Energy Efficiency in Industry 4.0: The Case of Batch Production Processes

Round 1

Reviewer 1 Report

Quite interesting approach to energy efficiency management in industrial batch processes. An extended literature revision has been conducted. However some improvements are necessary:

1) Format:

• Review sentences in lines 227 and 228: a full stop (".") has been wrongly placed.
• Review end of equation 8: the final bracket has moved to the next line.

2) Use of IS units:

• Please revise the inappropriate use if IS units such as "Kg" instead of "kg"; "Kw" instead of "kW"; and "Kw/h" instead of "kWh" along the document (at least lines 552, 553, 558, 562, 567, 580, 581, 588, 591...).

3) Methodology:

• In line 525 it is stated the the "ideal theoretical value" should be greater than 95% and no justification of such calculation or bibliographical reference is given. 
• Same in line 532, where a "theoretically established" value greater than 98% is mentioned.

4) Results:

• In lines 732 to 739, several decisions concerning management techniques have been presented, with very limited justification of the reason for such decisions.
• In line 746  the improvements in OEE have been mentioned, but no result on the CO2 emissions improvement have been presented. Since the method presented in this manuscript focuses both on OEE and CO2 emissions, I consider that this improved figure should be presented.
• In line 676 the energy losses have been estimated at 365.7 kg but it is unclear whether that figure stands for one batch, one day, or the whole analysed period (very unlikely).

5) Overall approach:

- In line 71 it is stated that the manuscript will focus on OEE, IoT, and CPPS to achieve energy savings, but conclusions in lines 684 and 687 just mention OEE and CPPS. IoT is only mentioned as a possible technology for maintenance activities. If Iot is not one of the focus of the manuscript, the initial statement should be modified.

Author Response

Journal Sustainability (ISSN 2071-1050)

Manuscript ID sustainability-881926

Type Article

Number of Pages 29

Title

Energy Efficiency in Industry 4.0: the Case of Batch Production Processes

Authors Giancarlo Nota * , Alonso Toro Lazo , Domenico Peluso , Francesco David Nota

Abstract

A promising approach to reducing the energy consumption necessary in manufacturing processes derives from the combination of management methodologies and industry 4.0 technologies. Based on a literature review and experts’ opinion, this work contributes to the efficient use of energy in batch production processes combining the analysis of the Overall Equipment Effectiveness with the study of variables managed by Cyber-Physical Production Systems. Starting from the analysis of loss cause identification, we propose a method that derives quantitative data about energy losses during the execution of batch processes. The implications of this research regard the acquisition of precise information about energy losses and the improvement of value co-creation practices so that the reduction of energy consumption can be achieved in manufacturing processes. Decision-makers can use the findings of this research to start a virtuous process aiming at the reduction of carbon footprint, also reducing the energetic costs, while the production goals are kept.

Thanks for your time and attention. All your comments are relevant and we have used them to improve the quality of our article as follows.

Comments and Suggestions for Authors

Quite interesting approach to energy efficiency management in industrial batch processes. An extended literature revision has been conducted. However some improvements are necessary:

1) Format:

• Review sentences in lines 227 and 228: a full stop (".") has been wrongly placed. (Restructured from line 225 to 229”)
• Review end of equation 8: the final bracket has moved to the next line. (Corrected, line 399)

2) Use of IS units:

• Please revise the inappropriate use if IS units such as "Kg" instead of "kg"; "Kw" instead of "kW"; and "Kw/h" instead of "kWh" along the document (at least lines 552, 553, 558, 562, 567, 580, 581, 588, 591...). (Changes made in accordance with the Standard Unit Notation consulted in https://physics.nist.gov/cuu/pdf/sp811.pdf. in lines 579, 580, 585, 587, 591, 596, 609, 610, 617, 620,635, 636, 640, 642, 658, 659, 665, 668, 678, 679, 683, 686, 698, 700, 704, 708).

3) Methodology:

• In line 525 it is stated the the "ideal theoretical value" should be greater than 95% and no justification of such calculation or bibliographical reference is given. (Bibliographic reference added in line 542).
• Same in line 532, where a "theoretically established" value greater than 98% is mentioned. (Bibliographic reference added in line 553).

