Solar Pyrolysis Research Articles

Feasibility of Biochar Preparation with Solar Pyrolysis Method

China is a large agricultural country with a large annual output of straw resources. Compared with other straw treatment technologies, pyrolysis technology has the advantages of simple operation and high utilization value of products, but the traditional pyrolysis technology takes the combustion of fossil fuels as heat source, which has the problem of high energy consumption. Solar pyrolysis has attracted much attention because of its cleanliness and sustainability. To explore the feasibility of solar pyrolysis of straw. In this paper, the corncob biochar prepared by solar pyrolysis device and traditional pyrolysis device (muffle furnace and tube furnace) were compared. The experimental results show that the solar pyrolysis device can reach the pyrolysis temperature range of biomass, and the yield and physicochemical properties of the biochar obtained by the solar pyrolysis device are similar to those obtained by the traditional pyrolysis device. Therefore, the preparation of biochar by solar pyrolysis is a feasible method.

The effects of char and potassium on the fast pyrolysis behaviors of biomass in an infrared-heating condition

During the solar pyrolysis of biomass, the heat transfer of biomass is restrained due to uncontrolled heating area and accumulation effect. So the co-pyrolysis reaction behaviors of biomass and char, and the secondary pyrolysis reactions of biomass under co-pyrolysis situation are worth exploring. The effects of char and potassium on fast pyrolysis products distribution by fully mixing and extruding sample materials under various heating rates (5 °C/s, 20 °C/s, 100 °C/s) and pyrolysis temperature (350 °C, 425 °C, 500 °C) were discussed. The results showed that high temperature was favorable to the release of volatiles, and higher heating rate promoted decomposition of bio-oils into gaseous products. Higher heating rate contributed to the release of O element and the accumulation of C element in bio-char to some extent. The char enhanced the secondary pyrolysis reaction resulting further decomposition of small molecular acids and the conversion of guaiacyl-contained structure into simple phenols and CH4 by demethylation and demethoxylation reaction. The influences of potassium were concentrated in increasing the reactivity of biomass pyrolysis, which promoted the conversion of bio-oils into gas (especially CO2) and the demethylation reaction of guaiacyl at low temperature.

Application of inverse methodology to estimate unknown parameters of the mathematical model of biomass solar pyrolysis

The goal of the work is to determine unknown parameters of reactor heating in the process of biomass solar pyrolysis. The lab-scale reactor is heated by a xenon lamp, but the fraction of heat absorbed by the reactor is unknown, as well as the heat transfer coefficient from the reactor walls to the nitrogen flowing through internal reactor channels, and the overall heat transfer coefficient through the external reactor walls to the surroundings. The missing parameters are impossible to measure, therefore they need to be determined by solving the inverse problem. As the problem is strongly ill-conditioned, since the quantities are directly dependent on each other, two different inverse algorithms were used to retrieve them, namely, the Levenberg-Marquardt method and the Metropolis-Hastings method. The effectiveness of both approaches was assessed and then they were applied to the real data. The inverse problem was implemented in the MatLab software, while validation of the mathematical model and optimisation procedure was carried out with a CFD model built in Ansys Fluent 19.2. Calculations showed that 14.4% of the lamp power penetrates inside the reactor and heat transfer coefficients to the flowing nitrogen equal 8.74 W/m2K and 0.965 W/m2K to the surroundings.

Sustainable production of self-activated bio-derived carbons through solar pyrolysis for their use in supercapacitors

