run 8. The results showed a relation between the activation energy and carbohydrates concentration in biomass. This indicates that the energy required to start the thermal degradation reaction increases as carbohydrate concentration increases. In terms of hydrothermal pretreatment, the temperature increment in the reactor raises the condition to extract carbohydrates from microalgae biomass. In contrast, the temperature increment decreases the reaction rate on the protein extraction. During the hydrothermal pretreatment, the best condition for the carbohydrates extraction in the Spirulina platensis biomass was 140oC for 45 min. At this condition, cell wall hydrolysis needs an energy supply of 18.65 kJ/mol. The development of this process will allow the fractionation of microalgal biomass and extraction of carbohydrates in terms of a biorefinery.
... Microalgae can be used to treat coal or any carbonaceous material before thermochemical processing, such as combustion, gasification, liquefaction, distillation, pyrolysis, and coking [19]. Microalgal biomass slurry have also been reported to easily adsorb onto coal fines, forming a new material, "Coalgae ® ," with different properties [20,21]. Scenedesmus has been identified as a promising microalgae strain, due to its high efficiency for CO2 capture amongst green microalgae [22][23][24]. ...
... 15.4 wt.%, 14.5 wt.%, and 13.6 wt.%, respectively. These ash yields were comparable to the ash yields obtained from proximate analysis and TGA, with a difference of up to 1.8 wt.% [21]. The slower combustion of the coal compared to the biomass has been reported in the literature on co-firing coal with different biomasses, including algae [29][30][31]. ...
This study investigated the effect of coal–Scenedesmus microalgae (with blending ratios of 100:0 (coal), 95:5 (Coalgae® 5%), 90:10 (Coalgae® 10%), 85:15 (Coalgae® 15%) and 80:20 (Coalgae® 20%)) on combustion temperature, mass loss, the formation of CO2, SO2 and NOx gases, and ash content under constant atmospheric air flow. Coalgae® refers to a material formed after blending coal and microalgae. The results showed that NOx came mainly from Coalgae® 10% and 15%, and this observation could be attributed to a variable air concentration level (O2 level) in the environment that could influence NOx during the combustion process, irrespective of the blending ratios. CO2 emission reductions (12%, 17%, 21% and 29%) and SO2 emission reductions (3%, 12%, 16% and 19%) increased with the increasing coal-microalgae blending ratio (Coalgae® 5–20%), respectively. Bubble-like morphology was observed in the ash particles of coal–microalgae blends through SEM, while the TEM confirmed the formation of carbon-based sheets and graphitic-based nanocomposites influenced by the microalgae amounts. Ash residues of the coal–microalgae blends contained high amounts of fluxing compounds (Fe2O3, K2O, CaO and MgO), which resulted in an increased base/acid ratio from 0.189 (coal) to 0.568 (Coalgae® 20%). Based on the above findings, the co-firing of coal–Scenedesmus microalgae led to a reduction in CO2, SO2, and NOx emissions. As such, lower Coalgae® blends can be considered as an alternative fuel in any coal-driven process for energy generation.
... Coal-Scenedesmus blends, under the commercial name Coalgae ® 5-20% (coal and microalgae ratio at mass basis) composite, have exhibited improved combustion behavior and evolved greenhouse gases [248]. In addition, a decrease in the emissions of CO 2 , NOx, and SO 2 from coal to Coalgae ® 5-20% was observed. ...
It was generally believed that coal sources are not favorable as live-in habitats for microorganisms due to their recalcitrant chemical nature and negligible decomposition. However, accumulating evidence has revealed the presence of diverse microbial groups in coal environments and their significant metabolic role in coal biogeochemical dynamics and ecosystem functioning. The high oxygen content, organic fractions, and lignin-like structures of lower-rank coals may provide effective means for microbial attack, still representing a greatly unexplored frontier in microbiology. Coal degradation/conversion technology by native bacterial and fungal species has great potential in agricultural development, chemical industry production, and environmental rehabilitation. Furthermore, native microalgal species can offer a sustainable energy source and an excellent bioremediation strategy applicable to coal spill/seam waters. Additionally, the measures of the fate of the microbial community would serve as an indicator of restoration progress on post-coal-mining sites. This review puts forward a comprehensive vision of coal biodegradation and bioprocessing by microorganisms native to coal environments for determining their biotechnological potential and possible applications.
... Results confirmed that the combustion behavior of these materials was different. Mass spectrometric data presented a decrease in the emissions of CO 2 , NOx, and SO 2 from coal to Coalgae ® due to the complex combustion mechanism in the presence of radicals [111]. ...
