Understanding the interactions between biowaste valorisation and the Sustainable Development Goals: insights from an early transition stage

ABSTRACT

The valorisation of urban biowaste can contribute to a circular and sustainable resource management. However, biowaste valorisation is not inherently sustainable. This study employs the Sustainable Development Goals (SDGs) to investigate the sustainability implications of biowaste valorisation. A narrative literature review provided an overview of the current scientific knowledge on interactions between biowaste valorisation and selected SDG targets. Then stakeholder interviews yielded insights into such interactions in a national context. Our findings show the potential for 19 synergies and 11 trade-offs between biowaste valorisation and 20 selected SDG targets that are addressed in detail. Although the synergies outnumber the trade-offs, different context-dependencies influence the nature and strength of the interactions. We highlight three types of context-dependencies relating to governance. This study informs the scientific community and decision-makers on planning for sustainable biowaste valorisation that addresses context-dependencies. The insights can guide countries and cities at early transition stages towards biowaste valorisation.

Keypoint Highlights

• Evidence to support the scientific community and decision-makers towards sustainable biowaste valorisation (BV)

• Analysis of BV context-dependencies relating to governance

• Horizontal and vertical policy coherence are prerequisites for sustainable BVInterdisciplinary and transdisciplinary collaboration essential towards sustainable BV

• BV and bioeconomy strategies must address context-dependencies

KEYWORDS:

• Biobased resource recovery and biorefinery
• circular bioeconomy
• organic fraction of municipal solid waste
• SDG interactions
• urban biowaste valorisation

1. Introduction

Cities worldwide have made significant efforts to achieve climate neutrality, aligning with the sustainability agendas at the local, national and global levels (Huovila et al. 2022). However, meeting the resource demands of the expanding urban population, including food, water and energy, remains a key challenge. To achieve the decarbonisation targets, urban resource needs must be met through sustainable production and consumption. In this context, the bioeconomy has gained attention for its potential contribution to sustainable resource management. While there is no universally accepted definition of the bioeconomy, the term can be understood as referring to an economic system that produces, utilises and conserves biological resources (International Advisory Council on Global Bioeconomy IACGB 2020). D’Amato et al. (2017) addressed the bioeconomy concept together with the concepts of the green and circular economy and highlighted their relevance as key sustainability avenues.

Developing sustainable bioeconomies requires the integration of biomass residues and waste as resources. Investigating their utilisation and applying circularity principles are essential to maximise the bioeconomies’ contribution to sustainable development (Stegmann et al. 2020). This study focuses on biomass residues from the municipal solid waste of cities (MSW), that is the organic fraction of MSW or ‘biowaste’. Biowaste is defined as: ‘biodegradable garden and park waste, food and kitchen waste from households, restaurants, caterers and retail premises, and comparable waste from food processing plants’ (European Commission 2018a). It comprises the largest MSW fraction accounting for approximately 44% in urban areas (Kaza et al. 2018). Biowaste management has gained scientific attention within the domains of waste management, circular economy (CE), and bioeconomy (Ranjbari et al. 2021).

The waste hierarchy is a widely acknowledged framework that prioritises waste management options from the most to the least environmentally favourable option (European Commission 2018a). In the biowaste context, the top priority in the waste hierarchy is to reduce and prevent the wastage of urban bioresources altogether. If that option is unfeasible, the bioresources should be redistributed for human or animal use. The remaining priorities focus on managing the unavoidable biowaste after consumption. Biowaste valorisation is the most preferable management option for unavoidable biowaste (Thiriet et al. 2020) and the focus of this paper. The term ‘biowaste valorization’ (BV) refers to any process that extracts value from biowaste to utilise it in the form of value-added products, ranging from compost and biogas to cosmetics and pharmaceuticals. Sorting biowaste at source is a prerequisite for efficient BV practices (Bernstad 2014). Finally, when BV is not feasible, the least preferred options in the waste hierarchy, listed in order of preference, are incineration with or without energy recovery, or disposal (Papargyropoulou et al. 2014).

Most cities still collect biowaste mixed with other types of MSW as ‘conventional waste’, and primarily disposing of it in landfills (37% of global MSW) or open dumps (33% of global MSW) (Kaza et al. 2018). As a result, the inherent resource value of biowaste goes unutilised, leading to wastage. It is essential to intensify societal efforts to advance biowaste management systems higher up the waste hierarchy (Slorach et al. 2019). In this context, there is a largely untapped potential to close resource loops through the valorisation of unavoidable biowaste (Kuznetsova et al. 2019). In terms of technological and commercial readiness, several types of BV technologies, such as composting and anaerobic digestion (AD), have long been available and applied to treat biowaste in some cities (Falconer et al. 2020). Other advanced technologies rapidly emerge including valorisation of biowaste with other types of biomass residues in biorefineries (Dahiya et al. 2018).

The inherent complexity of different bioeconomy pathways (Stark et al. 2022) as well as the limited data availability make it difficult to assess the full potential of the bioeconomy accurately (Ronzon et al. 2022). However, several studies have estimated the value added in a bioeconomy context. For example, Hanssen et al. (2020) estimated that biomass residues have the potential to meet 7–50% of the global bioenergy demand by 2050 which corresponds to 55 EJ/year by 2050. In the European Union (EU) context, the EU Biorefinery Outlook to 2030 shows that the supply of bio-based chemicals and materials can increase between 1–3 million tonnes compared to the 4.3 million tonnes supplied in 2019 (European Commission, Directorate-General for Research and Innovation, Platt R et al. 2021).

However, the transitions to BV and the bioeconomy are not sustainable by default. Heimann (2019) conducted a literature-based scenario analysis, revealing that a bioeconomy scenario that lacks supportive regulations, policies, and investments for sustainability can generate positive outcomes but also challenges to achieving various Sustainable Development Goals (SDGs) of the United Nations’ 2030 Agenda (United Nations 2015). For example, an unregulated bioeconomy scenario related to land use intensification and subsequent land degradation, posing risks for SDG 15 ‘Life on Land’. Conversely, a ‘sustainable bioeconomy scenario’ that included sustainability measures and regulations showed a significant contribution to SDG progress (Heimann 2019). Starke et al. (2022) also emphasised that the bioeconomy transition can entail significant controversies, including conflicts that arise from incompatible perspectives among different stakeholders. Therefore, the sustainability implications of both BV and the wider bioeconomy are highly dependent on the relevant visions and transition pathways (Starke et al. 2022). Comprehensive assessments that holistically evaluate their sustainability implications are thus essential (Ramanauske et al. 2023). Further research and enablement are needed to upscale BV from local and national niche applications to mainstream global implementation that contributes to a sustainable bioeconomy transition (Markard et al. 2012). Key remaining challenges include the insufficient regulations and policies, the high costs associated with bioeconomy practices and small-sized bio-based markets (Stegmann et al. 2020).

