Next Article in Journal
Deconstruction of the Green Bubble during COVID-19 International Evidence
Next Article in Special Issue
Decision Support Concept for Improvement of Sustainability-Related Competences
Previous Article in Journal
Study of Pedestrian Zone According to Superblock Criteria in the Casco Antiguo of Panama
Previous Article in Special Issue
Developing a Framework for Closed-Loop Supply Chain and Its Impact on Sustainability in the Petrochemicals Industry
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:

A Conceptual Model for Measuring a Circular Economy of Seaports: A Case Study on Antwerp and Koper Ports

Faculty of Logistics, University of Maribor, Mariborska c. 7, SI-3000 Celje, Slovenia
Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška c. 160, SI-2000 Maribor, Slovenia
Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, SI-2000 Maribor, Slovenia
Author to whom correspondence should be addressed.
Sustainability 2022, 14(6), 3467;
Received: 21 January 2022 / Revised: 11 March 2022 / Accepted: 13 March 2022 / Published: 16 March 2022
(This article belongs to the Collection Sustainable Consumption and Production)


This paper introduces a conceptual model for evaluating seaports’ acceleration towards the circular economy. The model is based on the identification and definition of circular economy indicators, weighted according to the 9 R-strategy transitions towards the circular economy. We have employed the analytical hierarchy process for weight detection and further calculations of the final seaport circularity value. Our results suggest conceptual validity and provide a detailed insight into the circular activities of the seaports from the indicators, as well as 9 Rs and sustainability perspectives.

1. Introduction

Circular economy has gained significant attention at the policy level since the publication of the Circular Economy Action Plan in 2015 [1]. In 2019 the European Commission launched the Green Deal (GD) [2], where circular economy represents an essential constituent for the future sustainability of European society. Furthermore, the GD recognises ports as entities of the utmost importance for achieving sustainability goals. At the beginning of 2020, the European Sea Ports Organisation (ESPO), representing port authorities in the European Union Member states, introduced a position paper regarding a GD and circular economy [3], mirroring seaports as strategic partners implementing the GD objectives. In the document, seaports are illustrated as excellent entities for practising and implementing circular economy. They are interlinked with the industry and urban areas, constantly exchanging materials and resource flows, including waste, with their neighbourhood environment and hinterland. Thus, seaports have recently been focusing on circular economy transition. However, limited research exists regarding the ports and their acceleration towards a circular economy, as discussed by several authors, such as Carpenter et al. [4]; Mankowska et al. [5]; Haezendonck and Van den Berghe [6]; Roberts et al. [7], especially from the practical and implementation perspectives. Roberts et al. [7] claim that current circular economy activities in ports are low. Still, substantial improvements are envisaged when ports overcome the implementation obstacles, causing the current implementation inhibition in adopting a circular economy.
However, we have detected ports’ initiatives towards the circular economy. They have been gathered under the umbrella of the LOOP Ports project, as part of the Circular Economic Network of Ports, funded within the Climate-KIC Programme [8]. The network carries out activities, such as sharing good practices and examples in ports regarding the circular economy, analysis of main drivers and barriers and identifying opportunities, development of training materials, establishing a database to map ports regarding circular economy activities, creation of a pan EU-network, etc. [8]. Furthermore, based on a review of annual sustainability reports, we have indicated agile circular economy activities. Seaports are very active in defining their circular economy visions, strategy, and participation in circular economy projects. Moreover, the scientific literature indicated vivid seaport activities. For example, the Port of Gävle showed that contaminated dredge material could create new land using a circular economy approach [4]. Karimpour et al. [9] examined the feasibility of the closed-loop at the Copenhagen–Malmö port, using a circular economy model and considering a cost–benefit analysis.
Likewise, Haezendonck and Van den Berghe [6] examined circular economy patterns at seaports in Belgium, mapping the circular economy initiatives considering their strategic focus, several initiatives, and alignment with R-strategies. At the same time, Roberts et al. [7] examined various perspectives on ports, assuming a current and future interest in adopting a circular economy, implementation barriers, and local inhabitants’ views. The authors indicated an increase of 60% in future adoption.
However, published seaports’ annual sustainability or circular reports and published papers reveal several challenges regarding the circular economy in seaports. These challenges relate to seaports’ actual and objective measurements or evaluations, using indicators that illustrate their acceleration towards a circular economy. In other words, to explicitly define their current status and their approximation towards circular economy goals. Some evaluation attempts were perceived. For example, the LOOP Ports [8] project identified 45 variables, merging into seven groups, where only one, in particular, relates to the circular economy and CE strategies. Other variables comprehend statistical data and information, such as cargo and industrial sector variables, statistics about the size of the areas, etc.
Moreover, Gravagnuolo et al. [10] developed a framework for evaluating circular cities, focusing on a built environment and using port cities as a testbed. However, the authors stated that their indicators represent a starting point for evaluation and cannot be presented as an actual degree of circularity. Another evaluation attempt emerged within the Horizon 2020—Defining the concept of “Port of the Future” [11]. A focus has been given to defining suitable sustainability indicators within the key performance indicator set. The United Nations’ sustainable development goals [12] were considered as a basis. Circularity is only briefly mentioned to support the UN SDGs and quantified only to reduce waste.
Furthermore, we have reviewed existing scientific literature in the Web of Science, and no results were obtained emphasising circular economy indicators for seaports. Thus, we have indicated that the topic is still unexplored but urgently needed to better understand the state of the art at the seaports regarding the circular economy and its implementation. In addition, such evaluations bring an objective comparative declaration, increasing the level of confidence in the circular economy activities of seaports and a more transparent decision-making process for seaport authorities as well as improvement possibilities towards the circular economy.
Our paper brings added value from two main perspectives. First, a methodological one, as we have developed a conceptual model for measuring and evaluating seaports from the circular economy perspective. The methodology offers an examination of numerous indicators that are aggregated into simplified one-dimensional information. The second one relates to implementing the conceptual model—the evaluations themselves, where seaports can carry out self-evaluations or comparisons with other seaports, particularly defining the state of the art in the circular economy activities and recognising weaknesses, strengths, opportunities, and improvement possibilities by using thirty-one indicators. Furthermore, such explicit evaluations, based on the objective data and methodology, foster decision-making processes, on the one hand, by the port authorities, and on the other introduce the level of circular economy transition by the ports concerning the European directives and policies, such as the GD goals or Circular Economy Action Plans [13,14]. The novelty and originality of this paper is reflected in a holistic and comprehensive set of indicators to measure the circular economy in seaports and in an approach that takes into account the weighing of specific indicators and groups them into the clusters of 9 Rs, following the definition of the circular economy concept by Kirchherr et al. [15], developed by Potting et al. [16]. The 9R framework is one of the most sophisticated R-structured frameworks, which represents core principles for CE, used as a framework among academics, industry, and CE practitioners on “how-to” implement and execute CE in practice [15]. We have developed a conceptual model and indicators to offer an in-depth view of the circular economy activities of seaports. In this paper, we have examined two ports—the Port of Koper, Slovenia, and the Port of Antwerp, Belgium—to reveal their level of circular economy transition.
The paper has been organised into the following sections: Section 2 presents the methods and the methodology, comprehending an introduction to the case studies and a data collection. Section 3 represents the results obtained, containing the weight results from indicators and the case study evaluations and comparisons from the indicators and 9 Rs perspectives. Section 4 presents the discussion, followed by conclusions.