This work aims to propose a sustainable green process to obtain bio-derived carbons (BDCs) for utilization in supercapacitors. The process consists in carrying out solar pyrolysis to produce BDCs from abundant lignocellulosic wastes, Agave Angustifolia leaves and pruned tomato plant. Concentrated solar radiation from a high flux solar furnace was utilized to reach sample temperatures between 450 and 1564 °C in a spherical reactor. Before pyrolysis, both wastes were characterized by thermogravimetric analysis to semi-quantify cellulose and hemicellulose as well as ash content. XRD was used to determine the ash composition in both wastes, and the effect of solar pyrolysis temperature on the obtained BDCs. Additional structural properties of BDCs were analyzed by SEM, Raman spectroscopy, and physisorption. Elemental analysis and EDAX were used to determine the chemical composition of wastes, and the effect of this on BDCs. Electrochemical properties of BDCs were analyzed by cyclic voltammetry in half cells, and those showing better performance were also tested in supercapacitor cells. Results show that BDCs from tomato plant waste have higher surface areas, with well-developed microporosity, without needing an additional activation process. This is attributed to self-activation during pyrolysis, produced by the high K and Ca content of the tomato plant pruning. Ragone plots indicate that the assembled supercapacitor cells employing the best BDCs from solar pyrolysis have specific energies and power values similar to a commercial carbon designed for supercapacitors. These results indicate that the proposed green procedure is suitable for obtaining BDCs with properties suitable for supercapacitors.

Characterization of char generated from solar pyrolysis of heavy metal contaminated biomass

Abstract Solar pyrolysis of raw and heavy metals (HMs) impregnated willow was performed at different temperatures (600, 800, 1000, 1200, 1400 and 1600 °C) with heating rate of 50 °C/s. CHNS, ICP-OES, SEM-EDX and BET were employed to investigate the effects of temperature and HMs contamination on char properties. The results indicated that a more ordered and aromatic char was formed with increasing pyrolysis temperature. Char carbon contents increased from 70.0% to 88.4% while hydrogen and oxygen contents declined. Char BET surface area firstly increased from 5.3 to 161.0 m2/g with rising the temperature from 600 to 1000 °C, then decreased at higher temperatures due to plastic deformation. Pyrolysis caused alkali and alkaline-earth metals (A&AEMs) enrichment in char as temperature increased from 600 to 800 °C, then their content decreased at higher temperatures. The presence of Cu or Ni led to the decrease of hydrogen and oxygen contents and significant increase of Ni or Cu in char compared with those in raw willow char. Besides, Raman and BET analysis showed that contaminated willow char had a higher ratio of G band area to the integrated area (IG/IAll) and bigger BET surface area than raw material indicating a more organized and porous structure of the char.

Carbon Nanofibers Prepared from Solar Pyrolysis of Pinewood as Binder-free Electrodes for Flexible Supercapacitors

Summary Solar pyrolysis of renewable biomass has huge potential for sustainable production of fuel or chemical feedstock for the activated carbon materials. Here, we report a method for producing high-quality carbon nanofiber (CNF) precursor and subsequently CNFs as a low-cost and eco-friendly energy storage material. Specifically, pinewood is pyrolyzed with solar energy to generate a phenol-rich bioliquid precursor that is found to be a strong candidate for synthesizing binder-free flexible electrode materials via electrospinning. The CNFs prepared with 30% solar-driven bioliquids and 70% polyacrylonitrile have a high specific surface area and rich microstructure, which are the key to its electrochemical performance in terms of specific capacitance (349 F g−1 at the current density of 0.5 A g−1) with notable rate performance, reversibility, and cycling stability in 6 M KOH aqueous electrolyte. Thus, solar bioliquids are feasible CNF precursors, and such derived CNFs have potential to be applied in energy storage devices.

Perspectives and economics of combining biomass liquefaction with solar PV for energy storage and electricity production

ABSTRACT This article provides perspectives on the opportunities and challenges of integrating biomass liquefaction plants (pyrolysis, hydro-pyrolysis, hydrothermal liquefaction, liquefaction in hydrocarbon solvents, etc.) with intermittent renewables such as wind and solar photovoltaic (PV) to provide energy storage and support the development of biofuel production. A techno-economic model is used to assess the levelized cost of electricity from a plant that integrates solar PV with bio-crude production from pyrolysis and its combustion in an engine. The analysis finds that the LCOE for solar PV and biomass pyrolysis is in the range of 65 to 85 USD/MWh when using woody biomass feedstocks, making the scheme competitive with solar PV and lithium-ion batteries. This article also discusses how the integration of biomass liquefaction with intermittent renewables can aid the development of liquid biofuel value-chains by increasing bio-crude supply and supporting the establishment of biorefineries.

