Modeling the Global Annual Carbon Footprint for the Transportation Sector and a Path to Sustainability
Round 1
Reviewer 1 Report
Dear Authors,
I have thoroughly reviewed your manuscript titled "A Technology Roadmap and Model for the Sustainable Transformation of the Transportation Sector." Your paper presents a comprehensive perspective on the transition to a sustainable transportation sector, including a roadmap and a model to show a plausible pathway to sustainability. However, I have some concerns and recommendations that should be addressed before the manuscript can be considered for publication in Modelling Journal by MDPI.
Generally:
Unrealistic Assumptions: The paper assumes an ideal trajectory of technological advancements and infrastructure development. This overlooks real-world scenarios such as economic, political, and societal influences, which often delay or obstruct technological growth and implementation. I recommend incorporating a realistic view of these factors into your model.
Unclear Methodology: The methodology section lacks clarity. It is not clear how specific technologies were selected or why certain years were chosen for full technology availability. This needs to be clarified and justified.
Absence of a Policy Framework: You propose significant changes to our infrastructure, but there's no discussion of policy implications. Achieving carbon neutrality will not be possible without relevant and supportive policies. This aspect needs to be integrated into your analysis.
Neglecting Other Sectors: The focus is heavily on the transportation sector, neglecting the interaction and impact this will have on other sectors, such as the power sector and raw material sectors. The interplay between sectors must be addressed.
Sensitivity Analysis: Your sensitivity analysis mainly considers changes in technology availability and growth rates. It would be more beneficial if this analysis were expanded to include various economic, policy, and social scenarios.
Negligence of Geographic Differences: The manuscript assumes a global homogeneity in terms of technological implementation and infrastructure changes. However, the rate of change varies significantly across regions due to varying economic and technological capabilities. Your analysis would benefit from a regional or country-specific approach.
Uncertain Technologies: Your model relies heavily on future technologies such as Mg-Ion batteries and biofuels, which are still in the experimental stage and their future is uncertain. A more cautious approach would be to also consider scenarios where these technologies do not mature as expected.
Lack of Robustness Check: Although the manuscript presents a variety of outcomes, it is unclear if these are robust to different assumptions about parameters or model structure. I suggest additional robustness checks.
Absence of a Literature Review: There's a distinct lack of reference to previous similar work. A proper literature review is needed to position your work within the existing research landscape.
Format and Grammar: The paper contains numerous grammatical and typographical errors. Moreover, the formatting of figures and tables could be improved to enhance clarity and readability.
Please consider addressing these comments in the revised version of the manuscript. It has the potential to provide valuable insights into the transition towards a sustainable transportation sector.
Going more detailed into the paper and providing deeper insights:
Broad Technological Scope: While it's beneficial to address multiple technologies, the sheer breadth of technologies covered in this paper dilutes the in-depth analysis of each one. It might be more beneficial to focus on a few pivotal technologies and analyze them in depth.
Dependency on Unproven Technologies: There is a significant dependency on unproven technologies like Mg-Ion batteries. If these technologies don't meet expectations, the whole model will suffer. Mitigating this issue requires considering the use of currently available or more reliable future technologies.
Hydrogen Economy Challenges: The paper seems to presume a smooth transition to a hydrogen economy, particularly for commercial vehicles and boats. It fails to address the considerable challenges in hydrogen storage, transportation, and infrastructure, which are still major hurdles to widespread hydrogen adoption.
Economic Feasibility: The paper neglects the issue of economic feasibility. While it's great to have a technological roadmap, without addressing costs, the whole analysis seems detached from reality. It would be worth incorporating cost models into your study to give a more balanced view of the future transportation sector.
Supply Chain Considerations: The discussion on electric vehicles and batteries overlooks the environmental and social implications of the raw materials needed, such as lithium and cobalt. Supply chain considerations and the implications of a massive increase in demand for these materials must be incorporated into your analysis.
Inadequate Data Source Justification: Throughout the paper, I noticed a lack of proper justification and transparency in the selection of data sources. It's essential to demonstrate why certain data were selected and how they're representative or superior to other potential data sources.
Lack of Comparative Analysis: The model predictions are presented without any comparison to other existing models or predictions. A comparison with other similar studies or models would provide a better understanding of where your predictions stand within the broader field.
Lack of Peer-Reviewed References: Many of your assertions seem to lack proper referencing to peer-reviewed sources, which undermines the academic credibility of your paper.
Assumptions on Global Uniformity: Your study seems to operate under the assumption that advancements will be evenly distributed globally. However, this is usually not the case, as developing countries may lag behind in adopting these technologies.
Unclear Figures: Some of your figures are unclear or not well explained in the text. Every figure and table must be clearly understandable without needing to read the full text.
Please take these criticisms into account when revising your manuscript. Your study has great potential and could contribute meaningfully to the ongoing discourse on sustainable transportation.
All the best!
The paper can benefit from a thorough improvement of the grammatical structure.
Author Response
Thank you for your time and effort in writing this review. You provided a tremendous amount of excellent feedback. The updated paper is a substantial improvement thanks to your keen insights.
Your comments are below in red. Our responses are in black. Generally, we concurred with all of your feedback (which was quite insightful and useful) and adjusted the paper accordingly.
Unrealistic Assumptions: The paper assumes an ideal trajectory of technological advancements and infrastructure development. This overlooks real-world scenarios such as economic, political, and societal influences, which often delay or obstruct technological growth and implementation. I recommend incorporating a realistic view of these factors into your model.
You are correct. The assumptions that we made in this paper were overly optimistic and best case scenario. We redid the analysis portion of the paper to discuss economic, political, and societal influences delaying the transitions of each market. In doing so, we reframed the model as being a tool for policy makers, which will allow them to better understand the impact of these policies on reaching sustainability. We made substantial changes to our paper, including a much more thorough analysis section (and background section).
Unclear Methodology: The methodology section lacks clarity. It is not clear how specific technologies were selected or why certain years were chosen for full technology availability. This needs to be clarified and justified.
We moved away from listing specific technologies. Rather we focused on alternative batteries, hydrogen storage, and generation 3 biofuels. We then discuss specific technologies that will help us meet these goals. In doing so, we were able to cut some of the technical material about the specific technologies, giving us additional space to add into our analysis portion. We included timelines as well for the development of these technologies.
Absence of a Policy Framework: You propose significant changes to our infrastructure, but there's no discussion of policy implications. Achieving carbon neutrality will not be possible without relevant and supportive policies. This aspect needs to be integrated into your analysis.
We added a section in the analysis portion of the paper detailing policy considerations. We also integrated policy implications (and the use of the model to support policy making) throughout the paper.
Neglecting Other Sectors: The focus is heavily on the transportation sector, neglecting the interaction and impact this will have on other sectors, such as the power sector and raw material sectors. The interplay between sectors must be addressed.
You are spot on about the power sector. It's one of the underlying themes of our paper is that sustainability of the transportation section requires a sustainable power grid! We made sure to make that clearer in both the discussion and the analysis portion of the paper.
The raw material sector is discussed somewhat in the individual technologies. We cleaned up the individual technology portion to be more straightforward. In doing so, important items, such as raw materials, did not get buried under a large amount of information. It is also revisited in the model limitations section.
Sensitivity Analysis: Your sensitivity analysis mainly considers changes in technology availability and growth rates. It would be more beneficial if this analysis were expanded to include various economic, policy, and social scenarios.
We significantly modified our sensitivity analysis and reframed as it as using our model to understand changes in policies. We then looked at the impact of different policy decisions related to government investments in infrastructure upgrades and technology advances.
Negligence of Geographic Differences: The manuscript assumes a global homogeneity in terms of technological implementation and infrastructure changes. However, the rate of change varies significantly across regions due to varying economic and technological capabilities. Your analysis would benefit from a regional or country-specific approach.
You are correct; this is a large limitation of the model. We added paragraphs in model limitations and future works to address this limitation. The overall goal of this model is to remain fairly simplistic to model large-scale impacts of new technologies on transportation sustainability. Once we start looking at regional variation, we need substantially more data, much of which is not available.
Uncertain Technologies: Your model relies heavily on future technologies such as Mg-Ion batteries and biofuels, which are still in the experimental stage and their future is uncertain. A more cautious approach would be to also consider scenarios where these technologies do not mature as expected.
You are spot on with regard to the uncertain technologies. We modified the paper to generalize the needs and propose a potential way to meet these needs. For example, rather than Mg-Ion, we use it as a likely technology for meeting the need of a cheaper battery chemistry. We also added in an analysis section that discusses what happens when certain technology advancements are delayed.
Lack of Robustness Check: Although the manuscript presents a variety of outcomes, it is unclear if these are robust to different assumptions about parameters or model structure. I suggest additional robustness checks.
We added in additional robustness checks into our model discussion. We also put address this issue in the analysis section of our paper, which is now much more in-depth.
Absence of a Literature Review: There's a distinct lack of reference to previous similar work. A proper literature review is needed to position your work within the existing research landscape.
We previously had a literature review section, but it was incredibly weak and did not speak to comparable models. We added a background section that has a much more in-depth look at comparable studies; this section also helps to explain the need for our model.
Format and Grammar: The paper contains numerous grammatical and typographical errors. Moreover, the formatting of figures and tables could be improved to enhance clarity and readability.
We went through and proofread the paper and tried to catch all of the grammatical mistakes. We also went through and updated the figures in an effort to ensure readability.
Please consider addressing these comments in the revised version of the manuscript. It has the potential to provide valuable insights into the transition towards a sustainable transportation sector.
Your feedback is very detailed, and we very much appreciate the time and effort that you put into providing this review.
Going more detailed into the paper and providing deeper insights:
Broad Technological Scope: While it's beneficial to address multiple technologies, the sheer breadth of technologies covered in this paper dilutes the in-depth analysis of each one. It might be more beneficial to focus on a few pivotal technologies and analyze them in depth.
Based off your other feedback and the feedback from other reviewers, we went in the opposite direction. We moved away from specific technologies and focused more on the needs. We then used the specific technology, with a much more succinct description, as a method of how to meet that need. In doing so, we were able to discuss the relevant aspects of the technology, without getting mired down in the technical challenges associated with each.
Dependency on Unproven Technologies: There is a significant dependency on unproven technologies like Mg-Ion batteries. If these technologies don't meet expectations, the whole model will suffer. Mitigating this issue requires considering the use of currently available or more reliable future technologies.
In the updates, we moved away from specific technologies, partially to address this concern. We also added in better details as to when these technologies will be available. In our new/improved analysis section, we look at the impact of these technologies reaching fruition.
Hydrogen Economy Challenges: The paper seems to presume a smooth transition to a hydrogen economy, particularly for commercial vehicles and boats. It fails to address the considerable challenges in hydrogen storage, transportation, and infrastructure, which are still major hurdles to widespread hydrogen adoption.
You are correct. We modified the model to account for this slower adoption. We also added discussion of these issues in the assumptions section and in the hydrogen storage section.
Economic Feasibility: The paper neglects the issue of economic feasibility. While it's great to have a technological roadmap, without addressing costs, the whole analysis seems detached from reality. It would be worth incorporating cost models into your study to give a more balanced view of the future transportation sector.
We added a section in the analysis section about cost and policy considerations to discuss economic feasibility. We also added discussion of cost into the technology section, since the major driver of new technologies is the cost associated with current technology.
Supply Chain Considerations: The discussion on electric vehicles and batteries overlooks the environmental and social implications of the raw materials needed, such as lithium and cobalt. Supply chain considerations and the implications of a massive increase in demand for these materials must be incorporated into your analysis.
We address this somewhat in the individual technology sections. As you stated lithium is in short supply, hence the need for an alternative battery chemistry that is more abundant (e.g., magnesium). We also address this in the biofuels section, where the resources needed for biofuels are resource intensive and compete with the fuel supply. In the earlier version of the paper, this was not clear and buried in a large amount of technical information about these technology advances. In the updated paper, we made those sections more succinct such that key information stands out better.
Inadequate Data Source Justification: Throughout the paper, I noticed a lack of proper justification and transparency in the selection of data sources. It's essential to demonstrate why certain data were selected and how they're representative or superior to other potential data sources.
We mention this now in our background section. For some of our larger assumptions (current state of the markets), we also explain our sources in text and why they were selected.
Lack of Comparative Analysis: The model predictions are presented without any comparison to other existing models or predictions. A comparison with other similar studies or models would provide a better understanding of where your predictions stand within the broader field.
We added a section to the paper (Section 6.4) which compares the results from this model to the results from other models in literature.
Lack of Peer-Reviewed References: Many of your assertions seem to lack proper referencing to peer-reviewed sources, which undermines the academic credibility of your paper.
We moved many of our references to being reports from highly credible international organizations that focus on climate change and sustainability. Those reports are heavily scrutinized. We also expanded our reference list to include more peer-reviewed sources. The paper now has over 40 references from peer-reviewed journal articles.
Assumptions on Global Uniformity: Your study seems to operate under the assumption that advancements will be evenly distributed globally. However, this is usually not the case, as developing countries may lag behind in adopting these technologies.
You are correct. We now address this in the model limitations section. We also now mention this in the future works.
Unclear Figures: Some of your figures are unclear or not well explained in the text. Every figure and table must be clearly understandable without needing to read the full text.
I went through and cleaned up all the figures and captions to ensure that they are understandable without needing to read the text.
Please take these criticisms into account when revising your manuscript. Your study has great potential and could contribute meaningfully to the ongoing discourse on sustainable transportation.
Thank you.
All the best!
Thanks! Same to you.
Reviewer 2 Report
The authors conducted a very important research, which helps to understand issues of energy environmental in different industries.
1. Necessary literature support is missing in the introduction.
2. In terms of the structure of the paper, I don't think “2.3. Literature Review” is in the right place.
3. The part of "Forecast of New Technologie" does not have to be so much, and it can be streamlined in the paper.
4. The research methodology of the paper could have been articulated more clearly and logically.
5. It is suggested that authors can consider the Model Assumptions more, such as global population will scale by approximately 1 percent by year.
The language is fine.
The elaboration of the paper could also be enhanced to accurately describe the content of the academic research.
Author Response
Thank you so much for the feedback. We truly feel much more excited about the updated version of the paper, which I believe is much stronger thanks to your recommendations.
Your comments are in red. Our responses are in black.
1. Necessary literature support is missing in the introduction.
We added a new Background section (2.1), which describes similar models used by international organizations, with a focus on their shortcomings, and how this model attempts to address those shortcomings. We think this provides a better explanation as to what the model is seeking to do.
2. In terms of the structure of the paper, I don't think “2.3. Literature Review” is in the right place.
We folded that section into the Background section. We got rid of 2/3 of it and added material about more comparable modeling efforts.
3. The part of "Forecast of New Technologie" does not have to be so much, and it can be streamlined in the paper.
That was a major focus of my revision. I cleaned that up and made the technology overview much more concise.
4. The research methodology of the paper could have been articulated more clearly and logically.
We went through and updated the relevant sections to make them more clear and logical. I think adding in the Background section feeds into the methodology and model architecture portion much better.
5. It is suggested that authors can consider the Model Assumptions more, such as global population will scale by approximately 1 percent by year.
We went through and added references to most of the model assumptions. The constant population growth is a rather bold assumption and is discussed in the model limitations section; it is also discussed in the section that compares this model to other models.
Reviewer 3 Report
The reviewer wishes to thank the authors for their efforts. This is an intriguing topic “Modeling the Global Annual Carbon Footprint for the Transportation Sector and a Path to Sustainability”. The subject is both fascinating and important. However, there are a few areas that require additional research before publication. I've outlined the necessary changes in the hopes that the feedback will be useful as you revise the paper.
· Improve the abstract and include the major model findings.
· Since the research focused on the Annual Carbon Footprint of the Transportation Sector. It is encouraging to add a section on sustainable materials and production processes. It is recommended to add relevant topics to the life cycle cost analysis to help understand the long-term viability of the proposed topic.
· Use passive voice and elaborate more on the trends of the results obtained.
· What are the shortcomings/drawbacks and challenges of the current proposed model.
· There are few English language and coherence issues in the research. It requires proofreading and improvement.
· What are the future recommendations based on the proposed model to help achieve carbon neutrality by the year 2070.
Finally, the manuscript should be modified according to above said comments and be reviewed again before accepting it for publication
Author Response
Thank you so much for your feedback. I feel that this updated paper is much stronger, having taken into account your keen insights.
Below are my responses. Your comments are in red.
Improve the abstract and include the major model findings.
The abstract has been updated to include the major findings.
Since the research focused on the Annual Carbon Footprint of the Transportation Sector. It is encouraging to add a section on sustainable materials and production processes. It is recommended to add relevant topics to the life cycle cost analysis to help understand the long-term viability of the proposed topic.
That is a great idea; however, with the flow of the paper, I thought that the discussion about sustainable materials and production processes would be better addressed in the individual technology sections (Section 4.2.X). I added in discussion about the materials and production processes associated with the new technologies.
Use passive voice and elaborate more on the trends of the results obtained.
I added an analysis section that better discusses the trends and results of the model.
What are the shortcomings/drawbacks and challenges of the current proposed model.
I added in a new section about the limitations of the current model. I feel somewhat embarrassed that I did not have that in my original paper.
There are few English language and coherence issues in the research. It requires proofreading and improvement.
I went through and attempted to find any coherence issue. I also proofread the paper, trying to find any grammatical/spelling mistakes.
What are the future recommendations based on the proposed model to help achieve carbon neutrality by the year 2070.
I added a section into the paper to specifically address future recommendations. In particular, I added a thorough analysis section that analyzes the results from the model.
Reviewer 4 Report
Point1:Please provide the details of Data analysis techniques in the model section and the flow chart used for modeling.This will make the modeling process more clear.
Point2: Conclusion please add discussion, the current discussion section is too little.
Point3:The analysis and research of the current situation are good., in line with the style of the journal.
Author Response
Thank you so much for the review and feedback. I went through and made substantial edits to my paper to address the points outlined in your review. Your comments are in red and my responses are in black.
Point 1: Please provide the details of Data analysis techniques in the model section and the flow chart used for modeling.This will make the modeling process more clear.
I adjusted Section 2 of the paper to better describe the model, including a much better description of the goals and outputs of the model. Furthermore, I added additional discussion on the data anlaysis techniques.
Point2: Conclusion please add discussion, the current discussion section is too little.
We added substantially more discussion into the conclusion, including a discussion of future works and a better summary of this paper.
Point3: The analysis and research of the current situation are good., in line with the style of the journal.
Thanks!
Round 2
Reviewer 1 Report
The paper can be accepted in the current form.
Reviewer 2 Report
Authors have made intensive revisions, and I think the manuscript can be accepted.
I think the English language is fine.