2. A Literature Review

This section presents a comprehensive literature review sourced from Web of Science databases. The literature review considers only research and review papers. The review comprehended the time frame from 2010 to 2022, which is in line with the development of the circular economy field. In this review, we have given special attention to the circular economy indicators, the methodologies for measuring circular economy in ports, and the practical implications.
As mentioned in Section 1, the circular economy concept has a strong and varied research coverage. We have found that many authors focus primarily on incorporating CE models and concepts in various industrial sectors. Some studies are proposing the importance of measuring the success of such endeavours [17]. Thus, a need for incorporating tools to measure CE clearly exists [18].
For example, the report for OECD countries by Căutişanu et al. [19] pointed out a need for indicators to cover renewable energy sources, solid waste and recycled waste quantities, and the average education level of companies’ employees. Moreover, Salguero-Puerta et al. [20], discussed a need for implementing sustainability indicators in waste management, while Florinda et al. [21] focus on analysing fuel consumption and its environmental impacts, suggesting a mathematical concept with the indicators as a basis.
Furthermore, we have detected studies, such as Calzolari et al. [22], focusing on the identification of the CE indicators in supply chains, and Nocca et al. [23], proposing an evaluation tool by the inclusion of indicators to ease the measurement of CE in cultural heritage conservation. Lindgreen et al. [24] exposed a need for practical evidence in assessment practices and sustainability indicators to ease the transition of a business from a linear economy towards a circular economy. In contrast, Pacurariu et al. [25] represented the current overview of indicators used under the Monitoring Framework in the transition to the CE and their contribution towards sustainable development.
At the same time, additional concepts were found in manufacturing sectors supporting circularity, such as circular economy rebound. Zink & Geyer [26] presented circular economy rebound as an approach, including the limited ability of secondary products to substitute primary products and price effects, used mostly in production processes. Furthermore, D’Adamo & Lupi [27] introduced the term “circular premium” to measure the difference between the circular price and the normal price, which is important for identifying sustainable products, as the authors illustrate with the example of the textile and clothing industry.
With CE being implemented across various industry sectors, with the inclusion of logistics and, more importantly, the shipping sector, it would be self-explanatory to include circularity in seaports. Although El Jihad & Bordanova [28] provide some insight into the current indicators used by ports in the EU, these indicators’ focus lies primarily in the economic sustainability pillar, with environmental and social pillars lagging behind. The lack of indicators to cover all aspects of CE is further mentioned by Mankowska [5], Haezendock and Van der Berghe [6], who provide insights into the CE initiatives in seaports but no practical models to measure them. It is visible that seaports are relying on CE to develop further and regenerate the surroundings. Yet, as Williams [29] suggests, there is a need to measure the success of such endeavours and their contribution. Thus, this research paper focuses on establishing a conceptual model to measure the circular economy and comprehensively analyse circular developments in seaports.

3. Methods

This section presents our methodological approach and methods, including the identification and definitions of circular economy indicators, a selection of case studies, and methods for measuring circular economy at seaports.

3.1. Identification and Definition of Circular Economy Indicators

We have carried out an in-depth literature and sources review to identify and define the appropriate indicators representing the circular economy in seaports. We have implemented this assignment in two ways. The initial activities were a selection of ports. We have selected two large EU northwestern ports, Antwerp and Amsterdam. According to Haezendonck and Van den Berghe [6], they are undertaking circular economy activities to become the flagship seaports in the field. Furthermore, we have added other larger ports, e.g., Port of Genova, Port of Barcelona, and Port of Koper, to comprehend a broader EU area. After identifying and selecting the ports, we have precisely reviewed and analysed all the circular economy accessible indicators on the seaports’ webpages and freely accessible annual and sustainability reports (see Table 1).
Simultaneously, a comprehensive literature review in the Web of Science has been carried out, using the following search combinations of terms: “circular economy” AND “ports”, “circular economy” AND “indicators”, and “indicators” AND “port(s)”. In total, the result amounted to 312 hits. We have reviewed these papers. However, it is important to notice that we have searched only for those papers which contained methods, methodologies on measuring CE, or proposals for quantitative indicators that would be linked to CE. Thus, a total of 34 papers containing information about circular economy indicators were identified and shortlisted. Within these two initial activities, we have identified 153 potential circular economy indicators, of which some were repeated. However, we have pre-defined features which the indicators and the final circular economy evaluation for the port should have, and which are based on the modified Directives of the European Commission [47,48]:
  • the indicator is made up of a definition, a value, and a measurement unit
  • the indicator is relevant to measure a circular economy
  • indicators are objective (assuring open accessibility) and expressed in a quantitative term
  • the indicator is linked to the circular economy policies or strategic dimensions
  • the indicator is based on needs and interventions
  • the evaluation methodology is designed in a transparent way and with high-quality indicators and data
  • simplified one-dimensional information about the circularity of the seaports give an added value, compared to the individual indicators
  • the weighing methods are transparent and statistically reliable
Considering the principles mentioned above or features regarding the indicators, a shortlist of 31 circular economy indicators for seaports has been established.

3.2. Grouping and Sorting Process

With the number of indicators amounting to n = 31, we were introduced to the complex problem of comprehensively evaluating the seaports’ circular economy transition. It is essential to note that our research focused on circular economy transition and group selected indicators. For this reason, two conceptualisations were used: the Kirchherr et al. [15] conceptualisation of the circular economy definition, and the Potting et al.’s [16] 9 Rs conceptualisation, which identifies a transition from the linear to the circular economy using recovery, recycling, repurpose, remanufacture, refurbish, repair, reuse, reduce, rethink, and refuse strategies. The 9R method enables a systematic distribution of ten identified circular economy strategies listed across a “focused dimension” from the established linear economy, on the left side, towards the circular economy, on the right side. This also indicates the relation of selected indicators to either one of the two economic models. According to the definition of an indicator, we have grouped it within the R0 to R9 strategies (see Figure 1).
Figure 1 shows a different group of indicators (I), belonging to R-strategies, marked with different colours. Thus, we have used a methodological approach to condense numerous indicators into more simplified information within the R-strategies, merging them into one-dimensional information on seaport circularity. This is vital information for seaports, their authorities and other stakeholders for identifying the acceleration towards a circular economy. However, some indicators belong to more than one R-strategies group. These indicators are marked with white colour. The upper squares represent the R strategies of the 9R framework, while the circles represent each of the identified indicators. Notice the colours representing each indicator’s relation towards an R strategy. In some cases, the indicator circle is white (e.g., I12, I15, etc.), indicating that the indicator falls under at least two or more R strategies. When the indicator is associated with several strategies, we used for its calculation the distributed weight obtained by equally distributing the weight of each strategy according to the number of strategies to which the indicator belongs.
Furthermore, upon the grouping, we have focused on the indicators’ sortation. We have listed them into three sustainability dimensions, onto which the indicators were distributed, namely:
  • The economic dimension, where the main focus lies in creating economic welfare and advantages for the ports while including the main principles of circularity and promoting the transition from linear activities into circular ones (e.g., waste management in ports, producing electricity with alternatives).
  • The environmental dimension, with the focus on reducing the environmental impacts of port activities in the port area and its vicinity, contributes to increasing biodiversity and mitigating the damage to the environment (e.g., cleaning operations, reducing bad economic practices).
  • The social dimension, which focuses on creating equality in the workforce and workplace, enabling further education and promotion among workers, and promoting the inclusion and integration of political, communal, and social entities within the port— all in the direction of promoting the circular economy (e.g., enabling different types of transport to work, funding activities and projects that encourage circularity in nearby communities).