Mathematical Model of the Solar Pyrolysis of Biomass

Abstract The paper presents a two-dimensional computational fluid dynamics (CFD) model of lab-scale fixed-bed pyrolytic reactor. The goal of the work was to verify assumptions regarding construction and operating parameters of the pyrolytic reactor and examining heat transfer conditions and the final temperature distribution in the system taking into account the endothermic pyrolysis reactions occurrence. The impact of the most important numerical parameters on simulation results was also investigated. Model was prepared in ansys fluent 18.2 software. The studies have shown large temperature gradients both in the biomass deposit and at the reactor walls. The analysis has confirmed the validity of the proposed reactor construction concept and allowed to specify the range of thermal power value necessary for obtaining the pyrolysis process in a system with given properties and dimensions. Increasing the heat flux supplying the reactor from 160 to 480 W caused acceleration and intensification of biomass thermal decomposition, while the average final bed temperature after 10 min of heating in each case was reaching similar level. Low thermal conductivity of the bed and strong heat absorption due to pyrolysis suppress heat transfer through the bed, which causes significant temperature differences between the warmest and coldest regions of the bed. However, temperature unevenness and hence the unevenness of the pyrolysis process can provide favorable conditions for measuring the gas composition leaving the reactor due to the relatively balanced time stream of pyrolysis gases.

Upgrading of bio-oil via solar pyrolysis of the biomass pretreated with aqueous phase bio-oil washing, solar drying, and solar torrefaction

In this study, three types of biomass were first pretreated with an aqueous phase bio-oil instead of traditional acid washing. Then, the washed samples were pretreated with drying (100 ℃, 30 min) and torrefaction (250 ℃, 30 min) using a parabolic-trough solar receiver system. The subsequent pyrolysis was performed at 550 ℃ for 10 min using a parabolic-dish solar receiver system. Results showed that the solar energy can effectively ensure the temperature required for biomass drying, torrefaction, and pyrolysis, having thus a potential to replace the conventional electric heating or fossil fuel heating. Such a strategy combines the advantages of the independent pretreatments, i.e., leaching out of metallic species and reduction of oxygen content. Consequently, the high heating value of bio-oil increased remarkably, the generation of acids was strongly inhibited, whereas the formation of phenols and anhydrosugars was promoted. Therefore, the method proposed herein is promising for upgrading of biomass and bio-oil.

A comparative study of the behavior of Chlamydomonas reinhardtii and Spirulina platensis in solar catalytic pyrolysis

A comparative study of the behavior of <i>Chlamydomonas reinhardtii</i> and <i>Spirulina platensis</i> in solar catalytic pyrolysis

Solar pyrolysis of waste biomass: Part 2 kinetic modeling and methodology of the determination of the kinetic parameters for solar pyrolysis of sewage sludge

Biomass pyrolysis is a fundamental thermal conversion method that has both industrial and economic potential. A deep knowledge of the pyrolysis character can give dramatically rise to the general development of thermal conversion methods for the effective use of biomass fuel in the incoming future. In this work, kinetic parameters estimation methods and methodology for sewage sludge pyrolysis has been presented. Special emphasis was put into combined use of the latest isoconversional methodology and model-fitting kinetics. The kinetic parameters estimation was based on a series of experiments using thermogravimetric analysis carried out for heating rates 20, 30 and 40 K/min. Complimentary use of model-based and isoconversional approach along with statistical analysis of both methods results has been presented. The proposed methodology, based on Friedman isoconversional kinetic parameters, Eα 31.4–244.9 kJ/mol and Aα 1.17–14.4 log(1/s), as initial guess values for optimization resulted in 10 independent reactions kinetic model, evaluating sewage sludge pyrolysis with R2 > 0.999 with activation energies E∈<30.34; 259.7> kJ/mol, pre-exponential factors A∈<1.17; 22.49> log(1/s) and reaction orders n∈<1.17; 3>. Isoconversional methodology resulted in excellent conversion rate and mass loss fit while the order-based kinetic model simultaneously gave insight into theoretical 10 elementary sludge decomposition rates.

