Biorefinery Based on Multiple Raw Materials and Wastes for the Production of Energy: A Proposal Tailored to Southwestern Europe

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript "Biorefinery Based on Multiple Raw Materials: Possibilities of 3 Interconnection" postulates the possibility of implementation of a biorefinery based on multiple raw materials, thus mitigating environmental concerns and leading to effective management of agro-industrial waste. It also targets to improve the efficiency of the energy/products obtained.

The authors have comprehended all the literature available wrt development of biorefineries using inexpensive feedstock and targeting to achieve sustainable development goals.

Whereas several literature has been taken into account, I think the key advancements shown in published patents have not been incorporated.

The postulated lab scale biorefineries for concomitant production of 2 or more products using biorefinery have been missed, but such attempts could lead to cutting down production costs. (e.g. Singh G, et al. Concomitant Production of Lipids and Carotenoids in Rhodosporidium toruloides under Osmotic Stress Using Response Surface Methodology. Front Microbiol. 2016 25;7:1686; Cassamo U. Mussagy, et al. 2022. A look into Phaffia rhodozyma biorefinery: From the recovery and fractionation of carotenoids, lipids and proteins to the sustainable manufacturing of biologically active bioplastics, Bioresource Technology, 362:127785)

The novelty is not very well stated. The idea behind this comprehension is not clear and should be enforced in the conclusion. What was the problem in existing ideas of biorefinery and what else should be done according to authors to make it a successful technology.

The review talks about many technological advances. It is improbable to include several modules together as all these have their own drawbacks!

Authors might ty to explain how they plan to mitigate drawbacks of the said technologies.

Smaller issues:

I dont agree with the topics: . Different components of the proposed biorefinery;  The proposed biorefinery and Discussion

It should be 'Components of the proposed biorefinery'; advanages/ drawbacks of the proposed biorefinery....

and so on....

 

Author Response

Dear reviewer,

First of all, thank you for your thorough review and comments. Our answers are the following:

1. The manuscript "Biorefinery Based on Multiple Raw Materials: Possibilities of 3 Interconnection" postulates the possibility of implementation of a biorefinery based on multiple raw materials, thus mitigating environmental concerns and leading to effective management of agro-industrial waste. It also targets to improve the efficiency of the energy/products obtained. The authors have comprehended all the literature available wrt development of biorefineries using inexpensive feedstock and targeting to achieve sustainable development goals. Whereas several literature has been taken into account, I think the key advancements shown in published patents have not been incorporated.

We have added a table with some representative patents related to the implementation of biorefineries.

2. The postulated lab scale biorefineries for concomitant production of 2 or more products using biorefinery have been missed, but such attempts could lead to cutting down production costs. (e.g. Singh G, et al. Concomitant Production of Lipids and Carotenoids in Rhodosporidium toruloidesunder Osmotic Stress Using Response Surface Methodology. Front Microbiol. 2016 25;7:1686; Cassamo U. Mussagy, et al. 2022. A look into Phaffia rhodozyma biorefinery: From the recovery and fractionation of carotenoids, lipids and proteins to the sustainable manufacturing of biologically active bioplastics, Bioresource Technology, 362:127785).

These references and examples have been added to the final text.

3. The novelty is not very well stated. The idea behind this comprehension is not clear and should be enforced in the conclusion. What was the problem in existing ideas of biorefinery and what else should be done according to authors to make it a successful technology.

The novelty of this work is an example of biorefinery based on multiple wastes, adapted to our context but also applicable to other scenarios. We have stated this fact in the introduction section. Also, in the conclusion section, we have stated this fact as the first conclusion, whereas the problems and their possible solutions were included in the last paragraph.

4. The review talks about many technological advances. It is improbable to include several modules together as all these have their own drawbacks! Authors might ty to explain how they plan to mitigate drawbacks of the said technologies.

We have talked about this issue in a new subsection called “3.2. Challenges related to biorefinery implementation”, including a new conclusion too. You are right that each process has its own pros and cons, but some of them, such as the generation of a certain waste, can be an offset if the suitable technology is used to valorize this waste. In any case, let’s not forget that this is only a proposal, and further studies and developments should be accomplished to solve the different challenges commented on the text.