3.3. Determining Weights by Using an Analytical Hierarchy Process

The final circular economy value for the seaports represents an integrated function of the separate groups of indicators (R-strategies). To define the importance of each R-strategy and, consequently, each indicator, we have employed the analytical hierarchy process (AHP) developed by Saaty [49], denoting the relative importance of the evaluated variables. AHP is a general theory of measurement used to obtain scales either from discrete or continuous paired comparisons [49,50]. The AHP method helps prioritise the importance of sustainability indicators. Therefore, it has been used to assess sustainability in various research areas, such as agriculture [51], sustainability assessment at the level of countries [52], regions [53], or companies [54]. In our case, the method was used as a priority evaluation theory, with the mutual comparison of priority scales based on a judgement matrix. The method was chosen for its practical implementation and ease of application.
Thus, we have prepared a pair-wise comparison of the 9R strategies, whereas in Saaty [49] a 9-point scale was used for the transformation of verbal judgements into numerical quantities, where a judgement matrix is obtained. According to Saaty [49,50,55], the priorities and weights are estimated by revealing the judgment matrix’s leading eigenvector (λmax). However, a consistency test must be carried out to examine the level of consistency required for the validity of results, using a consistency ratio (RC) (see Ramanathan [56]):
R C = I C   R I
where the R values of randomly generated matrices have been provided by Saaty [49,50], while the IC is a consistency index, which can be calculated from Equation (2):
I C   = λ max N N 1
where λmax introduces the largest eigenvalue of the matrix, while n represents the matrix’s dimension. If the IC of the matrix is higher, the input judgements are not consistent, and hence not reliable. In general, a consistency index of 0.10 or less is considered acceptable. If the consistency index value is higher, the judgements may not be reliable.
To carry out the weighing process, we have prepared a pair-wise questionnaire in Google forms, which has been sent to 30 individuals from several European countries (Slovenia, Denmark, Austria, Romania, The Netherlands) (see Appendix C), with each chosen expert being an individual with an in-depth knowledge of the circular economy, either from a practice or a research perspective. We checked the references of the experts (scientific publications in the last five years in the field of CE, published expert papers, and/or work on CE projects). The questionnaire was sent to the following groups of experts: Academics (professors, researchers), the real sector (ports, companies), and non-governmental organisations working in the field of circular economy. As online questionnaires are a “cold methodological approach” (links were sent to email addresses), the response rate was 0.53). The questionnaires were developed and distributed in May 2020 within the project Circular Economy in Seaports [57]. We have gathered 16 fully filled-in questionnaires used for further analyses.

3.4. Obtaining Seaports’ Data and Their Normalisation

In line with the identified indicators and the determination of the weighing process, we have carried out a secondary search to obtain seaports’ data for our calculations. We have divided this process into three approaches:
a secondary review of the literature provided in Table 1 focused on the identification of seaports’ data meaningful for further calculations of indicators and final seaport circularity
a secondary review of existing literature (e.g., scientific papers) as well as a Google search for calculating proposed indicators (In)
phone calls to the seaports listed in Table 1 in search of personnel responsible for circular economy and sustainability activities. After acquiring the email addresses, a short questionnaire was prepared and sent to each of the five mentioned seaports and their personnel.
Unfortunately, none of the seaports responded to our questionnaire. The results of the secondary review of the literature were also meagre, with many data either unavailable or not provided. Therefore, due to the lack of data, we have focused on the two seaports with the most available data, the Port of Antwerp, Belgium, and the Port of Koper, Slovenia. The search for statistical information was followed up by a need to normalise the values, since we cannot compare two ports by the data alone, and they need to be normalised by a common determinator. Thus, we have used a “maritime freight volume” as a normalisation value, which both ports in their annual reports have provided. We are enclosing a compilation of the data used in Appendix A.

4. Results

This section presents our results, composed of the results obtained from the AHP process to determine the weights and importance of the indicators, allowing us to evaluate each indicator and both seaports used as case studies regarding their circular economy performance.

4.1. Results from the Weighing Process

Following the questionnaire results provided by the circular economy experts, we have prepared an inverse matrix, as seen in Table 2, which has been calculated using the AHP method to obtain the importance (weight) of each R strategy. Before continuing the calculations, a consistency check has been carried out to affirm the validity of the results, employing Equations (1) and (2) from the Methods section. The RC value was 0.007, which aligns with the requirements, as RC has to be below 0.1. This has confirmed a satisfactory consistency and allowed us to continue with the calculations.
According to the 9R method, the indicators were classified into n = 10 strategies mentioned in the Methods (see Table 3). The distribution was conducted per adequacy of each indicator with the description of the aforementioned R strategies, with the results presented. As can be seen, the indicators are, according to their definitions, aligned with the strategies, which indicates an increased circularity from R4 to R0.
The calculated relative weights of the R strategies in correlation with the number of indicators emerging within the R-strategy allowed us to calculate each indicator’s weight for an overall view divided into three tables per dimension, as mentioned in the Methods section. This sortation can be seen in Table 4, Table 5 and Table 6. We can conclude that most of the indicators identified and defined focus on environmental challenges, followed by social and economic ones.
As a final check of the correctness of the indicator weights, a sum for each of the mentioned dimensions was conducted, with the value being 0.8426 for the environmental dimension, 0.0636 for the economic dimension, and 0.0938 for the social dimension. The result equals 1, confirming the correctness of the indicator weights and continuing with the next step.

4.2. Calculation of the Circularity Value of the Case-Study Seaports

A normalisation process was carried out to calculate the final circularity value of the seaport data obtained with open-access information. As mentioned in the Methods section, the maritime freight volume was used for the normalisation volume, which relates to the amount of annual manipulated tonnage (both loading and unloading) provided by both seaports (Antwerp and Koper). After the normalisation of the data, the calculation of the final values of 31 indicators has been conducted, as seen in Figure 2. As shown in Figure 2, some values were represented with zero values for both ports, e.g., indicator I4. Such discrepancies happened due to two reasons:
  • the seaports did not provide such data or the statistical data for the mentioned indicator and open access (e.g., annual reports), and they could not be obtained from the available literature and websites that are freely accessible, and
  • the seaports do not have such activities on the premise of their seaport area, and as such do not provide statistical data.
A notable exception to these complications is indicator I27 in the case of Port of Antwerp, which can be seen as a missing line in Figure 2. This happened because the logarithm scale cannot include negative values, which was the case of the Port of Antwerp. Thus the value is not represented in the graph itself.
Finally, an evaluation of the circular performance of both seaports was conducted from the 9R perspective (see Figure 3), along with a final circularity index for both seaports (see Table 7). As perceived from the results, the Port of Koper has better values within circular economy indicators, which is reflected in its higher final circularity value.

5. Discussion and Conclusions

The developed conceptual model has shown the implications of evaluating seaports according to the 9R strategies and analysed their transition towards a circular economy. As perceived from the results, both ports are very active and show a high measurement and performance in the field of circular economy, which is reflected in the higher performance of indicators within R0 to R4. Our case study evaluation has shown that from this conceptual model we can get many circular economy information about the seaports’ features, characteristics, and orientation, and about their actual transition towards the circular economy. Such an evaluation also allows for the assessment and analysis of the current state of the art and further development. However, as the indicators were also listed within the sustainability dimensions, this perspective can also be evaluated. As can be perceived from the Results section, such a model quickly reveals potential weaknesses and opportunities. Our conceptual model is transferable and flexible, enabling the inclusion of more circular economy indicators. There is no need to repeat the AHP process, as it has been carried out for the 9 R strategies of the circular economy transition.
In addition, a limitation exists in our study, which is related to the number of indicators comprehended (n = 31) and their essential features in terms of open accessibility and the objectivity obtained from the available public sources. This may entail that seaports are implementing circular economy principles even more in-depth, as proposed by our concept. However, the data or information were not available or accessible. As shown from our results, seaports are not publishing or evaluating data. For example, indicators such as I4 or I7–9 were not evaluated by the seaports but impaired the circular economy transition.
Thus, this conceptual model can offer a first step towards standardising circular economy seaport indicators for assessing the seaport transition towards the circular economy. This can also encourage seaports to gather circular economy indicators data and publish them openly within their sustainability or circular economy annual reports. Such an approach could also help implement the LOOP Port activities under the Climate-KIC supervision of developing a comprehensive circular economy data platform for the ports. Climate-KIC can help verify whether the data and information are authentic. It is vital to notice that all the information for testing the developed conceptual model has been obtained via open-access documents, from annual reports, seaports webpages, and Google searches. However, to fully evaluate the circular economy, ports need to measure and publish circular economy indicators and not put emphasis only on the financial and environmental ones.
Our case study suggests that the Port of Koper is very active in implementing circular economy activities. It is in a forefront position compared to Antwerp. This might be a consequence of the circular actions at the national level, where Slovenia has been chosen as a European and global leader in implementing circular economy models, within the project “Circular Slovenia”, commonly executed by the EIT Raw Materials, EIT Climate-KIC, the Joint Research Center of the European Commission, and the Government of the Republic of Slovenia. We should mention that our conceptual model has been created to examine the transition of the seaports towards the circular economy to determine their opportunities and improvement options, which will foster improvements at the seaport level and at broader levels, from a strategic point of view. Furthermore, the conceptual model offers a better understanding of seaports’ acceleration towards the circular economy.
However, further research is needed, especially in terms of port data disclosure, objectivity, access, and in-depth mapping of ports’ circular economy activities. CE also falls under the SDG framework, which includes the “3 pillar system” and the collection of “17 interlinked goals”. Further research on the subdivision of indicators under these goals would be interesting to correlate CE ports’ practices with future research, which could also focus on the role of the SEZ (Special Economic Zone) in providing financial support to seaport areas and investigating the role of the NGEU (NextGenerationEU) [58] in promoting the transition to greener, digitised, and circular seaports.

Author Contributions

R.K.L.: conceptualisation, methodology, data curation, writing—original draft preparation, writing—review and editing, supervision, K.B.: validation, formal analysis, investigation, data curation, writing—original draft preparation, visualisation, D.K.: methodology, validation, formal analysis, investigation, data curation, writing—original draft preparation, writing—review and editing, visualisation, supervision. All authors have read and agreed to the published version of the manuscript.


This research has received funding from RKL—the Slovenian Research Agency (Grant No. P1-0403), the European Commission European Social Fund, the Slovenian Ministry for Education, a Science and Sport and the Public Scholarship, the Development, Disability and Maintenance Fund of the Republic of Slovenia (project agreement no. 11081-4/2019).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.


The authors would like to acknowledge the financial support of the European Commission’s European Social Fund, the Slovenian Ministry for Education, Science and Sport and a Public Scholarship from the Development, Disability and Maintenance Fund of the Republic of Slovenia (project agreement no. 11081-4/2019). Rebeka Kovačič Lukman was supported by the Slovenian Research Agency (Grant No. P1-0403). The authors would also like to thank the students Domen Keblič, Vasja Omahne, Timitej Zorman, Maja Gabrič, Gordana Marković, Jaka Progar, and Tomaž Medved, as well as their mentors, Franka Cepak and Darko Kovačič, for having supported the research work and gathered some of the data for the indicators.

Conflicts of Interest

The authors declare no conflict of interest.

Appendix A

For the normalisation and further calculation of the ports’ circularity index, we needed initial values for the Port of Antwerp and the Port of Koper, as described in Section 3.4. The identified values were presented in a table, as seen in Table A1. Indicators for which values were unavailable due to not being disclosed by port authorities, or which the port did not include under its activities, received a value of 0.
Table A1. Distribution of initial values of the indicators for the Port of Koper and the Port of Antwerp.
Table A1. Distribution of initial values of the indicators for the Port of Koper and the Port of Antwerp.
IndicatorPort of Koper—Indicator ValuesPort of Antwerp—Indicator Values
I170% [46,59]67% [31]
I29% [46,59]84% [33]
I318% [46,59]36% [33]
I5n.a.49% [33]
I62% [46]18% [33]
I10n.a.24% [33]
I123.6% [46]15% [33]
I13n.a.8% [31]
I14n.a.40% [31]
I1535% [45]60% [31]
I1916% [46]25 [31]
I200.0267 Mt/a [46]0.5768 Mt/a [33]
I230.0050 bn EUR/a [46,60]0.0680 bn EUR/a [31,33,61]
I240.0200 bn EUR/a [46,60]0.0250 bn EUR/a [31,33,61]
I250.0800 bn EUR/a [46,60]0.3670 bn EUR/a [31,33,61]
I265% [46]15% [31]
I272% [46]−3% [31]
I2910% [46]20% [31]
I30No. 3 [60]No. 4 [61]
I3115% [46]25% [31]
n.a.: not available.

Appendix B

For the identification of the circular economy indicators, we needed initial literature sources, as described in Section 3.1. The identified and shortlisted papers in Table A2 provided valuable information about potential circular economy indicators. For a better overview, a research focus of each individual paper was provided.
Table A2. List of papers containing information about circular economy indicators.
Table A2. List of papers containing information about circular economy indicators.
YearAuthorResearch Focus
2010Lukman et al. [62]Indicators for school education on university
2016Instituto Mexicano del Transporte [63]Methodology for seaport indicators
2016Valenzuela-Venegas et al. [64]Indicators for the assessment of CE in Eco-Industrial parks
2016Gearaedts [65]Indicators for assessing energy adaptiveness in buildings
2016Franklin-Johnson et al. [66]Managerial indicators for CE performance in the resource sector
2016Niero et al. [67]LCA assessment of aluminium cans
2017Huysman et al. [68]Selection of performance indicators in CE with a focus on plastic waste
2018Yang et al. [69]Environmental and economic indicators in industrial parks
2018Jacobi et al. [70]Socio-economic indicators for CE (in the case of Austria)
2018Cobo et al. [71]Circularity indicator of components
2018Hens et al. [72]Cleaner Production and “Corporate Social Responsibility” assessment
2018Van Eygen et al. [73]Collection, selection, and recycling rate of waste
2018Paulik [74]Assessment of CE standard BS 8001:2007
2018Căutişanu et al. [19]Indicators for recycled resources, education level, waste, etc.
2019Zhao et al. [75]Emergy Sustainability Index
2019Williams [29]Green Space Index in seaports
2019Salguero-Puerta et al. [20]Sustainability indicators for Waste management
2019Florinda et al. [21]Consumption of fossil fuels for energy and environmental impacts
2019Kayal et al. [76]Economic index for the circularity of businesses
2019Howard et al. [77]CE indicators in the regenerative supply chain
2019Pieratti et al. [78]Economic and environmental indicators in the wood industry
2019Sterew et al. [79]Resource prod. and recycling rate of municipal waste indicators
2019Niero & Kalbar [80]Material circularity and lifecycle-based indicators
2019Girard & Nocca [81]Review of tools to measure circularity and CE
2020Kristensen & Mosgaard [82]Micro-level indicators of CE
2020Rossi et al. [83]CE indicators in the plastic, textile, and electronic industry sectors
2020Völker et al. [84]Indicator development on a par with CE policies within EC
2020Lindgreen et al. [17]Methods and Tools for assessing CE
2021Nocca et al. [23]Integration of CE with cultural heritage conservation
2021Pacurariu et al. [25]EU key indicators in transitioning towards CE
2021Stavropoulos et al. [85]Innovation in relation to circularity in economy
2022Agrawal et al. [86]Industry 4.0 integration within CE
2022Calzolari et al. [22]CE indicators for supply chains
2022Lindgreen et al. [24]Assessing practices engaged towards/within CE

Appendix C

List of experts and their fields to whom the questionnaires were distributed (Table A3).
Table A3. List of experts with gender and characterization explanation.
Table A3. List of experts with gender and characterization explanation.
Expert No.Gender 1Work Place and Working TimeResearch Field
1MOver 40 years’ experience in academiacleaner production, sustainability, circular economy
2MOver 25 years’ experience in academiasustainable indicators, LCA, circular economy
3FOver 20 years’ experience in academiasustainable production and consumption, LCA, circular economy
4MOver 40 years’ experience in academiacleaner production, sustainable production and consumption, circular economy
5MOver 40 years’ experience in academiasustainable production and consumption, circular economy, waste management
6MOver 25 years’ experience in academiasustainable production and consumption, circular economy
7FOver 25 years’ experience in companysustainable production and consumption, circular economy
8FOver 25 years’ experience in company (port)sustainability management, circular economy
9MOver 15 years’ experience in company (port)sustainability management, circular economy
10MOver 20 years’ experience in companies and NGOssustainability, circular economy
11MOver 20 years’ experience in academiasustainability, carbon footprint, circular economy
12MOver 20 years’ experience in academia and companiessustainability, measuring sustainability, circular economy
13MOver 30 years’ experience in academiaLCA, circular economy
14MOver 30 years’ experience in academiasustainability engineering, circular economy, environmental technologies
15FOver 30 years’ experience in academia and NGOsenvironmental impacts, circular economy
16FOver 10 years’ experience in academiasustainability, environmental impacts, circular economy
17FOver 7 years’ experience in academiasustainability, closed loops, environmental impacts
1MOver 6 years’ experience in academia and companiesbusiness processes, LCA, circular economy
19MOver 6 years’ experience in companiessustainability, circular economy
20MOver 6 years’ experience in companiessustainability, circular economy
21FOver 7 years’ experience in academia and companiessustainability management, circular economy
22MOver 30 years’ experience in academiasustainability, circular economy
23FOver 30 years’ experience in industryenvironmental protection, circular economy
24MOver 10 years’ experience in industry and NGOsustainability, circular economy
25FOver 20 years’ experience in NGOsustainability, climate change, circular economy
26MOver 20 years’ experience in industryrecycling, circular economy
27FOver 20 years’ experience in academia and researchsustainability, circular economy
28MOver 30 years’ experience in industryrecycling, circular economy
29FOver 30 years’ experience in industry, academia, NGOsclimate change, raw materials, circular economy
30FOver 15 years’ experience in industryeco-design, sustainability, circular economy
1 M = Male, F = Female.


  1. Kopnina, H.; Shoreman-Ouimer, E. Sustainability—Key Issues, 1st ed.; Routledge: London, UK, 2015; pp. 1–410. [Google Scholar]
  2. European Commission. Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions—The European Green Deal COM (2019) 640 Final. Available online: (accessed on 5 January 2022).
  3. ESPO. ESPO’s Roadmap to Implement the European Green Deal Objectives in Ports. 2020. Available online: (accessed on 5 January 2022).
  4. Carpenter, A.; Lozano, R.; Sammalisto, K.; Astner, L. Securing a port’s future through Circular Economy: Experiences from the Port of Gavle in contributing to sustainability. Mar. Pollut. Bull. 2018, 128, 539–547. [Google Scholar] [CrossRef] [PubMed]
  5. Mańkowska, M.; Kotowska, I.; Pluciński, M. Seaports as Nodal Points of Circular Supply Chains: Opportunities and Challenges for Secondary Ports. Sustainability 2020, 12, 3926. [Google Scholar] [CrossRef]
  6. Haezendonck, E.; Van den Berghe, K. Patterns of Circular Transition: What Is the Circular Economy Maturity of Belgian Ports? Sustainability 2020, 12, 9269. [Google Scholar] [CrossRef]
  7. Roberts, T.; Williams, I.; Preston, J.; Clarke, N.; Odum, M.; Gorman, S. A Virtuous Circle? Increasing Local Benefits from Ports by Adopting Circular Economy Principles. Sustainability 2021, 13, 7079. [Google Scholar] [CrossRef]
  8. LOOP Ports. LOOP Ports—Circular Economy Project for Ports. 2022. Available online: (accessed on 5 January 2022).
  9. Karimpour, R.; Ballini, F.; Ölcer, A.I. Circular economy approach to facilitate the transition of the port cities into self-sustainable energy ports—A case study in Copenhagen-Malmö Port (CMP). WMU J. Marit. Aff. 2019, 18, 225–247. [Google Scholar] [CrossRef]
  10. Gravagnuolo, A.; Angrisano, M.; Girard, L.F. Circular Economy Strategies in Eight Historic Port Cities: Criteria and Indicators Towards a Circular City Assessment Framework. Sustainability 2019, 11, 3512. [Google Scholar] [CrossRef][Green Version]
  11. Port of the Future. Port of the Future KIP Set. Deliverable 3.1. 2020. Available online: (accessed on 15 December 2021).
  12. United Nations. The 17 Goals—Sustainable Development Goals. Available online: (accessed on 15 December 2021).
  13. European Commission. Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions—Closing the Loop—An EU Action Plan for the Circular Economy COM (2015) 0614 Final. Available online: (accessed on 5 January 2022).
  14. European Commission. Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions—A New Circular Economy Action Plan for a Cleaner and More Competitive Europe COM (2020) 98 Final. Available online: (accessed on 5 January 2022).
  15. Kirchherr, J.; Reike, D.; Hekkert, M. Conceptualising the circular economy: An analysis of 114 definitions. Resour. Conserv. Recycl. 2017, 127, 221–232. [Google Scholar] [CrossRef]
  16. Potting, J.; Hekkert, M.; Worell, E.; Hanemaaijer, A. Circular Economy: Measuring Innovation in the Product Chain. 2017. Available online: (accessed on 5 January 2022).
  17. Lindgren, E.R.; Salomone, R.; Reyes, T. A critical Review of Academic Approaches, Methods and Tools to Assess Circular Economy at the Micro Level. Sustainability 2020, 12, 4973. [Google Scholar] [CrossRef]
  18. Balanay, R.; Halog, A. Tools for circular economy: Review and some potential applications for the Philippine textile industry. In Circular Economy in Textiles and Apparel; Muthu, S.S., Ed.; Woodhead Publishing: Cambridge, UK, 2019; pp. 49–75. [Google Scholar] [CrossRef]
  19. Căutişanu, C.; Asandului, L.; Borza, M.; Turturean, C. Quantitative approach to circular economy in the OECD countries. Amfiteatru Econ. Econ. Bus. Res. Period. 2018, 20, 262–277. [Google Scholar]
  20. Salguero-Puerta, L.; Leyva-Diaz, J.C.; Cortes-Garcia, F.J.; Molina-Moreno, V. Sustainability Indicators Concerning Waste Management for Implementation of the Circular Economy Model on the University of Lome (Togo) Campus. Int. J. Environ. Res. Public Health 2019, 16, 2234. [Google Scholar] [CrossRef][Green Version]
  21. Florinda, M.; Felgueiras, C.; Smitkova, M.; Caetano, N. Analysis of Fossil Fuel Energy Consumption and Environmental Impacts in European Countries. Energies 2019, 12, 964. [Google Scholar] [CrossRef][Green Version]
  22. Calzolari, T.; Genovese, A.; Brint, A. Circular Economy indicators for supply chains: A systematic literature review. Environ. Sustain. Indic. 2022, 13, 100160. [Google Scholar] [CrossRef]
  23. Nocca, F.; De Toro, P.; Voysekhovska, V. Circular economy and cultural heritage conservation: A proposal for integrating Level(s) evaluation tool. Aestimum 2021, 78, 105–143. [Google Scholar] [CrossRef]
  24. Lindgreen, E.R.; Opferkuch, K.; Walker, A.M.; Salomone, R.; Reyes, T.; Raggi, A.; Simboli, A.; Vermeulen, W.J.V.; Caeiro, S. Exploring assessment practices of companies actively engaged with circular economy. Bus. Strategy Environ. 2022, 1–25. Available online: (accessed on 10 February 2022). [CrossRef]
  25. Pacurariu, R.L.; Vatca, S.D.; Lakatos, E.S.; Bacali, L.; Vlad, M. A critical Review of EU Key Indicators for the Transition to the Circular Economy. Environ. Res. Public Health 2021, 18, 8840. [Google Scholar] [CrossRef] [PubMed]
  26. Zink, T.; Geyer, R. Circular Economy Rebound. J. Ind. Ecol. 2017, 21, 593–602. [Google Scholar] [CrossRef]
  27. D’Adamo, I.; Lupi, G. Sustainability and Resilience after COVID-19: A Circular Premium in the Fashion Industry. Sustainability 2021, 13, 1861. [Google Scholar] [CrossRef]
  28. El Jihad, A.R.; Bordanova, D.V. The Circular Economy in the Spanish Port Infrastructure. A Comparison with the European Context. Available online: (accessed on 10 February 2022).
  29. Williams, J. The Circular Regeneration of a Seaport. Sustainability 2019, 11, 3424. [Google Scholar] [CrossRef][Green Version]
  30. Port of Antwerp. Annual Report 2016. 2017. Available online: (accessed on 5 December 2021).
  31. Port of Antwerp. Facts & Figures. 2019. Available online: (accessed on 5 December 2021).
  32. Port of Antwerp. Yearbook of Statistics 2020. 2021. Available online: (accessed on 5 December 2021).
  33. Port of Antwerp. Sustainability Trend Report. Available online: (accessed on 5 December 2021).
  34. Port of Amsterdam. Annual Report 2017. 2018. Available online: (accessed on 5 December 2021).
  35. Port of Amsterdam. Annual Report 2018. 2019. Available online: (accessed on 5 December 2021).
  36. Port of Amsterdam. Annual Report 2019. 2020. Available online: (accessed on 5 December 2021).
  37. Port of Genova. Relazione Annuale 2014. 2015. Available online: (accessed on 5 December 2021).
  38. Port of Genova. Relazione Annuale 2015. 2016. Available online: (accessed on 5 December 2021).
  39. Port of Genova. Relazione Annuale 2016. 2017. Available online: (accessed on 5 December 2021).
  40. Port of Barcelona. Port of Barcelona Traffic Statistics—Accumulated Data December 2018. 2018. Available online: (accessed on 5 December 2021).
  41. Port of Barcelona. Port of Barcelona Traffic Statistics—Accumulated Data December 2019. 2019. Available online: (accessed on 5 December 2021).
  42. Port of Barcelona. Port of Barcelona Traffic Statistics—Accumulated Data December 2020. 2020. Available online: (accessed on 5 December 2021).
  43. Port of Koper. Annual Report 2018. Available online: (accessed on 5 December 2021).
  44. Port of Koper. Sustainability Report 2018. Available online: (accessed on 5 December 2021).
  45. Port of Koper. Annual Report 2019. Available online: (accessed on 5 December 2021).
  46. Port of Koper. Annual Report 2020. Available online: (accessed on 5 December 2021).
  47. European Commission. Commission of the European Communities—Communication from the Commission Structural indicators COM (2002) 551 Final. Available online: (accessed on 5 January 2022).
  48. European Commission. Indicative Guidelines on Evaluation Methods: Monitoring and Evaluation Indicators. 2006. Available online: (accessed on 15 December 2021).
  49. Saaty, T.L. The Analytic Hierarchy Process: Planning, Priority Setting, Resource Allocation; McGraw-Hill International Book Company: New York, NY, USA, 1980; pp. 1–287. [Google Scholar]
  50. Saaty, T.L. Fundamentals of Decision Making and Priority Theory with the Analytic Hierarchy Process, 1st ed.; Analytic Hierarchy Process Series; RWS Publications: Pittsburgh, PA, USA, 2000; Volume 6, pp. 1–477. [Google Scholar]
  51. Dekamin, M.; Barmaki, M.; Kanooni, A. Selecting the best environmental friendly oilseed crop by using Life Cycle Assessment, water footprint and analytic hierarchy process methods. J. Clean. Prod. 2018, 198, 1239–1250. [Google Scholar] [CrossRef]
  52. Ameen, R.; Mourshed, M. Urban sustainability assessment framework development: The ranking and weighting of sustainability indicators using analytic hierarchy process. Sustain. Cities Soc. 2019, 44, 356–366. [Google Scholar] [CrossRef]
  53. Kwatra, S.; Kumar, A.; Sharma, S.; Sharma, P. Stakeholder participation in prioritising sustainability issues at regional level using analytic hierarchy process (AHP) technique: A case study of Goa, India. Environ. Sustain. Indic. 2021, 11. [Google Scholar] [CrossRef]
  54. Krajnc, D.; Glavic, P. How to compare companies on relevant dimensions of sustainability. Ecol. Econ. 2005, 55, 551–563. [Google Scholar] [CrossRef]
  55. Saaty, T.L. Decision Making for Leaders: The Analytical Hierarchy Process for Decisions in a Complex World; Lifetime Learning Publications: Belmont, CA, USA, 1982; pp. 1–291. [Google Scholar]
  56. Ramanathan, R. A note on the use of the analytic hierarchy process for environmental impact assessment. J. Environ. Manag. 2001, 63, 27–35. [Google Scholar] [CrossRef] [PubMed][Green Version]
  57. Lukman, R.K.; Cepak, F.; Kovačič, D.; Keblič, D.; Omahne, V.; Zorman, T.; Gabrič, M.; Marković, G.; Progar, J.; Medved, T. Circular Economy Indicators in Seaports: Final Project Report. Call: Through Creative Way to Knowledge, Students’ Projects. Celje, 2020 (in Slovene). European Social Fund, the Slovenian Ministry for Education, Science and Sport and the Public Scholarship, Development, Disability and Maintenance Fund of the Republic of Slovenia (Project Agreement No. 11081-4/2019). Available online: (accessed on 15 December 2021).
  58. European Commission. Competition—State Aid—State Aid Rules and Coronavirus. Available online: (accessed on 14 February 2022).
  59. Cepak, F.; Marzi, B. Environmental Impacts of the Port of Koper. Varst. Narave 2009, 22, 97–116. [Google Scholar]
  60. Port of Koper. Luka Koper. 2022. Available online: (accessed on 5 December 2021).
  61. Port of Antwerp. Port of Antwerp. 2022. Available online: (accessed on 5 December 2021).
  62. Lukman, R.; Krajnc, D.; Glavič, P. University ranking using research, educational and environmental indicators. J. Clean. Prod. 2010, 18, 619–628. [Google Scholar] [CrossRef]
  63. Instituto Mexicano del Transporte. Port Indicators System: Methodology. 2016. Available online: (accessed on 20 November 2021).
  64. Valenzuela-Venegas, G.; Salgado, J.C.; Diaz Alvarado, F.A. Sustainability Indicators for the Assessment of Eco-Industrial Parks: Classification and criteria for selection. J. Clean. Prod. 2016, 133, 99–116. [Google Scholar] [CrossRef]
  65. Geraedts, R. FLEX 4.0, A Practical Instrument to Assess the Adaptive Capacity of Buildings. Energy Procedia 2016, 96, 568–579. [Google Scholar] [CrossRef][Green Version]
  66. Franklin-Johnson, E.; Figge, F.; Canning, L. Resource duration as a managerial indicator for Circular Economy performance. J. Clean. Prod. 2016, 133, 589–598. [Google Scholar] [CrossRef]
  67. Niero, M.; Irving Olsen, S. Circular economy: To be or not to be in a closed product loop? A Life Cycle Assessment of aluminium cans with inclusion of alloying elements. Resour. Conserv. Recycl. 2016, 114, 18–31. [Google Scholar] [CrossRef][Green Version]
  68. Huysman, S.; De Schaepmeester, J.; Ragaert, K.; Dewulf, J.; De Meester, S. Performance indicators for a circular economy: A case study on post-industrial plastic waste. Resour. Conserv. Recycl. 2017, 120, 46–54. [Google Scholar] [CrossRef]
  69. Yang, T.; Ren, Y.; Shi, L.; Wang, G. The circular transformation of chemical industrial parks: An integrated evaluation framework and 20 cases in China. J. Clean. Prod. 2018, 196, 763–772. [Google Scholar] [CrossRef]
  70. Jacobi, N.; Haas, W.; Wiedenhofer, D.; Mayer, A. Providing an economy-wide monitoring framework for the circular economy in Austria: Status quo and challenges. Resour. Conserv. Recycl. 2018, 137, 156–166. [Google Scholar] [CrossRef]
  71. Cobo, S.; Dominguez-Ramos, A.; Irabien, A. Trade-Offs between Nutrient Circularity and Environmental Impacts in the Management of Organic Waste. Environ. Sci. Technol. 2018, 52, 10923–10933. [Google Scholar] [CrossRef] [PubMed][Green Version]
  72. Hens, L.; Block, C.; Cabello-Eras, J.J.; Sagastume-Gutierez, A.; Garcia-Lorenzo, D.; Chamorro, C.; Herrera Mendoza, K.; Haeseldonckx, D.; Vandecasteele, C. On the evolution of “Cleaner Production” as a concept and a practice. J. Clean. Prod. 2018, 172, 3323–3333. [Google Scholar] [CrossRef]
  73. Van Eygen, E.; Laner, D.; Fellner, J. Circular economy of plastic packaging: Current practice and perspectives in Austria. Waste Manag. 2018, 72, 55–64. [Google Scholar] [CrossRef] [PubMed]
  74. Paulik, S. Critical appraisal of the circular economy standard BS 8001:2017 and a dashboard of quantitative system indicators for its implementation in organisations. Resour. Conserv. Recycl. 2018, 129, 81–92. [Google Scholar] [CrossRef]
  75. Zhao, Y.; Yu, M.; Kong, F.-W.; Li, L.-H. An emergy ternary diagram approach to evaluate circular economy implementation of eco-industrial parks. Clean Technol. Environ. Policy 2019, 21, 1433–1445. [Google Scholar] [CrossRef]
  76. Kayal, B.; Abu-Ghunmi, D.; Abu-Ghunmi, L.; Archenti, A.; Nicolescu, M.; Larkin, C.; Corbet, S. An economic index for measuring firm’s circularity: The case of water industry. J. Behav. Exp. Financ. 2019, 21, 123–129. [Google Scholar] [CrossRef]
  77. Howard, M.; Hopkinson, P.; Miemczyk, J. The regenerative supply chain: A framework for developing circular economy indicators. Int. J. Prod. Res. 2019, 57, 7300–7318. [Google Scholar] [CrossRef][Green Version]
  78. Pieratti, E.; Paletto, A.; De Meo, I.; Fagarazzi, C.; Migliorini Giovannini, M.R. Assessing the forest-wood chain at local level: A Multi-Criteria Deci-sion Analysis (MCDA) based on the circular bieconomy principles. Ann. For. Res. 2019, 62, 123–138. [Google Scholar] [CrossRef]
  79. Sterew, N.; Ivanova, V. From sustainability to a model of circular economy—The example of Bulgaria. In Proceedings of the Intcess 2019 6th International Conference on Education and Social Sciences, Dubai, United Arab Emirates, 4–6 February 2019; pp. 757–766. [Google Scholar]
  80. Niero, M.; Kalbar, P.P. Coupling material circularity indicators and life cycle based indicators: A proposal to advance the assessment of circular economy strategies at the product level. Resour. Conserv. Recycl. 2019, 140, 305–312. [Google Scholar] [CrossRef]
  81. Girard, F.L.; Nocca, F. Moving Towards the Circular Economy/City Model: Which Tools for Operationalizing This Model? Sustainability 2019, 11, 6253. [Google Scholar] [CrossRef][Green Version]
  82. Kristensen, S.H.; Mosgaard, M.A. A review of micro level indicators for a circular economy—moving away from the three dimensions of sustainability. J. Clean. Prod. 2020, 243, 118531. [Google Scholar] [CrossRef]
  83. Rossi, E.; Bertassini, A.C.; dos Santos Ferreira, C.; Neves do Amaral, W.A.; Ometto, A.R. Circular economy indicators for organisations considering sustainability and business models: Plastic, textile and electro-electronic cases. J. Clean. Prod. 2020, 247, 119137. [Google Scholar] [CrossRef]
  84. Völker, T.; Kovacic, Z.; Strand, R. Indicator development as a site of collective imagination? The case of European Commission policies on the circular economy. Cult. Organ. 2020, 26, 103–120. [Google Scholar] [CrossRef]
  85. Stavropoulos, P.; Papacharalampopoulos, A.; Tzimanis, K.; Petrides, D.; Chryssolouris, G. On the Relationship between Circular and Innovation Approach to Economy. Sustainability 2021, 13, 11829. [Google Scholar] [CrossRef]
  86. Agrawal, R.; Wankhede, V.A.; Kumar, A.; Luthra, S.; Huisingh, D. Progress and trends in integrating Industry 4.0 within Circular Economy: A comprehensive literature review and future research propositions. Bus. Strategy Environ. 2022, 31, 559–579. [Google Scholar] [CrossRef]
Figure 1. Grouping of individual indicators per R-strategy.
Figure 1. Grouping of individual indicators per R-strategy.
Sustainability 14 03467 g001
Figure 2. Distribution of values per indicator for the Ports of Koper and Antwerp.
Figure 2. Distribution of values per indicator for the Ports of Koper and Antwerp.
Sustainability 14 03467 g002
Figure 3. Distribution of values per R-strategy for the Ports of Koper and Antwerp.
Figure 3. Distribution of values per R-strategy for the Ports of Koper and Antwerp.
Sustainability 14 03467 g003
Table 1. Reviewed annual reports of the selected seaports during the search for circular economy.
Table 1. Reviewed annual reports of the selected seaports during the search for circular economy.
PortAnnual Reports
Port of AntwerpAnnual Report 2016 [30]
Facts & Figures 2019 [31]
Yearbook of Statistics 2020 [32]
Sustainability Trend Report [33]
Port of AmsterdamAnnual Report 2017 [34]
Annual Report 2018 [35]
Annual Report 2020 [36]
Port of GenovaRelazione annuale 2014 [37]
Relazione annual 2015 [38]
Relazione annuale 2017 [39]
Port of BarcelonaAnnual Report 2018 [40]
Annual Report 2019 [41]
Annual Report 2020 [42]
Port of KoperAnnual Report 2018 [43]
Sustainability Report 2018 [44]
Annual Report 2019 [45]
Annual Report 2020 [46]
Table 2. Inverse matrix for calculating the importance (weight) of R strategies.
Table 2. Inverse matrix for calculating the importance (weight) of R strategies.
Table 3. Indicator’s distribution within 9Rs strategies groups.
Table 3. Indicator’s distribution within 9Rs strategies groups.
R-StrategyIndicatorsNo. of Indicators
R0I20, I302
R1I17, I18, I19, I20, I23, I24, I26, I27, I28, I29, I3111
R2I15, I17, I18, I19, I20, I25, I28, I298
R3I7, I10, I18, I19, I20, I226
R5I12, I13, I14, I154
R6I12, I18, I193
R7I16, I18, I193
R8I1, I2, I9, I214
R9I3, I4, I5, I6, I115
Table 4. Indicators and their weights are arranged by the environmental dimension of the circular economy.
Table 4. Indicators and their weights are arranged by the environmental dimension of the circular economy.
IndicatorIndicator Full NameIndicator Weight
I1Fraction (in %) of recycled waste in comparison with the total waste produced0.0300
I2Fraction (in %) of recycled plastic waste in comparison with the total plastic waste produced0.0300
I3Faction (in %) of waste produced in the port that goes to landfill in comparison with the total waste produced0.0308
I4Amount of materials (e.g., plastic, tiers) used for alternative fuel (t/a)0.0308
I5Fraction (in %) of biogas produced from the total biodegradable waste produced0.0308
I6Fraction (in %) of waste used for energy production in comparison with the total waste incinerated0.0308
I7Quantity of the reused materials (t/a)0.0128
I8Fraction (in %) of repaired/maintained products0.0970
I9Fraction (in %) of the recycled goods used0.0300
I10Fraction (in %) of waste reused0.0128
I11Unsold products recovered for redistribution at the market itself or through nearby community facilities (t/a)0.0308
I12Fraction (in %) of water consumption for habitat (reduction, for example, thanks to harvesting rainwater on the roofs)0.0609
I13Fraction (in %) of green roofs0.0223
I14Fraction (in %) of food waste reused against the total food waste produced0.0223
I15Fraction (in %) of retrofitting interventions on buildings0.0303
I16Fraction (in %) of degraded buildings0.0403
I17Fraction (in %) of synergies in the supply chain (energy, resources), compared to the whole supply chain0.0144
I18Fraction (in %) of processes designed for flexibility by using modular, synergy systems0.1062
I19Fraction (in %) of symbiotic and synergistic relationships in the port area and among the port area and the city0.1062
I20Amount of sea sewage materials used for new products (e.g., bricks) (Mt/a)0.0732
SUM TOTAL 0.8426
Table 5. Indicators and their weights are arranged by the economic dimension of the circular economy.
Table 5. Indicators and their weights are arranged by the economic dimension of the circular economy.
IndicatorIndicator Full NameIndicator Weight
I21Revenue from recycled goods (bn EUR/a)0.0300
I22Value of material reused (bn EUR/a)0.0128
I23Circular economy innovation budget (bn EUR/a)0.0064
I24Circular-economy-related grants from the local, national EU budget (bn EUR/a)0.0064
I25Direct and indirect new investments generated and considering circular economy (bn EUR/a)0.0080
SUM TOTAL 0.0636
Table 6. Indicators and their weights are arranged by the social dimension of the circular economy.
Table 6. Indicators and their weights are arranged by the social dimension of the circular economy.
IndicatorIndicator Full NameIndicator Weight
I26A fraction (in %) of the circular-economy-related position in a port, compared to all the position0.0064
I27A fraction (in %) of new circular economy jobs created in a port, compared to all the position0.0064
I28A fraction (in %) of events and dissemination activities about circular economy within the port compared to all the events0.0144
I29A fraction (in %) of active employees in circular economy initiatives, compared to all employees0.0144
I30Number of innovation awards related to a circular economy0.0460
I31A fraction (in %) of employees attending internal/external circular economy capacity building0.0064
SUM TOTAL 0.0938
Table 7. Port circularity index for the studied ports.
Table 7. Port circularity index for the studied ports.
SeaportFinal Circularity Value
Port of Koper0.1041
Port of Antwerp0.0164
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Kovačič Lukman, R.; Brglez, K.; Krajnc, D. A Conceptual Model for Measuring a Circular Economy of Seaports: A Case Study on Antwerp and Koper Ports. Sustainability 2022, 14, 3467.

AMA Style

Kovačič Lukman R, Brglez K, Krajnc D. A Conceptual Model for Measuring a Circular Economy of Seaports: A Case Study on Antwerp and Koper Ports. Sustainability. 2022; 14(6):3467.

Chicago/Turabian Style

Kovačič Lukman, Rebeka, Kristijan Brglez, and Damjan Krajnc. 2022. "A Conceptual Model for Measuring a Circular Economy of Seaports: A Case Study on Antwerp and Koper Ports" Sustainability 14, no. 6: 3467.

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop