Italian Offshore Platform and Depleted Reservoir Conversion in the Energy Transition Perspective

Round 1

Reviewer 1 Report

This paper can be published after addressing the following issues:

1. Please, verify the English. There are issues of syntax and language correctness. 

2. The introduction provides an adequate overview. However, in the last paragraph, the scope of the paper, which is named an ''article'', is described as ''perspective''. 

3. This paper is not a regular article; it is more proper for other kinds, such as ''Opinion'' or ''Review''. In the case of a review paper, it must be more comprehensive. 

4. What are the own results, and what are the tools applied to obtain such results? The lack of this information denotes that the paper does not match a regular article. 

 

 

For instance, the following sentence: 

It consists in injecting into subsurface formations the carbon dioxide in the supercritical phase to achieve high fluid density and maximize storage capacity.

 

It should be expressed like this:

It consists of injecting the carbon dioxide in the supercritical phase into subsurface formations to achieve high fluid density and maximize storage capacity

 

Several passages and sentences must be changed. 

Author Response

The authors are very thankful to the reviewer for their valuable comments. We have addressed them thoroughly and we now believe the manuscript has significantly improved.

This paper can be published after addressing the following issues:

1. Please, verify the English. There are issues of syntax and language correctness. 

The text has been thoroughly revised to correct syntax and language.

2. The introduction provides an adequate overview. However, in the last paragraph, the scope of the paper, which is named an ''article'', is described as ''perspective''. 

The paper has been renamed “Perspective article”.

3. This paper is not a regular article; it is more proper for other kinds, such as ''Opinion'' or ''Review''. In the case of a review paper, it must be more comprehensive. 

The reviewer is correct in that the paper is neither a review or a regular article. However, it is more than just an “Opinion”. The aim of the publication is that of sharing possible conversion options investigated for the Italian offshore platforms. We added the following sentence at the end of the introduction “The main target of the study is to provide technical considerations contributing to the definition of guidelines for the identification of the most appropriate solution for the conversion of specific platforms close to decommissioning.” We hope that this clarifies the scope of this perspective paper.

4. What are the own results, and what are the tools applied to obtain such results? The lack of this information denotes that the paper does not match a regular article. 

Thank you for the remark. The paper aims at being a perspective paper, hence it focuses mainly on techniques, methods and philosophy rather than on tools; however, the design options have been developed based on the results coming from MATLAB scripts, as detailed in a dedicated paper numbered [21] in the reference list. Unfortunately, there was a mis-reference in the previous version of this article. The cross-reference has been fixed in the current revision of the paper. 

Reviewer 2 Report

1.    The content of the article is somewhat reminiscent of popular science descriptions, where the Authors do not present their ideas in a critical light, in terms of feasibility, effectiveness, and energy efficiency of the discussed systems, but only present development prospects on the horizon. I definitely miss references to specific scientific or engineering studies where ideas were evaluated objectively by performing all the necessary engineering and economic analyses.

2.    Introduction to the article (1. Introduction) and subsequent chapters (2. Conversion options for offshore platforms, 3. Conversion philosophy) are written in very general terms, and do not provide the reader with specific figures or facts that would describe the current achievements in the discussed topic, therefore the Authors deviate from the generally accepted standard in scientific articles. A thorough literature review is required.

3.    Provide the location of GREEN1, technical parameters of the platform, ambient conditions, e.g. average air and water temperatures, wind speed, total irradiation, etc. If possible, attach a photo of GREEN1.

4.    In Chapter 4.1. Option 1 - On-board installation of a photovoltaic system feeding a desalination unit for freshwater production. The Authors should present the technical data of the photovoltaic panels taken into account when designing the system.

5.    Include a drawing where the PV installation (distances, angles, etc.), desalination system, etc. are presented.  In this way, it can also be shown that with 132 m², the PV installation will deliver 33 MWh/year.

6.    Referring to comment no. 3. How did the authors estimate the energy yield from PV panels for each month? Weather data, technical data of the panels and their location are necessary.