5. Smaller issues:

I dont agree with the topics: . Different components of the proposed biorefinery;  The proposed biorefinery and Discussion

It should be 'Components of the proposed biorefinery'; advanages/ drawbacks of the proposed biorefinery....

and so on....

We have changed these terms in the title of the corresponding section. Thank you for your recommendation!

 

Again, thank you so much for your rewarding comments and sincerely,

Dr. Sergio Nogales Delgado.

Reviewer 2 Report

Comments and Suggestions for Authors

Nogales-Delgado et al had a view on Biorefinery Based on Multiple Raw Materials: Possibilities of Interconnection.

The manuscript is well written. It is in the scope of journal and novel. However, there are some minor points:

The introduction section has insufficient references. It must be improve.

More sections are needed for this type of manuscript. The manuscript just has two sections.

More tables and figures are needed.

Author Response

Dear reviewer,

Thank you for your time and suggestions, our answers to your comments are the following:

 

1. Nogales-Delgado et al had a view on Biorefinery Based on Multiple Raw Materials: Possibilities of Interconnection. The manuscript is well written. It is in the scope of journal and novel. However, there are some minor points:

Thank you for your encouraging words. We will try to complete all your requirements.

 

2. The introduction section has insufficient references. It must be improved.

We have added more references.

 

3. More sections are needed for this type of manuscript. The manuscript just has two sections.

We have added more subsections that explain each part in more detail (in red).

 

4. More tables and figures are needed.

More tables were added, like the patents related to biorefineries and the TRL of each technology used in this biorefinery. Also, we have added a new figure about the challenges of this biorefinery and the role of some tools like LCA.

 

Again, thank you for your help and sincerely,

Dr. Sergio Nogales Delgado.

Reviewer 3 Report

Comments and Suggestions for Authors

The Title does not properly convey the contents of the manuscript - there is not much discussion about possibilities of interconnection. Furthermore the biorefinery is focused on energy / biofuel production, which should be clearly stated in the title. In addition, this biorefinery is focused on a specific biomass, thus it should be in the Title.

There are some imprecisions in the text - ex. it is not clear how transesterification is used to produce biolubricants. 

The English language must be improved and polished.

There are too many lumped citations, which does not add value or enlighten the reader.

"Atom economy" is used frequently without a previous definition. Furthermore, it is not clear how it can be used to compare the performance of this biorefinery with others.

During the presentation of the work, authors make it seem that all the technologies are readily available and implemented at the industrial level. What is the TRL for each technology proposed?

Methanol is of non renewable nature (usually). However, it could also be produced within this biorefinery, thus making the whole biofuel more renewable.

No discussion was produced about the energy used in the process.

Additional details, comments and suggestions have been included in the commented version of the manuscript.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The English language needs polishing.

 

Author Response

Dear reviewer,

Firstly, thank you for your comments, which will contribute to the improvement of this communication. Our replies to your comments are the following:

 

1. The Title does not properly convey the contents of the manuscript - there is not much discussion about possibilities of interconnection. Furthermore the biorefinery is focused on energy / biofuel production, which should be clearly stated in the title. In addition, this biorefinery is focused on a specific biomass, thus it should be in the Title.

The title has been changed, removing the term “interconnection” and focusing on “energy”. The specific biomass was not included, as there are different starting points in the biorefinery, like vegetable oil, wastewater, agricultural waste, etc. Thus, the title was as follows (in red):

Biorefinery Based on Multiple Raw Materials and Wastes for Energy Purposes: a Proposal Applied to the South-West of Europe

2. There are some imprecisions in the text - ex. it is not clear how transesterification is used to produce biolubricants. 

We have checked these imprecisions throughout the text to avoid confusion. Regarding transesterification to produce biolubricants, we have clarified this fact (text in red):

Concerning biodiesel, transesterification is carried with methanol as a reagent, to produce fatty acid methyl esters and glycerol. On the other hand, biolubricant is produced by reacting fatty acid methyl esters with superior alcohols (like pentaerythritol or trimethylolpropane) to produce biolubricants and release methanol (which could be reused in the previous transesterification step).