Several studies have examined BV’s sustainability implications, especially through life cycle assessments (LCA). For example, Vea et al. (2018) reviewed 25 LCA-based decision support tools for waste management and evaluated their effectiveness in the facilitation of circular biowaste management systems. Among the reviewed tools, they identified that only two were suitable for a comprehensive assessment that also includes measuring the impact of biowaste-derived fertilisers and conditioners to soil. Zeller et al. (2020) studied the environmental performance of different BV options to manage the biowaste in Brussels, Belgium. They found that localised systems can have a better environmental performance than more centralised systems at larger transport distances from the city. Some studies have also applied exergy analysis to assess environmental performance (e.g. Vandermeersch et al. 2014; Soltanian et al. 2022).

Life cycle sustainability assessment (LCSA) extends life cycle approaches to address environmental as well as social aspects. However, LCSA in the BV context still addresses a fraction of the wide range of sustainability implications at a systems level (Ddiba et al. 2022). Other studies have focused on BV’s techno-economic performance and mainly address AD as an enabling technology (Braguglia et al. 2018). In the context of AD, Lindfors et al. (2019) suggested a multi-criteria decision analysis method to support the sustainability assessment of relevant projects considering aspects such as the potential, performance and feasibility. Table 1 provides an overview of the studies described above. The available research methods, frameworks and tools still face several limitations such as the level of detail, modelling flexibility and the parameters addressed. Moreover, recent studies have investigated the impact of the COVID-19 pandemic in the context of waste management (Singh et al. 2022), the circular economy (Rejeb et al. 2023) and the bioeconomy (Galanakis et al. 2022). Nevertheless, an analysis of the full range of BV’s sustainability implications and their context-dependencies at a systems level is missing from the scientific literature, thus constituting a significant research gap.

Table 1. Examples of studies addressing the sustainability implications of biowaste valorisation.

Reference	Research approach and relevant key findings	Technologies addressed
(Vea et al. 2018)	Review of LCA-based decision support tools for waste management Several limitations found in the reviewed tools	Anaerobic Digestion, Composting
(Zeller et al. 2020)	LCA Case study: environmental performance of the biowaste management system of Brussels, Belgium under different scenarios Under certain conditions, localised scenarios show environmental benefits	Incineration, Anaerobic Digestion, Composting
(Soltanian et al. 2022)	Review of exergetic indicators for the sustainability assessment of MSW systems Highlights the need to apply exergetic indicators in the development of integrated waste biorefinery systems	Incineration, Gasification, Anaerobic Digestion
(Ddiba et al. 2022)	A framework to assess the societal impacts of increased circularity in terms of resource recovery from organic waste streams at city scale Case study: Naivasha, Kenya	Anaerobic Digestion and Combined Heat and Power, Fly larvae composting
(Braguglia et al. 2018)	Literature review of anaerobic digestion for treatment of food waste Focus on the techno-economic performance and how to improve it	Anaerobic Digestion
(Lindfors et al. 2019)	Multi-criteria decision analysis method to assess the potential, performance and feasibility of AD projects Case studies: Chisinau, Moldova; Johannesburg, South Africa	Anaerobic Digestion

To address this research gap, this study investigates BV’s sustainability implications based on SDG interaction analysis. We apply a mixed-methods approach. Firstly, we synthesise current scientific knowledge through a literature-based analysis. Secondly, we investigate insights on BV-SDG interactions at a national context: we elicit stakeholder views through semi-structured interviews in Greece as a national case application. The Greek case presents scientific interest as an example of a country early in the transition towards sustainable BV with significant challenges and opportunities (Section 2.1). Finally, we synthesise and discuss the findings of the literature review and the interviews (Section 2). This approach can contribute to sustainable governance of BV and the bioeconomy.

The following research questions guide the analysis:

• What are the potential interactions between biowaste valorization (BV) and selected targets of the Sustainable Development Goals (SDGs) of the United Nations’ 2030 Agenda?

• How do the BV-SDG interactions identified through the scientific literature differ from the interactions identified by relevant stakeholders in the Greek context?

Following this section, which introduces the study and its objective, Section 2 presents and motivates the methods used in the study and the case of Greece. Section 3 provides the results and discussion of BV-SDG interactions of the narrative literature review, stakeholder interviews and the synthesis of the two analyses. Section 4 presents the study’s limitations and suggestions for further research. Conclusions are drawn in Section 5.

2. Methods

To identify BV-SDG interactions, we follow a mixed-methods research approach as shown in Figure 1. We apply two methods of SDG interaction analysis (Di Lucia et al. 2021): evidence synthesis based on a narrative literature review, and stakeholder elicitation through semi-structured interviews. The narrative literature review (LR) tracks evidence on potential interactions (synergies and trade-offs) between biowaste valorisation and 53 selected SDG targets in the global context (Section 2.3). The semi-structured interviews (SI) entail a stakeholder evaluation of interactions with 20 of the 53 SDG targets, with a focus on Greece (Section 2.4). Finally, the literature review and interview findings are synthesised as described in Section 2.5.

Figure 1. Overview of the research design of the study.

The Greek case presents scientific interest as an example of a country early in the transition towards sustainable BV with significant challenges and opportunities (Section 2.1). Since the BV transition is at an early stage both globally and in Greece, we follow an ex-ante approach to identify BV-SDG interactions (Ronzon and Sanjuán 2020). Section 2.2 motivates the SDG targets selected for the analysis.

SDG interaction studies (Bennich et al. 2020) or SDG interaction research (Nerland et al. 2022) analyse the potential interactions of the SDGs with entities that are internal or external to the Agenda through various methods. Internal interactions can occur between or across SDG goals, targets or indicators (e.g. target-to-target interactions), while external interactions refer to entities that impact sustainable development, but are not explicitly addressed in the Agenda (Bennich et al. 2020). This study approaches BV as an entity external to the 2030Agenda.

