A Simulation Study on Evaluating the Influence of Impurities on Hydrogen Production in Geological Carbon Dioxide Storage

Round 1

Reviewer 1 Report

Title:

Simulation study on evaluating the influence of impurities on  hydrogen production in geological carbon dioxide storage

Authors:

 Seungmo Ko, Sung-Min Kim, and Hochang Jang

 

This study focused on evaluating the influence of impurities on hydrogen production in geological carbon dioxide storage. CO₂ storage efficiency was analyzed when CO₂, along with impurities, such as methane and H₂S, which are captured by CO₂ in the hydrogen production process, was injected into a deep saline aquifer. Fluid modeling was conducted by mixing methane and H₂S with CO₂, followed by the simulation of injection into a 3-D saline aquifer model. It has research and application value.

 

1. Would you please change the “CO2” into “CO₂”in the line of 10, 285, 287, 291. Please revise after careful examination of your whole manuscript.

 

2. In the Table 3: “3.5 mol.%, 20 mol.%_l”

What’s it “_l”mean?

 

3. Why only choose the impurity concentrations of 3.5% and 20%?

 

4.10 y and 100 y

It should be shown that “y“ represents “year“

 

5. There are some grammar or expression errors.

Please revise after careful examination of your whole manuscript.

Extensive editing of English language required

Author Response

Amendments in response to the comments from Reviewer #1:

This study focused on evaluating the influence of impurities on hydrogen production in geological carbon dioxide storage. CO₂ storage efficiency was analyzed when CO2, along with impurities, such as methane and H2S, which are captured by CO2 in the hydrogen production process, was injected into a deep saline aquifer. Fluid modeling was conducted by mixing methane and H2S with CO2, followed by the simulation of injection into a 3-D saline aquifer model. It has research and application value.

Response: Thank you for appreciating our work. We thank reviewers for the thoughtful comments, which improved our manuscript. We hope our response has properly addressed the points raised in this review.

 

1. Would you please change the “CO2” into “CO2”in the line of 10, 285, 287, 291. Please revise after careful examination of your whole manuscript.

Response: Thank you for pointing this out. We have revised CO2 into CO₂ throughout the manuscript, as suggested.

 

2. In the Table 3: “3.5 mol.%, 20 mol.%l” What’s it “l”mean?

Response: The points you raised are typos. We have corrected them accordingly.

 

3. Why only choose the impurity concentrations of 3.5% and 20%?

Response: Thank you for the valuable comment. This is because 3.5% is the maximum percentage of impurities captured using amine absorbents in the literature and 20% is mixture of CO₂ and H₂S from gas plants that injects into a saline aquifer. In addition, the detailed explanation has been added in the manuscript as follows:

Line 272: “The impurity concentration was set at 3.5%, representing the maximum H₂S content for amine-based absorbents [15] and 20% as mixed in a project conducted in Borzecin, Poland [4].”

 

4. 10 y and 100 y. It should be shown that “y“ represents “year“

Response: Thank you for pointing this out. We have corrected this accordingly.

 

5. There are some grammar or expression errors. Please revise after careful examination of your whole manuscript.

Response: Thank you for bringing this to our attention. Following your suggestions, we have thoroughly checked the entire manuscript for grammatical and language-related errors and have made corrections accordingly. Moreover, the manuscript was proofread by a professional English language editor to ensure that there were no language-related errors. Additionally, we have attached the editing certificate provided by Editage.

Reviewer 2 Report

The manuscript entitled "Simulation study on evaluating the influence of impurities on hydrogen production in geological carbon dioxide storage" developed a numerical simulation for evaluating the CO₂ injection into deep saline aquifers, considering impurities present in blue hydrogen production. I recommend the revision of manuscript following to "Major Revision". The comments are presented as follows:

 

1)     The main objectives of manuscript must be mentioned at the end of Introduction.

2)     Each equation must be numbered.

3)     Page 3: the capturing of CO2 using amine absorbents doesn’t have suitable references. I suggest the authors to use references of 2018 till now to enrich the introduction;

4)     Use appropriate references for each equation.

5)     The advantages artificial intelligence in the CCS needs to be explained in detail.

6)     What is the reason of using Peng-Robinson non-ideal equation in the simulation?

7)     Computational time and applied operating system must be brought in the manuscript.

8)     Please provide a nomenclature list.

9)     Please provide a section about mesh independency (if possible).

Minor edition needs to be done

Author Response

Amendments in response to the comments from Reviewer #2:

The manuscript entitled "Simulation study on evaluating the influence of impurities on hydrogen production in geological carbon dioxide storage" developed a numerical simulation for evaluating the CO2 injection into deep saline aquifers, considering impurities present in blue hydrogen production. I recommend the revision of manuscript following to "Major Revision". The comments are presented as follows:

Response: We are grateful to you for appreciating our work and providing valuable feedback. We have revised the manuscript as per your suggestions. The pointwise response to your comments is provided below.

 

1. The main objectives of manuscript must be mentioned at the end of Introduction.

Response: We have added the main objectives of manuscript at the end of Introduction, as follows:

In this study, we examined CO₂ injection into deep saline aquifers, considering impurities present in blue hydrogen production.

 

2. Each equation must be numbered.

Response: We have reviewed all the equations and corrected the numbering accurately.

 

3. Page 3: the capturing of CO2 using amine absorbents doesn’t have suitable references. I suggest the authors to use references of 2018 till now to enrich the introduction;

Response: We have added the references for amine absorbents as follows:

• Lee, Y.; Kim, G.; Ki, S.; Seo, J. Development of Conceptual Cost Estimation Model for an Economic Analysis of Steam Methane Reforming based Hydrogen Production. Journal of the Korean Society of Mineral and Energy Resources Engineers 2022, 59(2), 193-204.
• Aghel, B.; Janati, S.; Wongwises, S.; Shadloo, M.S. Review on CO2 capture by blended amine solutions. International Journal of Greenhouse Gas Control 2022, 119. 103715. https://doi.org/10.1016/j.ijggc.2022.103715.

 

4. Use appropriate references for each equation.

Response: We have added the appropriate references in our equations, as suggested.

 

5. The advantages artificial intelligence in the CCS needs to be explained in detail.

Response: Accordingly, we have added a study of VLE and phase behavior of impure CO₂ using AI in Introduction on pages 78-80.

Line 79: Due to the recent increase in data availability, the application of AI in the CCS field is expanding and aiding in faster decision-making [10-11]. Kim et al. [10] presented an artificial neural network (ANN) model to predict CO₂ storage efficiency in deep saline aquifers, validated against the Gorae-V structure—a potential saline aquifer for CO₂ storage in Korea [10]. Sedaghat and Rouhinakhsh [11] used least square support vector machine (LSSVM) to study the vapor-liquid equilibrium (VLE) and phase behavior of impure CO_2, such as nitrogen, hydrogen, oxygen, and argon.

 

6. What is the reason of using Peng-Robinson non-ideal equation in the simulation?

Response: The PR EOS is well-suited for predicting the phase behavior of gas–liquid systems under high pressure, making it a common choice for CCS processes involving mixtures. This includes applications in gas processing, oil refining, and petrochemical processes. We have revised the manuscript as follows:

Line 203: The PR EOS is suitable for predicting the phase behavior of gas–liquid systems under high pressure and is commonly used for CCS processes involving mixtures, such as gas processing, oil refining, and petrochemical processes [22].

 

7. Computational time and applied operating system must be brought in the manuscript.

Response: Accordingly, we have described our operation system and simulation time as follows:

Line 241: The simulations are run on an Intel i9-12900K CPU, 32 GB RAM, and NVIDIA GeForce RTX 3070 GPU. Elapsed time for simulations required average 5 minutes.

 

8. Please provide a nomenclature

Response: We have added nomenclature list to the back matter of the revised manuscript.

 

 

9. Please provide a section about mesh independency (if possible).

Response: Accordingly, we have changed Analysis of simulation results from Results and Discussion section and made subsequent subsection regarding mesh independency:

4.1. Fluid Model Results.

4.2. Dynamic Simulation Model Results.

4.3. Effects of Impurities on CO₂ Trapping Efficiency.

Reviewer 3 Report

This work presents a simulation investigation on evaluating the influence of impurities on hydrogen production in geological carbon dioxide storage. It contains novelty and is interesting to the readers working in the field. It could be taken into consideration for publishing in the Sustainability after minor revisions are made in an appropriate way. The detailed comments are listed below.

Specific Comments:

1. Sustainability is paying more and more attention to the quality of articles, especially originality and innovation. The authors should state the innovation of the article more clearly and fully in the Abstract, Discussion and Conclusion sections.

2. There are several grammatical errors in the manuscript. Please revise the manuscript to further promote quality.

There are several grammatical errors in the manuscript. Please revise the manuscript to further promote quality.

Author Response

Amendments in response to the comments from Reviewer #3:

This work presents a simulation investigation on evaluating the influence of impurities on hydrogen production in geological carbon dioxide storage. It contains novelty and is interesting to the readers working in the field. It could be taken into consideration for publishing in the Sustainability after minor revisions are made in an appropriate way. The detailed comments are listed below:

Response: Thank you for the valuable feedback. We thank reviewers for the thoughtful comments, which improve our manuscript. We hope our response has properly addressed the points raised in this review.

 

1. Sustainability is paying more and more attention to the quality of articles, especially originality and innovation. The authors should state the innovation of the article more clearly and fully in the Abstract, Discussion and Conclusion sections.

Response: Accordingly, we have added the innovation of the article, as follows:

Abstract and Conclusions sections: The application of CCS to carbon dioxide emissions containing H₂S as an impurity is considered to enable economically viable operation by reducing additional costs.

Discussion section: The application of CCS to carbon dioxide emissions containing H₂S as an impurity allows operation by reducing additional costs and ensuring stable carbon storage. Additionally, the presence of H₂S did not significantly affect CCS efficiency. Therefore, it enables economically feasible CCS operations.

 

2. There are several grammatical errors in the manuscript. Please revise the manuscript to further promote quality.

Response: The manuscript has been thoroughly checked and revised by a native English speaker. Please refer to the highlighted text in the revised manuscript. Additionally, we have attached the editing certificate provided by Editage.

Round 2

Reviewer 2 Report

This manuscript can be published.

Almost good.