4) Results:

• In lines 732 to 739, several decisions concerning management techniques have been presented, with very limited justification of the reason for such decisions. (Added explanation from line 763 to 769).
• In line 746 the improvements in OEE have been mentioned, but no result on the CO2 emissions improvement have been presented. Since the method presented in this manuscript focuses both on OEE and CO2 emissions, I consider that this improved figure should be presented. (Added explanation from line 788 to 793).
• In line 676 the energy losses have been estimated at 365.7 kg but it is unclear whether that figure stands for one batch, one day, or the whole analysed period (very unlikely). (Updated wording on line 709 for clarity).

5) Overall approach:

- In line 71 it is stated that the manuscript will focus on OEE, IoT, and CPPS to achieve energy savings, but conclusions in lines 684 and 687 just mention OEE and CPPS. IoT is only mentioned as a possible technology for maintenance activities. If Iot is not one of the focus of the manuscript, the initial statement should be modified. (Updated from line 717).

Submission Date

10 August 2020

Author Response File: Author Response.pdf

Reviewer 2 Report

Assessing different benefits of I4.0 solutions systematically is a really hot topic especially regarding sustainability and other related questions. The authors suggest the use of Overall Equipment Effectiveness (OEE) and propose a Cyber-Physical System (CPS) architecture, based on those they present a case study evaluating the energy efficiency of an automotive press shop to justify their approach.

The objectives are clear; the reader is still in a difficult situation since the assumptions and conclusions are not or just hardly discussed. A very extensive amount of references are cited however the review parts lack their short and informative discussion. Many sentences would require rephrasing to express the original thought.

Since the topic and the approach are still promising the reviewer suggests considering the followings to improve your paper:

• Please give a very short introduction to the basic terms, like discrete and batch manufacturing. The use of the widely accepted S88 and S95 terminology is warmly suggested. In this sense, your process should be considered as a discrete manufacturing process instead of a batch process.
• Unfold a little bit more on CPS, since it is definitely not only IoT. Similarly, very shortly outlining the main objectives and approaches of I4.0 concept related to your paper would be useful.
• Please explain shortly whether the assumption of constant W0, W1, and W2 factors in case of different types of products is acceptable or can be considered as a good estimate.
• Similarly, please justify that energy consumption is always in a linear relationship with the time involved.
• Please give more details about the suggested CPS concept and introduce very shortly the role of the digital twin in your scheme. Why the digital twin is the source of commands for the manufacturing process (instead of the PPC part)?
• While the case study refers to 5 (five) presses in the production line, Figure 6 shows 6 (six) of them. Please explain or correct it.
• A table summarizing the energy consumption and CO₂ emission for each different cause of loss as well as the total energy consumption and CO₂ emission would help the reader greatly in comparing the effect of different causes.
• In general, please always give some reasoning or explanations about the selected relationships, structures, parameters, values, etc.
• Please have your paper checked by a native speaker to avoid unclear or hard to understand sentences.
• Although Appendix B gives a well-structured overview of papers related to the effect of factory layout, it is not clear how these tables correspond to the main objectives of the study.

Minor remarks for further improvements:

• The title of Section 3 is not appropriate.
• Please avoid piling up references in lists (e.g. lines 48, 50, 58, 314, 317, 332, …). Just mentioning what topics are covered in a paper is surely useful for the reader.
• Lifecycle stages indeed influence energy aspects however, in line 465 production stages are probably the right term to be used.
• Please refer to all figures, tables (even in the Appendix) in the main text.
• Please use the standard unit notation, like kg and kW.
• Correct the units in Table 9, 10, 12, 13, 14, 15. “kW/h” is incorrect.
• Figures 7, 8, 10, and 11 practically correspond to Figure 4. It would be more concise to give the appropriate time data in the corresponding Tables. Only Figure 9 should be left as an explanation (with the shutdown and start times should be shown by at least an approximate scaling).