A growing number of SDG interaction studies have addressed the bioeconomy transition and its potential sustainability implications. For example, Zeug et al. (2019) conducted stakeholder workshops to identify SDG targets that are relevant in the development of a bioeconomy monitoring framework in the German context. Ronzon and Sanjuán (2020) applied correlation analysis to investigate interactions between SDG targets in the context of the EU bioeconomy strategy of the European Union (EU). They found that several existing EU policy instruments address some trade-off domains, but there is a need to harness policy efficiency and coherence further. Previous research has also highlighted that the nature and strength of SDG interactions can vary due to context-dependencies such as time, geography, governance, technology and directionality (how one entity affects the other and vice versa) (McCollum et al. 2018). Through a literature review, Calicioglu and Bogdanski (2021) identified SDG indicators that are relevant in monitoring and evaluating a bioeconomy’s sustainability implications. They noted that the links between BV and the bioeconomy can vary between different countries depending on the design of their national bioeconomy strategy.

However, no study has applied methods of SDG interactions analysis to address BV’s sustainability implications. This is the first study to investigate the potential interactions between BV and the SDGs. The three sustainability pillars (environmental, economic, and social) are embedded in the design of the SDGs (Purvis et al. 2019). Different SDG targets address different aspects of these three pillars. The SDGs can thus guide a holistic assessment of BV’s sustainability implications and their context-dependencies.

To score the BV-SDG interactions, we used the seven-point Likert scale developed by Nilsson et al. (2016) and as visualised by Fuso Nerini et al. (2019). Figure 2 shows the scales used in the LR and the SI. The scale ranges from −3 to +3 to mark negative (−3, −2, −1), neutral (0) or positive (+1, +2, +3) types of SDG interactions. For the SI, we simplified the wording to make it more comprehensible to stakeholders who were not familiar with this Likert scale: e.g. +3 stated as ‘Indivisible interaction’ (Nilsson et al. 2016) was rephrased as ‘strongly positive interaction’. ‘Synergies’ (+1, +2, +3) are perceived as interactions where progress towards BV implementation favours progress in achieving a particular SDG target and vice versa, while ‘trade-offs’ (−3, −2, −1) are perceived as interactions where progress towards BV implementation hinders progress in achieving a particular SDG target and vice versa (Pradhan et al. 2017). In both the LR and the SI, one score was provided for synergies and/or one score for trade-offs identified between BV and each SDG target. The motivation behind the scores was also noted. A range in the score reflects the context-dependencies of the interactions, including their directionality.

Figure 2. The scales used to identify BV-SDG interactions in the literature review and the stakeholder interviews.

2.1. The biowaste valorization transition in Greece

As an EU member state, Greece has set ambitious sustainability goals for its biowaste management. At the EU level, the Waste Framework Directive sets that ‘bio-waste is either separated and recycled at source, or is collected separately and is not mixed with other types of waste’ in all Member States by end of 2023 (European Commission 2018a). At the national level, Greece set the target for end of 2022, one year earlier (Hellenic Republic 2021). Moreover, the National Waste Management Plan 2020–2030 set targets towards sustainable waste management in line with the EU policy. Key targets of the Plan for 2030 include (Hellenic Ministry of Environment and Energy 2020):

1. achieve 60% recycling of MSW, by weight

2. reduce the share of MSW sent to landfills to below 10%

3. achieve at least 25% energy production/recovery from waste.

However, achieving these targets presents challenges as Greece currently lags behind in terms of its waste hierarchy performance and ranks lower compared to other EU member states. According to the National Waste Management Plan, Greece’s biowaste generation was 2.4 million tonnes in 2018, and comprised approximately 44% of the total amount of MSW. While separate biowaste collection is a key prerequisite towards sustainable biowaste management, only 5.7% of the generated biowaste was collected separately. Greece has two types of facilities for the treatment of separately collected biowaste: biowaste treatment plants and plants treating residual waste (including biowaste). As of 2020, six such facilities are operational, ten are under procurement, and several more are planned under the National Waste Management Plan (Hellenic Ministry of Environment and Energy 2020). Greece’s status presents significant challenges but also opportunities for sustainable BV. An assessment of the potential BV-SDG interactions can be valuable towards mainstreaming sustainable BV practices. Moreover, the insights provided in this study can inform other cities at an early stage towards BV transition pathways that address sustainability implications and their context-dependencies.

2.2. Selection of SDG targets

This study does not address all 169 SDG targets, but a selection of targets that are particularly relevant in the bioeconomy context. It suggests a methodological approach that provides valuable insights on the interactions between BV and the selected targets. This methodological approach can be applied to address the other targets that are not covered in the scope of this paper. The target selection process is illustrated in Figure 3. As a starting point, it is built on the work of Ronzon and Sanjuán (2020), who matched the actions of the EU bioeconomy strategy (European Commission 2018b) with relevant SDG targets. They identified 53 bioeconomy-related SDG targets distributed across 12 SDGs. Furthermore, they noted that their methodological approach could be applicable to other study scopes, such as different bioeconomy concepts implemented in various countries or regions.

Figure 3. The selection of SDG targets addressed in this study.

Interactions between BV and these 53 SDG targets were investigated through the LR (Figure 5). The selection was then narrowed down to 20 SDG targets for the stakeholders’ evaluation. The 20 SDG targets were selected based on two criteria. Firstly, their relevance in the BV context based on the LR: SDG targets that exhibited high interaction scores and/or that presented controversies in the nature of interactions were prioritised. Secondly, the relevance of the SDG targets to the Greek context was considered. In this sense, SDG targets that primarily address progress in developing countries were beyond the study scope.

2.3. Narrative literature review

We conducted a narrative literature review to synthesise the current scientific evidence on BV-SDG interactions in the global context. The LR was based on two questions: ‘how can upscaling BV affect progress towards SDG target X?’ and reversely ‘how can progress towards SDG target X affect upscaling BV?’. Our LR approach built on the work of Schroeder et al. (2019) and Fuso Nerini et al. (2019). We selected records based on two eligibility criteria. The records should: 1) explicitly address interactions with the SDGs and not simply mention the SDGs, and 2) be relevant to biowaste valorisation. The literature review was conducted using the Scopus database with a time range from 2015 (establishment year of the 2030 Agenda) to 2022. The literature search targeted scientific articles written in English and published in peer-reviewed journals, and hence did not include book chapters, conference papers or grey literature. We complemented our literature search with searches using keywords specific to the SDG targets and a snowballing approach. Moreover, we considered a single record of published evidence as sufficient for the interactions with each target. We investigated all articles based on the criteria described above, which addressed a variety of BV technological processes such as anaerobic digestion, pyrolysis and composting etc., and products such as biogas, compost among many others. For further information, see S.1 in the supplementary material.

