Recent Development in Physical, Chemical, Biological and Hybrid Biogas Upgradation Techniques
, Elena A. Zhuravleva 3, Dmitriy A. Kovalev 2, Yuriy V. Litti 3, Shyam Kumar Masakapalli 4, Nidhi Pareek 5 and Vivekanand Vivekanand 1,*
Round 1
Reviewer 1 Report
This paper, entitled Recent development in physical, chemical, biological and hybrid biogas upgradation technique, is a scholarly work and can ncrease knowledge on this domain. The authors provide an interesting and original paper dealing with biogas upgradation as a review on this topic. The content is relevant to Sustainability.
I have some general and specific comments:
- the abstract and keywords are meaningful.
- the manuscript is quite well written and well related to existing literature.
- About Table 1, there's many other compounds in biogas, why focusing only on these principal compounds?
- About Table 3, is there any more recent data and studies after 2016? Why focusing on the period ending in 2016? There's many other data available on this subject and many other papers dealing with same topic. Please provide additional data and information, it will improve the quality of this present work and enhance the content.
- It will be very interesting to complete this work with costs analysis of the sereval methods described in this paper. What are the investment and operation costs of each application? What are OPEX and CAPEX? Please provide more details about this consideration. It is mandatory in order to improve the quality of content and to complete this hard work of compilation of information.
- Please provide also some commercial data from suppliers and provide data about the number of commercial solutions impletemented (when data available, it could in global region per region or country per country) and to compare this number qith the number of biogas plants and the number of biogas plants with gas injection into the grid, CHP or other application. Where are located the upgrading systems? Is there any trends about this? What is the best solution? What is the most implemented? is there any link between upgrading system and the biogas purpose?
As it, this paper is not fully acceptable and requires at least some amendments, additional data and information in order to increase the whole quality of the content. I encourage the authors to take into account all the comments when preparing the revised version of the manuscript if the editors give the chance to revise the version. I recommend the following decision: RECONSIDER AFTER MAJOR REVISION.
Author Response
The authors thank the reviewer for the comments to improve the article.
Responses to the reviewer:
the abstract and keywords are meaningful.
the manuscript is quite well-written and well-related to existing literature.
Response: Authors would like to thank the reviewers for appreciation and reviewing the manuscript with great input. These valuable inputs will help to improve the quality of the manuscript. Authors have incorporated all the given suggestions and made changes in the revised manuscript.
- About Table 1, there's many other compounds in biogas, why focusing only on these principal compounds?
Response: Authors would like to appreciate the suggestion however authors have considered the all compounds present in biogas which are mainly present in biogas such as CO2, H2S, H2O and siloxanes as these are the major compound that reduces the calorific value of biogas and in-turn biogas purification is required.
- About Table 3, is there any more recent data and studies after 2016? Why focusing on the period ending in 2016? There are many other data available on this subject and many other papers dealing with same topic. Please provide additional data and information, it will improve the quality of this present work and enhance the content.
Response: Authors have included the literature from 2014-2022 and there may be a possibility that reviewers are giving suggestions about Table 2 instead of Table 3 because the comment is related to Table 2. Additionally, authors have updated Table 2 and cited latest research articles.
- It will be very interesting to complete this work with costs analysis of the several methods described in this paper. What are the investment and operation costs of each application? What are OPEX and CAPEX? Please provide more details about this consideration. It is mandatory in order to improve the quality of content and to complete this hard work of compilation of information.
Response: Thanks for your valuable suggestion, the suggestion is well related to the techno-economic analysis of provided techniques which authors have planned to incorporate in future work. For this manuscript, Table no. 4 has been added as per your suggestion, which shows the estimated cost of the investment and operation of the upgrading technologies.
- Please provide also some commercial data from suppliers and provide data about the number of commercial solutions implemented (when data available, it could in global region per region or country per country) and to compare this number with the number of biogas plants and the number of biogas plants with gas injection into the grid, CHP or other application. Where are located the upgrading systems? Is there any trends about this? What is the best solution? What is the most implemented? is there any link between upgrading system and the biogas purpose?
Response: Authors appreciate your thoughtful suggestion, however, the data asked is very confidential for industries. We have requested several biogas plant owners to provide some data, but it was denied. That’s why authors have not included in the current manuscript.
As it, this paper is not fully acceptable and requires at least some amendments, additional data and information in order to increase the whole quality of the content. I encourage the authors to take into account all the comments when preparing the revised version of the manuscript if the editors give the chance to revise the version. I recommend the following decision: RECONSIDER AFTER MAJOR REVISION.
Response: Authors have updated the manuscript as per the given suggestions.
Reviewer 2 Report
The manuscript titled "Recent development in physical, chemical, biological and hybrid biogas upgradation techniques" provides an interesting review of all the upgrading technologies.
In my opinion, the paper can be published with the following minor changes:
-In section 6, It would be interesting to acknowledge that biogas is not the most profitable technology for waste processing. The number of plants is rising mainly because of environmental concerns and they are paid subsidies.
-In page 8, line 163. The reference must be checked.
-In page 9, line 178. It would be interesting to mention about heat integration. Purification of PEG or amines requires distillation and heat, but this energy can be reduced with proper heat integration. Some works do not consider the heat integration in the process design getting to worse energy results.
- In a similar way, it would be also interesting to point out that PSA requires electricity that is more expensive than heat.
-Page 14, line 461. check The subscript of CO2.
Author Response
The authors thank the reviewer for the comments to improve the article.
Responses to the reviewer:
-In section 6, It would be interesting to acknowledge that biogas is not the most profitable technology for waste processing. The number of plants is rising mainly because of environmental concerns and they are paid subsidies.
Response: Authors have added the suggested content in the manuscript.
-In page 8, line 163. The reference must be checked.
Response: Authors have critically checked and updated the manuscript (Page no. 8, line no. 163)
-In page 9, line 178. It would be interesting to mention about heat integration. Purification of PEG or amines requires distillation and heat, but this energy can be reduced with proper heat integration. Some works do not consider the heat integration in the process design getting to worse energy results.
Response: Authors have discussed about the disadvantage of the amine scrubbing technology and other scrubbing technologies in which energy consumption is the major challenge. However, idea of heat integration has been added as per the suggestion (page no. 9 and line no. 179).
- In a similar way, it would be also interesting to point out that PSA requires electricity that is more expensive than heat.
Response: Authors have incorporated the suggestions given by the reviewers (Page no. 11, line no. 275).
-Page 14, line 461. check the subscript of CO2.
Response: Authors have updated the typo error in the manuscript.
Round 2
Reviewer 1 Report
The authors provide a revised version of their manuscript taking into account all the comments and requests of amendments. The authors provide also detailed and justifed asnwers to all the comments. I agree with all the answers and I consider that this manuscript is now fully acceptable for publication. I recommend the following decision: ACCEPT IN PRESENT FORM.
