Review Reports - Is the Transition to Electric Passenger Cars Sustainable? A Life Cycle Perspective

Round 1

Reviewer 1 Report

Comments

1. Explain more comprehensively about what this research adds to the subject area compared with other published material.

2. Transfer and add the second paragraph of the second page to the last paragraph of section 1.

3. Please don’t use group referencing like lines 60, 189, 234, 243, and 268.

4. Add references to all tables on their titles.

5. Draw and present more attractive figures that better demonstrate the simulation results.

6. Discuss the results of the paper quantitatively in the conclusions.

7. Validate the results of this paper with similar papers in the literature.

Author Response

Thank you very much for your remarks. They have proven very useful for us in order to improve the meaning and structure of our paper, and hopefully, our research efforts will be easier to follow. Our answers are the following:

Explain more comprehensively about what this research adds to the subject area compared with other published material.

Subsection 5.1 now provides a clear description of the proposed methodology and the results obtained by applying it to the current passenger car models are discussed in Subsection 5.4. Also in Chapter 5, the new tables (Tables 8 to 12) highlight both the correlations with other studies and the differences between this study and them. The final table (Table 13) emphasizes what are the main strengths and limitations of our study in comparison to other relevant published materials in terms of life cycle assessment (LCA) methodology. The clear distinction between Energy and Vehicle Life Cycle (LC) stages assessed in the proposed methodology represents the starting point for tackling other studies’ high degree of uncertainty regarding life cycle costs, emissions and energy consumption. Other uncertainty aspects which are difficult to correlate with refer to the variety of car models in weight and type, and the type of energy mix used, as discussed in Subsections 5.3 and 5.4. In this regard, the simulations in GREET provide a lesser degree of uncertainty, as presented in Chapter 4.

Transfer and add the second paragraph of the second page to the last paragraph of section 1.

I have transferred this paragraph to the end of section 1, with some minor adjustments.

Please don’t use group referencing like lines 60, 189, 234, 243, and 268.

Up to now I have used in other papers published in MDPI Sustainability this type of group referencing, according to the template’s requirements: “References should be numbered in order of appearance and indicated by a numeral or numerals in square brackets—e.g., [1] or [2,3], or [4–6]”.

Add references to all tables on their titles.

To all the tables (1 to 13) I have added references at the end. I believe it is much helpful at the end since I could also provide details related to them and thus make correlations with the table’s data.

Draw and present more attractive figures that better demonstrate the simulation results.

The new changes in the figures are only related to the changes in the values obtained either by simulation or by applying the proposed LCA methodology, and therefore are not so noticeable. But, for better highlighting the results, the newly added tables (7 to 13) can prove more relevant, as they provide more details than the figures. Thus, the correlations between our study, others, and GREET are easier to follow.

Discuss the results of the paper quantitatively in the conclusions.

In the new version both the Abstract and Conclusions discuss quantitatively the results.

Validate the results of this paper with similar papers in the literature.

Especially in the newly added tables (Tables 11 to 13) the results obtained herein are highlighted and discussed by comparison to similar papers. Also, the new tables (Tables 8 to 10) highlight the correlations with GREET, in order to validate the results obtained for the test models for the proposed methodology in comparison with the results obtained for the predefined models in GREET.

Reviewer 2 Report

The manuscript addressed an old issue. However, transportation electrification has shown a successful future in most countries. The research design lack of novelty comparing the large amounts of similar references.

Neither the data nor the method is convincing.

English writing requires proof reading to improve readability.

Author Response

The issues regarding the adoption of current electric cars impose a lot of technological and energetical challenges with noticeable implications on the environment, climate, industry and thus, on the future of our society. The geographical context is of utter importance when addressing the electrification of transport systems, and although successful in same places, in many others the transition is not feasible at this moment. In the similar published material on life cycle costs, emissions and energy consumption there is no clear distinction between the Energy and Vehicle Life Cycle (LC) which the proposed methodology assesses herein in order to tackle other studies’ high degree of uncertainty regarding these aspects. Other uncertainty aspects which are difficult to correlate with refer to the variety of car models in weight and type, and the type of energy mix used, as discussed in Subsections 5.3 and 5.4. In this sense, the simulations in GREET provide a lesser degree of uncertainty, as presented in Chapter 4.

Neither the data nor the method is convincing.

English writing requires proof reading to improve readability.

For improving both the language and style of the paper, thus readability, we have operated some changes for a better understanding of the paper's scope (research question) and its main findings. Also, the abstract, the introduction and conclusion chapters were modified accordingly.

Reviewer 3 Report

Dear Authors

The paper deals with an interesting topic, however, some changes are required to improve the quality of the paper.

- Quality of figure 1 must improve. The words "Sustainable transport system" is blurred. The size of the words are different. Move the words "Recycled Materials" in order to be complete.

- Figure 5, extend (organize) the legend to optimize space.

- Improve the sentence from lines 438-440. Complete the idea.

- Authors should improve the analysis in subsection 5.1.

- Improve subsection 5.2. A complete analysis is required.

- Is necessary to maintain Energy with an uppercase? I think some of them are not required.

- Correct the location of the word Vehicle LC in Figure 2.

- A complete explanation of the content in Figure 13 is required.

Author Response

- Quality of figure 1 must improve. The words "Sustainable transport system" is blurred. The size of the words are different. Move the words "Recycled Materials" in order to be complete.

Figure 1 was modified accordingly.

- Figure 5, extend (organize) the legend to optimize space.

In more figures the legend was repositioned and adjusted in order to optimize space: Figures 5 to 12, 17 and 18.

- Improve the sentence from lines 438-440. Complete the idea.

The sentence was changed and moved in the last paragraph of Chapter 5 (Results and Discussion): Lines 525-528. Some details were provided for a better understanding.

- Authors should improve the analysis in subsection 5.1.

Subsection 5.1 now provides a clear description of the proposed methodology and the results obtained by applying it to the current passenger car models are discussed in Subsection 5.4. The clear distinction between Energy and Vehicle Life Cycle (LC) stages assessed in the proposed methodology represents the starting point for tackling other studies’ high degree of uncertainty regarding life cycle costs, emissions and energy consumption. Other uncertainty aspects which are difficult to correlate with refer to the variety of car models in weight and type, and the type of energy mix used, as discussed in Subsections 5.3 and 5.4. In this regard, the simulations in GREET provide a lesser degree of uncertainty, as presented in Chapter 4.

- Improve subsection 5.2. A complete analysis is required.

The old subsection 5.2 can be now found in the new version in the Subsections 5.3 and 5.4. As mentioned previously, the uncertainty aspects are treated in these sections. In this regard, the newly added tables (Tables 8 to 12) highlight both the correlations with other studies and the differences between this study and them. The final table (Table 13) emphasizes what are the main strengths and limitations of our study in comparison to other relevant published materials in terms of life cycle assessment (LCA) methodology.

- Is necessary to maintain Energy with an uppercase? I think some of them are not required.

The authors use in the new version of the paper Energy (with uppercase) only if it refers to an Energy LC stage. Both the tables and figures use this denomination. Therefore, it is much easier to delimit it from the rest of the text where energy is in lowercase.

- Correct the location of the word Vehicle LC in Figure 2.

The location was moved accordingly. In the new version this is Figure 13.

- A complete explanation of the content in Figure 13 is required.

New explanatory lines (Lines 366 to 369) were added before this figure (which is Figure 12 in the new version).