2.4. Stakeholder elicitation through semi-structured interviews

To address BV-SDG interactions in Greece, we elicited stakeholder views through semi-structured interviews (Bryman 2012). Previous SDG interaction studies have mainly used workshop methods to conduct stakeholder elicitation e.g. investigating cross-scale SDG interactions (Hernández-Orozco et al. 2021), and developing bioeconomy monitoring frameworks (Zeug et al. 2019). We chose an interview format instead in order to collect stakeholder views on BV-SDG interactions individually and without the influence of other parties, which can occur in a focus group or workshop format. Moreover, compared to a survey format, semi-structured interviews provide further space for participants to motivate their scoring of interactions and for the interviewer to ask follow-up questions, and they do not pigeonhole participants to pre-determined answers (Bryman 2012).

We identified stakeholders from biowaste-related value-chains in Greece using purposive and snowball sampling (Bryman 2012). We targeted stakeholders from four categories: academia, industry, non-governmental organisations, and public organisations. We conducted 18 interviews which are representative of a broad range of skills and knowledge relevant to BV. We interviewed one individual per organisation but we note that the views of a stakeholder do not necessarily represent their organisation’s views.

The average interview duration was 70 minutes. The SI were conducted remotely using video conferencing tools during June-November 2022. The interview guide addressed the following aspects: a) the background of the interviewee and their organisation, b) their experience with BV, c) their experience with the SDGs, and d) the scoring and motivation of BV-SDG interactions for the 20 selected SDG targets. The guiding questions were: ‘how can upscaling BV in Greece affect the national progress towards SDG target X?’ and reversely: ‘how can the national progress towards SDG target X affect upscaling BV in Greece?’. We did not predetermine the BV technological processes and products that should be addressed. Instead, we asked the interviewees to motivate their scores either referring to BV overall or with examples of specific technologies and products that they chose based on their experience. More information on the interviewees’ motivations is available in S3.1 of the supplementary material. At the end of each interview, the interviewees were asked whether they wanted to address relevant issues other than those connected to the 20 selected targets (see ‘Interview guide’ in the supplementary material). The interviews were conducted and transcribed in Greek and then translated into English for analysis. The data were transcribed and analysed using qualitative content analysis (D’Amato et al. 2022).

Figure 4 classifies the interviewees based on their backgrounds and experiences within the broad categories of waste management, energy, nutrients, and bioeconomy. The bioeconomy category includes interviewees who focus on types of biomass residues other than biowaste or have an explicit bioeconomy focus in their work. Several interviewees are found in the intersection of the categories (see supplementary material S2.1 and S2.2 for further information on the interviewees).

Figure 4. Classification of interviewees under different biowaste valorization dimensions (BV in the centre of the venn diagram). Each interview has been assigned a code where A: academia, I: industry, NGO: non-governmental organization, P: public authorities, followed by the number of the interview.

2.5. Synthesis of the literature review and interview results

Finally, we synthesised the LR and SI results on interactions between BV and the 20 selected SDG targets used in the SI. Both the LR and the SI provided ranges of scores for several BV-SDG interactions identified. To discuss the results of the two analyses jointly, we used the maximum (synergies) and minimum (trade-offs) score for each BV-SDG interaction identified in the LR and the median value as a single score for each BV-SDG interaction identified in the SI.

3. Results and discussion

This section provides the study’s results and discussion. Section 3.1 presents the LR results that address the global context. Section 3.2 presents the interview results that address the Greek context. In section 3.3, we synthesise and discuss the LR and SI results: we move from a preliminary overview of the current scientific knowledge on BV-SDG interactions to insights from a national context.

3.1. Interactions between biowaste valorization and the SDGs: state-of-the-art knowledge

In the LR, we identified interactions for 37 of the 53 selected SDG targets but no evidence of interactions for the remaining 16 targets. Figure 5 visualises the BV-SDG interactions: the numbered boxes represent the selected SDG targets with the symbol of the relevant SDG to their left. The targets are coloured based on the Likert scale which is visualised below them. Within the 37 targets, 16 targets showed the potential for both synergies and trade-offs, while other targets showed the potential for either synergies or trade-offs but not both. In total, we found synergies for 36 of the targets and trade-offs for 17 targets. This means that we found synergies for every target with evidence of BV-SDG interactions, with the exception of SDG 12.3 (Section 3.1.1).

Figure 5. Synergies and trade-offs between biowaste valorization and the selected 53 SDG targets as identified through the literature review. The targets marked in dark grey indicate absence of identified evidence, not necessarily absence of interaction. Graphics adapted from Fuso Nerini et al. (2019).

Moreover, we identified some patterns that influence whether BV will have synergies or trade-offs with a target, and the strength of the interactions. We observe that these patterns can be classified as types of context-dependencies relating to governance of BV implementation (governance aspects). We classify them as follows: 1) the interplay between BV and other waste hierarchy options, 2) the role of BV within a bioeconomy context, and 3) the management of the remaining challenges and knowledge gaps including technical, operational, and regulatory aspects. Table 2 classifies the SDG targets relating to each governance aspect and a discussion on these aspects is provided in the following sections (3.1.1, 3.1.2 and 3.1.3). The full LR results are reported in the supplementary material (S1).

Table 2. Governance aspects of BV implementation influencing BV-SDG interactions.

Governance aspects influencing the nature and strength of BV-SDG interactions	Identified SDG targets relating to each aspect
The interplay between BV and other waste hierarchy options	8.4, 9.4, 11.6, 12.2, 12.3, 12.5, 12.6, 12.7, 13.2, 14.3, 17.14
BV’s role within a bioeconomy context	All 37 targets with identified interactions
The management of remaining challenges and knowledge gaps (e.g. technical, operational, and regulatory)	2.4, 6.3, 6.6, 9.4, 14.1, 14.2, 17.14

3.1.1. Biowaste valorization’s interplay with other waste hierarchy options

BV is one among other biowaste management options in the waste hierarchy. On the one hand, BV contributes to resource efficiency and thus to a city’s waste hierarchy performance as it diverts biowaste from lower waste hierarchy options such as incineration, landfilling and open dumping (Teigiserova et al. 2020). On the other hand, strategies that promote BV, but neglect higher waste hierarchy options, could compromise progress towards some SDG targets. In the food waste context, case studies of BV practices applied at large scale, highlight that significant shares of edible surplus food can end up to valorisation instead of redistribution. Studies in Sweden (Johansson 2021), the United Kingdom (Bradshaw 2018) and France (Redlingshöfer et al. 2020) showed that the policy structures supporting BV implementation lacked parallel incentives to encourage food surplus prevention and/or redistribution e.g. to community kitchens and food banks. Currently, several local and national governments have focused on local resources as opportunities to increase domestic energy supply. Instead, a parallel focus on reducing resource consumption is needed (Redlingshöfer et al. 2020). Therefore, a city’s performance in the waste hierarchy and the interplay between BV practices and other waste hierarchy options influence the nature and strength of its BV-SDG interactions.