7.    Specify the technical data of the water desalination system. Compare the requirements of this system (the Authors cite values such as drinking water flow rate of 7.5 m³/day) to the power supplied by PV.

8.    Please explain how increasing the salt concentration in seawater will affect the construction of the platform and the local ecosystem. What are the acceptable salt concentrations?

9.    The content of Chapter 4.1.1. Linking freshwater and green-H2 production, should be supplemented with more accurate data on the systems in question, e.g. energy efficiency of the H­₂ production process, energy demand, efficiency, etc.

10.  The system described in Chapter 4.2. should be presented in a figure with appropriate descriptions. Moreover, once again, the authors do not cite any numbers to support their ideas.

11.  Similarly, the description in Chapter 4.3. mostly lacks specific data. The mere mention of the proposed methods for solving the system of equations is unsatisfactory. What are the results of the methods used for the example reservoir, and thus what are the predictions or practical guidelines for the design of such systems?

12.  In Chapter 5. Discussion of results and final remarks, the authors discuss options 1-4, but the Authors do so in general terms, there are no specific criteria, e.g. how the Authors define:

12.1.   „small reservoir”, or „large reservoir”. What are their volumes?

12.2.   „there is a minimum surface needed for the photovoltaic system to be economically convenient”. What is the criterion?

13.  The other statements of the Authors are also not supported by numbers.

14.  The Authors' conclusions are not supported by figures, so how can one claim that the proposed technologies, e.g. for the production and storage of hydrogen, will be so effective?

Minor editing of English language required

Author Response

The authors are very thankful to the reviewer for their valuable comments. We have addressed them thoroughly and we now believe the manuscript has significantly improved.

1. The content of the article is somewhat reminiscent of popular science descriptions, where the Authorsdo not present their ideas in a critical light, in terms of feasibility, effectiveness, and energy efficiency of the discussed systems, but only present development prospects on the horizon. I definitely miss references to specific scientific or engineering studies where ideas were evaluated objectively by performing all the necessary engineering and economic analyses.

The introduction and title have been updated in order to better clarify the intention of the authors to provide a perspective on the possible conversion options of aging platforms and the connected depleted reservoirs with reference to the Italian context.

The conversion options have been presented in the light of technical feasibility, whereas the social, economic and administrative aspects were out of the scope of the project. 

Furthermore, some options have a bibliographic framework richer than others, due to the different maturity of the implemented solutions and technologies. For those options (1-3) that have a poorer bibliographic background, they use technologies that are well known and currently used for onshore applications; here the interest is rather in their different application (for instance offshore) and in their technical readiness for contributing to support the new life of these offshore infrastructure otherwise intended for removal, an expensive and potentially impacting solution.     

 

2. Introductionto the article (1. Introduction) and subsequent chapters (2. Conversion options for offshore platforms, 3. Conversion philosophy) are written in very general terms, and do not provide the reader with specific figures or facts that would describe the current achievements in the discussed topic, therefore the Authors deviate from the generally accepted standard in scientific articles. A thorough literature review is required.

The remark has been addressed in the previous answer. The authors would like to add that additional technical details on figures and tools are available in already published papers (e.g. [26]) or in papers submitted for revision and dedicated to other specific options.

 

3. Provide the location of GREEN1, technical parameters of the platform, ambient conditions, e.g. average air and water temperatures, wind speed, total irradiation, etc. If possible, attach a photo of GREEN1.

The authors are sorry for the misunderstanding. As mentioned in the paper, GREEN1 is a “typical platform”, meaning that it is a representative, non-existing platform that collects the most relevant features of the Italian offshore platforms.

The choice of selecting an Italian infrastructure is due to two reasons: first, the Italian seas host 138 offshore platforms, of which more than 40 are more than 30 years old; second, the project aimed at identifying sustainable options for end-of-life platforms is being supported by the Italian Ministry of Environment and Energy Security (formerly, Ministry of Economic Development).