Advances in on-line thermally induced evolved gas analysis (OLTI-EGA) have been systematically reported by our group to update their applications in several different fields and to provide useful starting references. The importance of an accurate interpretation of the thermally-induced reaction mechanism which involves the formation of gaseous species is necessary to obtain the characterization of the evolved products. In this review, applications of Evolved Gas Analysis (EGA) performed by on-line coupling heating devices to mass spectrometry (EGA-MS), are reported. Reported references clearly demonstrate that the characterization of the nature of volatile products released by a substance subjected to a controlled temperature program allows us to prove a supposed reaction or composition, either under isothermal or under heating conditions. Selected 2019, 2020, and 2021 references are collected and briefly described in this review.
... Freshwater microalgae and macroalgae biomass have potential for expanded use in energy production through co-combustion with coal, supplementing and/or replacing woody biomass and reducing net carbon emissions created by electrical generation from coal-fired processes (Hope and Gary, 2019;Magida et al., 2019;Singh et al., 2011). To date, co-combustion of microalgae with conventional solid fuels has been reported (Hope and Gary, 2019;Magida et al., 2019), but no research exists investigating freshwater macroalgae co-combustion although Zhu et al. did explore the co-gasification of freshwater macroalgae and wood pellets (Zhu et al., 2016). ...
... Freshwater microalgae and macroalgae biomass have potential for expanded use in energy production through co-combustion with coal, supplementing and/or replacing woody biomass and reducing net carbon emissions created by electrical generation from coal-fired processes (Hope and Gary, 2019;Magida et al., 2019;Singh et al., 2011). To date, co-combustion of microalgae with conventional solid fuels has been reported (Hope and Gary, 2019;Magida et al., 2019), but no research exists investigating freshwater macroalgae co-combustion although Zhu et al. did explore the co-gasification of freshwater macroalgae and wood pellets (Zhu et al., 2016). In general, freshwater macroalgal biomass has several logistical advantages that favor its use over woody biomass (Ghadiryanfar et al., 2016;Milledge et al., 2014). ...
Freshwater macroalgae are an underutilized group of ubiquitous algae with greater yield potentials than most terrestrial energy crops, but whose combustion characteristics are not thoroughly understood. This effort compared the combustion of pelletized 100% pine and macroalgae-containing solid fuel mixtures (90%/10% and 75%/25% pine/macroalgae) using a fixed bed co-current reactor. Macroalgae increased pellet density as its protein and calcium content promoted hydrogen bonding and cross-linked the carboxylic acid functionality of polysaccharides. In addition, higher concentrations of freshwater macroalgal biomass required a greater air flow rate to achieve the mixing required for combustion. Since the macroalgae had a higher level of fuel nitrogen and fuel sulfur, emissions of nitrogen and sulfur oxides largely grew with an increasing proportion of this fuel. Overall, pelletized macroalgae can be co-combusted with woody biomass and its pre-treatment (water-rinsing and modulating cultivation conditions) can reduce or eliminate drawbacks found in the harvested naturally-occurring algal material.
... López et al. [49] calculated the combustion activation energy of microalgae and corn blend as approximately 171.5 kJ/ mol using Vyazovkin and Ozawa-Flynn-Wall methods. Magida et al. [50] examined the combustion kinetics of microalgae and coal blends in their study and found that the activation energy decreases as the microalgae ratio increases in the blends. Hu et al. [51] investigated the combustion characteristics of blends of different proportions of coal and masson pine raw materials using KAS and Coats-Redfern methods and reported that biomass combustion occurs in two different ranges and coal combustion occurs in a single range. ...
Utilization of macroalgae, which accumulated in the coastal area and considered as waste by municipals, for biofuel production is a good solution putting forward for both waste management and meeting the renewable energy requirement. This study aims to investigate the use of Ulva lactuca collected from the Marmara Sea coast as a raw material for solid biofuel production. Therefore, in this study, the combustion characteristics of Ulva lactuca and its biochar were investigated by the thermogravimetric method, and kinetic parameters were determined by using Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods. When the obtained thermograms are examined, it was observed that the combustion of raw seaweed occurs in three phases, while the combustion of biochars occurs in two phases. As a result of the calculations, the combustion activation energies of macroalga and its biochar were found to be approximately 261 kJ/mol and 146 kJ/mol, respectively, using the KAS method. It was found that the values calculated using the FWO method were similar to the KAS method. These data show that biochar requires less energy than raw algae during combustion.