 

3. The English language must be improved and polished.

The English language has been revised throughout the text, correcting typos and grammar mistakes.

4. There are too many lumped citations, which does not add value or enlighten the reader.

We have separated lumped citations, when possible.

5. "Atom economy" is used frequently without a previous definition. Furthermore, it is not clear how it can be used to compare the performance of this biorefinery with others.

The definition of atom economy was given, as follows:

The atom economy (or atom efficiency, defined as the amount of desired products that are obtained compared to the amount of reagents used, expressed in terms of percentage) of these processes is usually high…

This atom economy, expressed in percentage values (from 0 to 100%, from low to high atom economy) could be used to compare different technologies, along with other tools such as carbon footprint, life cycle assessment, etc.

6. During the presentation of the work, authors make it seem that all the technologies are readily available and implemented at the industrial level. What is the TRL for each technology proposed?

We have added a table with the TRL of each technology included in this work (see Table 3), with the corresponding comment. Also, we have added a conclusion to point out this fact, like the following (changes in red):

Another challenge is the fact that these technologies are not equally mature, requiring further research for those with lower TRL values, in order to make these processes more efficient and adaptable at industrial scale.

 

7. Methanol is of non renewable nature (usually). However, it could also be produced within this biorefinery, thus making the whole biofuel more renewable.

You are right. As observed in the figure, it was considered an intermediate product, but in a sense it the only artificial reagent that is added to start the transesterification process. This fact was pointed out in the final text, but the idea is that, once it is added, it can be reused to a certain extent depending on factors such as vacuum, collection methods, etc. It was explained in the text like the following (in red):

It should be noted the presence of methanol, one of the few synthetic reagents used in this biorefinery to start the process. Nevertheless, during the second transesterification, methanol can be regenerated and re-used in the first transesterification, partially recovering this intermediate product depending on many factors such as the collection system or the use of vacuum.

8. No discussion was produced about the energy used in the process.

We have discussed this fact in the corresponding section “3.2. Challenges related to biorefinery implementation”.

9. Additional details, comments and suggestions have been included in the commented version of the manuscript.

Your details, comments and suggestions (included in the pdf file) were taken into consideration, making most of the changes in the final text.

 

Again, thank you for your assistance and sincerely,

Dr. Sergio Nogales-Delgado.

Reviewer 4 Report

Comments and Suggestions for Authors

Dear authors, I had the chance to review your proposed manuscript. I like the small dimension of this entry, and the focus on delivering information quickly.

I would like to have seen a bigger focus on the concept of “atom economy”, namely how does one quantify it. It would be interesting to consider optimization algorithms to design biorefineries using this concept as a selection criterion.

Logistics and material transportation are often the downfall of biorefinery concepts, since biomass presents a very low energy density. It may be interesting to discuss in the text the challenges associated with implementation of a biorefinery that makes use of both WGO and agricultural products.

What is also lacking is the reality of the location of implementation, and the expected technological maturity of the place. Is the plant envisioned to be placed close to Badajoz? What specific feedstocks do you have in mind?

Regarding the fulcrum of the work, Figure 1 and the subsequent explanation, several of these pathways are discussable, while not being wrong. I would recommend a visual reorganization. It is also clear after reading that the authors made the proposal for a system without support from aforementioned decision algorithms, which is ok, but takes novelty from the final document presented. Some discussion about alternative uses for the products or intermediates could also be considered, based on the market value and demand. You also should make the choice of pathways more clear as “and/or”, in the sense that there is a degree of flexibility that may not come off in the scheme you present.

It is also sometimes unclear what is the level of technological maturity of the processes that you consider. For example, as much as HTC is an interesting technique in bench-scale, I am unaware of successful large-scale materializations. Pyrolysis, as well, has seen commercial success in relatively small scale, using biomasses of very low ash content and very low heterogeneity (prime wood), whereas you want to use agricultural residues. If you are going for bench-scale examples, you should broaden the horizons a bit and go for something more novel.

It is important for the reader to have an idea of the mass flows involved in this process to permit correct visualization. For example, how much of the vegetable oil would be converted into WGO instead of channeled to TE; how much of the biodiesel (I assume FAME/FAEE) should be converted into biolubricant; how much of the glycerol from TE / the char from pyrolysis/HTC should be reformed, etc… Market prices and market demands are important to contrast in this stage and no mention of it is made in your work at any point. You could even present the proportions assuming different scenarios.

Product separation is often capital- and operationally-costly, but the authors fail to include these steps in the concept image, while describing them to a good extent in page 4-5. For example, a gas separation system (several options, none are economic) is required after AD for the removal of CO2/H2S from the biogas, or do you reform the mix as is, and thus avoid that cost? Pyrolysis products need separation, SR products need readjusting (e.g., WGS), FT products typically make use of petroleum-like distillation. The presence of auxiliary equipment should be made obvious, such as dryers, distillation columns and decanters (etc...) that may be needed; and their absence when expected must be made obvious and justified.

While WCO is indeed derived from vegetable oil, the arrow may indicate to the reader that the conversion is done within the context of the biorefinery. Moreover, the use of pure vegetable oil can be very controversial, due to the land-use-controversy associated with growing crops for purely energetic purposes. It may be more interesting to consider only WCO as the raw material for TE.

Pyrolysis is not a cheap technology, and benefits well from economies of scale. It would be interesting if the authors discussed what kind of pyrolysis they would consider (fast vs slow or other alternatives), and how do you integrate the side products into the proposed system. HTC produces 4 different products and, again, only char is mentioned.

Fischer-Tropsch is a mature technology that benefits from the heavy focus of a couple of industrial parties with marked interest (check the rich SASOL data sources, and people who collaborated with them). However, the issues surrounding process control and product separation are well-known. Other techniques using methanol/DME as intermediates/reagents seem very promising, at least at pilot-scale, and should be explored in the context of this work.

You discuss catalysts in the context of TE and FT, while it would be benefiting to discuss them in the context of pyrolysis and HTC as well. Moreover, there is a wealth of studies on alternative biogenic or waste-based catalysts for all four of these processes. As it is unclear, from your choice of references and the nature of the processes considered, what is the technological maturity you demand, it may be interesting to consider the use of other product.

To finish, the general writing could benefit from a revision. The word order is sometimes difficult to read. The text reads as if it had been written by someone with low research maturity and language dominion. This per se is not a fault, and as a reviewer I cannot demand this. Nonetheless, with three authors, among which authors with a more extensive body of work, I would expect higher standards.

Finally, I have a series of comments/suggestions:

-        L. 34-35 “not only real wars, but also economic and commercial ones”: this sentence reads very immature and I am sure there are better way to communicate this information better;

-        Figure 1: Several of the acronyms you use are established (HTC, PSA, FT, AD) but others (PYR, EX) could be replaced with others that are clearer and less clunky. Also, you have many situations where two parallel chains are using the same technology, consider using the conversion technology as the node;

-        L. 54-58: this paragraph is clunky and difficult to read. Several industrial tragedies have happened within the food industry, and their pollutive impact has nonetheless been important. “It should be taken into account that many processes obtain products that are slightly modified from their precursors, assuming that many of their properties (such as biodegradability) are kept in final goods.” This sentence is difficult to comprehend;

-        L. 59-64: this paragraph can be misleading. I am not fully convinced of the “versatility” of a biorefinery, especially when comparing its capital investment with the actual expected revenue;

-        L. 72-77: this paragraph is interesting, but is unfortunately far from easy to implement. Not only are traditional uses for these wastes important for local communities in ways that are not only financial, the farmers are also aware of the value of these “wastes”, developing a commodity market for them, which paired with the logistical costs, can make the situation unfeasible.

Thank you.

Comments on the Quality of English Language

The quality of written English must be improved, as it can be difficult to understand the text correctly. I mentioned some examples in the general comments.

Author Response

Dear reviewer,

First of all, thank you for your encouraging words and complete feedback, which has clearly contributed to the improvement of this work. Our comments to your remarks and questions are the following:

 

1. Dear authors, I had the chance to review your proposed manuscript. I like the small dimension of this entry, and the focus on delivering information quickly.