Valorization of biomass waste to engineered activated biochar by microwave pyrolysis: Progress, challenges, and future directions

Biomass waste represents the promising surrogate of fossil fuels for energy recovery and valorization into value-added products. Among thermochemical conversion techniques of biomass, pyrolysis appears to be most alluring owing to its low pollutant emission and diverse products formation. The current pyrolysis applications for valorization of biomass waste is reviewed, covering the key concepts, pyrolysis mode, operating parameters and products. To date, existing types of pyrolysis include conventional pyrolysis (poor heat transfer due to non-selective heating), vacuum pyrolysis (lower process temperature because of vacuum), solar pyrolysis (entirely “green” with solar-powered), and a newly touted microwave pyrolysis. In microwave pyrolysis of biomass, the heat transfer is more efficient as the heat is generated within the core of material by the interaction of microwave with biomass. The plausible mechanisms of microwave heating are dipole polarization, ionic conduction and interfacial polarization. The lack of top-tier reactor design is identified as the main obstacle that impedes the commercialization of microwave pyrolysis in biomass recycling. Based on the existing works, it is surmised that microwave pyrolysis of biomass produces solid biochar as a main product. To confront the great market demand of activated biochar, it is proposed that the solid char could be upgraded into engineered activated biochar with desirable properties for wide application in pollution control, catalysis and energy storage. Hence, the production of engineered activated biochar from microwave pyrolysis process and its applications are reviewed and explicitly discussed to fill the research gap, and the key implications for future development are highlighted.

Multi-response optimization of bio-oil production from catalytic solar pyrolysis of Spirulina platensis

In this work, the solar catalytic pyrolysis of Spirulina platensis microalgae using hydrotalcite as a catalyst was studied to improve the yield and quality of the bio-oil obtained from the algae. The effects of biomass loading, reaction time, and catalyst percentage on the product distribution and bio-oil composition were evaluated. The desirability function was used to identify the pyrolysis conditions that maximize the bio-oil yield and its hydrocarbon content. The experimental results indicated that the catalytic pyrolysis of Spirulina platensis produced considerable solid product content, and high liquid yields were reached in some tests favored by the catalyst presence. The hydrotalcite contributed to increasing the hydrocarbon formation in the bio-oil at lower reaction times, demonstrating the great performance of this catalyst for microalgae pyrolysis. At the optimal conditions, a bio-oil yield of 35.94% with 21.71% hydrocarbon content was achieved.

Distribution of solar pyrolysis products and product gas composition produced from agricultural residues and animal wastes at different operating parameters

Solar energy and biomass are the two major sources of renewable energy, which can be integrated to produce heat, power and transportation fuels, chemicals and biomaterials using pyrolysis. In this work, separate samples of chicken-litter waste and rice husk of different particle sizes (280 and 500 μm) were pyrolysed with a concentrated solar radiation to produce pyrolysis gases of high calorific value. Different operating parameters were investigated under the solar pyrolysis conditions. Heating rates from 10 to 500 °C/s and temperatures in the range of 800–1600 °C, generated from a lab-scale solar furnace with maximum power capacity of 1.5 kW, were applied. Temperature was found to have the highest effect, changing the gas yield from 10 to 39 wt%; decreasing the bio-oil and char yields from 48 to 41 wt % and 42 to 18 wt%, respectively as the temperature increased from 800 to 1600 °C. The highest specific energy content of the gas (7255 kJ/kg) was obtained with the 280 μm particle size chicken litter at 1600 °C. Overall, gases produced from solar assisted biomass pyrolysis have a high concentration of combustible products that could be directly used as fuels in engines or power plants.

