Sustainable Solutions for Energy Production from Biomass Materials
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this paper, the authors investigate the combustion behavior of mixed pellets made from wood and sunflower husks, comparing it to that of pure wood and sunflower pellets. The thermal properties of the pellets were analyzed by the thermal analysis methods to reveal the potential for sustainable utilization of waste biomass-based pellets based on the thermal properties of the raw materials. This process was an effective way to provide a reliable and sustainable energy source and realize resource utilization of sunflower husks and wood biomass. This manuscript can be accepted for publication after minor revision.
1) Figures and captions on a single line should be centered.
2) The process of sample preparation mentioned in line 188 should be described in more detail.
3) In Section 2.2, specifically lines 216 to 217, please clarify why do the authors only use the heating rates of 5°C/min and 10°C/min.
4) The illustrations in Fig 2 to Fig 7 lack clarity and visual appeal, the author should to revises these figures to enhance their overall quality and improve the clarity of the information presented.
5) The bottom line of table 3 has a vacancy, the author should improve it.
6) In Section3, Figures 2 to 7 should be reformatted to more clearly highlight the effects of different heating rates.
7) In Section 4，the language used to cite references is not sufficiently precise, which needs to be modified by the authors.
8) In Reference, the year in line 429 should be bolded and the author needs to revise it.
9) The article is clearly written, but there are still a few errors in the text, please go through the manuscript and correct grammar and language mistakes.
Comments on the Quality of English LanguageThe article is clearly written, but there are still a few errors in the text, please go through the manuscript and correct grammar and language mistakes.
Author Response
First, we would like to thank the reviewer for the thoughtful comments and efforts towards improving our manuscript. We believe that in the following, we managed to highlight the general concerns of the reviewer and tried to address these concerns. We address comments to the reviewer below:
Comment 1: Figures and captions on a single line should be centered.
Response 1: Thank you very much for pointing this out. Following the provided by the journal Microsoft Word template the figures are left-aligned as the captions are justified. All figures and captions are formatted based on the above.
Comment 2: The process of sample preparation mentioned in line 188 should be described in more detail.
Response 2: We agree with this comment. We have modified the paragraph to emphasize this point. The following text was added “Why is it necessary to mix different hardness types of waste biomass? The combination of soft and hardwood in the pellets’ production process provides better technical characteristics and improves the energy value of the product. Softwood contributes to better bonding, which is the reason for the higher calorific value, while hardwood provides greater density and pellets stability. Using both types of wood together achieves a balance between easy ignition and continuous burning. Sunflower husks were chosen for the mixed pellets production due to their higher calorific value and low cost, as the end product of sunflower peeling for oil production. They are cost-effective and sustainable and are classified as a preferred material in the biofuel industry. In addition, the flakes provide good structure and density to the pellets, which improves their combustion efficiency. The 3:1 mixture of wood and sunflower husks was chosen because it guarantees optimal efficiency in the combustion process and ensures high pellet quality. It also gives good density, stable binding, and balanced calorific value, resulting in a longer and more efficient combustion. In addition, the combination of the two materials also has a positive environmental effect, due to the smaller amount of ash output.”.
Comment 3: In Section 2.2, specifically lines 216 to 217, please clarify why do the authors only use the heating rates of 5°C/min and 10°C/min.
Response 3: Thank the reviewer for the insightful comment. We agree with this comment and completed the paragraph with the following text: “The thermal stability of each type of pellet has been tested multiple times. Validation of the results obtained is based on several experimental studies and subsequent statistical processing. The analyses were conducted at two heating rates - 5°C/min and 10°C/min - with heating up to 750°C. The lower heating rate (5°C/min) was selected because of the lower chemical reaction time that highlighted the course of the phase transitions or decomposition processes. The higher heating rate (10°C/min) shortens the experiment time and simulates a faster reaction process. The proposed rates offer a balance between studying thermal processes and providing enough time to observe key changes while maintaining the duration of the experiment in a reasonable time span. The experimental studies show that a temperature of 750°C can be considered as an upper limit temperature because it is high enough to cover all the main stages of thermal decomposition of the organic components and combustion of the residual material. At lower temperatures, decomposition processes may not be fully completed, while at higher temperatures, undesirable additional reactions or excessive oxidation may occur.”
Comment 4: The illustrations in Fig 2 to Fig 7 lack clarity and visual appeal, the author should to revises these figures to enhance their overall quality and improve the clarity of the information presented.
Response 4: We agree with this comment. The figure's axes have been scaled for better appearance. Figures 4 and 7 y-axes have been also adjusted. The updated version of the figures took place in the revised version of the manuscript.
Comment 5: The bottom line of table 3 has a vacancy, the author should improve it.
Response 5: Agree! We have accordingly modified the Table 3 appearance in the revised version of the manuscript.
Comment 6: In Section 3, Figures 2 to 7 should be reformatted to more clearly highlight the effects of different heating rates.
Response 6: We agree with this comment. The figure's axes have been scaled for better appearance, especially those related to the different heating rates.
Comment 7: In Section 4，the language used to cite references is not sufficiently precise, which needs to be modified by the authors.
Response 7: We thank the reviewer for this comment. We modified the language for a better understanding of the cited text. The chances are traceable in the revised version of the manuscript.
Comment 8: In Reference, the year in line 429 should be bolded and the author needs to revise it.
Response 8: We agreed with this comment. The cited reference was revised.
Comment 9: The article is clearly written, but there are still a few errors in the text, please go through the manuscript and correct grammar and language mistakes.
Response 9: Thank you for the comment. A few mistakes have been corrected in the text as well as English language was revised.
Reviewer 2 Report
Comments and Suggestions for AuthorsDear Authors,
The topic of the work is current and interesting. You have presented numerous results, although I would like to make a few suggestions and remarks about your work.
Change and modify the title of the work itself. Biomass itself is waste
It is mandatory to shorten the introductory part of the paper. Be concise.
Why did you use the ratio of soft and hard wood and not individually? why sunflower And why the ratio 3:1? there must be a rationale for taking and examining samples.
Briefly write how pellet samples 1,2,3,4,5 were obtained
You did TG, DSC and DTA at 5°C/min and 10°C/min, why at those speeds? why didn't you take one or two more speeds to do chemical kinetics? Why did you go up to 750 C and not at a lower or higher temperature.
It is mandatory to do the content, the percentage of which your initial samples consist of. That is, to do the ultimate and proximate analysis.
It is mandatory to perform another analysis, the method of testing your samples (FTIR, SEM, EDS, XRD).
I did not see a specific purpose, goal and application of your results and work in your work.
Author Response
First, we would like to thank the reviewer for the thoughtful comments and efforts towards improving our manuscript. We believe that in the following, we managed to highlight the general concerns of the reviewer and tried to address these concerns. We address comments to the reviewer below:
Comment 1: Change and modify the title of the work itself. Biomass itself is waste
Response 1: We agree with the reviewer’s suggestion. To avoid any kind of waste products we changed the name of the paper as follows “Sustainable solutions for energy production from biomass materials”
Comment 2: It is mandatory to shorten the introductory part of the paper. Be concise.
Response 2: We agree with this comment. The introduction section was shortened. The changes are traceable in the revised version of the manuscript.
Comment 3: Why did you use the ratio of soft and hard wood and not individually? why sunflower And why the ratio 3:1? there must be a rationale for taking and examining samples.
Response 3: Thank the reviewer for the insightful comment. We agree with this comment and completed the paragraph with the following text: Why is it necessary to mix different hardness types of waste biomass? The combination of soft and hardwood in the pellets’ production process provides better technical characteristics and improves the energy value of the product. Softwood contributes to better bonding, which is the reason for the higher calorific value, while hardwood provides greater density and pellet stability. Using both types of wood together achieves a balance between easy ignition and continuous burning. Sunflower husks were chosen for the mixed pellets production due to their higher calorific value and low cost, as the end product of sunflower peeling for oil production. They are cost-effective and sustainable, and are classified as a preferred material in the biofuel industry. In addition, the flakes provide good structure and density to the pellets, which improves their combustion efficiency. The 3:1 mixture of wood and sunflower husks was chosen because it guarantees optimal efficiency in the combustion process and ensures high pellet quality. It also gives good density, stable binding, and balanced calorific value, resulting in a longer and more efficient combustion. In addition, the combination of the two materials also has a positive environmental effect, due to the smaller amount of ash output.
Comment 4: Briefly write how pellet samples 1,2,3,4,5 were obtained
Response 4: Thank the reviewer for the insightful comment. I would like to point out that those pellets are commercial ones i.e. produced by different manufacturers. They all observed the regulation of pellet production. Following this, the additional paragraph in the manuscript was added: “Pellet 1 type is made of 60% of SW and 40 of HW. Pellet 2 type is 70% SW and 30% HW. Pellet 3 type is a mix between 70% SW and 30% SH. Pellet 4 and 5 types are made of 100 SH different types. The producers of the discussed above pellets are using the standardized production methodology. The raw material is initially crushed to the specified size after which the crushed material is dried to the specified moisture content. Next comes a mixing process (for pellets that are made up of two types of material), followed by a pelletizing process.”
Comment 5: You did TG, DSC and DTA at 5°C/min and 10°C/min, why at those speeds? why didn't you take one or two more speeds to do chemical kinetics? Why did you go up to 750 C and not at a lower or higher temperature.
Response 5: Thank the reviewer for the insightful comment. We agree with this comment and completed the paragraph with the following text: “The thermal stability of each type of pellet has been tested multiple times. Validation of the results obtained is based on several experimental studies and subsequent statistical processing. The analyses were conducted at two heating rates - 5°C/min and 10°C/min - with heating up to 750°C. The lower heating rate (5°C/min) was selected because of the lower chemical reaction time that highlighted the course of the phase transitions or decomposition processes. The higher heating rate (10°C/min) shortens the experiment time and simulates a faster reaction process. The proposed rates offer a balance between studying thermal processes and providing enough time to observe key changes while maintaining the duration of the experiment in a reasonable timespan. The experimental studies show that a temperature of 750°C can be considered as an upper limit temperature because it is high enough to cover all the main stages of thermal decomposition of the organic components and combustion of the residual material. At lower temperatures, decomposition processes may not be fully completed, while at higher temperatures, undesirable additional reactions or excessive oxidation may occur.”
Comment 6: It is mandatory to do the content, the percentage of which your initial samples consist of. That is, to do the ultimate and proximate analysis.
Response 6: Thank the reviewer for the insightful comment. I would like to point out that those pellets are commercial ones i.e. produced by different manufacturers. They all observed the regulation of pellet production. Following this, the additional paragraph in the manuscript was added: “Pellet 1 type is made of 60% of SW and 40 of HW. Pellet 2 type is 70% SW and 30% HW. Pellet 3 type is a mix between 70% SW and 30% SH. Pellet 4 and 5 types are made of 100 SH different types. The producers of the discussed above pellets are using the standardized production methodology. The raw material is initially crushed to the specified size after which the crushed material is dried to the specified moisture content. Next comes a mixing process (for pellets that are made up of two types of material), followed by a pelletizing process.” No additional chemical analyses of the samples have been made.
Comment 7: It is mandatory to perform another analysis, the method of testing your samples (FTIR, SEM, EDS, XRD).
Response 7: Thank you for your comments. It is planned to perform additional studies, according to the proposed methods (FTIR, SEM, EDS, XRD), but they will be presented in a separate study.
Comment 8: I did not see a specific purpose, goal and application of your results and work in your work.
Response 8: Thank you very much for your comment. The advantage of the present work is actually to predict the temperature behavior of the pellets based on the composition of the samples. This is important both for their thermal efficiency and for the quality of the combustion process, which also has an environmental impact. Subsequent research will help to create a methodology for preparing a mix of pellets depending on their subsequent use. A paragraph was added in the conclusion section.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe study is the experimental investigation of mixed pellets made from wood and sunflower husks and the comparison of their combustion behavior with that of wood and sunflower pellets using thermal analysis methods. They blend the advantages of both types of biomasses, offering high-efficiency and environmentally friendly fuels. However, there are some issues should be discussed.
1. What is the necessity of the first paragraph of the introduction?
2. The whole introduction is too much and needs to be condensed.
3. In the experimental section, whether the thermal stability of each Pellet was tested multiple times, or only once, needs to be stated by the authors.
4. The author explains the reason for the change of the thermal stability curve in the result discussion section, and the corresponding temperature nodes should be marked in the figure. For example, lines 255-258.
5. Line 266: What exactly is “the point of ignition temperature”?
6. Line 291: “Table shows” should be “Table 2 shows”.
7. Table 3 is not fully displayed and needs to be redrawn.
8. Please modify the reference format as required by the journal.
Comments on the Quality of English LanguageAttention needs to be paid to the consistency of the language.
Author Response
First, we would like to thank the reviewer for the thoughtful comments and efforts towards improving our manuscript. We believe that in the following, we managed to highlight the general concerns of the reviewer and tried to address these concerns. We address comments to the reviewer below:
Comment 1: What is the necessity of the first paragraph of the introduction?
Response 1: We agree with this comment. The introduction section was improved based on the reviewers’ comments. The changes in the revised version of the manuscript are traceable via the word track-changes tool.
Comment 2: The whole introduction is too much and needs to be condensed.
Response 2: We agree with this comment. The introduction section was improved based on the reviewers’ comments, and also shortened. The changes in the revised version of the manuscript are traceable via the word track-changes tool.
Comment 3. In the experimental section, whether the thermal stability of each Pellet was tested multiple times, or only once, needs to be stated by the authors.
Response 3: Thank the reviewer for the insightful comment. The next paragraph explaining the experimental trials for pellets’ thermal stability was added in the manuscript: “For each of the five samples, experimental tests were performed to determine the temperature stability. Each of the samples was tested 15 times for thermal stability, and the results were processed (multifactorial experiment) and took place in the figures below.”
Comment 4. The author explains the reason for the change of the thermal stability curve in the result discussion section, and the corresponding temperature nodes should be marked in the figure. For example, lines 255-258.
Response 4: Thank you very much for pointing this out! The exodermis and endodermic regions are added to the figure to show the respective processes. Also, an additional explanation is added in the main body of the manuscript.
Comment 5. Line 266: What exactly is “the point of ignition temperature”?
Response 5: Thank you for the comment. The ignition temperature is also known as the ignition point. It is the temperature at which any substance may catch fire and start burning. The following adjustment of the text is made “At the moments where the value of ignition temperature is reached (fuel ignition point), the peak of maximum mass loss is also reached, and thereafter, minimal to no further mass loss is observed until the end of the experiment.”
Comment 6. Line 291: “Table shows” should be “Table 2 shows”.
Response 6: We agree with this comment. The table number is added.
Comment 7. Table 3 is not fully displayed and needs to be redrawn.
Response 7: Thank you for this comment. We fully agreed. The table borders are displayed in the revised version of the text.
Comment 8. Please modify the reference format as required by the journal.
Response 8: We fully agreed. All the references have been double-checked and the necessary adjustments in terms of journal guidelines have been made.
Reviewer 4 Report
Comments and Suggestions for AuthorsThe authors revealed the possibilities of sustainable usage of pellets produced from waste biomass based on the thermal properties of the processed raw material. The experimental study provides different sights for readers. Please see my some suggestions.
1. Please add some key numerical results into abstract.
2. Could you please write the current challenges/limitations as a tabular form after literature review to easily understand by readers?
3. Figures 4 and 7: Please re-scale the y-axis.
4. You should use more numerical results or statistical intervals while explaining the results. Thus, your investigation will be more powerful.
5. If it is possible, could you please compare your study with other studies to easily demonstrate its advantages.
6. Please add future scope and significance of the current study in the conclusion section.
Author Response
First, we would like to thank the reviewer for the thoughtful comments and efforts towards improving our manuscript. We believe that in the following, we managed to highlight the general concerns of the reviewer and tried to address these concerns. We address comments to the reviewer below:
Comment 1. Please add some key numerical results into abstract.
Response 2: Thank the reviewer for the useful comment. The following paragraph was added in the abstract section: “In addition, the outputs from the study reveal that pellets composed of wood reduce their mass the most at temperatures in the range of 310 up to 323 oC. In comparison, the mass loss of sunflower husk pellets is 35.6 %/℃ (at 5 ℃/min temperature gradient) less compared to wood pellets and about 42 %/℃ at 10 ℃/min temperature gradient.”
Comment 2. Could you please write the current challenges/limitations as a tabular form after literature review to easily understand by readers?
Response 2: Thank you very much for pointing this out! An additional paragraph and table in the introduction section have been added in the revised version of the manuscript.
Comment 3. Figures 4 and 7: Please re-scale the y-axis.
Response 3: We agree with this comment. The figure's axes have been scaled for better appearance. Figures 4 and 7 y-axes have been also adjusted. The updated version of the figures took place in the revised version of the manuscript.
Comment 4. You should use more numerical results or statistical intervals while explaining the results. Thus, your investigation will be more powerful.
Response 4: Thank you very much for your comment. In the discussion section, we have compared the obtained results with those from the literature survey. An accurate comparison can only be made in cases of the identity of the samples. The samples studied in the work were taken from commercial manufacturers and are available in the market. The main objective was to compare the thermal behavior as well as the energy value of pellets composed of sunflower husk and a mix of sunflower husk and wood waste material. The focus was the identification of exothermic and endothermic peaks, which were compared with one from the literature study using very similar composition pellet samples. The behavior of the curves is analogous, with differences being observed only in the limits of the temperatures at which the respective processes start, as well as the amount of moisture released, which is a function of the type and quality of the pellets. The authors believe that an analogy can be sought in terms of the type of curves, due to the impossibility of comparing identical samples, which is why such a comparison is not presented in the work.
Comment 5. If it is possible, could you please compare your study with other studies to easily demonstrate its advantages.
Response 5: Thank you very much for your comment. The advantage of the present work is actually to predict the temperature behavior of the pellets based on composition of the samples. This is important both for their thermal efficiency and for the quality of the combustion process, which also has its environmental impact. Subsequent research will help to create a methodology for preparing a mix of pellets depending on their subsequent use.
Comment 6. Please add future scope and significance of the current study in the conclusion section.
Response 6: Thank you for the comment. The following paragraph was added to comply with the reviewer’s comment: “Although the majority of pellets (mix) on the market are in ratios analogous to those examined in the paper, future research will be oriented at testing mix pellets in different ratios. This will allow us to analyze more precisely the temperature stability of the pellets, and from there to make conclusions about their calorific value and the amount of ash content. Additional experimental studies using (FTIR, SEM, EDS, XRD) are also planned, with the help of which it will be possible to create a methodology that prescribes the production of pellets in different ratios about their application. This, in turn, will allow more efficient use of the energy potential of the input raw material, as well as have a favorable impact on the environment as a result of the reduced ash content.”
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsIt can be accepted.
