Solid Fuels Research Articles

Reducing energy poverty by nearly universal pension coverage of rural China

This paper estimates the causal effect of income change on reducing energy poverty by exploiting age-based eligibility for China’s New Rural Pension Scheme (NRPS) through a regression discontinuity (RD) design. More than one billion people worldwide live in energy poverty, and the situation is even more difficult in developing world. It is an important development challenge to reduce energy poverty, which could be further associated with health outcome, labor productivity, and educational achievements. While public policies that increase income for poor households are the most direct ways to reduce energy poverty, the reverse causality makes establishing a convincing causal link between income and energy poverty challenging. Using the quasi-experimental variation in income induced by NRPS, this paper addresses the endogeneity of income and examines the impact of exogenous sharp changes in income on energy consumption behaviors. The findings indicate substantial increases in modern energy consumption and sizable reductions in solid fuels (e.g., straw and fuelwood), suggesting that “windfall income” by pension coverage alleviates energy poverty. Although individuals could anticipate the income shocks by pension coverage, the evidence suggests that they do not engage in anticipatory responses to smooth their consumption. Further evidence shows that liquidity constraints may be the underlying mechanism for the lack of anticipatory responses in household energy consumption. Besides reducing energy poverty, the results demonstrate that pension coverage leads to a decrease in elderly labor supply, an increase in subjective health and life satisfaction, and an increase in non-energy consumption, all of which are positively associated with the well-beings of senior citizens. We anticipate that the findings of this paper in the context of China may be extended to developing world which has been expected to set up targeted measures to tackle energy poverty in upcoming decades.

Characterization of risks and pathogenesis of respiratory diseases caused by rural atmospheric PM2.5

Forty-six percent of the world's population resides in rural areas, the majority of whom belong to vulnerable groups. They mainly use cheap solid fuels for cooking and heating, which release a large amount of PM2.5 and cause adverse effects to human health. PM2.5 exhibits urban-rural differences in its health risk to the respiratory system. However, the majority of research on this issue has focused on respiratory diseases induced by atmospheric PM2.5 in urban areas, while rural areas have been ignored for a long time, especially the pathogenesis of respiratory diseases. This is not helpful for promoting environmental equity to aid vulnerable groups under PM2.5 pollution. Thus, this study focuses on rural atmospheric PM2.5 in terms of its chemical components, toxicological effects, respiratory disease types, and pathogenesis, represented by PM2.5 from rural areas in the Sichuan Basin, China (Rural SC-PM2.5). In this study, organic carbon is the most significant component of Rural SC-PM2.5. Rural SC-PM2.5 significantly induces cytotoxicity, oxidative stress, and inflammatory response. Based on multiomics, bioinformatics, and molecular biology, Rural SC-PM2.5 inhibits ribonucleotide reductase regulatory subunit M2 (RRM2) to disrupt the cell cycle, impede DNA replication, and ultimately inhibit lung cell proliferation. Furthermore, this study supplements and supports the epidemic investigation. Through an analysis of the transcriptome and human disease database, it is found that Rural SC-PM2.5 may mainly involve pulmonary hypertension, sarcoidosis, and interstitial lung diseases; in particular, congenital diseases may be ignored by epidemiological surveys in rural areas, including tracheoesophageal fistula, submucous cleft of the hard palate, and congenital hypoplasia of the lung. This study contributes to a greater scientific understanding of the health risks posed by rural PM2.5, elucidates the pathogenesis of respiratory diseases, clarifies the types of respiratory diseases, and promotes environmental equity.

Thermodynamic and kinetic modeling and experiment on plasma ignition of pulverized high-ash coal

Solid fuels are relatively inexpensive and widely available, making them an attractive option for energy producers. However, they are currently inefficient in converting heat energy into electricity, and new technological advances are needed to make them more efficient. Plasma ignition and stabilization of pulverized coal flame provides a cost-effective and sustainable approach to boiler start-up and combustion stabilization, avoiding the traditionally used fuel oil or gas. This technology consists of heating the air-coal mixture with electric arc plasma to the temperature of coal devolatilization and partial gasification of the coke residue. Thus, a highly reactive two-component fuel, consisting of combustible gas and coke residue, is obtained from the original coal. In this paper, a comprehensive thermodynamic and kinetic analysis was carried out. A thermodynamic analysis was carried out to study the optimal parameters of plasma ignition and stabilization of combustion of a pulverized fuel flame. Kinetic modeling of the process of plasma ignition and stabilization of combustion of pulverized fuel made it possible to obtain changes in temperatures, velocities and concentrations of high-temperature two-component fuel components along the length of the plasma-fuel system. In experiments on plasma ignition of thermal coal, a stable coal-dust flame was obtained, and its temperature, composition and degree of carbon gasification were determined. Comparison of experimental and calculated data showed satisfactory agreement.