Thank you so much for your encouraging words.

2. I would like to have seen a bigger focus on the concept of “atom economy”, namely how does one quantify it. It would be interesting to consider optimization algorithms to design biorefineries using this concept as a selection criterion.

The definition of atom economy was presented in the final text, as follows:

The atom economy (or atom efficiency, defined as the amount of desired products that are obtained compared to the amount of reagents used, expressed in terms of percentage) of these processes is usually high…

3. Logistics and material transportation are often the downfall of biorefinery concepts, since biomass presents a very low energy density. It may be interesting to discuss in the text the challenges associated with implementation of a biorefinery that makes use of both WGO and agricultural products.

This issue has been commented in the final text, in the subsection called “3.2. Challenges related to biorefinery implementation”.

4. What is also lacking is the reality of the location of implementation, and the expected technological maturity of the place. Is the plant envisioned to be placed close to Badajoz? What specific feedstocks do you have in mind?

Related with the above, we have chosen this location, with some specific feedstocks as explained in the section: 3.2. Challenges related to biorefinery implementation.

5. Regarding the fulcrum of the work, Figure 1 and the subsequent explanation, several of these pathways are discussable, while not being wrong. I would recommend a visual reorganization. It is also clear after reading that the authors made the proposal for a system without support from aforementioned decision algorithms, which is ok, but takes novelty from the final document presented. Some discussion about alternative uses for the products or intermediates could also be considered, based on the market value and demand. You also should make the choice of pathways more clear as “and/or”, in the sense that there is a degree of flexibility that may not come off in the scheme you present.

We have reorganized Figure 1, where some arrows might seem confusing. Regarding the decision algorithms, it should be noted that this work is only based on our experience (as a department) with previous works. In any case, it would be a wonderful idea for a future research article, without a doubt. Finally, we have discussed the alternative uses of the products in the final text, especially in Table 2.

6. It is also sometimes unclear what is the level of technological maturity of the processes that you consider. For example, as much as HTC is an interesting technique in bench-scale, I am unaware of successful large-scale materializations. Pyrolysis, as well, has seen commercial success in relatively small scale, using biomasses of very low ash content and very low heterogeneity (prime wood), whereas you want to use agricultural residues. If you are going for bench-scale examples, you should broaden the horizons a bit and go for something more novel.

We have added a table with TRL of each technology to clarify this point (Table 3). Also, we have commented these results in the text and in the conclusion section. Thus, the differences in TRL is one of the challenges of the proposed biorefinery.

7. It is important for the reader to have an idea of the mass flows involved in this process to permit correct visualization. For example, how much of the vegetable oil would be converted into WGO instead of channeled to TE; how much of the biodiesel (I assume FAME/FAEE) should be converted into biolubricant; how much of the glycerol from TE / the char from pyrolysis/HTC should be reformed, etc… Market prices and market demands are important to contrast in this stage and no mention of it is made in your work at any point. You could even present the proportions assuming different scenarios.

The yields you mention are dependent on many factors, but we have added a proximate percentage of these values in the final text.

8. Product separation is often capital- and operationally-costly, but the authors fail to include these steps in the concept image, while describing them to a good extent in page 4-5. For example, a gas separation system (several options, none are economic) is required after AD for the removal of CO2/H2S from the biogas, or do you reform the mix as is, and thus avoid that cost? Pyrolysis products need separation, SR products need readjusting (e.g., WGS), FT products typically make use of petroleum-like distillation. The presence of auxiliary equipment should be made obvious, such as dryers, distillation columns and decanters (etc...) that may be needed; and their absence when expected must be made obvious and justified.

You are right about this subject. In this work, we have pointed out the main processes implied to produce the intermediate and final products that, in our opinion, are representative of our proposal. Nevertheless, the steps that you mentioned are equally important, but some of them are intrinsic of a certain process. For instance, anaerobic digestion is simplified in this work, but we should not ignore the required steps to obtain biogas without moisture, for instance. It is just a matter of simplification of this entry. We have pointed out this fact in the final text, after Figure 1.

9. While WCO is indeed derived from vegetable oil, the arrow may indicate to the reader that the conversion is done within the context of the biorefinery. Moreover, the use of pure vegetable oil can be very controversial, due to the land-use-controversy associated with growing crops for purely energetic purposes. It may be more interesting to consider only WCO as the raw material for TE.

You are right about WCO. We have removed the arrow, pointing out in the text that WCO can be derived from the culinary use of vegetable oils. The controversial use of vegetable oils, along with the corresponding discussion, is included in a new subsection about challenges.

10. Pyrolysis is not a cheap technology, and benefits well from economies of scale. It would be interesting if the authors discussed what kind of pyrolysis they would consider (fast vs slow or other alternatives), and how do you integrate the side products into the proposed system. HTC produces 4 different products and, again, only char is mentioned.

We have added more details about pyrolysis in Table 2. Also, more details about HTC products (especially liquid) are added in Table 2.

11. Fischer-Tropsch is a mature technology that benefits from the heavy focus of a couple of industrial parties with marked interest (check the rich SASOL data sources, and people who collaborated with them). However, the issues surrounding process control and product separation are well-known. Other techniques using methanol/DME as intermediates/reagents seem very promising, at least at pilot-scale, and should be explored in the context of this work.

Although it is out of our context (as we have not worked this chemical route), we have mentioned this fact in Table 2, when Fischer Tropsch was explained.

12. You discuss catalysts in the context of TE and FT, while it would be benefiting to discuss them in the context of pyrolysis and HTC as well. Moreover, there is a wealth of studies on alternative biogenic or waste-based catalysts for all four of these processes. As it is unclear, from your choice of references and the nature of the processes considered, what is the technological maturity you demand, it may be interesting to consider the use of other product.

We have added the role of catalysts in pyrolysis and HTC. Thank you for your suggestion.

13. To finish, the general writing could benefit from a revision. The word order is sometimes difficult to read. The text reads as if it had been written by someone with low research maturity and language dominion. This per se is not a fault, and as a reviewer I cannot demand this. Nonetheless, with three authors, among which authors with a more extensive body of work, I would expect higher standards.

We have revised the text to avoid typos and grammar mistakes. Thank you for your advice!

 

14. Finally, I have a series of comments/suggestions: L. 34-35 “not only real wars, but also economic and commercial ones”: this sentence reads very immature and I am sure there are better way to communicate this information better;

We have changed the sentence, as follows:

…or geopolitical issues (such as international conflicts with economic and commercial consequences) that…

15. Figure 1: Several of the acronyms you use are established (HTC, PSA, FT, AD) but others (PYR, EX) could be replaced with others that are clearer and less clunky. Also, you have many situations where two parallel chains are using the same technology, consider using the conversion technology as the node;

We have established new acronyms for pyrolysis (PYROL) and extraction (EXT), according to abbreviations used in journals. They are explained in the figure caption. Also, we have used the conversion technology as the node, (see Figure 1).

16. L. 54-58: this paragraph is clunky and difficult to read. Several industrial tragedies have happened within the food industry, and their pollutive impact has nonetheless been important. “It should be taken into account that many processes obtain products that are slightly modified from their precursors, assuming that many of their properties (such as biodegradability) are kept in final goods.” This sentence is difficult to comprehend;

We have corrected this paragraph. We meant that these processes are usually less pollutant compared to petroleum-based processes. The resulting paragraph was the following:

Considering that the products obtained are derived from natural sources, their environmental impact if there is an accidental release would be less negative compared to petroleum products. It should be taken into account that some of these processes obtain products that partially retain the molecular structure of their precursors, keeping some characteristics (such as high biodegradability).

 

17. L. 59-64: this paragraph can be misleading. I am not fully convinced of the “versatility” of a biorefinery, especially when comparing its capital investment with the actual expected revenue;

You are right about the efforts to implement a biorefinery, but we mean that these biorefineries can be adapted depending on the demand. Maybe the word “easily” can be misleading in this case, and we have removed it from the final text. We meant that technically is feasible, although other factors should be considered, like economic impact or LCA (which is explained in the section “challenges”, newly added.

18. L. 72-77: this paragraph is interesting, but is unfortunately far from easy to implement. Not only are traditional uses for these wastes important for local communities in ways that are not only financial, the farmers are also aware of the value of these “wastes”, developing a commodity market for them, which paired with the logistical costs, can make the situation unfeasible.

You are absolutely right. As you say, local farmers are aware of the potential of these wastes, but some practices can be equally polluting. Of course, again, economy and LCA would play an important role in this sense, to assess the introduction of these wastes in biorefinery production chains. We have specified this fact in the final text.

19. Thank you.

On the contrary, thank you for your thorough work and clarifying comments!

 

Sincerely,

Dr. Sergio Nogales Delgado.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The revised manuscript is acceptable in the present form. Authors have incorporated the corrections as suggested. 

Author Response

Dear reviewer, our reply to your comment is the following:

The revised manuscript is acceptable in the present form. Authors have incorporated the corrections as suggested. 

Again, thank you for your attention and your positive feedback.

 

Sincerely, 

Dr. Sergio Nogales Delgado.

Reviewer 2 Report

Comments and Suggestions for Authors

The modifications are good. It can be accepted.

Author Response

Dear reviewer,

Regarding your comment, our reply is the following:

The modifications are good. It can be accepted.

Thank you so much, we are glad that the changes are suitable for you.

Sincerely,

Dr. Sergio Nogales Delgado.

Reviewer 4 Report

Comments and Suggestions for Authors

Dear authors,

I must give you appraisal for the marked improvements. The document reads better and a lot of my previous marks have been fixed or properly contextualized.

While I find the new title more descriptive, I find it too verbose. Here is a proposal: "Biorefinery Based on Multiple Raw Materials and Wastes for the Production of Energy: a proposal tailored to Southwestern Europe". Also, drop the capitalization of every word, it doesn't read well.

Figure 1 reads much more clearly now and is the fulcrum of your manuscript. It also connects better to the text, but stands on its own.

Section 3.2 was a good idea. You're missing references for table 3. I feel that figure 2 could be reworked into a graphical abstract, but in its position it feels irrelevant in a way.

Thank you.

Author Response

Dear reviewer, 

Thank you so much for your recommendations. Our replies to your comments are the following:

Dear authors,

I must give you appraisal for the marked improvements. The document reads better and a lot of my previous marks have been fixed or properly contextualized.

Thank you for your kind words!

 

While I find the new title more descriptive, I find it too verbose. Here is a proposal: "Biorefinery Based on Multiple Raw Materials and Wastes for the Production of Energy: a proposal tailored to Southwestern Europe". Also, drop the capitalization of every word, it doesn't read well.

We think that your title is OK, and we have accepted it. Regarding the capitalization of every word, we think this is a requirement of the journal, according to previous pubished articles. In any case, we will leave this issue to the proofreading editor, if necessary.

Figure 1 reads much more clearly now and is the fulcrum of your manuscript. It also connects better to the text, but stands on its own.

Thank you.

 

Section 3.2 was a good idea. You're missing references for table 3. I feel that figure 2 could be reworked into a graphical abstract, but in its position it feels irrelevant in a way.

The references were, actually, based on all the works included in this article, according to the criteria followed by NASA. Thus, this reference was added in the text, and this column was deleted. Regarding the figure, as far as we can remember, it was a requirement of another reviewer, but you are right that this figure could be useful for a graphical abstract.

 

Thank you.

Thank you for your help!

Round 3

Reviewer 4 Report

Comments and Suggestions for Authors

Dear Authors,

I appreciate your replies to the comments I made. I understand your interest in keeping the original flow of the manuscript, while addressing the points me and the other reviewer made.

I find section 3.2 and table 3 to be important additions to the document. Having this in mind, I find the use of technologies of such different TRL to be potentially unwise, though I understand your goal is to maximize the use of wastes, and that you don't want to greatly modify your initial concept.

The placement of the refinery in Badajoz is very interesting. Having the dynamic of a medium-sized city that is relatively isolated is a very important backdrop, that would resonate with readers in many similar circumstances. If there is still a chance for further modifications, I would like you to move this data to the introduction, or to its own section (I believe it to be too central to be a bullet point), discussing the reality of the location, future expectations and political/environmental evolution. For example, discuss how easy it would be to ship out products, comparing the current situation (no cheap access to the sea or to cargo trains) with the short-term, medium-term and long-term future (current EU programs of regional support, future lines to Madrid, Sines and Lisbon). The expected impact of desertification and water stress should be taking into consideration when discussing this topic, and the availability/nature of biowastes from the immediate vicinity.

All in all, a very good improvement. Thank you.

 

This new version may be too long to be considered an Encyclopedia entry, and may fit other journals or publication styles better.

Comments on the Quality of English Language

Dear editor,

My points have been addressed and the overall quality of written language has improved noticeably. I did include new comments, that I believe should be addressed, that build on the changes made between the first submission and the improvement. However, I understand that there may not be the chance to make these changes.

Thank you.

Author Response

Dear Reviewer,

Thank you for your comments! This conversation is really enriching for us, as you make us consider new points about this work. Our replies are the following:

I appreciate your replies to the comments I made. I understand your interest in keeping the original flow of the manuscript, while addressing the points me and the other reviewer made.

Sometimes it is difficult to find a balance between the comments of different reviewers, I hope you understand. To date, four reviewers have seen this work, and it is a challenge to completely satisfy all the requirements. Sorry for the possible inconvenience.

I find section 3.2 and table 3 to be important additions to the document. Having this in mind, I find the use of technologies of such different TRL to be potentially unwise, though I understand your goal is to maximize the use of wastes, and that you don't want to greatly modify your initial concept.

You are right that the joint implementation of different technologies is a challenge, which has been commented in the final text. Indeed, we have added a new conclusion about this point (changes in red):

Another challenge would be the technological development of new or innovative technologies to valorize wastes. For this purpose, homogenization of TRLs of the processes involved in this biorefinery would be necessary, with an important role of multidisciplinary teams to promote industrial-scale facilities.

The placement of the refinery in Badajoz is very interesting. Having the dynamic of a medium-sized city that is relatively isolated is a very important backdrop, that would resonate with readers in many similar circumstances. If there is still a chance for further modifications, I would like you to move this data to the introduction, or to its own section (I believe it to be too central to be a bullet point), discussing the reality of the location, future expectations and political/environmental evolution. For example, discuss how easy it would be to ship out products, comparing the current situation (no cheap access to the sea or to cargo trains) with the short-term, medium-term and long-term future (current EU programs of regional support, future lines to Madrid, Sines and Lisbon). The expected impact of desertification and water stress should be taking into consideration when discussing this topic, and the availability/nature of biowastes from the immediate vicinity.

These ideas were extended in the introduction section (adding a new reference), like the following:

Specifically, this biorefinery would be located in the southwest of Europe, although its location could be different due to the versatility and adaptation to multiple raw materials. In this sense, the city of Badajoz (150000 city residents) was selected as a location with a great potential due to the near presence of a wastewater treatment plant and multiple agricultural areas, which could provide the different wastes or raw materials to feed the whole process. This way, the location was selected to avoid further environmental impacts due to changes in agricultural practices, being adapted to the reality of this region and avoiding the contribution to further environmental problems such as desertification or water stress. Also, the location of this city is interesting, with near strategic cities such as Madrid (330 km), Seville (187 km) and Lisbon (188 km). Thus, shipment of generated products would be feasible, although commercial communications could be improved, as expected with the implementation of railroad lines for high-speed trains between Madrid and Lisbon, among other measures taken by the European Union [23].

 

All in all, a very good improvement. Thank you.

Thank you for your encouraging words and comments!

 

This new version may be too long to be considered an Encyclopedia entry, and may fit other journals or publication styles better.

Again, the extension of the entry was precisely extended due to comments of assistant editors and reviewers. The original idea was to add a relatively shorter entry, but they wanted us to increase the number of words. Afterwards, they recommended new subsections, and so on… At the end of the day, we had the current version of this work, which can be considered long depending on the criteria of the Encyclopedia.