Author Response

Inizio modulo

Journal Sustainability (ISSN 2071-1050)

Manuscript ID sustainability-881926

Type Article

Number of Pages 29

Title

Energy Efficiency in Industry 4.0: the Case of Batch Production Processes

Authors Giancarlo Nota * , Alonso Toro Lazo , Domenico Peluso , Francesco David Nota

Abstract

A promising approach to reducing the energy consumption necessary in manufacturing processes derives from the combination of management methodologies and industry 4.0 technologies. Based on a literature review and experts’ opinion, this work contributes to the efficient use of energy in batch production processes combining the analysis of the Overall Equipment Effectiveness with the study of variables managed by Cyber-Physical Production Systems. Starting from the analysis of loss cause identification, we propose a method that derives quantitative data about energy losses during the execution of batch processes. The implications of this research regard the acquisition of precise information about energy losses and the improvement of value co-creation practices so that the reduction of energy consumption can be achieved in manufacturing processes. Decision-makers can use the findings of this research to start a virtuous process aiming at the reduction of carbon footprint, also reducing the energetic costs, while the production goals are kept.

Thanks for your time and attention. All your comments are relevant and we have used them to improve the quality of our article as follows.

Comments and Suggestions for Authors

Assessing different benefits of I4.0 solutions systematically is a really hot topic especially regarding sustainability and other related questions. The authors suggest the use of Overall Equipment Effectiveness (OEE) and propose a Cyber-Physical System (CPS) architecture, based on those they present a case study evaluating the energy efficiency of an automotive press shop to justify their approach.

The objectives are clear; the reader is still in a difficult situation since the assumptions and conclusions are not or just hardly discussed. A very extensive amount of references are cited however the review parts lack their short and informative discussion. Many sentences would require rephrasing to express the original thought. (The conclusions (from line 717) have been rewritten to better clarify the results obtained from some of the results previously appeared in the literature review section.)

Since the topic and the approach are still promising the reviewer suggests considering the followings to improve your paper:

• Please give a very short introduction to the basic terms, like discrete and batch manufacturing. The use of the widely accepted S88 and S95 terminology is warmly suggested. In this sense, your process should be considered as a discrete manufacturing process instead of a batch process. (Added definition of batch production according ISA 88 and scenario explanation according to Groover. From line 103).

• Unfold a little bit more on CPS, since it is definitely not only IoT. Similarly, very shortly outlining the main objectives and approaches of I4.0 concept related to your paper would be useful. (CPPS and Industry 4.0 definitions added from line 456 to 480. In the same way, a better explanation of the proposed model was included from line 487 to 512).
• Please explain shortly whether the assumption of constant W0, W1, and W2 factors in case of different types of products is acceptable or can be considered as a good estimate. (The values W0, W1, and W2 correspond to average values measured every day during the observation period (two months) and have been considered as a reasonable approximation for the daily energy consumption of the line on a 24-hour basis. A brief explanation was given from line 582).
• Similarly, please justify that energy consumption is always in a linear relationship with the time involved. (A brief explanation was given from line 643, since it is important to clarify that the linear behavior presented in figure 9 is an approximation of a non-linear behavior with respect to absorption. Additionally, with the intention of giving greater clarity in this regard, Figures 7, 8, 9, 10 and 11 have been updated with a more suitable scale.).
• Please give more details about the suggested CPS concept and introduce very shortly the role of the digital twin in your scheme. Why the digital twin is the source of commands for the manufacturing process (instead of the PPC part)? (A better explanation of the proposed model was included from line 487 to 512).
• While the case study refers to 5 (five) presses in the production line, Figure 6 shows 6 (six) of them. Please explain or correct it. (Corrected in line 520).
• A table summarizing the energy consumption and CO₂emission for each different cause of loss as well as the total energy consumption and CO₂ emission would help the reader greatly in comparing the effect of different causes. (A table summarizing the energy consumption and CO2 emission for each different cause of loss as well as the total energy consumption and CO2 emission has been added in line 702).
• In general, please always give some reasoning or explanations about the selected relationships, structures, parameters, values, etc. (This request has been considered in paragraph 4.4 where some details have been specified about the components of the proposed CPPS model, its structure and its relationships. Some considerations are also included in the discussion (from line 780). Likewise, the arguments related to the adoption of some approaches to improve the performances of the production process (line 763), and the selection of professional maintenance activities developed to allow to restore the operation of the faulty machine have been expanded in the discussion, presented as relationships in Table 16 along with some considerations in the following lines. Also included in some parts of the text are the arguments that allow the reader to understand the origin and meaning of some parameters and values presented, such as those corresponding to daily energy consumption (line 582), time involved (line 643) and CO2 emissions (line 709 and 788), among others).  
• Please have your paper checked by a native speaker to avoid unclear or hard to understand sentences. (The paper was checked by an English review service).
• Although Appendix B gives a well-structured overview of papers related to the effect of factory layout, it is not clear how these tables correspond to the main objectives of the study. (The literature cited in the article inspired our research in at least three ways:
  • As indicated by line 194 onwards, the analysis of the literature provided us with indications on the research that had not received sufficient coverage, and this inspired our work.
  • Following your suggestion, we have enriched the final discussion, citing the works that have most influenced this research.
  • The classification into categories has facilitated the analysis of the problem dealt with and has oriented the research approach towards multidisciplinary analysis.)
• Minor remarks for further improvements:
• The title of Section 3 is not appropriate. (Changed by “Literature review” in line 169).
• Please avoid piling up references in lists (e.g. lines 48, 50, 58, 314, 317, 332, …). Just mentioning what topics are covered in a paper is surely useful for the reader. (Indeed, the citations as they were listed in the first version submitted was difficult to digest. We have opted for a simplification as many of the citations previously listed already appear in other parts of the article. Now, the citations on a single topic are, in most cases, single or limited to a few papers that deal with the same topic. Changes can be seen in lines 34, 35, 41, 48, 49, 50, 51, 53, 57, 59, 260, 262, 265, 270, 272, 275, 277, 281, 285, 301, 303, 305, 314, 315, 316, 317, 321, 322, 325, 326, 329, 330, 331, 332, 333, 337, 352, 361, 362, 365, 366, 367, 734, 735, 740, 835, 837, 839).
• Lifecycle stages indeed influence energy aspects however, in line 465 production stages are probably the right term to be used. (Changed “lifecycle” by “production” in line 471).
• Please refer to all figures, tables (even in the Appendix) in the main text. (Added Figure 1 in line 121, added reference to figure 8 in line 602, figure 9 in line 627, figure 10 in line 652, figure 11 in line 674, table A1 in line 173, tables B1, B2 and B3 Appendix B in line 195, table 8 in line 554, table 11 in line 631, table 12 in line 638, table 13 in line 663, table 14 in line 681, table 15 in line 696 and 700, table 16 in line 702).
• Please use the standard unit notation, like kg and kW. (Changes made in accordance with the Standard Unit Notation consulted in https://physics.nist.gov/cuu/pdf/sp811.pdf. in lines 579, 580, 585, 587, 591, 596, 609, 610, 617, 620, 635, 636, 640, 642, 658, 659, 665, 668, 678, 679, 683, 686, 698, 700, 704, 708).
• Correct the units in Table 9, 10, 12, 13, 14, 15. “kW/h” is incorrect. (Changed “Kw/h” by “kWh” according to the Standard Unit N Lines 591, 617, 640, 665, 683, 686, 704, 791).
• Figures 7, 8, 10, and 11 practically correspond to Figure 4. It would be more concise to give the appropriate time data in the corresponding Tables. Only Figure 9 should be left as an explanation (with the shutdown and start times should be shown by at least an approximate scaling). (We already knew that the model in figure 4 was a pattern but the decision to put images 7 to 11 was taken since each one allows a specific context to be explained in more detail, and it is important that each context is properly understood by the reader. Figure 4 must be understood as a pattern which can be applied to various contexts, as will be shown in the case study of the section 5. Added explanation in line 433. In addition, Figures 7, 8, 9, 10 and 11 organized with a suitable scale.).

Submission Date

10 August 2020

Author Response File: Author Response.pdf

Reviewer 3 Report

Well-written introduction, good review on topcs of sustainability and Industry 4.0.

Definitions in 2.1. and 2.2. also sufficient. 

It is not very clear based on wht the machine tool model was chosen. 

Materials and methods are clear and well-presented.

Results section:

• you could mention other factors than OEE here

Case study - no commments here

Overall a very decent publication

Author Response

Inizio modulo

Journal Sustainability (ISSN 2071-1050)

Manuscript ID sustainability-881926

Type Article

Number of Pages 29

Title

Energy Efficiency in Industry 4.0: the Case of Batch Production Processes

Authors Giancarlo Nota * , Alonso Toro Lazo , Domenico Peluso , Francesco David Nota

Abstract

A promising approach to reducing the energy consumption necessary in manufacturing processes derives from the combination of management methodologies and industry 4.0 technologies. Based on a literature review and experts’ opinion, this work contributes to the efficient use of energy in batch production processes combining the analysis of the Overall Equipment Effectiveness with the study of variables managed by Cyber-Physical Production Systems. Starting from the analysis of loss cause identification, we propose a method that derives quantitative data about energy losses during the execution of batch processes. The implications of this research regard the acquisition of precise information about energy losses and the improvement of value co-creation practices so that the reduction of energy consumption can be achieved in manufacturing processes. Decision-makers can use the findings of this research to start a virtuous process aiming at the reduction of carbon footprint, also reducing the energetic costs, while the production goals are kept.

Thanks for your time and attention. All your comments are relevant and we have used them to improve the quality of our article as follows:

Comments and Suggestions for Authors

Well-written introduction, good review on topics of sustainability and Industry 4.0.

Definitions in 2.1. and 2.2. also sufficient. 

It is not very clear based on what the machine tool model was chosen. (This aspect has been clarified in line 526 and the discussion).

Materials and methods are clear and well-presented.

Results section:

• You could mention other factors than OEE here. (According to the observation made, other aspects and investigations have been treated in the discussion.).

Case study - no comments here

Overall a very decent publication

Submission Date

10 August 2020

Author Response File: Author Response.pdf

Reviewer 4 Report

This manuscript is interesting, it is quite interesting and informative to most readers of this field. The manuscript has included interesting ideas and concepts; it is well grounded in the body of knowledge in the area and it is well written and organized. The technical depth of the proposed approach is well presented. The approach followed looks useful and the results are promising.

Good work!!!

Author Response

Inizio modulo

Journal Sustainability (ISSN 2071-1050)

Manuscript ID sustainability-881926

Type Article

Number of Pages 29

Title

Energy Efficiency in Industry 4.0: the Case of Batch Production Processes

Authors Giancarlo Nota * , Alonso Toro Lazo , Domenico Peluso , Francesco David Nota

Abstract

A promising approach to reducing the energy consumption necessary in manufacturing processes derives from the combination of management methodologies and industry 4.0 technologies. Based on a literature review and experts’ opinion, this work contributes to the efficient use of energy in batch production processes combining the analysis of the Overall Equipment Effectiveness with the study of variables managed by Cyber-Physical Production Systems. Starting from the analysis of loss cause identification, we propose a method that derives quantitative data about energy losses during the execution of batch processes. The implications of this research regard the acquisition of precise information about energy losses and the improvement of value co-creation practices so that the reduction of energy consumption can be achieved in manufacturing processes. Decision-makers can use the findings of this research to start a virtuous process aiming at the reduction of carbon footprint, also reducing the energetic costs, while the production goals are kept.

Comments and Suggestions for Authors

This manuscript is interesting, it is quite interesting and informative to most readers of this field. The manuscript has included interesting ideas and concepts; it is well grounded in the body of knowledge in the area and it is well written and organized. The technical depth of the proposed approach is well presented. The approach followed looks useful and the results are promising.

The paper has been revised according to the referee comments. Thank you for your time and attention.

Submission date

10 August 2020

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors clarified and complemented the formerly less detailed parts of the paper and provided the missing details regarding their proposed methodology. They made all the suggested major and minor corrections. The paper can be published in its present form.