BV-SDG trade-offs can also occur due to rebound effects. The so-called ‘Jevons paradox’ is a potential rebound effect for all CE practices (Iacovidou et al. 2017): since biowaste becomes a commodity that adds value and generates economic profit, it could eventually lead to increased biowaste generation (Santagata et al. 2021). In terms of consumer behaviour, empirical evidence suggests that raising awareness about both prevention and valorisation can result in higher food waste generation compared to solely raising awareness on food waste prevention (Qi and Roe 2017). Moreover, Salvador et al. (2021) highlighted that the research on the rebound effects of bioeconomy practices is limited, despite their potential risks.

Consequently, for SDG 12.3, ‘By 2030, halve per capita global food waste at the retail and consumer levels and reduce food losses along production and supply chains, including post-harvest losses’, we find no synergies with BV, even in cases promoted together with higher waste hierarchy options. We address BV as an option to manage post-consumer biowaste, while SDG 12.3 focuses on preventing and reducing food waste generation prior to this stage. Trade-offs may occur if higher waste hierarchy options are neglected (BV to SDG direction). Conversely, progress towards SDG 12.3 could lead to less feedstock availability for BV (SDG to BV direction). As shown in Figure 5, this was the only target for which we found potential trade-offs but not synergies.

For SDG 12.5 ‘By 2030, substantially reduce waste generation through prevention, reduction, recycling and reuse’, we find a potential ‘indivisible’ interaction (+3) with BV, when BV implementation encompasses higher waste hierarchy options. In contrast, neglecting prevention and redistribution can lead to rebound effects and a potential ‘counteracting’ interaction (−2) between with BV (BV to SDG direction). However, the strength of rebound effects is uncertain and requires further research. Moreover, even siloed BV transition pathways contribute to achieving SDG 12.5 compared to lower options in the waste hierarchy which do not. More comprehensive efforts towards holistic approaches are essential meaning that BV should be implemented with parallel efforts to enhance biowaste prevention and redistribution (Teigiserova et al. 2020).

3.1.2. Biowaste valorization in a bioeconomy context

BV-SDG interactions also depend on how BV is implemented within a bioeconomy context. A sustainable bioeconomy cascades the use of all types of biomass, making the most of available bioresources and extending their life cycle (Stark et al. 2022). The LR findings highlight that, to maximise synergies and minimise trade-offs, BV should be approached not solely as a waste management option, but as a component in the development of a wider bioeconomy together with other types of biomass residues. In this context, the development of biorefineries that can (co-)treat different types of biomass residues is an integral component towards sustainable bioeconomies (Venkata Mohan et al. 2019). In the context of SDG 7.2, ‘By 2030, increase substantially the share of renewable energy in the global energy mix’, the potential contribution of biowaste is limited compared to that of other biomass residues such as forestry and agricultural residues (Muscat et al. 2021). Therefore, upscaling BV alone is likely to have a limited contribution to SDG 7.2 compared to the contribution of all types of biomass residues (BV to SDG direction).

Nevertheless, it is also essential to address the full range of BV technologies and products and their impact on various sectors from waste management to energy, water and agriculture. Several cities and countries have based their strategies for valorisation of biomass residues on narratives towards increasing their domestic energy supply. For example, Hoolohan et al. (2019) identified energy recovery as the key motivation for implementing AD in the United Kingdom. AD implementation was supported mainly by energy policy incentives such as the national ‘Renewable Heat Incentive’ (Hoolohan et al. 2019). However, such an explicit and siloed energy focus neglects other opportunities to capture value, such as the potential for nutrient recovery. For instance, Drangert et al. (2018) found that reuse and recovery of food waste and human excreta could replace up to 30% of EU’s mined phosphorus (P), a key nutrient in fertilisers. Holistic approaches capitalise on all suitable BV practices in each context and thus provide a diversity of products, compared to approaches that focus exclusively on energy output. Such approaches may thus result in a lower BV contribution to SDG 7.2. However, holistic approaches can maximise synergies between BV and several other targets. Notably, there are synergies between BV progress and progress towards SDG 8.4 which aims to enhance resource efficiency (BV to SDG direction).

3.1.3. Management of the remaining challenges and knowledge gaps

Whether relevant stakeholders deal with unresolved challenges and knowledge gaps for BV, and how they manage them, can also trigger synergies or trade-offs. For example, the heterogeneity and seasonality of biowaste is a key challenge towards sustainable BV implementation. The quantity and quality of the available biowaste fluctuates and can thus influence its reliability as a secondary raw material for bio-based products (Muscat et al. 2021). Biowaste collection systems also entail technical challenges. Steiner et al. (2022) found that residues from biodegradable plastic bags can be polluting. Using such bags in the process of upscaling BV can compromise environmental performance.

Furthermore, biowaste-based products, which recover nutrients, can be used in fertilisers to enrich soil. However, biofertilizers can cause groundwater pollution if applied in amounts beyond the soil’s assimilative capacity (Weidner et al. 2020). Moreover, biofertilizers can include micro-pollutants, such as heavy metals, which also need to be controlled (Vea et al. 2018). Recent studies have brought attention to the policy dilemma arising from the conflicting goals of increasing resource circularity while also minimising the release of hazardous substances (Johansson and Krook 2021). Establishing effective regulations and control mechanisms is crucial towards a sustainable BV implementation. For instance, introducing separate biowaste collection systems can help mitigate the potential risk of elevated heavy metal content (Alvarenga et al. 2015). However, regulatory gaps persist in many cases and stall BV upscaling (Ntostoglou et al. 2021). Our findings indicate that regulatory gaps can lead to trade-offs with SDG targets connected to soil and water quality such as SDG 6.3 ‘improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials’ (BV to SDG direction).