The choice of selecting a fictitious infrastructure is due to the fact that the final goal of the project is the development of guidelines for selecting the most appropriate conversion solution for each platform based on its specific technical features.

A specification is inserted in the text.

4. In Chapter 4.1. Option 1 - On-board installation of a photovoltaic system feeding a desalination unit for freshwater production. The Authors should present the technical data of the photovoltaic panels taken into account when designing the system.

The remark has been addressed in the answer to the first comment. The design option has been developed based on the results coming from a MATLAB script, as detailed in a dedicated paper numbered [26] in the reference list. Unfortunately, there was a mis-reference in the previous version of this article. The cross-reference has been fixed in the current revision of the paper.

5. Include a drawing where the PV installation (distances, angles, etc.), desalination system, etc. are presented.  In this way, it can also be shown that with 132 m², the PV installation will deliver 33 MWh/year.

See the answer to comment 4.

6. Referring to comment no. 3. How did the authors estimate the energy yield from PV panels for each month? Weather data, technical data of the panels and their location are necessary.

See the answer to comment 4.

7. Specify the technical data of the water desalination system. Compare the requirements of this system (the Authors cite values such as drinking water flow rate of 7.5 m³/day) to the power supplied by PV.

See the answer to comment 4.

8. Please explain how increasing the salt concentration in seawater will affect the construction of the platform and the local ecosystem. What are the acceptable salt concentrations?

Additional insight and references have been added about brine management.

9. The content of Chapter 4.1.1. Linking freshwater and green-H2 production, should be supplemented with more accurate data on the systems in question, e.g. energy efficiency of the H­₂production process, energy demand, efficiency, etc.

We have added references addressing the questions raised by the reviewer.

10. The system described in Chapter 4.2. should be presented in a figure with appropriate descriptions. Moreover, once again, the authors do not cite any numbers to support their ideas.

See the answer to comment 1. Also for option 2, described in chapter 4.2, the design has been developed based on the results coming from a MATLAB script. To give an indication of typical pressure ranges to be dealt with in such a configuration the authors have provided data in the text.

11. Similarly, the description in Chapter 4.3. mostly lacks specific data. The mere mention of the proposed methods for solving the system of equations is unsatisfactory. What are the results of the methods used for the example reservoir, and thus what are the predictions or practical guidelines for the design of such systems?

See the answer to comment 1. Also for option 3, described in chapter 4.3, the design has been developed based on the results coming from a MATLAB script. To give an indication of typical pressure ranges to be dealt with in such a configuration the authors have provided some additional details in 4.3.2. 

12. In Chapter 5. Discussion of results and final remarks, the authors discuss options 1-4, but the Authors do so in general terms, there are no specific criteria, e.g. how the Authors define:

12.1.   „small reservoir”, or „large reservoir”. What are their volumes?

A classification of the reservoirs based on their historical production has been added. Production data were used because they are publicly available, while the original gas in place is not accessible. However, production data are considered representative because the reservoirs are depleted or nearly so.

12.2.   „there is a minimum surface needed for the photovoltaic system to be economically convenient”. What is the criterion?

As mentioned in the answer to comment 3, the final goal of the project is the development of guidelines for selecting the most appropriate conversion solution for each platform based on its specific technical features. At the moment, work is still going on to define these guidelines. In this sense, for example, the minimum size of the photovoltaic system will be determined according to the possible final use (pure renewable energy, drinking water, etc.) imagined for the plant. For this reason, it is not possible to provide a univocal pre-determined threshold value of the features mentioned by the reviewer; the target is rather to suggest how to select the threshold value specific for each study case.

13. The other statements of the Authors are also not supported by numbers.

Please see comments above.

14. The Authors' conclusions are not supported by figures, so how can one claim that the proposed technologies, e.g. for the production and storage of hydrogen, will be so effective?

