Costs and Distributional Effects of Climate Transformation of the Vehicle Fleet in the EU
Round 1
Reviewer 1 Report
The paper is very interesting with rightly conducted research procedure. All equations are well described. Some concerns may be related to sensitivity of the cost estimates, but the authors are aware of research limitations (they inform about them in discussion and conclusion, which is crucial in optimization model researches). Below I listed some additional points for consideration:
- Strengthening the description of the policy implications for the economies with the highest emissions of carbon dioxides analyzed in the research sample.
- Addition of a paragraph with the definition of climate transformation risk (general definition beside vehicle fleet).
- Additional chart presenting sensitivity analysis to the assumptions will be beneficial.
Author Response
Comment: The paper is very interesting with rightly conducted research procedure. All equations are well described. Some concerns may be related to sensitivity of the cost estimates, but the authors are aware of research limitations (they inform about them in discussion and conclusion, which is crucial in optimization model researches). Below I listed some additional points for consideration:
Response: Thank you for the positive comments
- Comment: Strengthening the description of the policy implications for the economies with the highest emissions of carbon dioxides analyzed in the research sample.
Response: The five countries with the highest emissions (UK, Spain, Germany, France and Italy) account for the largest emissions and also the highest cost in the cost effective solutions, which is discussed on rows 466 – 471 in the revised version. The variation in cost burdens for these countries is smaller than for the variation among all EU countries and UK, which can be an advantage when implementing vehicle transformation. This is discussed in the final section on rows 574-579 in the revised version.
- Comment: Addition of a paragraph with the definition of climate transformation risk (general definition beside vehicle fleet).
Response: We define climate transformation of the vehicle fleet as reductions in CO2 emission from light duty vehicles, which is clarified on rows 24-25 in the revised version. In our view, a general definition of climate transformation risk, which would consider the entire society under conditions of uncertainty, is beyond the scope of the paper.
- Comment: Additional chart presenting sensitivity analysis to the assumptions will be beneficial.
Response: We agree and have inserted a figure showing the results from the sensitivity analysis with changes in different parameter values (discount rate, price of cars, and car price elasticity) in Section 6, ‘Discussion and conclusions’
Reviewer 2 Report
This is an interesting paper that presents an exsiting problem and how to confront it by making use of a dynamic optimazitation model. In general the paper is well-written though Figures alignment must be improved according ot the paper's template so to be able to be accepted, thus my reccomendation for acceptance after minor revision once seen also the attached reviewed file.
Author Response
Comment: This is an interesting paper that presents an exsiting problem and how to confront it by making use of a dynamic optimazitation model. In general the paper is well-written though Figures alignment must be improved according ot the paper's template so to be able to be accepted, thus my reccomendation for acceptance after minor revision once seen also the attached reviewed file.
Response: Thank you, the suggested corrections are made in the revised version.
Reviewer 3 Report
The paper is an interesting one and tackle an interesting point related to transport-related carbon emissions.
An issue remains, at least to be mentioned, about the carbon shift deriving from energy production. Some mentions considering the different EU countries' preference in terms of sources' mix - i.e., nuclear, coal, oil, etc. - should be done
Author Response
Comments: The paper is an interesting one and tackle an interesting point related to transport-related carbon emissions. An issue remains, at least to be mentioned, about the carbon shift deriving from energy production. Some mentions considering the different EU countries' preference in terms of sources' mix - i.e., nuclear, coal, oil, etc. - should be done
Response: We agree and have added a discussion on this when presenting carbon emissions from electric cars on rows 270-275 in the revised manuscript, and when discussing the scenarios on development of carbon efficiency on rows 391-395 in the revised manuscript.
Reviewer 4 Report
The paper is interesting especially when we take into account that the problem can be solved by energy balance accompanied by statistical and stoichiometric analysis, introducing financial aspects at the very end.
Main recommendation is that supplementary information: Appendix A and B should be shorter and some parts of them should become an integral part of the paper. By constantly referring to the appendix (21 times) readability of the paper is reduced.
The paper itself is sloppily written!
Insted of ''Abstract:'' it is writen ''This'' in bold.
It is not advisable to use e.g. when referring to literature ''(e.g. [5]).''
When writing, use a third person and an indefinite form;'' In our view'' it is not advisable.
I recommend that you refer to your study as a paper so that readers are not confused because the word study is often repeated in the introduction (overview) part of the paper.
Line 133 - zeros and omega are written in a larger font.
Line 134 - Please further explain the assumption: ''differs among countries but is the same for vehicle types''
Line 137 - larger font
Line 160 - ''Et'' larger font
Line 184 - ''The cost function is assumed to be continuous, decreasing'' Please explain the expectation of increased prices of a new vehicle.
Line 193 - Unfortunately ''discount rate ?, which is assumed to be the same for all countries'' it is not the same for all EU countries
Figure 1. disassembled into its constituent elements and because of that is not visible (readable).
Due to its complexity, it would be good to present Chapter 2 in the form of an algorithm of the analysis procedure or to make some other form of visualization that will bring math relations closer to the reader.
Line 280 - Energy unit written with small letters ''kwh'' => kWh
Chapter 3 is full of assumptions. How Figure 2 was obtained should be described in more detail and compared with the number of vehicles in each country.
The presentation of data announced in subtitle 3.1 should be nice to see in graphical form.
Line 405 - Table 1. abnormal font size
The Generalized Algebraic Modeling System used in chapter 5 should be described in more detail i.e. how you came to Figures 3, 4, 5, and 6.
Figure 3. there is no yellow line in the legend
There is no place for references in the conclusion, it would be nice to see separate discussion (analysis) from the formal conclusions.
Author Response
Comment: The paper is interesting especially when we take into account that the problem can be solved by energy balance accompanied by statistical and stoichiometric analysis, introducing financial aspects at the very end.
Response: Note that we are using mathematical programming for estimating cost effective solutions to achieve emission reductions targets. There are no statistical or stoichiometric methods in the paper.
Comment: Main recommendation is that supplementary information: Appendix A and B should be shorter and some parts of them should become an integral part of the paper. By constantly referring to the appendix (21 times) readability of the paper is reduced.
Response: In our view, it is necessary to provide all underlying analysis and data. Much data is used as inputs into the mathematical programming model. In our view it would difficult to include most of these tables in the main text. The interested reader can find details in Supplementary Information
We moved the table with results from the sensitivity analysis to the main text, since this can be general interest.
Comment: The paper itself is sloppily written!
Insted of ''Abstract:'' it is writen ''This'' in bold.
Response: This is changed in the revised version.
Comment: is not advisable to use e.g. when referring to literature ''(e.g. [5]).''
Response: This abbreviation is much used in the scientific literature. It is appropriate to use when the study referred to is only one of several studies, without e.g. the reader may get the impression it is the only study
Comment: When writing, use a third person and an indefinite form;'' In our view'' it is not advisable.
Response: It is changed to ‘in the authors’ view’
Comment: I recommend that you refer to your study as a paper so that readers are not confused because the word study is often repeated in the introduction (overview) part of the paper.
Response: The point is well taken
Comment: Line 133 - zeros and omega are written in a larger font.
Response: Correction is made
Comment: Line 134 - Please further explain the assumption: ''differs among countries but is the same for vehicle types''
Response: It refers to travel in km per vehicle and is explained as ‘…..the travel intensity measured as kilometers travelled per vehicle, fi, differs among countries but is the same for vehicle types, i.e. .’ on rows 131-134 in the revised version
Comment: Line 137 - larger font
Line 160 - ''Et'' larger font
Response: Thank you, corrections are made
Comment: Line 184 - ''The cost function is assumed to be continuous, decreasing'' Please explain the expectation of increased prices of a new vehicle.
Response: There are no expectations on price increases of cars in the paper, instead it is assumed that technical development reduces the car prices which is explained on rows 159-166 in the revised version and shown in Supplementary material Appendix A.
Comment: Line 193 - Unfortunately ''discount rate ?, which is assumed to be the same for all countries'' it is not the same for all EU countries.
Response: We refer to the social discount rate, which is clarified on row 185 in the revised version. Unfortunately, there is no data on the social discount rate for different countries, which is in contrast to data on market or central bank discount rate.
Comment: Figure 1. disassembled into its constituent elements and because of that is not visible (readable).
Response: Corrections are made in the revised version.
Comment: Due to its complexity, it would be good to present Chapter 2 in the form of an algorithm of the analysis procedure or to make some other form of visualization that will bring math relations closer to the reader.
Response: The cost minimization model in described in Section 2 which includes the relations between vehicle transports and emissions, costs of switching from fossil fuel to other vehicles, and the objective function. This is a standard approach in mathematical programming. We realize that it can be difficult for readers without basic knowledge in economics and mathematics and have therefore presented the derivations of the first-order conditions in Appendix A.
Comment: Line 280 - Energy unit written with small letters ''kwh'' => kWh
Response: The correction is made
Comment: Chapter 3 is full of assumptions. How Figure 2 was obtained should be described in more detail and compared with the number of vehicles in each country.
Response: The calculations of emissions presented in Figure 2 are described on rows 257-325 in the revised version. Actual vehicles in each country provide inputs into the calculations of actual CO2 emissions in 2018 Figure 2. Data on actual vehicles are presented in Table B1 in Supplementary information.
Comment: The presentation of data announced in subtitle 3.1 should be nice to see in graphical form.
Response: The emissions are presented in Figure 2 and all underlying data inputs are provided in Supplementary information Appendix B.
Comment: Line 405 - Table 1. abnormal font size
Response: Corrections are made
Comment: The Generalized Algebraic Modeling System used in chapter 5 should be described in more detail i.e. how you came to Figures 3, 4, 5, and 6.
Response: Section 2 describes the optimization problem used in the calculations, and necessary data for the numerical analysis are presented in Section 3. The results from the optimization are presented in Figures 3-6. The optimization problem is non-linear and includes 2688 control variables, which requires a powerful solver. GAMS provides a number of solvers which are used by scientists in many disciplines. This is clarified in the revised version on rows 410-415 in the revised version.
Comment: Figure 3. there is no yellow line in the legend
Response: Correction is made.
Comment: There is no place for references in the conclusion, it would be nice to see separate discussion (analysis) from the formal conclusions.
Response: We have added information on the sensitivity analysis in Section 6.
Reviewer 5 Report
This is a good topic, the conclusions are supported by the results. It can be accepted after mojor revision. The comments are as the follows:
The writing of this paper should be further polished.
The main contribution of this paper should be indicated at the end of the manuscript.
Introduction section should be enriched by more papers. The following papers should be cited in the introduction. “On the emission reduction through the application of an electrically heated catalyst to a diesel vehicle” and "Can regional transportation and land-use planning achieve deep reductions in GHG emissions from vehicles?".
Figure 1: I think there is a mistake about the figure 1. Where are A, B, 1?
Figure 4: Why was 2018 chosen as the start? If so, do you have data of 2019 and 2020 to compare with the data shown in the figure?
Author Response
Comment: The writing of this paper should be further polished.
Response: The paper has been subject to English proofreading.
Comment: The main contribution of this paper should be indicated at the end of the manuscript.’
Response: The main contribution of the paper is the numerical dynamic optimization with calculations of cost effective time paths of vehicle transformation in the EU and UK to reduce CO2 emissions, which is stated in the introduction. It is now repeated in the conclusions on rows 534-535 in the revised version
Comment: Introduction section should be enriched by more papers. The following papers should be cited in the introduction. “On the emission reduction through the application of an electrically heated catalyst to a diesel vehicle” and "Can regional transportation and land-use planning achieve deep reductions in GHG emissions from vehicles?".
Response: The introduction refers to papers with similar objective as our paper, i.e. minimization of costs for reduction GHG emissions from the transport sector and assessment of distributional effects. None of the suggested papers estimate costs for emission reductions or address distributional issues. Instead we refer to one of the papers in the final section.
Comment: Figure 1: I think there is a mistake about the figure 1. Where are A, B, 1?
Response: Corrections are made in the revised version.
Comment: Figure 4: Why was 2018 chosen as the start? If so, do you have data of 2019 and 2020 to compare with the data shown in the figure?
Response: As described in Section 3, 2018 is used as a base year since it is the latest year for which all necessary data are available. Note that the results presented in Figure 4 are outputs from the numerical optimization model which show the minimum cost path for each year for reaching 40 % emission reduction in 2050.
Round 2
Reviewer 4 Report
Unfortunately, I cannot accept a paper that calls for an Appendix 19 times. The second problem there is no conclusion chapter but 'Discussion and conclusions' that contain graphs that do not provide information. If the values are so close that the difference is barely visible on the graph, they should be presented in tabular form.
Author Response
Comment: Unfortunately, I cannot accept a paper that calls for an Appendix 19 times.
Response: the references to the different proofs and tables in the appendix are made to facilitate for the reader to find the correct numbers. Since this reviewer thinks it is too much, we have reduced the number of references to 7 in the revised manuscript by providing general statements in Sections 2 (rows 106-107) and 3 (rows 255-256) that all proofs and data can be found in Supplementary information.
Comment: The second problem there is no conclusion chapter but 'Discussion and conclusions' that contain graphs that do not provide information. If the values are so close that the difference is barely visible on the graph, they should be presented in tabular form
Response: The section contains sensitivity analysis, which is standard in empirical economic studies. It is important since it gives information on the robustness of the results under different scenarios, and to which parameters the results are most sensitive. This means that small differences in costs for different parameter changes are interesting. We agree that it would be better to present the results in a table, which is made on rows 543-546 in the re-revised version.
Reviewer 5 Report
It can be accepted.
Author Response
Comment: It can be accepted
Response: Thank you.