BV’s complexity and multidimensionality also show a critical interaction with SDG 17.14, which aims to ‘Enhance policy coherence for sustainable development’. ‘Policy coherence’ is achieved when different policy goals align to function synergistically (Christensen 2022). This paper refers to policy coherence across geographic and governance levels (vertical policy coherence) and across different sectors (horizontal policy coherence) (Nilsson et al. 2012). In the BV context, coherence is essential across geographic and governance levels from international, to national and local. Moreover, the variety of BV technologies, products and their uses requires coherence across different policy sectors such as waste, energy and agriculture policy (Muscat et al. 2021). Therefore, the level and speed of achieving policy coherence can highly influence BV’s sustainability implications. Progress towards this target also connects with addressing regulatory gaps effectively.

3.2. Interactions between biowaste valorization and the SDGs in the Greek context

This section presents the key SI findings. To gain an overview of the SI scores, we used the median as a measure of central tendency, noting that the mean is not intended for the analysis of Likert scale data (Jamieson 2004). Figure 6 provides the overview of the interview scores per SDG target: the median for synergies (the green web), the median for trade-offs (the orange web), as well as the minimum (the striped grey web) and maximum scores (the grey web) assigned in an individual interview. Note that each circle’s size represents the number of interviewees who chose that score, while the circle’s colour corresponds to the Likert scale described in Section 2. Since 19 synergies (in green) and 1 trade-off (in orange) were identified between BV and the 20 selected SDGs, the circles for trade-offs are mostly in grey colour (no interaction identified). Despite the agreement on only 1 trade-off, the interviewees identified a varying number of trade-offs individually. The inner web (in striped grey) represents the minimum scores for each BV-SDG interaction and shows that trade-offs were identified for 13 targets in different interviews (−1 and −2 scores). S2.3 in the supplementary material includes further details on the SI findings.

Figure 6. BV-SDG interactions (median and extreme values) as identified through the stakeholder interviews. The size of the circles represents the number of interviewees who chose the equivalent score, while the colour of the circles corresponds to the likert scale of Figure 2. The numbers around the diagram represent the equivalent SDG target.

The three types of governance context-dependencies identified in the LR (Table 2) also emerged in some of the interviews. All the interviewees reflected on BV’s role in the waste hierarchy as well as its relation to other waste hierarchy options (see Section 3.1.1). Moreover, several interviewees recognised that the nature of BV-SDG interactions is context-dependent in terms of the types of BV technologies and products utilised (see Section 3.1.2). For example, interviewees I2 and I4 commented that BV technologies with energy products, such as AD, can contribute to achieving SDG 7.2 (BV to SDG direction) as opposed to technologies with non-energy products, such as composting. Finally, the interviewees mentioned several challenges for BV implementation (see Section 3.1.3). Particularly, they recognised policy coherence (SDG 17.14) as crucial towards BV implementation in Greece. Several interviewees suggested that achieving SDG 17.14 can contribute to upscaling BV (SDG to BV direction). In turn, that the process of upscaling BV can expose regulatory gaps, overlaps and/or contradictions between policy sectors; if these are acknowledged, addressed, and overcome, then BV upscaling can contribute towards SDG 17.14 (BV to SDG direction). However, they noted significant gaps towards achieving the target, e.g. in terms of coherence in the regulations for commercialising BV products (I3).

As shown in Figure 4, the interviewees had diverse backgrounds and thus experience with different BV aspects. In some cases, there were similarities in their motivations, while in others, different aspects of potential BV-SDG interactions were raised in each interview. For example, for SGD 6.3, most interviewees with experience in waste management and energy focused on BV’s potential to divert biowaste from landfills. In contrast, interviewees with experience in nutrient management focused on the heavy metals content of BV products and its impact on surface water quality. These findings highlight BV’s multidimensionality and the need for interdisciplinary and transdisciplinary collaboration towards sustainable BV implementation. Harnessing collaboration between diverse stakeholders can facilitate a holistic identification of BV’s sustainability implications through BV-SDG interactions and other analytical approaches (Hakkarainen et al. 2022).

As a detailed example, Table 3 summarises the interview findings for SDG 12.3. It was the only target for which several interviewees found potential trade-offs with BV and limited potential synergies. Some interviewees recognised that progress towards SDG 12.3 requires biowaste prevention which is not guaranteed through BV upscaling. S3.1 provides summaries of the SI findings for all 20 SDG targets.

Table 3. Interactions between BV and SDG 12.3: interview findings and connection to the literature review.

Synergies	This target strongly relates to biowaste prevention and does not have synergies with BV. However, since BV contributes to the waste hierarchy, there are potential synergies with SDG 12.3 such as contribution to behaviour change towards sustainable consumption (7 interviewees).
Trade-offs	Implementing BV without biowaste prevention may delay progress towards achieving SDG 12.3. Achieving SDG 12.3 results in biowaste management systems with improved environmental performance. However it may pose challenges for the economic sustainability of BV projects e.g. limited feedstock availability (I2, R1).
Insights into the Greek context	Need for behavioural change to achieve the target. Challenges in harnessing sustainable behaviours.
Evidence based on the literature review	The interviewer clarified that BV is here viewed as a method that manages post-consumer biowaste (Section 3.1.1). No evidence of synergies between BV and SDG 12.3 based on the LR.

Notably, while all the interviewees demonstrated familiarity with the SDGs, none had prior experience with explicitly addressing SDG targets or methods of SDG interaction analysis. Some interviewees found it challenging to evaluate BV-SDG interactions. They found the SDGs too theoretical and ‘away’ from their reality as practitioners. This connects to previous literature on SDG interaction methods that showed that practitioners struggle to integrate the SDGs into their work in a meaningful way (Di Lucia et al. 2021).

3.3. Synthesis of results: from a literature review to insights from a national context

In the final step of our study, we synthesise the LR and SI results for the 20 selected SDG targets. The findings largely agree in terms of the number and scores of synergies. Both the LR and the SI showed synergies with 19 SDG targets, with 12.3 being the only target without potential synergies. However, there are notable discrepancies regarding the trade-offs identified in the LR and the SI. Among the 20 targets analysed, the LR showed 11 trade-offs, contrasting with stakeholders agreeing on only one trade-off. Figure 7 compiles the scores from the LR next to the SI median scores. S3.2 includes further details on the comparison, and S3.3 presents the motivations for the scores provided in the two analyses.

Figure 7. Comparison of BV-SDG interactions as identified through the literature review and the stakeholder interviews. The synergies are shown in green and the trade-offs in orange. Scores from the literature review are represented with solid fill colours, while scores from the stakeholder interviews with strip patterns. The median values were used.