We respectfully disagree with the reviewer. The conclusion does not claim that the proposed technologies are effective. Based on our investigations, we say that results did not reveal any specific critical issues in the deployment of the current technologies related to energy transition as long as the selection of the conversion option to deploy is designed taking into account the characteristics of the whole system, which comprises the platform and the depleted reservoir to which it is connected.

Reviewer 3 Report

The manuscript provides an investigation into the potential conversion of offshore platforms in the context of the energy transition. However, there are areas in the full text where improvement and clarification can be made. Here are specific suggestions for modification:

1.      Introduction:

(1) Expand the introduction to provide a more comprehensive overview of the energy transition and the importance of repurposing existing offshore platforms in achieving renewable energy goals.

(2) Clearly state the objectives of the study, emphasizing the focus on conversion options related to renewable energy production, hydrogen generation, CO2 capture, and fluid storage.

(3) Provide a brief review of the current state of offshore platforms and their potential environmental impact, highlighting the need for sustainable alternatives.

2. Methodology:

(1) Provide a detailed description of the methodology used to evaluate the technical feasibility of converting offshore platforms. Explain the selection criteria for the case histories and the rationale for choosing a typical platform in the Adriatic Sea, Italy.

(2) Clearly outline the tools, models, or simulations employed to assess the different conversion options. Explain the parameters considered and the assumptions made during the evaluation process.

3. Results and Discussion:

(1) Present the findings of the study in a structured and organized manner, discussing each conversion option separately.

(2) Provide quantitative data, performance metrics, or case study results to support the claim that no specific critical issues prevent the successful conversion of offshore platforms.

(3) Discuss the economic, environmental, and social implications of each conversion option, including their potential contributions to achieving energy transition targets and reducing CO2 emissions.

(4) Address any limitations or challenges associated with the conversion options and propose mitigation strategies or further research directions to overcome these challenges.

4. Conclusion:

(1) Summarize the main findings of the study, highlighting the technical feasibility of converting offshore platforms for renewable energy production, hydrogen generation, CO2 capture, and fluid storage.

(2) Emphasize the economic opportunities and potential benefits of utilizing existing offshore platforms and depleted reservoirs in achieving the goals of the energy transition.

(3) Relate the conclusions to the broader context of the European Green Deal and the global energy transition, underscoring the importance of resource efficiency, competitiveness, and emission reduction.

4. Language and Style:

(1) Review the entire text for grammatical errors, clarity of expression, and scientific writing conventions.

(2) Ensure consistent terminology throughout the paper, particularly when referring to conversion options and their potential benefits.

(3) Consider restructuring and rephrasing sentences or paragraphs to improve the flow and readability of the text.

The manuscript provides an investigation into the potential conversion of offshore platforms in the context of the energy transition. However, there are areas in the full text where improvement and clarification can be made. Here are specific suggestions for modification:

1.      Introduction:

(1) Expand the introduction to provide a more comprehensive overview of the energy transition and the importance of repurposing existing offshore platforms in achieving renewable energy goals.

(2) Clearly state the objectives of the study, emphasizing the focus on conversion options related to renewable energy production, hydrogen generation, CO2 capture, and fluid storage.

(3) Provide a brief review of the current state of offshore platforms and their potential environmental impact, highlighting the need for sustainable alternatives.

2. Methodology:

(1) Provide a detailed description of the methodology used to evaluate the technical feasibility of converting offshore platforms. Explain the selection criteria for the case histories and the rationale for choosing a typical platform in the Adriatic Sea, Italy.

(2) Clearly outline the tools, models, or simulations employed to assess the different conversion options. Explain the parameters considered and the assumptions made during the evaluation process.

3. Results and Discussion:

(1) Present the findings of the study in a structured and organized manner, discussing each conversion option separately.

(2) Provide quantitative data, performance metrics, or case study results to support the claim that no specific critical issues prevent the successful conversion of offshore platforms.

(3) Discuss the economic, environmental, and social implications of each conversion option, including their potential contributions to achieving energy transition targets and reducing CO2 emissions.

