The Water–Energy Nexus in Thermoelectric Power Plants: A Focus on Italian Installations Regulated Under the Integrated Emission Directive
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript analyzes the Water-Energy Nexus (WEN) in thermoelectric power plants across Italy, examining water consumption, energy generation, fuel usage, and related regulatory aspects. Although the research addresses a relevant issue, significant shortcomings remain, requiring major revisions.
Specific problems:
- The literature review lacks depth, particularly recent research on WEN within the European and Italian contexts, leaving the study’s novelty and positioning unclear.
- The methodology section inadequately explains analytical processes, and lacks detail on specific statistical tools or methods, reducing replicability.
- The manuscript acknowledges missing data from several power plants but does not properly discuss how these data gaps impact findings, raising questions about the validity of conclusions.
- Analysis is predominantly descriptive, with insufficient exploration of underlying factors affecting differences in water-energy efficiency across plant types.
- The manuscript briefly references relevant regulations (EU directives and Italian legislation) but does not effectively evaluate their practical impact on water-energy management or provide substantial insights for policymakers.
Author Response
Dear reviewer, thanks for your valuable suggestions. Your comments have been useful to detail and strengthen specific sections of the research, in particular Materials and Methods (Section 2) and Results (Section 3). The paper has been amended according to your comments. Please find the detailed responses below and the corresponding revisions/corrections highlighted in the re-submitted files.
Comment 1: The literature review lacks depth, particularly recent research on WEN within the European and Italian contexts, leaving the study’s novelty and positioning unclear.
Response 1: The literature review has intentionally focused on the Integrated Emission Directive framework, which forms the core of our study. Accordingly, we chose to keep the review deliberately narrow, without extending it to all types of TEPPs or their various dimensions. The state of the art has thus been presented in a selective manner, aligned with the specific objectives of our research (see Section 1.5). While we acknowledge that a broader review could be of interest, we believe such an extension would not be consistent with the goal defined for this work.
Comment 2: The methodology section inadequately explains analytical processes, and lacks detail on specific statistical tools or methods, reducing replicability.
Response 2: The description of the applied methodology is provided in Section 2, Pages 5-7, lines 182–248. This section outlines the key methodological steps (lines 190–196), illustrates the workflow through a flowchart (Figure 3), and details the procedures adopted for each individual phase (lines 202–248). This study is built upon a publicly available database, accessible online and managed by the Italian Ministry of the Environment (MASE). Details are provided in lines 202–205 with regard to the MASE online repository (please see reference [38]). Furthermore, a description of the specific tools employed has been added in lines 240–248. Additionally, in response to feedback from other reviewers, we have included a more comprehensive explanation of the rationale behind the selected methodology (Lines 182–189).
Comment 3: The manuscript acknowledges missing data from several power plants but does not properly discuss how these data gaps impact findings, raising questions about the validity of conclusions.
Response 3: The data gap first concerns three installations (ID 16, ID 49, and ID 194) out of a total of 72. Considered the size of the overall sample analysed, the impact of this gap can be evaluated negligible. Specifically, these installations are included in the IED framework just for registration and mapping purposes, but they are not working. Therefore, they do not generate statistical data that can invalidate the statistical values. Further clarifications have been added in Page 7, lines 264–270, as well as in the caption of Figure 5 (lines 331-337). Please note that the Figure 5 has been modified, following feedbacks from other reviewers, to improve its readability and comprehensibility. However, the content remains the same.
Comment 4: Analysis is predominantly descriptive, with insufficient exploration of underlying factors affecting differences in water-energy efficiency across plant types.
Response 4: We deepened the correlation between water use and plant type. We introduced a more detailed list of these plant types in Table 1, (Page 7, lines 275-277), moved the Figure 4 below to enhance clarity of the distribution, proposing further connections by considering the water use for cooling across different TEPP typologies (Page 14, lines 369-379). In support we have introduced Table 2 with the water use for TEPP category and the average performance indicator for category (Pages 14-15, lines 380-383). However, it’s to be considered that we cannot establish a specific efficiency indicator by TEPP type and process, as the sample size within each category is too heterogeneous. In fact, as illustrated in Section 4.1, we highlighted such aspect as limitation of the study (Page 18, lines 475-480).
Comment 5: The manuscript briefly references relevant regulations (EU directives and Italian legislation) but does not effectively evaluate their practical impact on water-energy management or provide substantial insights for policymakers.
Response 5: As stated in Response 1, the scope of the study is deliberately limited to the Water-Energy Nexus within the framework of the IED directive. This framework is based on a continuous update of regulations starting from the scientific evidence to develop the Best Available Techniques (BAT) Reference Documents and BAT Conclusions. The study provides an up-to-date overview of the current situation — particularly in the Italian national context — with a focus on the large combustion plants category. BAT assessment is also based on the analysis of cross-media effects, so assessing how BATs related to energy production affect water use, and fuel consumption, is also useful to establish these effects. Moreover, the practical contribution for policymakers lies in offering a methodology for analysing the data reported by operators within this framework. To the best of our knowledge, no similar published contributions currently exist.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper reports water use in energy production in industrial plants in Italy from 2021 to 2023, considering Water-Energy Nexus to promote sustainable water and energy management. Large amounts of water for cooling in electricity production cycle were analyzed for reduce water consumption, recycle water flows, and minimize the environmental impact of power plants. It is interested in studying resource use trends over a 10-year period of data collection and three-time phases, including the TEPP study. I suggest that the manuscript require major revision before considering acceptance. Some comments and questions follow below.
- There are areas missing ID numbers in Figure 4.
- Figure 5 and Figure 4 do not match
- Missing values ​​in Appendix A
Author Response
Dear reviewer, thanks for your valuable suggestions. The paper has been amended accordingly your comments and responding to your answers. Please find the detailed responses below and the corresponding revisions/corrections highlighted in the re-submitted files.
Comment 1: There are areas missing ID numbers in Figure 4.
Response 1: Figure 4 has been updated by highlighting all the ID numbers of the analysed installations. Also taking into account the suggestions of other reviewers, Figure 4 has been moved to Section 3 (Page 9, line 278), following the table with the description of TEPPs types detected in the study.
Comment 2: Figure 5 and Figure 4 do not match
Response 2: Figure 5 has been rethought and modified to improve its clarity and comprehensibility. All the installation IDs have been entered in the vertical axis to match with Figure 4. In particular, a clarification has been added in the caption to make it clear that some plants which have been surveyed have been included in this list but are not working (so they have not provided data). Therefore, these installations are excluded from normalizing process, but are still represented in the graph as elements without values.
Comment 3: Missing values in Appendix A
Response 3: In Appendix A, all the values in the tables have been deliberately omitted, to maintain the confidentiality of some data. This allows us avoiding possible conflicts with the operators of the installations. The appendix merely illustrates the structure of the database, without providing values.
Reviewer 3 Report
Comments and Suggestions for AuthorsReview of the Manuscript entitled:
Water Energy Nexus in IED thermoelectric power plants in Italy
Dear Editor,
In this article, the authors investigated the impact of water use in energy production in industrial plants, considering the interdependence between water and energy, or Water-Energy Nexus, to promote sustainable water and energy management. More in detail, it focuses on the industrial sector, particularly on electricity production in thermoelectric power plants, which require large amounts of water for cooling in its production cycle. The Italian situation is outlined, exposing consumption data from major thermoelectric power plants in 2021 and 2023, highlighting the water usage trend and electricity production. It is also analyzed the application of Best Available Techniques to reduce water consumption, recycle water flows, and minimize the environmental impact of power plants. … I think that the subject of this manuscript is interesting and applicable. I recommend this article for publication in the journal water; however, it needs some revisions:
- The abstract is more descriptive, and it is recommended the authors consider some data from the Results section accompanying the applied method in this work.
- The novelty of the works has not been clarified.
- Besides, in the title the Water Energy Nexus should be written as other parts in the manuscript as Water-Energy Nexus.
- Please introduce the limitation of the usage of natural gas, coal, and biomass in the mentioned plants.
- It is better the abbreviation of IED in the title be replaced by Industrial Emission Directive. Besides, all abbreviation for the first time should be defined.
- Please write the parameter title of x and y axes in Figures 1&2.
- Please re-read the manuscript to correct any grammatical mistakes, errors or typos.
- Page 5, lines 179-181: “The research method was designed in four phases. The analysis started from the information on the TEPPs collected by ISPRA under the framework of Directive 2010/75/EU for national EIA.”
Would you please define the applied architectural design in this work.
- Page 8, lines 274-275: “The fuels detected are solid (solid biomass, coal, solid fuels from non-hazardous waste), liquid (liquid biomass, diesel, fuel oil) and gaseous (natural gas, steel gas, syngas).”
Would you please describe more about these materials including solids, non-hazardous gases, …through some examples. Moreover, how about hazardous gases and their limitation in the process of the design such as CO, CO2, NO, NO2,…? Have you had any prediction for the removal of noxious gases?
- Please improve the quality of graph in Figure 5. It is not clear.
- What is Sankey diagram? Please illustrate it.
- The discussion part is well-written.
Comments for author File: 
Comments.pdf
Author Response
Dear reviewer, thanks for your valuable suggestions. The paper has been amended accordingly your comments and responding to your answers. Please find the detailed responses below and the corresponding revisions/corrections highlighted in the re-submitted files.
Comment 1: The abstract is more descriptive, and it is recommended the authors consider some data from the Results section accompanying the applied method in this work.
Response 1: Data from the Results section and insights have been inserted in the abstract. Please see Page 1, lines 18-20.
Comment 2: The novelty of the works has not been clarified.
Response 2: An explication of the novelty of the work has been implemented in the Discussion (Section 4). Please see Page 16, lines 410-413.
Comment 3: Besides, in the title the Water Energy Nexus should be written as other parts in the manuscript as Water-Energy Nexus.
Response 3: The title has been adjusted and corrected.
Comment 4: Please introduce the limitation of the usage of natural gas, coal, and biomass in the mentioned plants.
Response 4: The major limitation of the usage of natural gas, coal, and biomass in the mentioned plants have been introduced in Page 16, lines 409-414.
Comment 5: It is better the abbreviation of IED in the title be replaced by Industrial Emission Directive. Besides, all abbreviation for the first time should be defined.
Response 5: Please see the previous answer in point 3. The abbreviation has been removed.
Comment 6: Please write the parameter title of x and y axes in Figures 1&2.
Response 6: Figures 1 and 2 have been updated with the title of x and y axes.
Comment 7: Please re-read the manuscript to correct any grammatical mistakes, errors or typos.
Response 7: Grammatical mistakes, errors or typos found have been corrected.
Comment 8: Page 5, lines 179-181: “The research method was designed in four phases. The analysis started from the information on the TEPPs collected by ISPRA under the framework of Directive 2010/75/EU for national EIA.” Would you please define the applied architectural design in this work.
Response 8: The research methodology has been described in more detail. Please see Page 5, lines 182-189. We noticed that, maybe, the use of word “design” has been misunderstood.
Comment 9: Page 8, lines 274-275: “The fuels detected are solid (solid biomass, coal, solid fuels from non-hazardous waste), liquid (liquid biomass, diesel, fuel oil) and gaseous (natural gas, steel gas, syngas).” Would you please describe more about these materials including solids, non-hazardous gases, …through some examples. Moreover, how about hazardous gases and their limitation in the process of the design such as CO, CO2, NO, NO2,…? Have you had any prediction for the removal of noxious gases?
Response 9: Major effects from fuel combustion and environmental impacts, through atmospheric emissions, have been described on page 10, lines 299-303.
Comment 10: Please improve the quality of graph in Figure 5. It is not clear.
Response 10: Figure 5 has been rethought and modified to improve its clarity and comprehensibility. All the installation IDs have been entered in the vertical axis. In particular, a clarification has been added in the caption to make it clear that some plants which have been surveyed have been included in this list but are not working (so they have not provided data). Therefore, these installations are excluded from normalizing process, but are still represented in the graph as elements without values.
Comment 11: What is Sankey diagram? Please illustrate it.
Response 11: The Sankey diagram model is clearly described in the text. Please see Page 15, lines 384-390, and caption of Figure 9 (lines 392-402). However, we added a short entry in lines 384-385 to better introduce the resource flow, and adjusted the caption of Figure 9.
Comment 12: The discussion part is well-written.
Response 12: Thank you for the appreciation.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsIt can be accepted.
Reviewer 2 Report
Comments and Suggestions for AuthorsIn the revised submission the authors have satisfactorily addressed my comments and concerns raised on their original submission. I recommend publication of this manuscript in Water.
Reviewer 3 Report
Comments and Suggestions for AuthorsDear Editor,
Regarding the author’s revision, I am pleased to inform my satisfaction of the present form of the manuscript entitled: “Water Energy Nexus in IED thermoelectric power plants in Italy” for publication in the journal Water.