Reflecting on the findings, we propose some reasons as to why the SI showed fewer trade-offs than the LR. Firstly, several interviewees may be optimistic in their evaluation of interactions: Greece is at an early transition stage, and all the interviewees viewed BV as inherently sustainable. For some targets (e.g. SDG 12.5), some interviewees recognised potential BV-SDG trade-offs, but considered their likelihood low to score such interactions negatively (−1, −2, −3). Secondly, some interviewees reported limited experience with particular aspects of the SDG targets. For example, several interviewees had difficulty scoring interactions relating to water management (SDG 6.4 and 6.5) and sustainable public procurement (SDG 12.7). As raised by one interviewee, the current national framework does not address public procurement practices that are relevant to biowaste, which explains why some interviewees were not familiar with such practices.

Nevertheless, the insights provided were influenced by each interviewee’s background. For instance, interviewees with experience in nutrient management discussed different aspects compared to interviewees with focus on the energy sector, as described in Section 3.2, the interviewees working closer to nutrient management raised different aspects from the interviewees working closer to the energy sector. These findings underscore the ongoing need for interdisciplinary and transdisciplinary collaboration among professionals across different fields. The need for interdisciplinary and transdisciplinary collaboration to implement CE practices has been emphasised in the CE literature (Witjes and Lozano 2016; Iacovidou et al. 2017). Through such collaboration, stakeholders can better address the multidimensionality and complexity of BV-SDG interactions and thus enhance the understanding and management of synergies and trade-offs. Some emerging Greek bioeconomy organisations e.g. energy communities and bioeconomy clusters, can enable collaboration across a variety of stakeholders. Our sample included stakeholders from such organisations. Greece would profit from investing further on the development of holistic approaches, which engage diverse stakeholders towards the implementation of BV and wider bioeconomies.

Our findings indicate a tendency among interviewees to emphasise synergies while overlooking or remaining unaware of potential trade-offs. Similar findings have been identified in the current discourse on the CE where ‘win-win’ rhetoric dominates rather than reflexive deliberations about trade-offs (Johansson 2022). Nonetheless, the interviewees appeared to recognise the complexity of BV’s sustainability implications. This leads us to a third reason as to why the SI yielded less trade-offs than the LR. As the interviewees also addressed, it is challenging to evaluate the nature and strength of BV-SDG interactions due to their inherent complexity and uncertainties particularly in the context of an ex-ante analysis. For example, the potential rebound effects such as the Jevons paradox were documented both in the LR and the SI. However, there is limited scientific evidence to measure the likelihood and strength of such effects in different cases (Salvador et al. 2021). Like other SDG interaction studies, this study finds a greater number of synergies than trade-offs. However, the study of Kostetckaia and Hametner (2022) demonstrated that trade-offs can have a higher strength than synergies, and potentially hindering SDG progress more significantly. Therefore, all interactions must be addressed with attention to their nature and strength.

Furthermore, the LR led to three BV context-dependencies relating to governance that can influence the nature and strength of the interactions. The three governance context-dependencies also emerged in the interviewees’ motivations. Further addressing these aspects can support the study of BV-SDG interactions and BV implementation under holistic approaches: 1) integrating BV as part of the waste hierarchy, 2) integrating BV as part of wider bioeconomy strategies considering the full range of potential biomass residues, technologies and products, and 3) managing unresolved challenges and knowledge gaps (e.g. technical, operational, and regulatory). This study aligns with previous studies that highlight the context-dependencies of SDG interactions (McCollum et al. 2018; Nilsson et al. 2018), and the importance of minimising trade-offs, and, when possible, turning them into synergies (Kroll et al. 2019). Among others, our findings highlight that the level and speed of acquiring policy coherence can highly influence BV’s sustainability implications. Although, the importance of cross-sectoral strategies has long been highlighted in biomass research (Elghali et al. 2007), such strategies remain limited and underdeveloped (Muscat et al. 2021). Table 4 summarises the key study findings and their relevance to previous scientific research.

Table 4. Key study findings and their relevance to previous scientific research.

Key study findings Context: biowaste valorization (BV)	Relevance to previous research (not exhaustive) Context: circular economy (CE) and bioeconomy
BV-SDG interactions Narrative literature review: overview of the current scientific knowledge Stakeholder interviews: insights from a national context	Several studies of SDG interactions including CE (Schroeder et al. 2019) Bioeconomy (Calicioglu and Bogdanski 2021)
Insights into context-dependencies of BV-SDG interactions relating to governance	Management of SDG synergies and trade-offs (Kroll et al. 2019) The strength of trade-offs can be higher than that of synergies (Kostetckaia and Hametner 2022) Context-dependencies of SDG interactions (McCollum et al. 2018; Nilsson et al. 2018)
Policy coherence: a key prerequisite for sustainable BV implementation	Need for cross-sectoral synergies in biomass systems (Elghali et al. 2007) Need for policy coherence in bioeconomy development (Muscat et al. 2021)
A tendency among interviewees to emphasize synergies while overlooking or remaining unaware of potential trade-offs	CE context: ‘win-win’ rhetoric dominates rather than reflexive deliberations about trade-offs (Johansson 2022)
Need for interdisciplinary and transdisciplinary collaboration for a comprehensive assessment of BV-SDG interactions and planning of sustainable BV implementation	Need for interdisciplinary and transdisciplinary collaboration in the CE (Witjes and Lozano 2016; Iacovidou et al. 2017) Bioeconomy (Hakkarainen et al. 2022)
Several BV-SDG interactions identified but limited scientific evidence (quantitative and qualitative)	Limited research on the rebound effects of bioeconomy practices, despite their potential risks (Salvador et al. 2021)

4. Limitations and suggestions for further development

This study serves as a starting point for investigating BV-SDG interactions. Further research can build on this study to enrich the scientific evidence and knowledge on BV-SDG interactions addressing their context-dependencies relating to time, geography, governance, technology and directionality (McCollum et al. 2018). One potential way forward is to assess BV-SDG interactions in the context of specific BV projects as well as to focus on specific BV technological processes and products. In doing so, integrated assessment tools must be developed further and synthesised. For example, in the bioeconomy context, Gheewala (2023) addressed the current status of LCA tools for sustainability assessment. Misslin et al. (2022) developed a tool for integrated environmental, social and economic assessment of the valorisation of agricultural biomass residues. Furthermore, Christensen et al. (2022) discussed the challenges and opportunities in bridging modelling with policymaking in the development of the bioeconomy, further emphasising the need for integrated assessment approaches. As previous studies have highlighted, no single perfect tool exists. On the contrary, to enhance the quality of the assessment, it is essential to integrate different sustainability assessment tools (Aghbashlo et al. 2022). Our study findings can inform further research on the integration of BV sustainability assessment tools such as the examples provided above.

The scope and methodology of this study introduce certain limitations. This focuses on selected SDG targets rather than encompassing all. Moreover, it focuses on a national context, meaning that spillover effects (Engström et al. 2021) are beyond its scope: e.g. How does upscaling BV in Greece affect other countries? How do the BV-SDG interactions at the national scale impact SDG progress globally? Furthermore, we intended to address bi-directional interactions between BV and the selected SDG targets. In both the LR and the SI, one score was provided for synergies and/or one score for trade-offs identified between BV and each SDG target. The directionality of the interactions was considered in the reasoning of the score assigned for each BV-SDG interaction (see Supplementary Material). Despite our efforts to address directionality, the SDG targets are wider than BV implementation. In most cases, the targets support BV implementation. However, achieving progress towards a target can involve various measures, making it challenging to precisely determine the target’s impact on BV implementation. Further research can build on this analysis and address such limitations.

We applied a Likert scale to score the BV-SDG interactions. However, assigning such scores can be a subjective process. The LR revealed limited scientific evidence explicitly and comprehensively addressing the interactions between BV and the SDGs at the target and/or indicator level. Consequently, the evaluation of the strength of the interactions was significantly influenced by the authors’ judgement. To develop a context-specific assessment, we elicited stakeholder views. Therefore, the scoring is influenced by the stakeholders’ personal agendas, professional backgrounds, and experiences.

Finally, our study addressed interactions between selected SDGs and BV as an external entity. This approach also revealed internal target-to-target interactions (Bennich et al. 2020) e.g. potential trade-offs between SDG 7.2 and SDG 12.3, attributable to rebound effects in scenarios with an explicit focus on energy and/or negligence for biowaste prevention. Further research can address SDG interactions with internal entities.

5. Conclusions and recommendations

This study applies SDG interaction analysis to investigate BV’s sustainability implications. Our findings show that more synergies than trade-offs are expected between BV and the SDGs. However, different types of context-dependencies can influence the nature and strength of the interactions. We highlight three types of context-dependencies that relate to governance of BV implementation: 1) the interplay between BV and other waste hierarchy options, 2) the role of BV within a bioeconomy context, and 3) the management of remaining challenges and knowledge gaps (e.g. technical, operational, and regulatory). The comparison between the LR and the SI findings shows more agreement on the synergies identified, compared to the trade-offs. Through the insights of stakeholders from various backgrounds, the SI enrich the LR findings with focus on the Greek context. Given Greece’s early transition stage, assessing the potential BV-SDG interactions is valuable for planning and mainstreaming sustainable BV practices. Our findings suggest that holistic approaches and interdisciplinary collaboration for BV are currently underdeveloped in Greece. Some emerging bioeconomy organisations, e.g. energy communities and bioeconomy clusters, can support cooperation across diverse stakeholders. Such cooperation can lead to a more holistic identification of BV’s sustainability implications through BV-SDG interactions and other analytical approaches.

Our findings have significant implications for both policy and practice in waste management, planning, and sustainable development. The identification of numerous synergies between BV and the SDGs emphasises the potential for integrating waste management policies and practices with broader sustainable development objectives. This calls for policymakers to prioritise and support BV as a strategy to achieve multiple SDGs simultaneously. Similarly, practitioners in waste management, planning, and sustainable development should prioritise and promote BV as a means to contribute to the SDGs. However, the study also underscores the importance of considering context-specific factors such as waste hierarchy priorities, the role of BV in the bioeconomy, and existing challenges and knowledge gaps. Both policymakers and practitioners should adopt a holistic and interdisciplinary approach, fostering collaboration. Our findings align with those of SDG interaction studies in the CE and bioeconomy context.

This is the first study to address the sustainability implications of BV through methods of SDG interactions analysis. While our analysis is not exhaustive, it does confirm an approach to identify and understand BV-SDG interactions and a starting point for unpacking their context-dependencies. The evidence provided can support the scientific community and decision-makers towards sustainable BV and bioeconomy practices. Future case studies can further address context-dependencies including the three governance aspects raised in this study. Although the insights from the Greek case application should not be generalised, they can inform other countries and cities at early stages in the BV transition. Finally, this is the first study to synthesise LR findings on SDG interactions with SI findings at a national scale. Therefore, this mixed-methods research approach contributes to the field of SDG interactions analysis.

List of abbreviations

AD	=	Anaerobic digestion
BV	=	Biowaste valorisation
CE	=	Circular economy
EU	=	European Union
IACGB	=	International Advisory Council on Global Bioeconomy
LCA	=	Life Cycle Sustainability Assessment
LCSA	=	Life Cycle Sustainability Assessment
LR	=	Literature review
MSW	=	Municipal solid waste
RQ	=	Research question
SDG	=	Sustainable development goal
SI	=	Stakeholder interviews

CRediT authorship contribution statement

Eftychia Ntostoglou: Conceptualisation, Data curation, Formal Analysis, Investigation, Methodology, Resources, Visualisation, Writing – original draft, Writing – review & editing Daniel Ddiba: Methodology, Visualisation, Writing – review & editing, Dilip Khatiwada: Methodology, Supervision, Visualisation, Writing – review & editing, Viktoria Martin: Methodology, Supervision, Visualisation, Writing – review & editing Rebecka Ericsdotter Engström: Methodology, Writing – review & editing, Maryna Henrysson: Writing – review & editing, Katia Lasaridi: Writing – review & editing

Acknowledgments

The authors thank the Greek stakeholders, who agreed to be interviewed, for sharing their valuable time and insights, including stakeholders from the following organisations: Aristotle University of Thessaloniki, Center for Renewable Energy Sources-Biomass Department (CRES), Energy Community of Karditsa (ESEK), Greenpeace, National Green Fund (Prasino Tameio), and stakeholders from other organisations that wish to remain anonymous. The authors would also like to thank Francesco Fuso Nerini for his guidance on SDG interactions analysis in the initial stages of the study. Finally, we thank the anonymous reviewers for their valuable suggestions for improving the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/19463138.2024.2319795

Additional information

Funding

The Swedish Research Council FORMAS supported Eftychia Ntostoglou through the project: Bio-based circular recovery model for sustainable urban economies [Grant No 2017-00266] and Daniel Ddiba through the UrbanCircle project [Grant No. 2017–00268].

Notes on contributors

Eftychia Ntostoglou

Eftychia Ntostoglou is a PhD candidate at the Division of Energy Systems, Department of Energy Technology, KTH Royal Institute of Technology. