Digital Product Passport Design Supporting the Circular Economy Based on the Asset Administration Shell

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This article is devoted to interesting and actual topic. This paper is clearly structured and understandable. The paper cited relevant and appropriate range of literature sources. Methodology section is well designed and methods explained. However, minor improvements could increase the quality of the paper. Two main suggestions are:

1. Results should be compared with the previous studies in this field, if possible.

2. Please state the main limitations of the study.

Author Response

Comments 1: Results should be compared with the previous studies in this field, if possible.
Response 1: Thank you for this suggestion. We did compare our results with Plociennik et al. (2022) and Psarommatis et al. (2024) in the discussion section. See lines 680–730. We think comparing the results in depth with two previous studies is sufficient, as additional comparisons would make the paper too long.

Comments 2: Please state the main limitations of the study.
Reponse 2: Thank you for pointing this out. We revised the document to include the main limitations at the end of the discussion section. See lines 851 and following.

Reviewer 2 Report

Comments and Suggestions for Authors

In the context of the current circular economy is widely valued, this paper uses the AAS framework developed by the Industry 4.0 platform, takes advantage of the adaptability and comprehensive data exchange capabilities of the AAS framework, and designs the DPP based on the AAS framework to support the circular economy, while ensuring cross-industry applicability. The topic selection of the thesis has a high practical guiding role. However, the paper has the following shortcomings: 1. The theoretical contribution and innovation of the paper are not clear. 2. The paper is more like a compilation of working materials than a research paper. 3. The advanced and scientific nature of the modeling method used in this paper lacks experimental verification. It is suggested to carry out in-depth theoretical research on theoretical problems and supplement comparative experiments to prove the advanced and scientific nature of the method.

Author Response

Comments 1: The theoretical contribution and innovation of the paper are not clear.
Response 1: You have raised an important point. We have revised the conclusion section to present the theoretical contribution and innovation more clearly. See lines 872 and following. The innovation of the paper is to base the DPP design on the R-strategy framework for supporting the Circular Economy in combination with building on top of existing standards for data exchange (AAS), data requirements and KPIs (DIN EN 45554, DIN SPEC 91472).

Comments 2: The paper is more like a compilation of working materials than a research paper.
Response 2: The research contribution of this paper is about modeling R-strategies in the form of an asset administration shell. This includes circular economy KPIs and the required information for the application of R-strategies. The revised version of this manuscript makes this more clear.

Comments 3: The advanced and scientific nature of the modeling method used in this paper lacks experimental verification.
Response 3: We agree that further comparative experiments are important to prove the method. Indeed, this is planned for a subsequent, more practical paper. We added a remark in the evaluation section to make this more clear. See lines 676–678. However, the focus of this paper is on the theoretical concept of using the AAS to model a DPP for the circular economy. The battery passport in the evaluation section serves as a proof of concept. It shows that it is possible to model a DPP using our DPP design.

 

Reviewer 3 Report

Comments and Suggestions for Authors

REVIEW REPORT

Summary: The article investigates the digital product passport based on Shell's stewardship asset framework to support the circular economy in industrial sustainability. The study consolidates existing standards and scientific literature that aligns with the circular economy principle. The specific model is suitable for European Union battery approval and can be applied to various sectors.

The authors could describe the results more in the summary, which would enrich the work.

Comment: The article investigates a topic that is interesting, relevant and current in the 2030 agenda. Its subject matter is of particular interest because it deals with the impacts on the circular economy, sustainability and more efficient production models, which makes this research specific to environmental impacts, but not only.

Article: in the article the authors conducted their research around the circular economy, sustainability and more efficient production models.  As such, the article is more focused on the environmental component than any other aspect of sustainability.

The article doesn't make it clear what the principles of the circular economy are, nor what the concept of the circular economy or sustainability is. It would be interesting to include them to create more value in the article.

Review: the topic under study is very relevant because it accumulates literature on sustainability, the circular economy and more efficient industrial production models.

The article is well-written, structured and appropriate to the content of the journal. The authors have followed recent and relevant literature, which is commendable in this research, although it is suggested that more work be included for the year 2024.

The authors did not define the circular economy, sustainability or more efficient industrial production models. The authors' approach to the European Green Deal does not fill this gap, which is why it is advisable to include it in the literature review.

The authors have produced an article that is of interest not only to the academic community but also to the global economy. However, it is important to ascertain whether the models and indicators can be applied across sectors, or whether they are specific. Explaining these aspects can clarify many doubts for the reader.

In terms of methodology, the authors believe that the existence of different models and measures requires greater precision. I fully agree.

Results and conclusions: the article deals with a subject that, although not new, is relatively recent and very important not only in the academic world but also in the business world. The article presents a form of discussion that constitutes an interesting approach, which can be seen as an advance in knowledge.

In terms of results, the authors were careful to follow the AAS model to avoid data redundancy, which is commendable. Also noteworthy is the authors' perspective in creating a sub-model to model the PMF that supports the circular economy. I would also highlight as a strength of the work the detail in the identification of existing sub-models, as well as the detail of the information provided in each one. It should also be noted that, for each model analysed, the authors were able to highlight the environmental impact in line with the sustainability initiative.

However, it is important to go beyond the environmental perspective and realise in financial terms what real impact this more efficient form of production can have on a company. A link could have been made between the cost of manufacturing the product in compliance with environmental legislation and following the product passport or battery passport. The environmental component must accompany the economic and financial component, otherwise the richness of any study could lose some of its importance.

The authors' conclusions are interesting, although without the exploration of the concept and principles of the circular economy, sustainability and more sustainable manufacturing models that would have added more value to the article's content.

I recommend the publication of this article in the journal, as it is an interesting, relevant and current topic, and its discussion by the authors adds to the existing literature.

Recommendations: it is suggested that the authors include even more recent literature.

It is suggested that the authors indicate the financial impact in addition to the environmental impact, which has been duly emphasised.

It is suggested that the authors indicate which principles of the circular economy could be applied in this study. They should also describe the concept of sustainability and more efficient manufacturing regimes.

It is suggested that the authors make the conclusions more robust and with the necessary theoretical and conceptual depth.

Author Response

Thank you for the detailed review of our paper.

Comments 1: It is suggested that the authors include even more recent literature.
Response 1: Thank you for this suggestion. We included an additional article from 2024 which focuses on KPIs for sustainability in Digital Twins, as this is something which we have not had properly covered in the state-of-the-art section. See lines 160–164. As this section is already quite long, we opted not to include more articles.

Comments 2: It is suggested that the authors indicate the financial impact in addition to the environmental impact, which has been duly emphasised.
Response 2: We agree that financial impacts are important to convince industry stakeholders to implement circular manufacturing methods. Therefore, we included brief mention of possible financial impacts in the introduction section and contextualized them as the economic dimension of sustainability. See lines 42–50. Since the financial impacts are not the focus of this study, we do not go in depth on this aspect.

Comments 3: It is suggested that the authors indicate which principles of the circular economy could be applied in this study. They should also describe the concept of sustainability and more efficient manufacturing regimes.
Response 3: Thank you for pointing this out. We included an additional paragraph in the in introduction section that describes the concept of sustainable manufacturing and highlights the R-strategy framework as the guiding principle of the circular economy for this work. See lines 31–54 and lines 67–69.

Comments 4: It is suggested that the authors make the conclusions more robust and with the necessary theoretical and conceptual depth.
Response 4: We agree. We edited the conclusion section to make the theoretical background more clear and refer to the more theoretical background about sustainable manufacturing and circular economy in the introduction section. See lines 872 and following.

Reviewer 4 Report

Comments and Suggestions for Authors

This study discussed the digital product passport design supporting the circular economy. I have the following questions and comments for the authors.

1. How authors identified the research problem? Authors did not clearly explained the research problem.

2. Introduction section should include few examples of the digital product passport design. Also, authors need to clearly describe their research objective.

3. It is recommended to further strengthen the literature review work and cite the up-to-date articles from the relevant journals.

4. Results need to be discussed in detailed with the support of previously studies published in database/ journals.

5. Authors should also focus on the theoretical contributions of this work and practical value.

6. research limitations are missing 

Digital Product Passport Design supporting the Circular Econ-2 omy based on the Asset Administration Shell

Author Response

Comments 1:  How authors identified the research problem? Authors did not clearly explained the research problem.
Response 1: Thank you for pointing this out. We added lines 50–54 in the introduction to state the research problem more clearly.

Comments 2: Introduction section should include few examples of the digital product passport design. Also, authors need to clearly describe their research objective.
Response 2: We agree. We added the DPP4.0 as an example for DPP design to the introduction. The introduction already includes a description of the DPP design for the PCDS. We added additional sentences and moved the description of the PCDS to make this more clear. See lines 117–140. Also, we added lines 50–54 in the introduction to explain the research objective more clearly.

Comments 3: It is recommended to further strengthen the literature review work and cite the up-to-date articles from the relevant journals.
Response 3: Thank you for this suggestion. We included an additional article from 2024 which focuses on KPIs for sustainability in Digital Twins, as this is something which we have not had properly covered in the state-of-the-art section. See lines 160–164. As this section is already quite long, we opted not to include more articles.

Comments 4: Results need to be discussed in detailed with the support of previously studies published in database/ journals.
Response 4: We agree. We did compare our results with Plociennik et al. (2022) and Psarommatis et al. (2024) in the discussion section. See lines 680–730. We think comparing the results in depth with two previous studies is sufficient, as additional comparisons would make the paper too long.

Comments 5: Authors should also focus on the theoretical contributions of this work and practical value.
Response 5: We agree. We revised the conclusion section to present the theoretical contribution and innovation more clearly. See lines 873 and following.

Comments 6: research limitations are missing.
Response 6: Thank you for pointing this out. We included research limitations at the end of the discussion section. See lines 851 and following.

 

 

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

This is the second review of the paper. The author has modified the paper according to the revised opinions, and the paper has been improved, but there are still the following problems: 1. The relationship between circular economy and AAS is not clear. Transitions and explanations should be given among paragraphs in Chapter one. 2. The application instance is not detailed enough. Examples should be added, especially those applied by small and medium-sized enterprises, to illustrate the key issues in the application process, as well as the effects and benefits achieved.

Author Response

Comments 1: The relationship between circular economy and AAS is not clear. Transitions and explanations should be given among paragraphs in Chapter one.

Response 1: Thank you for pointing this out. We agree. Therefore, we have included explanations detailing the relationship between the circular economy and AAS among the paragraph about R-strategies and the paragraph about AAS (see lines 81-91).

Comments 2: The application instance is not detailed enough. Examples should be added, especially those applied by small and medium-sized enterprises, to illustrate the key issues in the application process, as well as the effects and benefits achieved.

Response 2: Agree. Accordingly, we have added more explanations and examples on how we filled out the existing templates. We also added sentences to illustrate key issues of applying the model, as well as describing the key benefit of calculating circularity indicators (see lines 784-823 and 877-887).

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

This paper is reviewed for the third time. This paper has made some improvements and been optimized, but it has not fundamentally solved the existing problems, failed to clearly describe the problems existing in practice, and refined this problem into a theoretical problem, and used theoretical models to analyze and solve it. It is suggested to add a real case, describe in a graphical way, point out the engineering problems, and describe the relevant theoretical model and the solution process.

Author Response

While we appreciate the reviewer’s feedback, we respectfully disagree. Unfortunately, we are not able to further improve upon the reviewer's sentiment because we think the points are already addressed:

1. "failed to clearly describe the problems existing in practice":
   We argue that DPP design is still in its early stages and data models regarding circular economy are currently underrepresented. Relevant standards explain data requirements but do not provide DPP models themselves, making it difficult for SMEs to implement DPPs. This is the fundamental problem that we want to solve.
2. "has not fundamentally solved the existing problems": 
   We argue that by designing the DPP with the AAS standard, we can achieve interoperable and standardized exchange of DPPs. We recognized the informational gap in AAS to describe sustainability and proposed AAS Submodel templates to model this data based on data requirements found in standards.
3. "refined this problem into a theoretical problem and used theoretical models to analyze and solve":
   The DPP across sectors and products is a broad topic that can only be solved by generalization of DPP models. Several standards exist that describe the requirements in theory but do not provide data models. We tested our proposed AAS data templates with a battery example to evaluate whether it is applicable. Further evaluation should be done by specific sectors and companies.
4. "add a real case":
   Our evaluation applies the proposed templates on a Bosch 12V starter battery and calculates the Repairability Score described in DIN EN 45554 standard. Further cases could be evaluated in the future, but the battery passport will be one of the first sectors to adopt the DPP (see EU Battery Regulation). This evaluation is based on the battery pilot from the Circular TwAIn project (https://www.circular-twain-project.eu/use-cases).
5. "describe in a graphical way":
   We visualized several template structures and the R-strategy framework. After further examination, we do not see sections where graphics would improve understanding significantly.
6. "point out the engineering problem":
   We described several standards and data requirements that are relevant in the engineering of DPP models. The problem and design principles were clearly stated, i.e. "specific enough to be applied in a real world scenario and flexible enough to accommodate cross-industry use".
7. "describe relevant theoretical model and solution":
   The engineering of the DPP model was directly derived from several standards, both in the AAS and non-AAS domain (PCDS, DIN EN 45554, DIN SPEC 91472, IDTA templates, 9R strategy framework)