(4) Address any limitations or challenges associated with the conversion options and propose mitigation strategies or further research directions to overcome these challenges.

4. Conclusion:

(1) Summarize the main findings of the study, highlighting the technical feasibility of converting offshore platforms for renewable energy production, hydrogen generation, CO2 capture, and fluid storage.

(2) Emphasize the economic opportunities and potential benefits of utilizing existing offshore platforms and depleted reservoirs in achieving the goals of the energy transition.

(3) Relate the conclusions to the broader context of the European Green Deal and the global energy transition, underscoring the importance of resource efficiency, competitiveness, and emission reduction.

4. Language and Style:

(1) Review the entire text for grammatical errors, clarity of expression, and scientific writing conventions.

(2) Ensure consistent terminology throughout the paper, particularly when referring to conversion options and their potential benefits.

(3) Consider restructuring and rephrasing sentences or paragraphs to improve the flow and readability of the text.

Author Response

The authors are very thankful to the reviewer for their valuable comments. We have addressed them thoroughly and we now believe the manuscript has significantly improved.

The manuscript provides an investigation into the potential conversion of offshore platforms in the context of the energy transition. However, there are areas in the full text where improvement and clarification can be made. Here are specific suggestions for modification:

1. Introduction:

(1) Expand the introduction to provide a more comprehensive overview of the energy transition and the importance of repurposing existing offshore platforms in achieving renewable energy goals.

References have been added to address the comment from the reviewer.

(2) Clearly state the objectives of the study, emphasizing the focus on conversion options related to renewable energy production, hydrogen generation, CO2 capture, and fluid storage.

The objectives of the study have been re-stated and clarified.

(3) Provide a brief review of the current state of offshore platforms and their potential environmental impact, highlighting the need for sustainable alternatives.

Unfortunately, the authors cannot access the data needed to provide a reliable review of the current state of offshore platforms. References have been added to support the statements about the potential environmental impact of platform decommissioning and the need for sustainable alternatives.

2. Methodology:

(1) Provide a detailed description of the methodology used to evaluate the technical feasibility of converting offshore platforms. Explain the selection criteria for the case histories and the rationale for choosing a typical platform in the Adriatic Sea, Italy.

The paper aims at being a perspective paper, hence only a short description of the methodology is here reported. The complete methodology is detailed in a dedicated paper numbered [26] in the reference list. Unfortunately, there was a mis-reference in the previous version of this article. The cross-reference has been fixed in the current revision of the paper. 

The choice of selecting an Italian infrastructure is due to two reasons: first, the Italian seas host 138 offshore platforms, of which more than 40 are more than 30 years old; second, the project aimed at identifying sustainable options for end-of-life platforms is being supported by the Italian Ministry of Economic Development (now Italian Ministry of Environment and Energy Security - MASE).

The choice of selecting a fictitious infrastructure is due to the fact that the final goal of the project is the development of a guideline for selecting the most appropriate conversion solution for each platform based on its specific technical features.

(2) Clearly outline the tools, models, or simulations employed to assess the different conversion options. Explain the parameters considered and the assumptions made during the evaluation process.

Thank you for the remark. The paper aims at being a perspective paper, hence it focuses mainly on techniques, methods and philosophy rather than on tools; however, the design options have been developed based on the results coming from MATLAB scripts. Moreover, additional technical details on figures and tools are available in already published papers (e.g. [26]) or in papers submitted for revision and dedicated to other specific options.

3. Results and Discussion:

(1) Present the findings of the study in a structured and organized manner, discussing each conversion option separately.

The authors have chosen to discuss results according to different key issues arisen during the development of the design for each option rather than considering option by option. In fact, most of the issues are common to all the options and related to the general framework.

Moreover, since the project's final objective is the development of guidelines providing an indication for the conversion of specific installations (this activity is still ongoing), the approach to address the different key issues seemed to be more functional to this goal.

(2) Provide quantitative data, performance metrics, or case study results to support the claim that no specific critical issues prevent the successful conversion of offshore platforms.

The authors understand the reviewer’s remark but stress that the perspective should be reversed: the guidelines under development, which will contain the performance metrics, should prevent the arising of critical issues when proceeding toward a conversion option. 

(3) Discuss the economic, environmental, and social implications of each conversion option, including their potential contributions to achieving energy transition targets and reducing CO2 emissions.

We respectfully note that the implications mentioned by the reviewer are out of the scope of this work.

The introduction has been updated in order to better clarify the intention of the authors to provide a perspective on the possible conversion options of aging platforms and the connected depleted reservoirs, under the light of technical feasibility, whereas the social, economic and administrative aspects were out of the scope of the project. 

(4) Address any limitations or challenges associated with the conversion options and propose mitigation strategies or further research directions to overcome these challenges.

The authors understand the reviewer’s remark but the comments are general because they are included in coherence with the perspective nature of the paper and with the objective to highlight the main potential obstacles to the realization of the selected option for the sake of completeness. A case-by-case investigation will be necessary for future conversion activities.

4. Conclusion:

(1) Summarize the main findings of the study, highlighting the technical feasibility of converting offshore platforms for renewable energy production, hydrogen generation, CO2 capture, and fluid storage.

We recapped the different conversion options that we investigated. As for the technical feasibility, our results did not reveal any specific critical issues in the deployment of the current technologies related to energy transition as long as the selection of the conversion option to deploy is designed taking into account the characteristics of the whole system, which comprises the platform and the depleted reservoir to which it is connected.

The conclusion now better reflects this outcome.

(2) Emphasize the economic opportunities and potential benefits of utilizing existing offshore platforms and depleted reservoirs in achieving the goals of the energy transition.

The conclusion has been updated in order to restate the focus of the study on the technical aspects rather than on the social, economic and administrative issues, which were out of the scope of our investigation.

(3) Relate the conclusions to the broader context of the European Green Deal and the global energy transition, underscoring the importance of resource efficiency, competitiveness, and emission reduction.

We added a brief reference to the European Green Deal, however we feel that expanding on the European Green Deal would be out of the scope of the paper. We hope that the reviewer agrees with the authors.

4. Language and Style:

(1) Review the entire text for grammatical errors, clarity of expression, and scientific writing conventions.

Done.

(2) Ensure consistent terminology throughout the paper, particularly when referring to conversion options

Done.

(3) Consider restructuring and rephrasing sentences or paragraphs to improve the flow and readability of the text.

Done.

Round 2

Reviewer 2 Report

 

1.    I must say that I am not satisfied with the answers given by the Authors. The article has been slightly improved. It has not been supplemented with specific data that would be definitely interesting and show the actual possibilities of using the Italian offshore platforms and depleted reservoirs.

2.    The quality of Fig. 1 – 4 is very low.

3. The description of the article has been changed from "article" to "perspective article", if the JMSE Journal Editor is interested in such publications, I will also accept this article.

 

 

Minor editing of English language required

Author Response

1. We are sorry that the reviewer is not satisfied with our answers. As we highly valued the first round of comments from the reviewer, we have enriched the current version of the paper with additional data whenever possible and referenced the relevant papers where more details are provided to avoid duplicating already published information. Yet the paper is meant to demonstrate that there are no technical obstacles to implementing solutions for platform conversion rather than showcasing specific examples of conversion. In this respect, we don’t have design data specific to a selected platform and reservoir that we can share. This further step will be developed in the next future when a platform to be converted and feasible conversion options will be identified.
2. The quality of figures was poor due to a conversion issue, we are sorry for the inconvenience. The issue should be fixed now. However, figures 2 and 3 were also adjusted to make the axis values and titles more visible.
3. Thank you.

Reviewer 3 Report

Accept

Author Response

Thank you.

Round 3

Reviewer 2 Report

1.    I thank the Authors for their efforts. The quality of the article has been improved (including drawings). I hereby recommend the article for publication in the JMSE Journal.

Minor editing of English language required