Kinetic modelling of waste wood devolatilization during pyrolysis based on thermogravimetric data and solar pyrolysis reactor performance

Within presented paper complex kinetic analysis of waste wood solar pyrolysis with fuel characterisation has been presented. Thermogravimetric (TGA) data were obtained for heating rates denoted in solar pyrolysis experiments: 5, 10, 15 and 20 K/min. Study presents alternative approach to lignocellulosic biomass kinetics using NETZSCH Kinetics Neo (v. 2.1.2.2) software. TGA data were enriched with the gas analyser indications and experiments results from solar pyrolysis examined on self-designed laboratory reactor. Presented methodology consisted of (1) isoconversional analysis: Friedman, Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall analysis yielding apparent activation energies Eα, varying from 185.37 to 375.56 kJ/mol at reaction extent 0.1–0.9, (2) reaction model identification with generalised master plot method which showed that decomposition was driven by three-dimensional diffusion (D3) with transition to three-dimensional phase boundary (R3) and reaction order based models (F1,F2,Fn) at the end of conversion. Finally, (3) kinetic model construction was performed based on experiments observations, resulting in modelling of 3 main reactions of pyrolysis products formations. The most intensive condensable release was observed between 250 and 440 °C what correlated with CO2 release described by dominant two-step D3-F2 consecutive reaction with activation energies and logarithmic pre-exponential factors 159.92 kJ/mol, 10.44 log(1/s) and 256.78 kJ/mol, 19.05 log(1/s) for first and second step respectively. CO formation obeyed R3 reaction mechanism with activation energy 181 kJ/mol and pre-exponential factor 12.16 log(1/s). Last stage of pyrolysis, charring, was described by two-step consecutive reaction Fn(n = 3.463)-F2 resulting in formation of CH4 and H2 with activation energies and pre-exponential factors of 249.72 kJ/mol, 15.87 log(1/s) and 162 kJ/mol, 6.61 log(1/s) respectively. Kinetic models and isoconversional methods results were tested using Fisher-Snedecor test. Presented methodology was compared with traditional three pseudo-component wood pyrolysis model and discussed.

Solar pyrolysis of heavy metal contaminated biomass for gas fuel production

The study presented an innovative way to dispose and upgrade heavy metal (HM) contaminated biomass by solar pyrolysis. Pyrolysis of raw and HM (Cu and Ni) impregnated willow wood was performed in a solar reactor under different temperatures (600, 800, 1000, 1200, 1400 and 1600 °C) and heating rates (10 and 50 °C/s). The combined effects of HM and heating parameters (temperature and heating rates) on solar pyrolysis products were investigated. The results indicated that a threshold temperature of 1000 °C was required in impregnated willow pyrolysis to make sure copper and nickel catalytic effects on promoting the cracking and reforming reactions of tar. It led to the gas yields from copper or nickel impregnated willow pyrolysis at 1200 °C increased by 14.76% and 34.47%, respectively, compared with that from raw willow. In particular, the H2 and CO production from nickel impregnated willow were higher than those from raw willow (10.30 and 12.16 mol/kg of wood versus 6.59 and 8.20 mol/kg of wood) in case of fast pyrolysis (50 °C/s). Under heating rate of 10 °C/s, H2 and CO yields from only nickel impregnated willow increased compared with that from raw willow. Solar pyrolysis of HM contaminated biomass is a promising way to produce valuable syngas.

Just or bust? Energy justice and the impacts of siting solar pyrolysis biochar production facilities

Biochar has seen an explosion of research over the past decade as an environmentally sustainable material for enhancing agricultural yields, treating wastewater, and sequestering atmospheric carbon. In contrast, there is a lack of research into the social and economic sustainability of biochar. To address this gap, we propose environmental justice (EJ) indicators as a proxy for social and economic considerations when siting biochar production facilities. Specifically, we develop a siting index for a biochar pyrolysis facility using low-cost, carbon-neutral solar energy. This siting index provides a framework for analyzing potential facility locations based on both technical and environmental and energy justice considerations. Results indicate that EJ analyses may influence the planning processes for industrial facility siting and that incorporating EJ into siting decisions would represent a commitment to environmental sustainability as well as the social and economic conditions of communities.

Solar pyrolysis of waste biomass: Part 1 reactor design

In light of the latest regulations in the energy sector, renewable energy sources are quickly becoming more important. Among renewable energy sources, the one that has the greatest potential for use in Poland is natural and waste biomass. Application of solar energy to biomass thermal conversion methods e.g., pyrolysis, affords the opportunity for additional solar energy storage as well as amplification of the pro-ecological effect of the entire conversion process. Precise control of waste biomass pyrolysis via an investigation into the process thermodynamics, kinetics, and heat transfer phenomena allows to direct the reaction for production of desirable products, ranting reduction in of disposal cost of biomass, even sewage sludge. The goal of this study was to develop new design of laboratory-scale solar pyrolytic reactors to investigate the solar pyrolysis of waste biomass. Within presented paper, pyrolysis fundamentals, including process thermodynamics and kinetic principles, were reviewed. In addition, recently-developed, and artificial-powered solar pyrolytic reactors were discussed with a brief comparison of popular light sources for solar pyrolysis studies. After numerous consultations with artificial light sources producers and researchers, own design of a solar pyrolytic reactor is presented, along with a project development, preliminary experiment results and basic methodology for future studies.

The effects of temperature and molten salt on solar pyrolysis of lignite

Molten salt pyrolysis driven by concentrated solar radiation is well positioned to utilize solar energy and lignite effectively. This study focused on the effects of temperature (500, 600, 700 and 800 °C) and molten carbonate salt (Li2CO3-Na2CO3-K2CO3) on properties of char obtained from lignite pyrolysis, as well as gas and tar products for revealing their formation mechanism and transformation process. Molten salt pyrolysis of HulunBuir lignite produced more gas products and less char compared to conventional pyrolysis owing to the enhanced heat transfer and catalytic effect of molten salt. The char yield decreased from 58.4% to 43.4%, and the gas yield (especially CO2, H2 and CO) increased from 28.3% to 46.1% at 800 °C. CO2, CO and H2 production increased about 60.43%, 103.42% and 65.2% at 800 °C, respectively. Additionally, the presence of molten salt improved the tar quality with more hydrocarbon content (maximum increase of 5.8%) and less oxygenated compounds. The structure and reactivity relationship of char was characterized by XRD, BET, SEM, FTIR, Raman spectroscopy and TGA. Molten salt generated char had a higher reactivity due to the increase of disorder, surface area, microporosity (maximum of 71.74%) and active sites.

Solar pyrolysis of cotton stalk in molten salt for bio-fuel production

Solar pyrolysis of cotton stalk was carried out in a molten salt reactor heated by 4 kW solar simulator. The effects of pyrolysis temperature and mass ratio of molten salt to biomass on pyrolysis products properties were investigated. The use of molten salt as pyrolysis media increased gas yield. At 850 °C, the gas yield (mainly of CO and H2) continued to rise from 41.35 wt% to 82.57 wt% when mass ratio of molten salt to cotton stalk increased from 0 to 10. Pyrolysis in molten salt significantly decreased bio-oil acids and phenols, while increased aromatics among pyrolysis temperature range of 450–850 °C. There was positive correlation between the increased content of aromatics and mass ratio of molten salt to cotton stalk (from 0.5 to 10). The bio-char carbon content showed a general decreasing trend while oxygen, BET surface area and pore volume increased with using molten salt as pyrolysis media. Bio-char obtained from CS1MS5 pyrolysis at 850 °C had the highest BET surface area of 972.57 m2/g and the biggest total pore volume of 0.6203 cm3/g. High quality pyrolysis products with more uniform chemistry suggest catalytic reactions occur inside the solar reactor due to the intermediates degradation with molten salt.