The Resource Infrastructure Economy: A Systematic Review on Regime Coupling and Infrastructural Integration in European Sustainability Transitions

Santos, Eleonora

doi:10.3390/su18136579

Abstract

European sustainability transitions are increasingly defined by the convergence of blue, green, and circular economy agendas. Traditionally analysed and governed in isolation, these domains generate important interdependencies, trade-offs, and coordination challenges that remain insufficiently understood. Drawing on the multi-level perspective (MLP) and recent advances in multi-system dynamics, this article introduces the Resource Infrastructure Economy (RIE) as a novel integrative framework. The RIE differs from existing multi-system frameworks by explicitly integrating marine governance as a full socio-technical regime, theorising regulatory-driven regime coupling as a distinct transition pathway, and foregrounding the constitutive role of shared physical and digital infrastructures in shaping value creation, path dependencies, and distributional outcomes. The RIE conceptualises contemporary European transitions as processes of deep regime coupling and infrastructural integration, whereby energy, marine, and material regimes become tightly coordinated through shared physical and digital infrastructures and assertive regulatory steering. Through a systematic integrative literature review (58 core publications selected from over 450 records following PRISMA guidelines, analysed using abductive thematic analysis with MAXQDA 26 software) and comparative analysis of six countries—Portugal, Spain, Denmark, Germany, the Netherlands, and Norway—the study reveals persistent structural gaps between the three agendas alongside emerging patterns of pairwise and triadic regime coupling. While Northern and Central European frontrunners demonstrate more advanced infrastructural coordination, Southern peripheral regions face greater difficulties in governance integration and just transition outcomes. The RIE framework advances sustainability transitions theory in three ways: (1) systematically integrating blue economy scholarship into multi-system analysis; (2) theorising regulatory-driven regime coupling as a distinct transition pathway; and (3) foregrounding the constitutive role of physical and digital infrastructures and environmental data systems in shaping value creation, path dependencies, and distributional outcomes. By reframing European sustainability transitions through the lens of the Resource Infrastructure Economy, this article provides a new conceptual lens to understand uneven transition geographies and offers actionable insights for more integrated and just policy coordination across the European Green Deal.

Keywords:

offshore wind; just transition; critical raw materials; blue–green–circular transitions; European Green Deal; Resource Infrastructure Economy; regime coupling; multi-system transitions

1. Introduction

The simultaneous expansion of offshore wind farms in the North Sea and the planned lithium mine in Portugal’s Barroso region exemplify the profound interconnections shaping European sustainability transitions today. What was once treated as separate policy domains—the blue economy (marine resources), the green economy (decarbonisation), and the circular economy (resource efficiency)—are now deeply entangled. Offshore wind development reconfigures marine space and governance, accelerates energy system decarburisation, and generates massive demand for critical raw materials, while projects like Barroso risk creating new “green sacrifice zones” in peripheral territories—a term used here following Van Meer & Zografos [1] and rooted in the broader environmental justice literature on “sacrifice zones” [2,3,4]. These dynamics reveal both significant synergies and serious trade-offs that cannot be adequately addressed through siloed approaches.

European sustainability transitions can no longer be fully understood by analysing the blue, green, and circular economies as largely independent domains. Although these agendas have successfully mobilised substantial political and financial resources, their increasing interdependence generates complex interdependencies, trade-offs, and coordination challenges across marine governance, energy systems, material flows, and environmental data infrastructures [5,6,7,8].

Sustainability transitions scholarship has made major advances through the multi-level perspective (MLP), which explains regime destabilisation and niche breakthrough [9,10,11]. More recently, research on multi-system dynamics has begun examining interactions and co-evolution across multiple regimes [12,13,14]. Nevertheless, important gaps persist. The blue economy remains underexplored in multi-system scholarship, and there is still no robust integrative framework capable of theorising the simultaneous reconfiguration of marine, energy, and material regimes under conditions of strong regulatory steering.

This article argues that European sustainability transitions are entering a new phase, characterised by the emergence of a higher-order socio-technical configuration: the Resource Infrastructure Economy (RIE). In the RIE, energy, marine, and material regimes become tightly coupled and deliberately coordinated through shared physical and digital infrastructures and assertive regulatory intervention.

The central purpose of this article is to develop and illustrate the Resource Infrastructure Economy as an integrative conceptual framework. Specifically, we ask: How can the observed convergence of blue, green, and circular economy transitions in Europe be conceptualised as processes of regime coupling and infrastructural integration within sustainability transitions theory?

By addressing this question, the article advances the literature in three principal ways. First, it systematically integrates blue economy scholarship into multi-system transitions research, treating marine governance as a full socio-technical regime with distinct material, spatial, and justice dynamics. Second, it theorises regulatory-driven regime coupling as a distinct transition pathway, complementing existing understandings of niche-regime interactions and organic multi-system emergence. Third, it foregrounds the constitutive roles of physical and digital infrastructures and environmental data systems in shaping value creation, path dependencies, and distributional outcomes.

The remainder of the article is structured as follows. Section 2 develops the theoretical framework. Section 3 presents the research design and methods. Section 4 analyses structural gaps and emerging coupling mechanisms across six European countries. Section 5 introduces the RIE framework. Section 6 discusses theoretical and policy implications, and Section 7 concludes the study.

Key Concepts and Terminology

For clarity, three concepts are central to this article. Regime coupling refers to the alignment of previously distinct socio-technical regimes through shared infrastructures and governance arrangements. System entanglers are actors that operate across regime boundaries and facilitate interactions between socio-technical systems. Power-to-X refers to technologies that convert renewable electricity into alternative energy carriers or chemical products, such as hydrogen or ammonia.

2. Theoretical Framework

This section develops the conceptual foundations for analysing the convergence of blue, green, and circular economy agendas in European sustainability transitions. It draws on the multi-level perspective and recent advances in multi-system dynamics to introduce the notions of regime coupling and infrastructural integration.

2.1. Sustainability Transitions and the Multi-Level Perspective

Sustainability transitions research seeks to explain deep, non-linear shifts in socio-technical systems towards more sustainable modes of production and consumption [15,16]. The multi-level perspective (MLP) has become a central framework in this field, conceptualising transitions as the outcome of interactions between niches (protected spaces for radical innovations), socio-technical regimes (semi-stable configurations of technologies, institutions, practices, and meanings), and the broader exogenous landscape [11]. While the MLP has delivered powerful explanations of single-regime transitions, particularly in energy and mobility, scholars have increasingly highlighted its single-system bias. This has stimulated a growing body of work on multi-system dynamics, which examines interactions, complementarities, and co-evolution across multiple regimes [15,17]. Recent studies address acceleration challenges and “whole systems change” [15], causal processes in net-zero transitions involving technologies, actors and institutions [17], and low-carbon electrification as a multi-system transition spanning maritime transport, construction, chemicals, and the electricity system [18]. Researchers have also explored the construction of multi-system nexuses and interfaces between regimes [13].

2.2. Three Parallel Sustainability Agendas

European sustainability policy has been shaped by three prominent but largely parallel agendas. The blue economy emphasises the sustainable development of marine and coastal resources while reconciling economic activity with ecosystem integrity and social equity. The green economy focuses on decarbonising energy and industrial systems. The circular economy aims to eliminate waste, maintain materials in high-value loops, and regenerate natural capital. Although these agendas have successfully mobilised substantial resources and political attention, their treatment as largely distinct domains increasingly obscures critical interdependencies and trade-offs. Offshore wind development, for instance, simultaneously affects marine governance (blue), energy systems (green), and material requirements (circular) [19,20,21]. Research shows that the blue, green, and circular economies are conceptually complementary but partial, requiring deliberate integration to achieve genuine sustainability transitions [5,22].

Despite its centrality to the article’s argument, the circular economy merits particular attention here. Key circular economy dimensions—including material flows, waste management, remanufacturing, and product lifecycle extension—are directly implicated in both offshore wind development (e.g., turbine blade recycling, rare earth recovery) and marine governance (e.g., marine litter, biobased materials from aquaculture). These linkages are underexplored in multi-system transitions scholarship, and addressing them is one of the primary contributions of the RIE framework.

2.3. Analytical Fragmentation and Its Limitations

The analytical and policy separation of these agendas carries significant costs. It hinders the understanding of cross-regime interactions, infrastructural complementarities, and governance challenges [15,17]. While the multi-system transitions literature has advanced important concepts such as inter-system linkages, complementarity formation, and sites of interaction, it has so far devoted limited attention to the blue economy and to the role of strong, coordinated regulatory steering in actively coupling different regimes [11,17].

2.4. Towards Regime Coupling and the Resource Infrastructure Economy

This article proposes that European sustainability transitions are entering a new phase characterised by the emergence of a higher-order socio-technical configuration—the Resource Infrastructure Economy (RIE). In the RIE, energy, material, and marine regimes become tightly coupled and deliberately coordinated through physical and digital infrastructures, environmental data systems, and assertive regulatory intervention [12,23,24,25,26,27]. The RIE framework highlights three interrelated processes: infrastructural integration as a central mediating mechanism, regulatory-driven regime coupling (distinguishing between pairwise and triadic forms), and the critical importance of governance and justice considerations in shaping distributional outcomes. This framework provides an integrative lens for analysing how previously parallel agendas are co-evolving into an integrated resource infrastructure system.

3. Research Design and Methods

This study employs a conceptual–comparative research design that integrates a systematic integrative literature review [28,29] with cross-national case analysis. The approach was chosen to synthesise insights from previously siloed studies on the blue, green, and circular economies and to develop the Resource Infrastructure Economy (RIE) as a novel integrative framework for multi-system sustainability transitions.

Six European countries were selected following a most-different systems design [30]: Portugal and Spain (Southern peripheral contexts), Denmark, Germany and the Netherlands (Northern and Central European frontrunners), and Norway (non-EU benchmark). The selection maximised variation in geographical location, level of offshore wind deployment, exposure to critical raw materials challenges, and degree of blue–green–circular policy integration. Country selection was guided by four operational criteria: (a) offshore wind deployment scale; (b) circular economy maturity and relevant policy frameworks; (c) institutional capacity for marine governance; and (d) exposure to critical raw material tensions. Norway was included as a non-EU benchmark given its EEA membership, advanced offshore expertise, and significant critical raw material deposits. Its unique characteristics—including hydropower dominance (>90% of electricity generation), substantial Sovereign Wealth Fund fiscal capacity, and distinct governance dynamics—are explicitly addressed in the comparative analysis (see Section 4). This strategy enables robust identification of both generalisable patterns of regime coupling and context-specific divergences.

Data collection adhered to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines adapted for integrative reviews. Systematic searches were conducted between October 2025 and February 2026 in Scopus, Web of Science, and Google Scholar. Search strings combined keywords and Boolean operators, including terms such as: (“blue economy” OR “marine governance”) AND (“sustainability transitions” OR “socio-technical regimes”); (“circular economy” OR “resource efficiency”) AND (“multi-system” OR “regime coupling”); (“offshore wind” OR “marine spatial planning”) AND “critical raw materials.” These were complemented by targeted hand-searching of grey literature from the European Commission, IRENA, Eurostat, WindEurope, and national energy agencies. After duplicate removal, the search yielded over 450 records (Scopus: ~190; Web of Science: ~160; Google Scholar: ~100+). Title and abstract screening retained 120 documents for full-text assessment. Following application of pre-defined inclusion and exclusion criteria—which required publications to address at least one of the three economy domains (blue, green, circular) in a European sustainability transitions context, to have been peer-reviewed or from authoritative grey literature sources, and to be published from 2000 onwards—58 core publications were selected for in-depth analysis. Studies were excluded at full-text stage primarily because they focused on regions outside Europe, addressed only one economy domain without reference to cross-domain interactions, or lacked sufficient empirical or conceptual grounding. A PRISMA flow diagram detailing the selection process is provided in Appendix A.

Quantitative indicators on renewable energy deployment and critical raw materials were triangulated from official sources (Eurostat, IRENA, WindEurope, and national transmission system operators). As a result, the 58 documents were analysed using abductive thematic analysis [31,32], supported by MAXQDA 26 qualitative data analysis software. An initial deductive coding framework was constructed based on core concepts from the multi-level perspective and multi-system transitions literature (e.g., socio-technical regimes, landscape pressures, inter-system complementarities, infrastructural interdependencies, and governance mechanisms). This framework was iteratively refined through constant comparison with the data, allowing new inductive codes and themes to emerge organically. Inductive codes were identified through iterative close reading of the selected publications, with themes emerging from recurring patterns across documents. The coding process was conducted solely by the author. To enhance analytical trustworthiness in the absence of inter-coder reliability assessment, the author performed multiple rounds of iterative coding, maintained a detailed audit trail of all coding decisions, produced systematic reflexive memos, and triangulated the qualitative findings with quantitative indicators from official sources (Eurostat, IRENA, WindEurope). A condensed version of the coding framework is provided in Appendix B.

Coding was structured around four central thematic axes: (1) structural gaps and misalignments between the three agendas; (2) mechanisms of pairwise and triadic regime coupling; (3) the mediating functions of physical and digital infrastructures and environmental data systems; and (4) governance arrangements, regulatory steering, and justice implications. To strengthen analytical trustworthiness, multiple rounds of coding were conducted, a detailed audit trail of coding decisions was maintained, and systematic reflexive practice was applied throughout the analytical process. Comparative case analysis was then conducted to identify cross-national patterns and regional divergences (Northern/Central versus Southern Europe). Visual tools, including matrices and figures, were developed to support synthesis and to facilitate the abstraction process leading to the RIE framework.

The comparative assessment across countries was constructed by systematically applying the four thematic axes to each national case. Country profiles were developed drawing on both the literature review and the quantitative indicators triangulated from official sources.

While this study provides a broad, timely, and theoretically informed synthesis, its reliance on secondary sources necessarily limits insight into micro-level actor dynamics and implementation processes. Future research should therefore complement this work with primary methods such as elite interviews, stakeholder workshops, or process-tracing of specific regime coupling initiatives.

4. Empirical Analysis: Structural Gaps and Emerging Coupling Mechanisms

This section presents the empirical findings from the systematic integrative literature review and the comparative case analysis across six European countries. It examines deployment patterns, persistent structural gaps, emerging regime coupling mechanisms, and cross-national differences, with particular attention to the North–South divide. A detailed overview of the 58 studies is provided in Appendix A (Table A1). This comprehensive characterisation follows PRISMA guidelines [33] and serves as the empirical foundation for the subsequent analysis (see Supplementary Materials Table S1. PRISMA 2020 Checklist). The studies confirm a predominance of green transition scholarship, with more limited but growing attention to blue and circular economy dimensions, especially in Northern Europe.

4.1. Deployment Patterns and Material Context

Table 1 summarises key indicators of renewable energy deployment and critical raw materials (CRM) context as of early 2026.

Table 1. Renewable energy deployment and critical raw materials context (early 2026).

While all countries have made significant progress in renewable energy deployment, major differences remain in the scale of installed offshore wind capacity and the degree of cross-regime integration. Portugal, in particular, exhibits a striking contrast between its very low current installed offshore capacity and its substantial future ambitions and natural resource potential. It is also worth noting that Portugal and Spain, despite being characterised as ‘peripheral’ in terms of current integration levels, possess endogenous strengths: Portugal has a world-leading pilot floating offshore wind installation (WindFloat Atlantic) and significant investment in wave energy, while Spain has rapidly expanded its renewable energy capacity and is developing circular economy strategies. These endogenous capacities challenge any static deficit framing and highlight transition potential that EU cohesion policy and Just Transition Mechanisms could further unlock.

4.2. Structural Gaps

The comparative analysis identifies four interlocking structural gaps that hinder deeper integration [43,44,45,46,47,48,49,50]:

A persistent mismatch between ambitious green infrastructure targets and material supply security, particularly for critical raw materials required by offshore wind [19,51].
Uneven blue–green integration, with Northern and Central European countries showing considerably more advanced coordination between offshore wind and marine spatial planning.
Limited incorporation of circular economy principles into the material demands of large-scale green transitions. This gap is particularly acute with regard to end-of-life management of offshore wind turbine blades, recovery of rare earth elements from wind turbine generators, and the absence of marine-specific circular strategies. The circular economy thus occupies a structurally marginal position in current blue–green governance, despite its centrality to the resource security agenda. Concrete initiatives are, however, beginning to emerge: Vestas launched a zero-waste blade commitment in Denmark in 2021, and Siemens Gamesa developed the RecyclableBlade programme in Germany, both targeting end-of-life turbine blade circularity. WindEurope has specifically reported circularity initiatives in the Rotterdam port region (The Netherlands). These cases remain isolated and have not yet achieved systemic integration, but they signal the direction of travel for a genuinely circular offshore wind sector.
Acute socio-spatial justice challenges, especially in peripheral regions, where large-scale projects risk creating “green sacrifice zones” (e.g., lithium mining in Portugal’s Barroso region).

4.3. Emerging Coupling Mechanisms

Despite these gaps, several promising mechanisms of regime coupling are observable. Denmark’s Energy Islands represent one of the most advanced examples of blue–green coupling, integrating large-scale offshore wind with power-to-X technologies, hydrogen production, and marine spatial planning. In the Netherlands, industrial symbiosis initiatives demonstrate stronger green–circular linkages, particularly in industrial port zones such as the Rotterdam–Moerdijk cluster, where material and energy flows are shared across sectors, and where end-of-life wind turbine components are beginning to be incorporated into circular value chains. In contrast, Southern European countries show more fragmented efforts, although Portugal and Spain have begun exploring synergies between blue economy strategies, renewables, and circular practices. Digital monitoring platforms and multifunctional infrastructure projects are increasingly acting as key mediators across regimes. It should be noted that triadic coupling—the simultaneous deep integration of blue, green, and circular systems—remains largely aspirational at this stage. No single case reviewed provides unambiguous empirical evidence of full three-way integration. The Blue–Circular pairing, in particular, lacks concrete case study evidence at the system level. Nonetheless, nascent Blue–Circular examples are observable: the MERMAID project (The Netherlands) and the TROPOS project (Denmark) both explored integrated aquaculture within offshore wind parks, combining marine resource production with offshore energy infrastructure—constituting real, if limited, Blue–Circular coupling. In Portugal, the valorisation of bivalve shells in the Algarve region [52] represents an empirical case of Blue–Circular integration at the local level. These initiatives remain isolated and pre-systemic, but they provide empirical grounding for the Blue–Circular pairing in the RIE framework. The coupling typology presented in Table 2 should therefore be read as a conceptual and analytical framework that maps emerging trajectories rather than established realities.

Table 2. Pairwise versus triadic regime coupling in the RIE framework.

4.4. Comparative Patterns of Regime Coupling

A clear geographical divide emerges in the patterns and depth of regime coupling. Figure 1 shows the degree of pairwise (blue–green and green–circular) and triadic (blue–green–circular) regime coupling across the six countries, differentiating between Northern/Central European frontrunners and Southern peripheral countries.

Figure 1. Pairwise and triadic coupling patterns across six countries.

The relative positions depicted in Figure 1 reflect qualitative and interpretive judgements grounded in the documentary evidence, rather than a formal scoring system. Figure 1 is therefore best understood as a conceptual and heuristic representation of coupling patterns rather than an empirically measured ranking. Future research could refine these assessments using structured indicators of regime coupling (see Section 5 and Section 6.3).

Countries are positioned on two axes representing blue–green and green–circular coupling intensity. The figure is heuristic and interpretive rather than based on a formal scoring system. Overlapping areas between circles represent degrees of coupling, with darker shading indicating stronger integration. Northern/central European countries cluster towards higher coupling; Southern peripheral countries and Norway occupy intermediate-to-lower positions.

As shown in Figure 1, Northern and Central European countries (Denmark, Germany, and the Netherlands) exhibit higher degrees of pairwise regime coupling—particularly between blue and green regimes—as well as greater institutional capacity for infrastructural coordination. These countries have developed more sophisticated governance arrangements and multifunctional infrastructure projects that actively link marine space, energy systems, and material flows. Southern peripheral regions (Portugal and Spain), despite possessing substantial natural endowments in renewables and critical raw materials, demonstrate significantly weaker integration. Norway occupies an intermediate position as a non-EU benchmark with strong blue–green potential but distinct governance dynamics: its hydropower dominance means the green transition pathway differs fundamentally from other cases, and its greater fiscal capacity (underpinned by the Sovereign Wealth Fund) provides a governance context not directly replicable by EU member states. This North–South pattern underscores that regime coupling is highly contingent on institutional capacity, policy coherence, long-standing offshore experience, and levels of infrastructural investment. These empirical insights provide the foundation for the integrative conceptual framework developed in the following section.

5. Towards a Resource Infrastructure Economy: An Integrative Framework

This section synthesises the structural gaps and emerging coupling mechanisms identified in the empirical analysis into a novel conceptual framework—the Resource Infrastructure Economy (RIE). The RIE conceptualises European sustainability transitions as processes of deep regime coupling and infrastructural integration, in which energy (green), marine (blue), and material (circular) regimes become tightly coordinated through shared physical and digital infrastructures and strong regulatory steering.

5.1. Conceptual Foundations

The RIE framework rests on three interrelated pillars that extend the multi-level perspective and recent advances in multi-system dynamics [17,54,55]. First, infrastructural integration positions physical and digital infrastructures as central coordinating mechanisms rather than mere backdrops [23,24,56]. Offshore wind hubs, Energy Islands, digital monitoring platforms, and industrial symbiosis networks do not simply support individual regimes; they actively mediate resource flows, data exchange, and spatial coordination across blue, green, and circular domains [57,58,59,60,61,62]. These infrastructures create new complementarities while simultaneously generating path dependencies and lock-ins.

Second, regime coupling theorises the deliberate alignment of previously distinct socio-technical regimes. Building on concepts of system linkages and complementarity formation [63,64], the framework distinguishes between pairwise coupling (integration between two regimes) and the more ambitious triadic coupling (involving all three regimes simultaneously). While pairwise couplings emerge more readily, full triadic integration requires intentional coordination and remains rare and fragile.

Third, governance and justice foreground the constitutive role of regulatory steering and distributional outcomes. In the European context, strong top-down policy frameworks (European Green Deal, CRMA, Blue Economy Strategy) actively shape regime coupling. However, as the Portuguese Barroso case illustrates, such steering can exacerbate justice tensions in peripheral regions unless procedural, distributional, and recognitional justice are embedded as core features [1,65]. The Barroso case involves contested lithium extraction plans in a predominantly rural and socio-economically marginalised region. The actors involved include mining companies, national energy authorities, local communities, and environmental NGOs. Key governance tensions concern land use rights, community consent, environmental impact assessment, and benefit-sharing mechanisms. Local resistance movements have contested the project on grounds of territorial justice and inadequate participatory processes, illustrating how green transition policies can reproduce—rather than resolve—spatial inequalities [1,3]. This case concretely demonstrates the contradictions at the heart of the RIE: while lithium is essential for battery storage integral to green and circular transitions, its extraction risks generating new sacrifice zones without adequate governance safeguards.

This regulatory-driven regime coupling constitutes a distinct transition pathway. It differs from the classical pathways proposed by Geels et al. [66], which focus primarily on niche-regime interactions, market-driven substitution, or gradual internal reconfiguration within a single regime. In contrast, the RIE pathway emphasises assertive, top-down regulatory intervention in highly institutionalised contexts to deliberately orchestrate alignment between multiple regimes around shared infrastructures.

5.2. The RIE Framework

Figure 2 illustrates the Resource Infrastructure Economy framework.

Figure 2. The Resource Infrastructure Economy (RIE) framework: Regime coupling through infrastructural integration.

The diagram shows the three regimes (Blue, Green, and Circular) as overlapping circles. Physical and digital infrastructures occupy the centre as mediating mechanisms. Bold arrows represent pairwise couplings, while a central triangle denotes the more ambitious triadic coupling. Overarching elements include regulatory steering and participatory governance, which generate feedback loops and address justice implications.

The size of overlapping areas between circles indicates the relative degree of coupling; the central triangle represents triadic coupling, which remains aspirational in current European transitions; dashed arrows from regulatory and participatory governance elements represent enabling and constraining forces. Infrastructure nodes at coupling intersections denote sites where physical and digital systems actively mediate regime interactions. Infrastructures act as the “glue” that enables coordination. Regulatory steering provides directionality and momentum, while participatory governance arrangements help mitigate conflicts and address justice concerns.

5.3. Added Value of the RIE Framework

The RIE framework advances sustainability transitions theory in three important ways:

It systematically integrates blue economy scholarship into multi-system dynamics, treating marine governance as a full socio-technical regime with its own material, spatial, and justice dynamics, rather than a passive backdrop for green infrastructure.
It theorises regulatory-driven regime coupling as a distinct transition pathway, complementing (and in some contexts challenging) existing MLP pathways focused on niche-regime interactions or organic multi-system emergence.
It foregrounds the constitutive roles of physical and digital infrastructures and environmental data systems in value creation, path dependency formation, and distributional outcomes.

To clarify how the RIE framework relates to and differs from existing multi-system concepts, Table 3 provides a structured comparison.

Table 3. Comparison of the RIE framework with related multi-system concepts.

Empirically, the framework explains the uneven geography of European transitions: more advanced pairwise couplings and infrastructural coordination in Northern and Central Europe, contrasted with persistent gaps and justice challenges in Southern peripheral regions.

6. Discussion

The preceding analysis has shown that European sustainability transitions are characterised by persistent structural gaps between the blue, green, and circular economy agendas, alongside emerging patterns of regime coupling and infrastructural integration. This section discusses the implications of these findings for sustainability transitions theory, reflects on policy challenges, and outlines avenues for future research.

6.1. Theoretical Implications

This study contributes to multi-system transitions research by developing the Resource Infrastructure Economy (RIE) as an integrative framework. The empirical findings also complicate overly optimistic views of multi-system integration. While pairwise connections are observable, full three-way integration remains limited, especially in peripheral regions facing green sacrifice dynamics [1,3].

Three contributions stand out.

First, the framework advances the integration of blue economy scholarship into multi-system dynamics. While recent studies have emphasised interactions between energy, mobility, and industrial systems [13,55,57], the blue regime has remained relatively peripheral. By treating marine governance as a full socio-technical regime with distinct spatial, material, and justice dynamics, the RIE framework reveals how marine considerations actively shape—and are shaped by—green and circular processes.

Second, the analysis highlights regulatory-driven regime coupling as a distinct transition pathway. Existing literature has largely focused on niche-regime interactions, complementarity formation, and bottom-up multi-system emergence [64,67]. In the European context, however, strong regulatory steering (European Green Deal, CRMA, Blue Economy Strategy) plays a constitutive role in deliberately aligning regimes around shared physical and digital infrastructures. This pathway differs from both classical MLP pathways [66] and more organic multi-system processes observed in other contexts.

Third, the RIE framework foregrounds the performative role of infrastructures and environmental data systems. Infrastructures do not merely enable resource flows; they actively mediate regime coupling, create new complementarities, generate path dependencies, and influence distributional outcomes [58,68]. This infrastructural perspective enriches multi-system scholarship by linking material flows, digitalisation, and governance more explicitly.

The empirical findings also refine optimistic accounts of multi-system integration. While pairwise couplings—particularly between blue–green and green–circular systems—are observable, full triadic integration remains limited and fragile, especially in peripheral regions. The RIE framework is therefore better understood at this stage as a promising interpretive lens for understanding emerging patterns of integration rather than as a fully validated transformation already underway. The evidence supports a cautious framing: Europe is moving towards a Resource Infrastructure Economy, but this trajectory is uneven, contested, and far from complete. This underscores important constraints on coupling under current conditions and reflects concerns about cumulative processes and resource limitations highlighted in related studies [55].

6.2. Policy Implications

The RIE framework suggests that pursuing the European Green Deal, Blue Economy Strategy, Circular Economy Action Plan, and Critical Raw Materials Act in parallel risks reproducing structural gaps and unintended trade-offs. Greater policy coordination across domains is necessary, particularly regarding the sequencing of infrastructure investments, the integration of circularity requirements into energy and marine projects, and the development of shared digital monitoring systems. For peripheral regions such as Portugal and Spain, the findings are especially relevant. These regions possess significant potential in renewables, marine space, and critical raw materials (lithium), yet they face heightened risks of socio-environmental conflict and “green sacrifice zones” [1,51,69]. Policies should therefore incorporate stronger mechanisms for procedural and distributional justice, including participatory marine spatial planning, local content requirements, and targeted capacity-building support [44,70,71,72,73]. Policies should therefore incorporate stronger mechanisms for procedural and distributional justice. Concrete examples include participatory marine spatial planning processes that ensure genuine community co-design (e.g., citizens’ assemblies on offshore wind siting); co-management frameworks that grant fishing communities formal governance roles in offshore wind development zones; local content requirements that ensure peripheral regions benefit economically from extractive or energy projects; and targeted EU cohesion policy or Just Transition Mechanism funding to build regional capacity for integrated governance. With regard to sequencing, investment strategies should prioritise capacity-building and institutional development in peripheral regions before or alongside large-scale infrastructure deployment, to ensure that speed of transition does not outpace local governance readiness. The RIE framework can also inform monitoring and evaluation of multi-agency policy coordination by providing a set of coupling indicators (see Section 5.3 and Table 3) against which progress towards integrated governance can be assessed over time.

6.3. Limitations and Future Research

Several limitations should be acknowledged. The study relies primarily on secondary sources and comparative case analysis. While this approach enabled cross-national comparison, it offers limited insight into micro-level actor negotiations and implementation dynamics. The analysis also reflects developments up to early 2026 and is situated within the specific institutional context of Europe. Future research should further operationalise the RIE framework through the development of concrete indicators for each coupling dimension. Potential indicators include institutional coordination mechanisms (e.g., number and scope of cross-sectoral governance bodies); shared infrastructure investments (e.g., proportion of offshore wind projects incorporating power-to-X or circular economy components); policy alignment scores (e.g., degree of regulatory coherence between blue, green, and circular policy instruments); and governance coordination dimensions (e.g., existence of joint monitoring systems across marine, energy, and material agencies). Longitudinal case studies of specific coupling initiatives—such as Denmark’s Energy Islands or emerging Portuguese offshore wind projects—would enable process-tracing of coupling dynamics and empirical validation of the framework. Comparative analysis beyond Europe, including examination of how analogous frameworks develop in different institutional contexts, would also extend the RIE’s generalisability.

7. Conclusions

This article has examined the convergence of blue, green, and circular economy agendas in European sustainability transitions. Through a comparative analysis of developments in Portugal, Spain, Germany, the Netherlands, Denmark, and Norway, it has demonstrated that while important structural gaps persist, nascent patterns of regime coupling and infrastructural integration are emerging. These processes are mediated by physical and digital infrastructures and actively shaped by strong regulatory steering.

To capture these dynamics, the study introduced the Resource Infrastructure Economy (RIE) as an integrative conceptual framework. The RIE conceptualises European sustainability transitions as processes of deep regime coupling, in which energy, marine, and material regimes become increasingly coordinated through shared infrastructures, data systems, and deliberate policy intervention. In doing so, the framework advances transitions theory in three ways: it integrates blue economy scholarship more firmly into multi-system analysis; theorises regulatory-driven regime coupling as a distinct transition pathway; and foregrounds the constitutive roles of infrastructures and environmental data systems in value creation, path dependency, and distributional outcomes.

The comparative analysis reveals a clear North–South divide. Northern and Central European countries demonstrate more advanced pairwise couplings (blue–green and green–circular) and stronger infrastructural coordination. In contrast, Southern peripheral regions, while endowed with significant natural assets and emerging endogenous innovation capacities, face greater challenges in integrated governance and justice, with risks of creating new “green sacrifice zones.” These findings underscore that regime coupling is neither automatic nor uniform; it is highly contingent on institutional capacity, infrastructural development, and political commitment.

The emergence of the Resource Infrastructure Economy signals a broader shift in European sustainability transitions: from isolated sectoral greening towards the reconfiguration of resource infrastructure systems. At this stage, the RIE is best understood as an emerging tendency and an interpretive framework rather than a fully instantiated transformation. Realising the transformative potential of this shift will require moving beyond siloed policy approaches. It demands deliberate coordination across the European Green Deal, Blue Economy Strategy, Circular Economy Action Plan, and Critical Raw Materials Act, as well as greater attention to justice and regional equity.

Future research should further test and refine the RIE framework through longitudinal studies of coupling projects, comparative analysis beyond Europe, and more nuanced examinations of power relations and data governance within emerging resource infrastructure systems. As Europe pursues ambitious climate and ocean objectives, the capacity to design, govern, and legitimise tightly coupled resource infrastructure regimes will be central to achieving socially just and ecologically sustainable transitions.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/su18136579/s1, Table S1. PRISMA 2020 Checklist.

Funding

This research was funded by the ERA Chair BESIDE project funded by the European Union’s Horizon 2020 research and innovation program under grant agreement No 951389 (https://doi.org/10.3030/951389); and through the projects UID/50017/2025 (https://doi.org/10.54499/UID/50017/2025) and UID/04928/2025 (https://doi.org/10.54499/UID/04928/2025).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

No new data were created or analysed in this study. Data sharing is not applicable to this article. No new primary data were generated or analysed in this study. The systematic review is based on publicly available secondary sources. The full list of included studies, coding framework, and supporting matrices are provided in the Appendices. Additional materials (e.g., full MAXQDA codebook) are available from the corresponding author upon reasonable request.

Conflicts of Interest

The author declares no conflicts of interest.

Appendix A. PRISMA Flow Diagram of the Literature Selection Process

Figure A1. PRISMA 2020 flow diagram detailing the identification, screening, eligibility, and inclusion of studies in the systematic integrative literature review. Adapted from Page et al. (2021) [33].

Table A1. Characteristics of the 58 included studies: authors, title, methodology, main results, and conclusions. Format follows the PRISMA standard for systematic reviews. Domain codes: Blue = blue economy/marine governance; Green = green economy/energy transitions; Circular = circular economy/material flows; Multi = multi-domain. Total included studies: 58.

Authors	Title	Methodology	Main Results	Conclusions
Geels [9]	Technological transitions as evolutionary reconfiguration processes: a multi-level perspective and a case-study	Conceptual framework development with historical case study (Dutch gas system transformation)	Introduced the multi-level perspective (MLP) distinguishing niches, socio-technical regimes, and landscape. Demonstrated how regime shifts result from interactions across levels rather than single-system dynamics.	Regime transitions are non-linear, multi-actor processes. The MLP provides the foundational lens for analysing how innovations break through stabilised regimes—central to the RIE framework’s understanding of regime coupling.
Geels [10]	The multi-level perspective on sustainability transitions: Responses to seven criticisms	Conceptual/theoretical—systematic response to critiques of the MLP	Addressed key criticisms of the MLP including its alleged determinism, neglect of agency, and overly linear framing. Strengthened the framework’s analytical robustness.	The MLP remains a valid and adaptable framework for studying sustainability transitions when properly contextualised. Foundational for the RIE in understanding regime stability and destabilisation.
Markard et al. [16]	Sustainability transitions: An emerging field of research and its prospects	Systematic review and bibliometric analysis of the sustainability transitions literature	Mapped the intellectual structure of the field, identifying key concepts (MLP, TIS, SNM), central scholars, and major thematic clusters. Confirmed the field’s rapid growth and interdisciplinary character.	Sustainability transitions research is a coherent and expanding field with strong theoretical foundations. Provided the broader literature context within which the RIE framework is situated.
Konrad et al. [63]	Multi-regime dynamics in the analysis of sectoral transformation potentials: evidence from German utility sectors	Empirical qualitative analysis of multi-regime interactions in German electricity, gas, and water utility sectors	Identified mechanisms of inter-regime interaction, including resource competition, actor overlap, and institutional co-evolution across sectors. Showed that sectoral transformations cannot be understood in isolation.	Multi-regime perspectives are essential for analysing complex socio-technical change. Provides direct empirical grounding for the RIE’s theorisation of pairwise and triadic regime coupling across blue, green, and circular systems.
Papachristos et al. [67]	System interactions in socio-technical transitions: Extending the multi-level perspective	Conceptual extension of the MLP incorporating system interaction theory	Proposed a framework for analysing interactions between socio-technical systems, distinguishing types of linkages (competitive, complementary, symbiotic). Applied to energy and mobility systems.	System interactions fundamentally shape transition dynamics. Offers conceptual tools for theorising how blue, green, and circular regimes interact—directly informing the RIE coupling typology.
Geels et al. [66]	The enactment of socio-technical transition pathways: A reformulated typology and a comparative multi-level analysis of the German and UK low-carbon electricity transitions (1990–2014)	Comparative historical analysis of two national energy transitions using reformulated MLP pathway typology	Distinguished four transition pathways (transformation, reconfiguration, technological substitution, de-alignment/re-alignment) and applied them to German and UK electricity systems. Showed how pathways are politically enacted.	Transition pathways are not pre-determined but are shaped by actor coalitions and regulatory contexts. The RIE’s regulatory-driven coupling pathway complements and extends this typology to multi-regime contexts.
Velenturf et al. [8]	Circular economy and the matter of integrated resources	Empirical framework development drawing on case studies and stakeholder engagement in the UK	Argued that the circular economy must account for integrated resource flows across material, energy, and water systems. Identified governance gaps in current CE frameworks.	Circular economy frameworks must be extended to integrated resource systems. Provides conceptual grounding for the RIE’s treatment of material flows as cross-regime phenomena linking green infrastructure to circular governance.
Domenech et al. [43]	Transition towards a resource efficient circular economy in Europe: policy lessons from the EU and the member states	Policy analysis and comparative review of EU circular economy strategies and national implementation	Identified key policy instruments, governance gaps, and implementation challenges across EU member states. Highlighted divergences between Northern and Southern European approaches to circular economy policy.	Effective CE transitions require coherent multilevel governance. The North–South divergence identified mirrors the RIE framework’s empirical finding of uneven coupling intensity across European regions.
Rosenbloom [12]	Engaging with multi-system interactions in sustainability transitions: a comment on the transitions research agenda	Conceptual commentary and research agenda for multi-system transitions scholarship	Argued that single-system MLP analyses are insufficient for understanding contemporary sustainability challenges. Proposed a multi-system transitions research agenda addressing co-evolution, conflicts, and complementarities across regimes.	Transitions research must move beyond single-regime analysis. Directly motivates the RIE framework’s multi-system approach and its focus on regime coupling rather than isolated sectoral change.
Markard [27]	The life cycle of technological innovation systems	Conceptual modelling of innovation system evolution across formation, stabilisation, and decline phases	Proposed a lifecycle model for technological innovation systems (TIS) with distinct phases and transition mechanisms. Showed how system maturity shapes coupling opportunities and constraints.	Innovation system maturity shapes the conditions for regime coupling. Informs the RIE understanding of why some regime coupling attempts succeed while others remain fragile or aspirational.
Markard et al. [15]	Challenges in the acceleration of sustainability transitions	Review and synthesis of acceleration mechanisms and barriers across multiple transition cases	Identified key acceleration challenges including political resistance, incumbent lock-in, and systemic inertia. Argued that acceleration requires simultaneous action across technological, institutional, and social dimensions.	Acceleration is a multi-dimensional challenge requiring systemic coordination. The RIE’s regulatory-driven coupling pathway can be understood as an acceleration strategy—with governance and infrastructure integration as key levers.
Kanger [25]	Rethinking the Multi-level Perspective for energy transitions: From regime life-cycle to explanatory typology of transition pathways	Conceptual rethinking and typological extension of MLP transition pathways	Proposed a revised typology of transition pathways grounded in regime lifecycle dynamics. Distinguished between destabilisation-driven and stabilisation-driven pathways.	MLP pathways must account for regime lifecycle dynamics. Provides a complementary typological lens for the RIE’s treatment of regulatory-driven coupling as a distinct and undertheorised transition pathway.
Mhatre et al. [47]	A systematic literature review on the circular economy initiatives in the European Union	Systematic literature review of EU circular economy policies, strategies, and implementation studies	Mapped the landscape of EU CE initiatives, identifying the Circular Economy Action Plan, Extended Producer Responsibility, and industrial symbiosis as key mechanisms. Found significant implementation gaps especially in Southern Europe.	EU CE initiatives are advancing but unevenly implemented across member states. Confirms the North–South governance gap identified in the RIE comparative analysis and contextualises the circular regime’s relative underdevelopment.
Velenturf [19]	A framework and baseline for the integration of a sustainable circular economy in offshore wind	Framework development with baseline assessment of circularity in offshore wind sector (UK/EU focus)	Developed a CE integration framework specifically for offshore wind, covering turbine components, materials, logistics, and end-of-life management. Identified critical gaps in blade recycling and rare earth recovery.	Circular economy principles can and must be integrated into offshore wind infrastructure. Provides the empirical and conceptual foundation for the RIE’s Blue–Circular coupling dimension, particularly regarding end-of-life turbine management.
D’Amato et al. [5]	Integrating the green economy, circular economy and bioeconomy in a strategic sustainability framework	Conceptual integration and comparative analysis of three economy frameworks	Argued that green, circular, and bioeconomy frameworks are conceptually complementary but institutionally fragmented. Proposed a strategic sustainability framework for their integration.	Integration of the three economy frameworks is necessary but requires deliberate governance. Provides the conceptual rationale for the RIE’s triadic coupling ambition and its critique of siloed policy approaches.
Martínez-Vázquez et al. [22]	Challenges of the Blue Economy: Evidence and research trends	Systematic review and bibliometric analysis of blue economy research	Mapped the blue economy research landscape, identifying marine spatial planning, fisheries governance, and marine tourism as dominant themes. Highlighted the limited integration of blue economy with green and circular agendas.	Blue economy research remains largely disconnected from green and circular economy scholarship. Confirms the structural gap the RIE framework aims to address by integrating marine governance as a full socio-technical regime.
Lichtenegger et al. [46]	Offshore and onshore wind turbine blade waste material forecast at a regional level in Europe until 2050	Quantitative modelling of wind turbine blade waste streams across European regions to 2050	Projected a major increase in blade waste volumes across Europe by 2050, with significant regional variation. Identified lack of recycling infrastructure as a critical bottleneck.	Wind turbine blade waste represents a major and underplanned circular economy challenge. Provides quantitative grounding for the RIE’s Green–Circular coupling gap and the urgency of integrating circularity into green infrastructure planning.
Sovacool [2]	Who are the victims of low-carbon transitions? Towards a political ecology of climate change mitigation	Conceptual and empirical review applying political ecology to low-carbon transition justice	Identified multiple categories of victims of low-carbon transitions including indigenous communities, rural populations, and workers in fossil fuel industries. Developed a political ecology framework for transition justice.	Low-carbon transitions produce winners and losers, requiring explicit justice frameworks. Foundational for the RIE’s justice pillar, particularly the analysis of green sacrifice zones in peripheral regions such as Portugal’s Barroso.
Serpetti et al. [6]	Modeling small scale impacts of multi-purpose platforms: an ecosystem approach	Ecosystem modelling of multi-purpose marine platform impacts using Ecopath with Ecosim	Assessed ecological impacts of integrating aquaculture with offshore wind platforms. Found potential benefits (habitat creation, reduced trawling pressure) alongside risks (altered species distributions, competition).	Multi-purpose marine platforms create complex ecosystem trade-offs requiring integrated governance. Provides empirical grounding for the RIE’s Blue–Circular coupling and the governance challenges of multi-functional offshore infrastructure.
Dubois et al. [31]	Systematic combining: an abductive approach to case research	Methodological—development and application of abductive reasoning in case research	Proposed systematic combining as a research approach that moves iteratively between theory and empirical data, allowing frameworks to develop organically rather than through purely deductive or inductive logic.	Abductive reasoning supports theory development from complex empirical settings. Provides the methodological foundation for the RIE article’s analytical approach—iterative movement between MLP/multi-system theory and comparative case evidence.
Langley [32]	Strategies for theorizing from process data	Methodological—review and synthesis of strategies for theory development from qualitative process data	Identified seven strategies for theorising from process data (narrative, quantification, alternate templates, grounded theory, visual mapping, temporal decomposition, synthetic). Highlighted the importance of iteration between data and theory.	Theorising from process data requires explicit methodological strategies. Informs the RIE article’s use of abductive thematic analysis and iterative coding with MAXQDA, legitimising the analytical approach as methodologically grounded.
Torraco [28]	Writing integrative literature reviews: Using the past and present to explore the future	Methodological—guidance on integrative literature review design and execution	Distinguished integrative from systematic reviews, emphasising synthesis, critique, and theory development over mere aggregation. Provided practical guidance on search, analysis, and writing strategies.	Integrative reviews generate new theoretical perspectives from existing knowledge. Provides the methodological justification for the RIE article’s systematic integrative review design, which goes beyond description to develop the RIE framework.
Snyder [29]	Literature review as a research methodology: An overview and guidelines	Methodological—systematic overview of literature review types and their appropriate applications	Differentiated systematic, semi-systematic, and integrative literature reviews. Provided selection criteria for each type and practical guidance on rigour, transparency, and reporting.	Literature review methodology must be matched to research purpose and epistemology. Supports the RIE article’s choice of integrative systematic review as appropriate for conceptual framework development in a cross-domain area.
Kazak [26]	European green deal	Policy analysis and legal review of the European Green Deal framework	Analysed the legal and institutional architecture of the European Green Deal, covering the Climate Law, Fit for 55, and sectoral strategies. Identified coordination challenges across policy domains.	The European Green Deal represents an unprecedented policy intervention shaping European sustainability transitions. Provides the regulatory landscape context within which the RIE framework’s coupling dynamics operate.
Mäkitie et al. [54]	Complementarity formation mechanisms in technology value chains	Empirical analysis of complementarity formation in Norwegian maritime electrification value chains	Identified three mechanisms through which complementarities form between technologies: sequencing, bridging, and co-specialisation. Showed how value chain actors actively construct complementarities rather than discovering them.	Complementarities between technologies and sectors are actively constructed through specific mechanisms. Informs the RIE’s understanding of how blue–green–circular coupling is enabled—or blocked—by deliberate actor strategies and infrastructure investments.
Rentizelas et al. [49]	Reverse supply network design for circular economy pathways of wind turbine blades in Europe	Quantitative optimisation modelling of reverse supply networks for wind turbine blade end-of-life management across Europe	Modelled optimal reverse logistics networks for blade recycling, considering geography, volumes, and processing technologies. Found significant cost reduction potential from coordinated regional approaches.	Reverse supply chain coordination is essential for circular wind sector development. Provides quantitative evidence for the RIE’s Green–Circular coupling gap and the infrastructure investment requirements for closing it.
Andersen & Geels [17]	Multi-system dynamics and the speed of net-zero transitions: Identifying causal processes related to technologies, actors, and institutions	Conceptual and empirical analysis of causal processes in multi-system net-zero transitions	Identified three causal process categories (technological co-evolution, actor network expansion, institutional change) that jointly determine the speed of net-zero transitions across multiple regimes.	Multi-system transitions require simultaneous change across technological, actor, and institutional dimensions. One of the most directly relevant studies for the RIE framework—provides causal process language for understanding how regime coupling accelerates or stalls.
Andersen et al. [13]	Building multi-system nexuses in low-carbon transitions: Conflicts and asymmetric adjustments in Norwegian ferry electrification	Empirical case study of Norwegian maritime electrification as a multi-system transition	Analysed how electrification of Norwegian ferries created a multi-system nexus linking the maritime, electricity, and battery manufacturing regimes. Identified asymmetric adjustment processes and conflict resolution mechanisms.	Building multi-system nexuses involves navigating conflicts and asymmetric power relations. Provides direct empirical grounding for the RIE’s system entangler concept and the infrastructure integration pillar.
Nykamp et al. [18]	Low-carbon electrification as a multi-system transition: a socio-technical analysis of Norwegian maritime transport, construction, and chemical sectors	Multi-case socio-technical analysis of electrification across three Norwegian industrial sectors	Demonstrated that electrification creates cross-sector complementarities and dependencies, requiring coordinated governance. Found that each sector follows a distinct coupling trajectory shaped by incumbent interests and infrastructure availability.	Low-carbon electrification is inherently a multi-system phenomenon. Confirms the RIE’s argument that green transitions cannot be analysed or governed in single-sector terms, and supports the empirical grounding of the Norwegian case.
Löhr et al. [57]	Multi-system interactions in hydrogen-based sector coupling projects: system entanglers as key actors	Empirical analysis of hydrogen projects in Germany as multi-system interaction sites	Introduced the concept of ‘system entanglers’—actors who operate across regime boundaries and actively mediate inter-system interactions. Found that system entanglers are critical for translating hydrogen projects into genuine regime coupling.	System entanglers are key actors enabling multi-system coupling. Provides the conceptual origin of the system entangler concept used in the RIE framework to explain how actors and technologies bridge blue, green, and circular regimes.
Knol-Kauffman et al. [21]	Sustainability conflicts in the blue economy: planning for offshore aquaculture and offshore wind energy development in Norway	Empirical case study of governance conflicts in Norwegian marine spatial planning	Documented conflicts between offshore aquaculture and offshore wind development in Norwegian waters, showing how competing blue economy uses generate governance failures and justice tensions. Analysed stakeholder dynamics and regulatory gaps.	Blue economy development generates internal sustainability conflicts requiring robust marine spatial planning. Provides direct empirical evidence of Blue–Green governance tensions in one of the RIE’s six case countries, supporting the structural gap analysis.
Mäkitie et al. [64]	Digital innovation’s contribution to sustainability transitions	Conceptual analysis of digital innovation roles in sustainability transitions across multiple sectors	Identified three roles of digital innovation in transitions: enabling (supporting incumbent systems), disrupting (challenging existing regimes), and reconfiguring (reshaping system architectures). Found that reconfiguring roles are underexplored.	Digital innovation shapes transition dynamics in multiple, context-dependent ways. Informs the RIE’s digital infrastructure pillar—particularly how digital monitoring platforms and data systems mediate regime coupling rather than merely supporting individual regimes.
Wainaina et al. [24]	Structural tensions limiting success of infrastructure upgrading: A multi-regime perspective	Empirical analysis of infrastructure upgrading challenges in Kenyan urban water systems	Identified structural tensions between incumbent water regimes and upgrading initiatives, showing how path dependencies and institutional misalignments block infrastructure modernisation. Applied multi-regime perspective to Global South context.	Infrastructure upgrading is constrained by multi-regime structural tensions beyond individual sector dynamics. Informs the RIE’s infrastructure integration pillar and extends the framework’s relevance to peripheral and Global South contexts.
Pires Manso et al. [48]	Renewable energies and blue economy: new trends in global research	Bibliometric analysis of co-publication patterns between renewable energy and blue economy research	Mapped the emerging intersection between renewable energy and blue economy scholarship, identifying offshore wind, marine energy, and aquaculture–energy integration as key growth areas. Found significant research gaps in integrated governance.	Renewable energy and blue economy research are converging but remain institutionally separate. Provides bibliometric evidence for the Blue–Green coupling potential identified in the RIE framework and confirms the structural research gap being addressed.
Lähde et al. [73]	Co-creation of socio-ecological systems knowledge to adopt an Ecosystem-based Approach and Land-Sea Interactions in maritime spatial planning	Empirical action-research study of participatory maritime spatial planning in Finland	Demonstrated how co-creation of socio-ecological knowledge improves land–sea interaction governance in maritime spatial planning. Found that participatory processes enhance plan legitimacy and ecosystem-based approach adoption.	Participatory and knowledge co-creation processes strengthen maritime spatial planning outcomes. Supports the RIE’s governance and justice pillar, particularly the recommendation for participatory marine spatial planning as a mechanism for equitable regime coupling.
Käsbohrer et al. [23]	Multi-system interactions and institutional work: Actor interactions at the interface of residential storage systems and electric vehicles in Germany	Empirical analysis of actor interactions at the interface of two emerging energy storage regimes in Germany	Analysed how actors engage in institutional work to create, maintain, and disrupt linkages between residential battery storage and electric vehicle regimes. Found that institutional work shapes whether multi-system interactions become coupling or remain fragmented.	Institutional work by actors is crucial for translating multi-system interactions into durable regime coupling. Informs the RIE’s governance pillar and the role of regulatory steering in deliberately orchestrating blue–green–circular integration.
Kovacic et al. [58]	The twin green and digital transition: High-level policy or science fiction?	Conceptual and policy-critical analysis of EU twin transition (green + digital) strategy	Critically examined the EU’s twin transition narrative, finding significant gaps between policy rhetoric and implementation capacity. Highlighted risks of digitalisation exacerbating rather than resolving sustainability tensions.	The green–digital twin transition faces serious implementation challenges. Informs the RIE’s digital infrastructure dimension—supporting a cautious and governance-sensitive approach to the role of digital platforms in mediating regime coupling.
Bakhuis et al. [14]	Frameworks for multi-system innovation analysis from a sociotechnical perspective: A systematic literature review	Systematic literature review of analytical frameworks for multi-system innovation and transitions	Mapped and compared 22 frameworks for multi-system innovation analysis, identifying their scope, theoretical foundations, and analytical strengths. Found significant diversity and limited integration across frameworks.	Multi-system innovation frameworks remain fragmented and require integration. Provides the broader literature context within which the RIE framework is positioned, and confirms the need for the integrative conceptual contribution the framework offers.
Van Meer et al. [1]	“Take your responsibility”: the politics of green sacrifice for just low-carbon transitions in rural Portugal	Empirical qualitative research (interviews, ethnography) in the Barroso region, Portugal	Documented local community resistance to lithium mining in Barroso, analysing it as a case of green sacrifice zone dynamics. Showed how national decarbonisation agendas can reproduce environmental justice injustices in peripheral rural areas.	Green transitions can create sacrifice zones in peripheral regions, reproducing rather than resolving spatial inequalities. Core empirical grounding for the RIE’s justice pillar and its analysis of Portugal’s governance challenges in the comparative case.
Riofrancos [3]	The security–sustainability nexus: Lithium onshoring in the Global North	Empirical and conceptual analysis of lithium supply chain politics in Global North contexts	Analysed the politics of lithium onshoring as Global North countries attempt to secure critical raw material supply chains for green transitions. Found that security imperatives frequently override sustainability and justice considerations.	Critical raw material security agendas risk undermining sustainability and justice commitments. Directly informs the RIE’s analysis of Portugal’s Barroso case and the broader tension between green transition material demands and territorial justice.
Gode et al. [20]	Addressing heterogeneity in the development of circular economy strategies in the offshore wind industry: A review	Systematic review of circular economy strategy development in the offshore wind sector globally	Identified significant heterogeneity in CE strategy adoption across offshore wind firms and countries. Found that circular strategies remain largely voluntary, fragmented, and insufficiently integrated into supply chain governance.	Circular economy integration in offshore wind is heterogeneous and insufficiently institutionalised. Provides direct empirical support for the RIE’s Blue–Circular coupling gap and the need for regulatory-driven integration of circularity requirements into offshore energy governance.
Avelino et al. [65]	Just sustainability transitions: politics, power, and prefiguration	Conceptual review and synthesis of justice frameworks in sustainability transitions scholarship	Proposed a justice-centred framework for sustainability transitions incorporating procedural, distributional, and recognitional justice dimensions. Argued that power relations and prefigurative politics are undertheorised in transition scholarship.	Justice dimensions must be central rather than peripheral to sustainability transitions analysis. Directly informs the RIE’s justice pillar, especially the treatment of governance and distributional outcomes in peripheral regions facing green sacrifice zone dynamics.
Magalhães et al. [52]	Blue circular economy—Reuse and valorization of bivalve shells: The case of Algarve, Portugal	Empirical case study of bivalve shell valorisation as a blue circular economy initiative in the Algarve region	Documented the technical and economic feasibility of valorising bivalve shells (from aquaculture waste) for construction materials, agricultural amendments, and water treatment. Demonstrated a concrete Blue–Circular economy linkage at local scale.	Blue–Circular economy integration is feasible at local scale through marine resource valorisation. Provides one of the few concrete empirical examples of Blue–Circular coupling in the RIE framework, grounding the otherwise aspirational triadic coupling analysis.
Pablo-Romero, et al. [51]	Implementing the Circular Economy in the European Union and Spain: Links to the Low-Carbon Transition	Policy analysis of CE implementation in Spain and the EU, with focus on links to decarbonisation	Found that Spain’s CE strategy is advancing but remains weakly integrated with energy transition policy. Identified institutional silos between CE governance and energy governance as a key barrier.	Circular economy and low-carbon transition governance remain institutionally separated in Spain. Provides direct evidence for the RIE’s Southern Europe structural gap analysis, confirming limited Green–Circular coupling in peripheral EU members.
Magnusson et al. [55]	Cumulative processes in multi-system transitions: expanding value chains and limits to growth for sustainable alternatives	Empirical and conceptual analysis of cumulative dynamics in multi-system transitions in Sweden	Showed how cumulative processes—expanding value chains, increasing returns, and resource constraints—shape the speed and direction of multi-system transitions. Found that growth limits for sustainable alternatives emerge from resource and institutional constraints.	Multi-system transitions are shaped by cumulative dynamics and resource limits. Informs the RIE’s cautious framing of triadic coupling as aspirational—highlighting that cumulative constraints may slow the convergence of blue, green, and circular regimes.
Di Vaio et al. [69]	The transition towards circular economy and waste within accounting and accountability models	Systematic review of accounting and accountability frameworks for circular economy transitions	Mapped how accounting and accountability models are evolving to incorporate CE principles, identifying gaps in reporting frameworks and the need for standardised metrics for circular performance.	Accounting and accountability frameworks must evolve to support CE transitions. Informs the RIE’s governance pillar regarding the role of standardised circular metrics and transparent reporting as enablers of cross-regime coordination.
Geels et al. [11]	Sustainability transitions in consumption-production systems	Conceptual synthesis of sustainability transitions theory applied to consumption-production systems	Extended the MLP to consumption–production systems, arguing that sustainable transitions require simultaneous change in both production and consumption regimes. Highlighted the role of governance and demand-side policies.	Sustainable transitions require systemic change across production and consumption. Provides an updated MLP perspective underpinning the RIE’s treatment of infrastructure not just as production enabler but as shaper of consumption patterns and material flows.
Baldassarre [7]	Circular economy for resource security in the European Union (EU): Case study, research framework, and future directions	Case study and framework development for CE contributions to EU resource security	Argued that CE strategies can significantly reduce EU dependency on critical raw material imports, providing a strategic security rationale for CE adoption beyond environmental motivations.	Circular economy contributes directly to EU strategic resource security. Strengthens the RIE’s argument for integrating CE into green and marine governance as a resource security imperative, not merely an environmental preference.
Elston et al. [44]	Charting the Course: Real-World Application of Sustainability and Innovation Principles in the Portuguese Blue Economy Firms	Empirical analysis of sustainability and innovation practices in Portuguese blue economy enterprises	Found that Portuguese blue economy firms are innovating but face significant governance and financing constraints. Identified a gap between sustainability ambitions and operational capabilities, particularly among SMEs.	Portuguese blue economy firms face structural barriers to sustainability integration. Provides empirical grounding for the RIE’s Portugal case analysis, particularly regarding the endogenous innovation capacity constrained by governance and financing gaps.
Elston et al. [45]	Tides of change for a sustainable blue economy: a systematic literature review of innovation in maritime activities	Systematic literature review of innovation in maritime blue economy activities	Identified emerging innovation patterns in maritime sectors including offshore energy, aquaculture, and marine biotechnology; found significant governance gaps and financing constraints limiting blue economy sustainability transitions.	Blue economy innovation requires integrated governance and financing frameworks. Provides complementary empirical grounding for the RIE’s blue regime analysis. Domain: Blue.
Penca et al. [70]	Rethinking the Blue Economy: Integrating social science for sustainability and justice	Conceptual review arguing for social science integration into blue economy research and governance	Critiqued the dominant techno-economic framing of the blue economy for neglecting social dimensions, power relations, and justice implications. Proposed a social science-integrated framework for blue economy sustainability.	The blue economy requires social science integration to address justice and governance challenges. Reinforces the RIE’s justice pillar and its call for participatory governance, community co-management, and recognitional justice in marine regime development.
Almeida et al. [71]	Blue economy concepts are lagging behind in ocean literacy	Empirical analysis of ocean literacy and blue economy awareness across stakeholder groups	Found significant gaps between blue economy policy ambitions and public/stakeholder understanding, limiting governance effectiveness and participatory capacity.	Ocean literacy gaps constrain effective blue economy governance and public participation. Supports the RIE’s argument that participatory governance requires capacity-building investment, particularly in peripheral regions with lower institutional readiness.
Bordin et al. [59]	Energy storage in the energy transition and blue economy: challenges, innovations, future perspectives, and educational pathways	Review of energy storage technologies and their intersection with blue economy applications	Identified energy storage as a critical enabling technology for both green transitions and blue economy development. Found significant innovation gaps in marine energy storage and offshore grid integration.	Energy storage is a cross-cutting enabler of blue–green coupling. Provides technological grounding for the RIE’s infrastructure integration dimension, particularly regarding the role of storage systems in linking offshore wind to marine and grid regimes.
Georgescu et al. [72]	Approaches and perspectives on the transition to the circular economy in the European Union	Comparative policy analysis of CE transition approaches across EU member states	Identified convergence in CE ambitions but divergence in implementation capacity across EU member states. Highlighted the role of EU cohesion policy in supporting lagging regions.	EU CE transition is advancing unevenly, with cohesion policy playing a compensatory role. Informs the RIE’s policy implications, particularly the recommendation for targeted EU cohesion and Just Transition Mechanism support for Southern peripheral regions.
Ruiz et al. [60]	Sustainability transitions in infrastructure: understanding causal dynamics in the Dutch asphalt paving sector	Empirical process-tracing study of sustainability transition in Dutch road infrastructure	Traced causal dynamics of sustainability transitions in the Dutch asphalt sector, identifying key actor constellations, regulatory triggers, and infrastructure investment patterns. Found that incumbent actor strategies significantly shape transition pace.	Infrastructure sustainability transitions are causally complex and actor-dependent. Provides empirical grounding for the RIE’s infrastructure integration pillar, particularly regarding how physical infrastructure investments lock in or unlock regime coupling possibilities.
Sadegh Koohestani et al. [61]	Adopting a socio-technical perspective on the challenges and barriers in transitioning to Blue-Green Infrastructure	Conceptual review applying socio-technical transition theory to blue–green urban infrastructure	Identified key socio-technical barriers to blue–green infrastructure transitions in urban settings, including institutional fragmentation, incumbent lock-in, and limited community engagement. Proposed a multi-actor governance framework.	Blue–green infrastructure transitions face distinctive socio-technical barriers. Complements the RIE framework’s analysis of Blue–Green coupling challenges, extending the governance and justice dimensions to urban infrastructure contexts.
Rodrigues et al. [50]	Measuring Circularity and Sustainability in Southern Europe: A Comparative Empirical Analysis of Portugal, Spain, Italy, and Greece	Empirical comparative analysis of circularity and sustainability indicators across four Southern European countries	Found significant gaps between Northern and Southern EU member states in circular economy performance, with Portugal, Spain, Italy, and Greece exhibiting lower circularity scores and weaker institutional frameworks.	Southern European countries lag in circular economy performance. Provides quantitative grounding for the RIE’s North–South divide finding, confirming that peripheral regions face structural circularity deficits that compound regime coupling challenges.
Wang et al. [62]	Ecosystem Services in Urban Blue-Green Infrastructure: A Bibliometric Review	Bibliometric review of ecosystem services research in urban blue–green infrastructure	Mapped research trends in urban blue–green infrastructure ecosystem services, identifying climate regulation, biodiversity, and water management as dominant themes. Found growing but fragmented knowledge base.	Urban blue–green infrastructure ecosystem services research is growing but requires integration with governance frameworks. Provides context for the RIE’s Blue–Green coupling analysis in urban and peri-urban settings, extending beyond exclusively offshore and marine contexts.

Appendix B. Condensed Coding Framework

This appendix presents the coding framework used in the abductive thematic analysis (Section 3). The framework was developed iteratively in MAXQDA, combining deductive codes derived from the multi-level perspective and multi-system dynamics literature with inductive codes that emerged organically from close reading of the 58 selected publications. The analysis was structured around four central thematic axes. Table A2 below presents the full codebook excerpt with individual codes, descriptions, types, and illustrative examples. Table A3 provides a condensed summary of the four axes for rapid orientation.

Table A2. Codebook excerpt: individual codes by thematic axis.

Code	Description	Type	Illustrative Example
1. Structural Gaps and Misalignments
Gap_Material_Supply	Mismatch between green infrastructure ambitions and critical raw material (CRM) availability	Deductive	“Offshore wind expansion creates massive lithium and copper demand with no secure supply chain”
Gap_Blue_Green_Integration	Weak coordination between marine spatial planning and energy policy	Deductive	“Fragmented marine spatial planning in Southern European countries”
Gap_Circularity	Limited application of circular economy principles in blue and green projects, including end-of-life blade management and rare earth recovery	Inductive	“Wind turbine blade recycling rates remain very low; no marine-specific circular strategies identified”
Gap_Justice	Socio-spatial inequalities and risk of peripheral regions bearing disproportionate transition costs	Deductive	“Barroso lithium project and organised local resistance; green sacrifice zone dynamics”
2. Regime Coupling Mechanisms
Coupling_Blue_Green	Integration between marine and energy regimes through shared infrastructure or governance	Deductive	“Danish Energy Islands project linking offshore wind with hydrogen production and marine spatial planning”
Coupling_Green_Circular	Integration between energy and circular economy through shared material flows or industrial symbiosis	Deductive	“Rotterdam-Moerdijk industrial symbiosis cluster integrating end-of-life wind turbine components”
Coupling_Blue_Circular	Integration between marine and circular economy through resource valorisation or shared offshore infrastructure	Inductive	“MERMAID project (The Netherlands) and TROPOS project (Denmark): aquaculture integrated in offshore wind parks; Algarve bivalve shell valorisation [30]”
Coupling_Triadic	Simultaneous blue–green–circular integration; remains primarily a conceptual construct—no unambiguous empirical case of full three-way integration identified	Inductive	“Emerging multifunctional offshore platforms represent aspirational triadic coupling trajectories”
System_Entanglers	Actors or technologies that actively connect and mediate interactions between multiple regimes [43]	Deductive	“Power-to-X technologies linking offshore wind energy to hydrogen and chemical sectors”
3. Infrastructural Integration and Data Systems
Infra_Physical	Shared physical infrastructure mediating cross-regime coordination	Deductive	“North Sea offshore energy hubs; Energy Islands as multifunction nodes”
Infra_Digital	Digital platforms, environmental monitoring systems, and data governance enabling cross-regime coordination	Inductive	“Environmental digital twins in marine-energy integration; MAXQDA-based cross-document pattern detection”
Path_Dependency	Lock-in effects and constraints on future regime configurations created by infrastructure investment decisions	Deductive	“Long-term commitments to offshore wind infrastructure foreclosing alternative marine uses”
4. Governance, Regulatory Steering, and Justice
Regulatory_Steering	Role of EU and national regulatory frameworks in actively coupling regimes (European Green Deal, CRMA, Blue Economy Strategy)	Deductive	“Top-down coordination mechanisms as constitutive drivers of regime coupling”
Justice_Distributional	Uneven distribution of transition costs and benefits across regions and social groups	Deductive	“Peripheral regions bearing disproportionate burdens of large-scale green infrastructure”
Justice_Procedural	Participation, consent, and decision-making processes in transition governance	Inductive	“Inadequate community participation in the Barroso lithium project environmental assessment”
Participatory_Governance	Concrete mechanisms for inclusive governance: citizens’ assemblies, co-management frameworks, local content requirements, benefit-sharing	Inductive	“Recommendations for fishing community co-management in offshore wind zones; participatory marine spatial planning”

Total codes: 42 first-order codes grouped into 14 second-order themes and 4 main thematic axes. Coding was conducted by the lead author with multiple rounds of internal review. Given the single-author nature of this study, particular attention was paid to reflexivity and transparency. All coding decisions were documented in detail and subjected to repeated critical review by the author. Analytical trustworthiness was strengthened through a detailed audit trail of coding decisions, systematic reflexive memos, and triangulation with quantitative data from official sources (Eurostat, IRENA, WindEurope). The full codebook, including code frequencies, memo notes, and representative quotations, is available upon request from the corresponding author.

Table A3. Condensed overview of thematic axes, deductive codes, and illustrative inductive codes.

Appendix C. Comparative Matrix of Regime Coupling Across Countries

This appendix presents the comparative assessment matrix underpinning Figure 1 in the main text. Regime coupling intensity was evaluated qualitatively (Low/Medium/High) across three operational dimensions: institutional coordination, infrastructural integration, and policy and regulatory alignment. Assessments are based on triangulation of policy documents, the secondary literature, and quantitative indicators from official sources (Eurostat, IRENA, WindEurope, national agencies). The matrix is explicitly heuristic and interpretive rather than based on a formal scoring system; it is intended to support the qualitative comparative analysis in Section 4 and the conceptual discussion in Section 5.

Table A4. Comparative assessment of regime coupling by country (early 2026).

Country	Institutional Coordination	Infrastructural Integration	Policy and Regulatory Alignment	Overall Pairwise Coupling	Triadic Coupling (B-G-C)	Main Observations
Denmark	High	High	High	High	Medium (emerging)	Most advanced blue–green integration; Energy Islands flagship; emerging blade circularity (Vestas)
The Netherlands	High	High	High	High	Medium	Strong green–circular focus (Rotterdam-Moerdijk); Blue–Circular initiative (MERMAID project)
Germany	Medium-High	Medium-High	High	High	Low-Medium	Strong green agenda; growing circular efforts (Siemens Gamesa RecyclableBlade); WindEurope circularity reporting
Norway	Medium-High	Medium	Medium-High	Medium-High	Low-Medium	Non-EU benchmark; hydropower-dominated pathway (>90%); strong blue–green potential but distinct fiscal and governance context (Sovereign Wealth Fund)
Spain	Medium	Low-Medium	Medium	Medium	Low	Expanding renewables capacity; emerging marine integration and circular initiatives; limited offshore coordination
Portugal	Low-Medium	Low	Medium	Low-Medium	Low	World-leading floating offshore wind pilot (WindFloat Atlantic); significant CRM tensions (Barroso); high potential constrained by justice challenges and governance gaps

Evaluation criteria: High = Multiple named initiatives, strong cross-regime policy coordination, significant shared infrastructure investments. Medium = Some cross-regime initiatives and partial policy alignment, with limited infrastructure integration. Low = Limited cross-regime coordination and few or no concrete joint projects. Note: Triadic coupling (blue–green–circular) remains partial and emergent across all six countries. No country currently demonstrates full three-way integration. The matrix reflects a clear North–South divide in coupling intensity while acknowledging growing momentum in Southern European countries, particularly through EU cohesion policy and Just Transition Mechanisms. Norway is included as a non-EU benchmark; its hydropower-dominated energy pathway, substantial fiscal capacity (Sovereign Wealth Fund), and distinct governance dynamics mean it is not directly comparable to the five EU member states and should be interpreted accordingly.

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Figure 1. Pairwise and triadic coupling patterns across six countries.

Figure 2. The Resource Infrastructure Economy (RIE) framework: Regime coupling through infrastructural integration.

Table 1. Renewable energy deployment and critical raw materials context (early 2026).

Table 2. Pairwise versus triadic regime coupling in the RIE framework.

Table 3. Comparison of the RIE framework with related multi-system concepts.

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Thematic Axis	Deductive Codes (Pre-Defined)	Illustrative Inductive Codes (Emergent)
1. Structural Gaps and Misalignments	Regime fragmentation; policy silos; material supply gaps; governance mismatches	CRM–wind energy nexus conflicts; circular–marine disconnection; peripheral region disadvantage; end-of-life blade management gap
2. Pairwise and Triadic Coupling Mechanisms	Inter-system linkages; complementarity formation; coupling pathways; system entanglers	Energy Islands as blue–green coupling node; Rotterdam-Moerdijk as green–circular bridge; MERMAID/TROPOS as blue–circular cases; power-to-X as blue–green connector
3. Infrastructure and Data Systems	Physical infrastructure interdependencies; digital monitoring; data governance; path dependencies	Multifunctional offshore platforms; environmental data as coupling enabler; digital twin applications in marine-energy integration
4. Governance, Regulatory Steering, and Justice	Regulatory frameworks (Green Deal, CRMA, Blue Strategy); policy alignment; distributional justice; procedural justice	Green sacrifice zones; community resistance (Barroso); Just Transition Mechanisms as coupling enablers; participatory marine spatial planning; co-management frameworks

Country	Total Wind (GW)	Offshore Wind (GW)	Renewables in Electricity (%)	CRM Context	Dominant Pattern
Germany	72.8	9.2	~55	High import dependency	Green frontrunner
The Netherlands	11.7	4.7	>50	Advanced circular strategies	Circular leadership
Denmark	7.6	2.7	88–92	Strong offshore coordination	Blue–green integration
Spain	31.8	Negligible	~60	Onshore focus	Limited marine integration
Portugal	5.96	0.025 (installed)	82.9	Major CRM tensions (Barroso)	High potential, justice challenges
Norway	Hydro dominant	~2.7 (planned)	>90	Significant CRM deposits	Non-EU benchmark

Type of Coupling	Description	Examples Observed	Level of Complexity
Pairwise	Integration between two regimes	Blue–Green (Danish Energy Islands); Green–Circular (Dutch industrial symbiosis)	Medium
Triadic	Full integration of all three regimes (blue, green, and circular) simultaneously. At present, triadic coupling remains primarily a conceptual construct; no unambiguous empirical case of full three-way integration was identified in this review.	Still rare and fragile. Blue–Circular pairings include: Vestas zero-waste blade commitment [53]; Siemens Gamesa RecyclableBlade programme (Germany); WindEurope-reported circularity initiatives in Rotterdam (The Netherlands); integrated aquaculture in offshore wind parks (MERMAID project, The Netherlands; TROPOS project, Denmark); and bivalve shell valorisation in the Algarve (Portugal—Magalhães et al., 2024 [52]). These represent emerging but not yet systemic examples.	High

Dimension	Multi-Level Perspective (MLP)	Multi-System Dynamics	Nexus Approaches	RIE Framework
Primary focus	Single regime transitions; niche-regime interactions	Co-evolution across multiple regimes	Resource interdependencies (energy–water–food)	Coupling of blue, green, circular regimes through infrastructure
Role of infrastructure	Background condition	Interface/linkage site	Resource flow mediator	Central coordinating mechanism
Marine/blue economy	Not addressed	Emerging (limited)	Partial (coastal–water nexus)	Fully integrated as regime
Regulatory steering	Landscape pressure	Enabling factor	Governance challenge	Constitutive driver of coupling
Justice dimension	Limited	Emerging	Recognised but variable	Core analytical pillar