A Comprehensive Technical, Environmental, Economic, and Bibliometric Assessment of Hydrogen Production Through Biomass Gasification, Including Global and Brazilian Potentials

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors address a relevant topic regarding profound advances in hydrogen production through biomass gasification. While the manuscript holds a lot of aspects relevant to the topic, the authors completely failed to adress one of the main review  articles that already dealt with a lot of these issues before.

An overview of advances in biomass gasification (2016)
https://doi.org/10.1039/C6EE00935B

The authors did not even notice this publication exists... with over 431 references.

From an outstanding perspective, this former review should be intensively studied and key issues should be integrated regarding a comparison of previous works & findings as well as the authors present perspective. Otherwise a sufficicient depth is not available regarding publication.

 

Comments on the Quality of English Language

Please make sure a native-speaker once more reviews the final manuscript.

Author Response

Dear Editor and reviewers,

We would like to thank the reviewers for their crucial and constructive criticism, which significantly improved our work's scientific quality. Please find below the answers to their comments, suggestions and questions. For ease of reference, all modifications were marked in yellow to Reviewer #1, green to Reviewer #2, and blue to Reviewer #3, in the revised manuscript version (V2_sustainability-3121919_manuscript_Revised-Done), attached.

Reviewer #1:

Comments and Suggestions for Authors:

• The authors address a relevant topic regarding profound advances in hydrogen production through biomass gasification. While the manuscript holds a lot of aspects relevant to the topic, the authors completely failed to address one of the main review articles that already dealt with a lot of these issues before. An overview of advances in biomass gasification (2016) - https://doi.org/10.1039/C6EE00935B. The authors did not even notice this publication exists... with over 431 references.

Thank you for your comment. The article “An overview of advances in biomass gasification (2016)” is indeed a very interesting review that currently has 986 citations. The reason it didn't appear in our bibliometric analysis was that we only presented three more recent papers with the greatest impact, which have at least 1000 citations. However, this article is an excellent reference, so it has been added to the topic in which it best fits (lines 260 and 255), since it corroborates           the proposals.

• From an outstanding perspective, this former review should be intensively studied and key issues should be integrated regarding a comparison of previous works & findings as well as the authors present perspective. Otherwise a sufficient depth is not available regarding publication.

Thank you for your comment. Previous studies were evaluated and compared with the proposed study on several topics, please see the revised paper ().

 

• Please make sure a native-speaker once more reviews the final manuscript.

Thank you for your comment. The work has been sent for a careful revision of the English. Throughout the text you may notice markings “like this” on isolated words or phrases that were not mentioned in your corrections, these represent changes made from the English.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The author's research is interesting. Parts 2-6 of this paper are also based on the analysis of literature. What is the significance of Part 7 separately? In addition, is it necessary to adjust the structure of the article and advance the bibliometric measurement? Some other questions are as follows:

1. Technology, economy and solid biomass are the three indicators. However, bibliometric results are the current global practice. The reviewers felt that they should not be equivalent, so line 23 of the abstract is ambiguous. The author's novelty should be the innovation of method or technology, which should not be confused. Please modify it further.

2. Keywords should reflect the characteristics of the research and be ranked in order of importance. For example, judging from the title and abstract, bibliometric is innovative, but no authors have listed it.

3. Does the world not include Brazil? Why put Brazil alone alongside the rest of the world?

4. Judging from the content presented in lines 56-87 of the introduction, the content expressed by the author in the title and abstract is not perfect, and there are some differences. It is suggested that the author re-examine the content of the research and revise the title and abstract.

5. What does the white ○ in Figure 1 represent?

6. The reference proposals in Figure 2 are listed in the corresponding position, not the map name.

7. Notice that 2 is displayed as a subscript in H2. Other chemical formulas look something like this. Please revise it in full.

8. “d) [31.], [36]” in Figure 5 should be changed here.

9. The conclusions are divided into sections. Each article shows the key results of this study.

Author Response

Dear Editor and reviewers,

We would like to thank the reviewers for their crucial and constructive criticism, which significantly improved our work's scientific quality. Please find below the answers to their comments, suggestions and questions. For ease of reference, all modifications were marked in yellow to Reviewer #1, green to Reviewer #2, and blue to Reviewer #3, in the revised manuscript version (V2_sustainability-3121919_manuscript_Revised-Done), attached.

Reviewer #2:

Comments and Suggestions for Authors

The author's research is interesting. Parts 2-6 of this paper are also based on the analysis of literature. What is the significance of Part 7 separately? In addition, is it necessary to adjust the structure of the article and advance the bibliometric measurement? Some other questions are as follows:

Thank you for your comment. Bibliometric analysis was applied in order to observe the main topics (keywords, titles, highlights, etc.) of research related to biomass gasification for hydrogen production. However, the evaluation of the literature for this route is different from the evaluation of methods and results proposed in the other topics (2-6). Bibliometric analysis is essential for understanding which topics have been pertinent to past studies and which will guide future research. After careful analysis, it was found that it would be better suited as an introductory topic to the others, so the bibliometric analysis was moved to topic 4.1, please see the revised paper.

1. Technology, economy and solid biomass are the three indicators. However, bibliometric results are the current global practice. The reviewers felt that they should not be equivalent, so line 23 of the abstract is ambiguous. The author's novelty should be the innovation of method or technology, which should not be confused. Please modify it further.

Thank you for your comment. The abstract has been changed to make it as clear as possible.

2. Keywords should reflect the characteristics of the research and be ranked in order of importance. For example, judging from the title and abstract, bibliometric is innovative, but no authors have listed it.

Thank you for your comment. The keywords have been changed.

3. Does the world not include Brazil? Why put Brazil alone alongside the rest of the world?

It was assessed that Brazil has an excellent potential for hydrogen production through solid biomass, since it has a potential of 23% of the world's potential.  In addition to its great availability of land and waste. So it's essential to emphasize it. (Lines 457-461).

4. Judging from the content presented in lines 56-87 of the introduction, the content expressed by the author in the title and abstract is not perfect, and there are some differences. It is suggested that the author re-examine the content of the research and revise the title and abstract.

Thanks for your comment, the title and summary have been revised. Please note in the revised file.

5. What does the white ○ in Figure 1 represent?

Thank you for your comment. The white ○ in Figure 1 represents biomass particles.

6. The reference proposals in Figure 2 are listed in the corresponding position, not the map name.

Thank you for your comment. The Figure 2 is based on information from: [16], [17], [18], [19], [20], [21], but not necessarily in that order. The caption has been changed to make it more accurate.

7. Notice that 2 is displayed as a subscript in H2. Other chemical formulas look something like this. Please revise it in full.

Thank you for your comment. The manuscript has been revised in detail.

8. “d) [31.], [36]” in Figure 5 should be changed here.

Thank you for your comment. The reference has been corrected.

9. The conclusions are divided into sections. Each article shows the key results of this study.

Thank you for your comment. Yes, that's it.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The paper reviews the production of hydrogen from biomass sources. It concentrates on the various available techniques ad it considered output. Furthermore it presents two short calculations of global and regional (Brazil) potentials. And there is finally a bibliometrics analysis of the current literature of the subject.

To my opinion the review may present a review not yet presented in that details by other authors. But it is certainly not the first review on this subject. 

The assessment of global and regional potential is very rough and I miss a comparison with other pathways of energy conversion of these raw materials. The conversion to hydrogen makes much less use of the energy content of the biomass such that other routes of conversion may much more efficient. Furthermore, as at current there is a lot of discussion about using biomass for energy purposes these assessments are certainly to optimistic. The authors should at least discuss these aspects.

The bibliometric analysis is nice but the implications for the current and further research should be discussed. In Fig. 8 there is a large green dot between Malaysia and Italy which is not named. 

Author Response

Dear Editor and reviewers,

We would like to thank the reviewers for their crucial and constructive criticism, which significantly improved our work's scientific quality. Please find below the answers to their comments, suggestions and questions. For ease of reference, all modifications were marked in yellow to Reviewer #1, green to Reviewer #2, and blue to Reviewer #3, in the revised manuscript version (V2_sustainability-3121919_manuscript_Revised-Done), attached.

Reviewer #3:

Comments and Suggestions for Authors

The paper reviews the production of hydrogen from biomass sources. It concentrates on the various available techniques ad it considered output. Furthermore, it presents two short calculations of global and regional (Brazil) potentials. And there is finally a bibliometric analysis of the current literature of the subject. To my opinion the review may present a review not yet presented in that details by other authors. But it is certainly not the first review on this subject.  The assessment of global and regional potential is very rough and I miss a comparison with other pathways of energy conversion of these raw materials. The conversion to hydrogen makes much less use of the energy content of the biomass such that other routes of conversion may much more efficient. Furthermore, as at current there is a lot of discussion about using biomass for energy purposes these assessments are certainly to optimistic. The authors should at least discuss these aspects.

Thank you for your comments. There are indeed some other routes for biomass energy conversion, but the point is in the case of hydrogen production by other routes, even if they are sustainable, the process is costly, whereas biomass is expected to be cheaper. Therefore, biomass could be an asset in supporting the energy transition of countries that, for example, need to power their cars with renewable fuels.

Here are some other possible advantages of the biomass to hydrogen route:

• Lower cost of H₂ than when obtained through electrolysis using green electricity.
• The possibility to storage biomass H₂ for further utilization in fuel cells to compensate the variability of renewable sources.
• Conversion efficiencies to H₂ are higher than the ones to electricity and biofuels.

Please see (Lines 322-327).

The bibliometric analysis is nice but the implications for the current and further research should be discussed. In Fig. 8 there is a large green dot between Malaysia and Italy which is not named.

Thank you for your comment. From the bibliometric analysis it can be inferred that obtaining hydrogen by gasifying biomass is a current topic, which includes important issues such as the use of catalysts, steam as a gasification agent, process simulation, life cycle analysis, CO2 capture, the steam reforming process, gasification in supercritical water, pyrolysis. The concentration of research on the subject in just a few countries makes it necessary to encourage the implementation of international projects on the subject (Lin-587). In addition, correlations between the main researchers on the topic of biomass gasification can also be observed (topic 4), thus providing a broad overview of the best in the field (Lin-263). The Fig.8, now Fig 7 has been rectified (Lin-287).

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript has been considerably improved by following the comments and suggestions of the reviewers.