Harnessing the potential of pigeonpea and maize feedstock biochar for carbon sequestration, energy generation, and environmental sustainability

Crop residues in agriculture pose disposal challenges and contribute to air pollution when burned. This study aims to use pigeonpea and maize stalks to produce biochar at different pyrolysis temperatures. Biochar can serve in carbon sequestration, as a soil amendment, and as an alternative fuel source. Pyrolysis was conducted at 400, 500, and 600 °C to examine the effects on physicochemical properties, fuel, and energy related properties. Increase in temperatures resulted in decrease of biochar yield, volatile matter, and O/C and H/C atomic ratios, while ash content and essential nutrients increased. Yield was observed to be higher in pigeonpea stalks derived biochar compared to maize stalks derived biochar at same pyrolysis temperatures. The yields of pigeonpea stalks derived biochar at 400 °C, 500 °C, and 600 °C are 34, 33 and 29%, respectively, and the yields of maize biomass-derived biochar at 400 °C, 500 °C, and 600 °C are 29, 28, and 26%, respectively. The organic carbon content is found to be higher in the biochar samples prepared at 600 °C, i.e., 10.44%, and 10.39% for pigeonpea and maize-derived biochar, respectively. The essential elements of biochar were increased with an increase in pyrolysis temperature except nitrogen which is conversely related to temperature. The biochar obtained through pyrolysis at 400 °C demonstrated superior characteristics compared to biochar produced at other temperatures. It exhibited a higher biochar yield, with approximately 84.60% for pigeonpea and 64.85% for maize fixed carbon content. Additionally, the energy retention efficiency was higher, reaching 67.33% for pigeonpea and 42.70% for maize-derived biochar at a pyrolysis temperature of 400 °C. The fixed carbon recovery efficiency was also notable at around 200.44% for PPS and 142.37% for maize biochar which is higher compared to biochar produced at other temperatures. Furthermore, the higher heating value (HHV) was approximately 30.75 MJ kg−1 for both the biochars, indicating their suitability as alternative solid fuels. A significant CO2 reduction potential of 84 CO2 eq kg−1 and 55 CO2 eq kg−1 was observed for pigeonpea and maize biochar, respectively. Hence, biochar is a promising and effective option for carbon sequestration, offering environmental benefits.Graphical

Assessment of pyrolysis potential of Indian municipal solid waste and legacy waste via physicochemical and thermochemical characterization

This study explores the viability of utilizing municipal solid waste (MSW) and legacy waste as a renewable energy source through pyrolysis, akin to solid fuels. The heating value of MSW and legacy waste were found to be 37737.89 and 40432.84 kJ/kg, respectively. Proximate analysis shows that MSW fits within Tanner diagram parameters, eliminating the need for auxiliary fuel in pyrolysis. With 47.6 % and 44.16 % lignin content in MSW and legacy waste were deemed suitable for char production. Thermal degradation resulted in mass losses of 68 % for MSW and 82 % for legacy waste. The kinetic and thermodynamic assessment indicates lower activation energy (Ea) and Gibbs free energy (ΔG) for MSW (5.72 kJ/mol and 170.37 kJ/mol, respectively) compared to fossil fuels, suggesting faster reactions without additional energy requirement. MSW emerges as a promising alternative to fossil fuels, aligning with the United Nations’ 2030 Sustainable Development Goals.

Biochar from agricultural biomass: Green material as an ecological alternative to solid fossil fuels

The stalks left after harvesting corn, tomatoes, and tobacco have no further use and are usually burned on agricultural land. In our work samples of this waste were collected and pyrolyzed at 400 ? for 30 min in a nitrogen atmosphere. The solid residue (biochar) obtained by pyrolysis was analyzed, and the results were compared with widely used solid fuels such as wood, coal, coke and charcoal. The heat values of biochar from tomato, tobacco, corn ZP 6263, and corn BC 398 stalks were 24.12, 23.09, 26.24 and 25.78 MJ kg-1, respectively. These values are significantly higher than the heat value of wood, which is about 12.50 MJ kg-1. The ash content of biochar was 12?20 %, which is consistent with the ash content of solid fuels. No heavy metals were found in biochar samples. The results show that biochar obtained from the pyrolysis of agricultural waste, such as tomatoes, tobacco and corn stalks, has good potential for use as a solid fuel.

Rate and Change in Household Solid Fuels Usage Among Residents Aged 40 and Older - China, from 2014-2015 to 2019-2020.

Solid fuel combustion is a significant source of household air pollution and an important risk factor for chronic obstructive pulmonary disease (COPD). This study presents the rates and change in the use of solid fuels for cooking and heating in China. Based on data from the Chinese Chronic Obstructive Pulmonary Disease Surveillance, the research estimated the rates and change of solid fuels usage for cooking and heating from 2014-2015 to 2019-2020 and the rate of primary cooking solid fuels usage in 2019-2020, and analyzed the association between solid fuels usage and COPD. The rates of solid fuels usage for cooking and heating significantly decreased, dropping from 45.3% to 28.0% and from 33.5% to 23.2%, respectively. Usage rates were higher among rural residents, with 47.2% using it for cooking and 37.7% for heating in 2019-2020. The usage of solid fuels for cooking is associated with increased risk of COPD. Among rural residents, combined usage of biomass and coal for cooking (OR=1.29, 95% CI: 1.12, 1.48) and using coal as primary fuel for cooking (OR=1.18, 95% CI: 1.00, 1.38) are associated with higher risk of COPD. The usage of biomass for cooking is associated with an increased risk of COPD in urban residents (OR=1.17, 95% CI: 1.03, 1.32). The study demonstrates a significant decline in the use of household solid fuels. Nevertheless, high utilization rates persist among individuals in rural settings and those from lower socioeconomic backgrounds. It is of great public health importance to propose targeted fuel substitution measures for various solid fuels in different regions to reduce the risk of COPD.

ASSESSING FUEL FRAGMENTATION IN AN OXIDIZING ATMOSPHERE FOR HYBRID ROCKET PROPELLANT SAFETY COMPREHENSION

Although hybrid rockets are considered safe, when solid fuel forms dust during impact and mixes with leaked oxidizer, a combustible gas mixture might form and burn rapidly. Therefore, to ascertain whether or not solid fuels burn by fragmentation in an oxidizing atmosphere, efforts are being made to fragment microcrystalline wax, which tends to generate dust among solid fuels under air and oxygen atmospheres. Earlier test results showed differences between results obtained in oxygen and air; however, the influence of experimental configurations cannot be ruled out. Therefore, experiments were conducted again with the air and oxygen experimental configurations combined. A transparent balloon was filled with a specimen and air or oxygen. A detonator and explosives were used to fragment the specimen. Then, the fragmentation was observed and a pressure-time history around the specimen was obtained. In all, nine experiments were conducted while varying the atmosphere, explosive mass, and presence of specimens. In all of the experiments, the pressure-time history comparisons under oxygen showed the same or higher peak overpressure and impulse compared to air. Furthermore, movies taken of experiments under an oxygen atmosphere showed strong luminescence, indicating clearly that combustion occurred in the oxygen atmosphere. The impulse values were highest in the oxygen atmosphere where the specimen was present, suggesting that the specimen burned.

Time evolution of sulphur dioxide concentration generated by solid fuel combustion systems during the cold periods of the year

About 99% of sulphur dioxide present in the atmosphere comes from anthropogenic activities, the main source being industrial activity that processes sulphur materials, including burning fuels (coal, oil or gas), thus releasing sulphur dioxide into the air. The purpose of this paper is to monitor the concentration of sulphur dioxide during two seasons, in the ambient air of Petroșani, with the aim of highlighting the possible atmospheric pollution caused by thermal power plants that use solid fuel during the winter period. The monitoring periods were distributed over a period of 6 months (three in summer and three in winter), namely the summer months (May, June, July of 2022), the winter months of December (2022), January and February of 2023. The main objective of the measurements is to identify if there is an increase in sulphur dioxide concentration in the atmosphere, resulting from the burning of solid fuels from household activities during the winter period. Results indicate that there is a higher degree of SO2 pollution in the winter period, but the recorded values are far below the limits set by national legislation. The paper presents some measures to limit sulphur dioxide pollution in the context of climate change.

Association of Exposure to Indoor Air Pollution with Unhealthy Symptoms among Middle-aged and Older Adults in India: Evidence from a Large-scale Survey.

The usage of solid cooking fuels is widely prevalent in low and middle-income countries, including India, and contributes to indoor air pollution (IAP), which has detrimental health effects. Moreover, time spent inside the house increases as people age. In this context, the present study tried to understand the association between exposure to indoor air pollution and unhealthy symptoms, including shortness of breath, dizziness, headache, fatigue, wheezing, and cough among middle-aged and older adults in India. We extracted the unit-level individual data (N = 63 790) from the Longitudinal Aging Study in India (LASI)-Wave 1 (2017-2018). The statistical analyses used were Chi-square test and binary logistic regression, which estimated the odds ratio to identify the determinants of the unhealthy symptoms. The odds of shortness of breath (adjusted OR: 1.14, 99% CI: 1.05-1.23), dizziness (adjusted OR: 1.28, 99% CI: 1.21-1.35), fatigue (adjusted OR: 1.32, 99% CI: 1.26-1.39), wheezing (adjusted OR: 1.30, 99% CI: 1.19-1.42), and cough (adjusted OR: 1.36, 99% CI: 1.27-1.45) were higher among individuals from households where solid cooking fuels was used. Similarly, the odds of shortness of breath, headache, wheezing, and cough were higher among individuals with a household member who smoked inside the house. The results indicated that the odds of shortness of breath, headache, and cough were significantly lower among participants exposed to incense use. Based on the results of this study, we suggest developing programs to combat the sources of indoor air pollution and the associated unhealthy symptoms, especially in rural settings. It is also important to bring awareness and practice clean fuel usage at individual and community levels to improve population health.

Перспективи виробництва синтетичного бензину в Україні

DOI: 10.31081/1681-309X-2024-0-1-34-40 Specialty 161. U.D.C. 662.7 PROSPECTS FOR THE PRODUCTION OF SYNTHETIC PETROL IN UKRAINE © K.V. Shevchenko, Ph.D. in Technical Sciences, A.B. Grigorov, Doctor of Technical Sciences (National Technical University "Kharkiv Polytechnic Institute", 2, Kyrpychova str., Kharkiv, 61002, Ukraine) The article analyses the possibility of using various hydrocarbon feedstocks (including secondary ones) in the technology of synthetic motor petrol production, which, together with petrol produced by classical technology (from oil or gas condensate), can satisfy the existing demand for this type of motor fuel. It is shown that, taking into account the possible production volumes and demand for raw materials, as well as the complexity (energy intensity) of their technological processing, the most promising types of raw materials are biomass, solid fossil fuels and secondary polymers. Biomass (mainly agricultural waste) is a feedstock for biogas production, which is currently being used quite successfully in the European Union. The product of this production is methane, which can be used for energy purposes or processed into petrol and biomethanol. Another promising area in biomass processing is the direct production of alcohols (biomethanol and bioethanol), which can be used as a raw material for organic synthesis and for the production of blended petrol (e.g., grades E5, E7 and E10). Given Ukraine's reserves of various grades of coal, its processing into synthetic gasoline by gasification followed by synthesis using the Fischer-Tropsch method or hydrogenation can also be considered very promising. However, to date, these processes have not been widely used in industry due to their high energy intensity. It has been determined that secondary polymers - production and consumption wastes represented by polyethylenes (HPDE and LPDE) and polypropylene (PP) - are more promising for Ukraine than other types of raw materials. The main process for their processing is thermal or thermocatalytic pyrolysis, which produces both liquid petrol fractions (boiling point 30-210 °C) and gases, represented by ethylene, propylene and butylene. Given their conversion rate (70-90 % and 100 %, respectively), propylene and butylene can be processed into polymer gasoline, which, after purification, will be suitable for use in mixed or synthetic commercial motor gasoline. Keywords: natural gas, biomass, solid fossil fuels, polymers, processing, hydrogenation, synthesis, pyrolysis, methane, propylene, butylene, synthetic petrol. Corresponding author: A.B. Grigorov, e-mail: grigorovandrey@ukr.net

Comparison of CO2 emissions during the operation of autonomous heating systems

The issue of CO2 emissions from heat generators in autonomous heating systems is one of the most important indicators of human technological impact on the Earth's atmosphere. Heat generation is carried out by heat pumps, gas and electric boilers, and systems using solid and liquid hydrocarbon fuels. The purpose of this work is to assess the CO2 emission rate per kilowatt of thermal energy for the specified generators of heating systems based on the actual energy efficiency of heat generators in heating systems with radiator-type heating devices. The study uses official data from Rosstat RF, reports from the Ministry of Energy, the Ministry of Economic Development, current GOST standards, and regulatory documents. CO2 emission values per kilowatt of thermal energy are determined for autonomous water heating systems when generating thermal energy with air-source heat pumps (ASHP), gas condensing and convection boilers, and boilers using solid and liquid fuels. The assessment of CO2 emissions from heat generators of autonomous water heating systems showed a dependency on the structure of electricity production and transportation, climate, and the heating devices used. All these parameters vary across different countries. Analyzing data for specific countries shows that different heating units have the minimal carbon footprint.

The Era of Exploitation of Waste Rubber Tires to Valuable Products

Producing modern types of new and renewable energy locally represents an inevitable necessity, through planning energy policies based on diversifying renewable and non-traditional sources by exploiting local resources, which contributes to securing the increasing energy requirements for daily and industrial needs and reducing dependence on traditional sources of energy resulting from oil and gas derivatives. Optimal exploitation of resources, including plastic waste, which is an important source to produce energy and liquid or solid fuels.

Co-hydrothermal carbonization of pretreated sludge and polyethylene terephthalate for the preparation of low-nitrogen clean solid fuels.

In this work, polyethylene terephthalate (PET) and sewage sludge (SS) were co-hydrothermally carbonized to produce low-nitrogen solid fuels. To minimize the effect of nitrogen, this work introduces a co-hydrothermal carbonization method involving alkali (A), ultrasonic cell disruptor (UCC), and sodium dodecyl sulfate (SDS) for both individual and combined pretreatment of SS and PET. Comparative analysis of the products shows that the combined pretreatment with sodium dodecyl sulfate (SDS) and alkali (A) effectively disrupts the SS cell structure, leading to the loosening of stable extracellular polymeric substances (EPS). This condition is conducive to the release and hydrolysis of proteins during hydrothermal carbonization. Moreover, under conditions where PET serves both as an acid producer and a carbon source, and through parameter optimization at a temperature of 240 °C, reaction time of 2 h, PET addition of 20 wt%, and water addition of 0.6 g cm-3, a high-quality, low-nitrogen clean solid fuel was produced (N: 0.51 wt%, C: 19.10 wt%).

Efficiency Investigation of Coffee Production Waste Drying by Filtration Method

This article presents the results of determining the technologically feasible parameters of filtration drying of coffee production waste based on experimental data on the kinetics of material drying and the hydrodynamics of thermal agent filtration. The lowest total energy costs were observed with the following process parameters: the material layer height of 120 mm, the thermal agent temperature of 90 °C, the velocity through the stationary layer of 1.76 m/s, and the specific energy consumption of 5857 kJ per 1 kg of water. Based on the determined technologically feasible process parameters, an evaluation of the filtration drying method for coffee production waste was performed at an industrial installation. According to the calculation, using the filtration method, 1164 kW h of energy was required to dry about 1000 kg of coffee production waste. A total energy of about 1.65 kW h/kg was required to remove 1 kg of moisture from the material in an industrial filtration drying installation. The results were compared with a drying material with similar initial parameters. It was calculated that to dry 1000 kg of coffee production waste in a rotary dryer, it is necessary to spend about 1625 kW h, and the total energy consumption for removing 1 kg moisture from the studied material is approximately 2.37 kW h/kg. Thus, for a similar output of about 1000 kg/h, filtration drying can reduce energy consumption by about 465 kW·h and reduce the required drying time by more than 20 times. The overall economic effect of using the filtration drying method in industry is expected to be higher, given the significant heat losses to the environment for a rotary dryer due to its large size, long drying time, design features, and the need for energy-intensive auxiliary equipment. After calculating the energy consumption per 1 kg of dry material, it is necessary to spend 12 950 kJ/kg of dry matter, about 41.5 % less than the higher calorific value for experimental samples of briquetted solid fuel made from this material. This result makes it economically feasible to further dry coffee production waste to produce alternative solid fuels.

Household air pollution exposure and risk of tuberculosis: a case–control study of women in Lilongwe, Malawi

IntroductionGlobally, 3–4 billion people rely on solid fuels for cooking, and 1 billion use kerosene to light their homes. While household air pollution (HAP) emitted from burning these fuels has...

Hydrogen storage as liquid solar fuels

This review article focuses on catalytic interconversion between hydrogen and liquid or solid solar fuels using metal complexes as redox catalysts.

CHEMICAL STABILITY OF CELLULOSE NITRATES: REVIEW

The results of the analysis of literature data on updated methods for determining the chemical stability of cellulose nitrates are presented. The relevance of research is due to the need to control the operation and storage of a widespread component of solid rocket fuels and explosive compositions. The criterion for chemical resistance is the value of the decomposition rate or the time dependence of the degree of decomposition of the sample. It is shown that methods for assessing the chemical resistance of cellulose nitrates are based on determining the rate of its thermal decomposition, which is measured by a specific parameter accompanying decomposition. These parameters include weight loss, amount of gaseous decomposition products released, decomposition temperature or thermal effects. Studies are carried out at elevated temperatures and allow you to control the magnitude or rate of change in the parameter that accompanies thermal decomposition. The possibility of using modern analytical methods for evaluating chemical resistance is shown: differential scanning calorimetry, thermogravimetric analysis, chemiluminescent analysis, infrared spectroscopy, high-performance liquid and thin-layer chromatography, gas chromatography, electron paramagnetic resonance, mass spectrometry, X-ray diffraction analysis. The preference for methods of differential scanning calorimetry or differential thermal analysis is substantiated. The results of studies on improving the chemical resistance of cellulose nitrates and compositions based on it with the use of new stabilizers of the aniline series, stabilizers of natural origin with the advantage of the latter on the examples of curcumin and lignins are presented. Due to the insufficient stability of cellulose nitrates, stabilizers added to the formulation of explosive compositions lengthen the induction period of the decomposition of nitro compounds and do not allow the development of the autocatalytic decomposition stage. Methods for determining the chemical stability of cellulose nitrates obtained from alternative sources of raw materials are presented. For citation: Vdovina N.P., Korchagina А.А., Budaev I.А. Chemical stability of cellulose nitrates: Review. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 5. P. 6-20. DOI: 10.6060/ivkkt.20236605.6725.

Analyzing technological alternatives of solid and gaseous fuels for iron ore compact sintering machines applying a multiphase mathematical modeling

Analyzing technological alternatives of solid and gaseous fuels for iron ore compact sintering machines applying a multiphase mathematical modeling

Discussion on Torrefaction Parameters for Making the Refuse-Derived Fuels by Response Surface Methodology

The torrefaction process is one of the mild pyrolysisor the low-temperature carbonization, which is a thermochemical conversion in which biomass is heated in an inert or nitrogen atmosphere, and the temperature ranges from 200°C to 300°C. It is considered to be an effective pretreatment method to make solid fuels. This study utilizes low-temperature carbonization technology to improve the combustion efficiency of solid-derived fuel (RDF-5) made from biomass. In this experiment, a tubular furnace was used to feed nitrogen gas for 15 min, and four raw materials of pennisetum, rice straw, wood chips and Camellia seed cakes were fed. The analysis was carried out, and the effects of temperature and residence time on the calorific value, energy yield and energy density of the four raw materials were explored using response surface methodology (RSM). It can be seen from the experimental results that among the four raw materials, the carbon content and calorific value of Camellia seed cakes are the highest. Elemental analysis showed that the proportions of nitrogen and sulfur in these four raw materials are very low. These four substances were understood to be suitable to be refuse-derived fuels (RDF-5). Comparing the calorific value of the four kinds of biomass after torrefaction process, the calorific value of pennisetum, Camellia seed cakes, wood chips and rice straw increased by 42.5%, 38.7%, 52.7%, and 18.6%, respectively. These findings revealed that the higher temperature and the longer residence time, the smaller energy yield and the higher energy density.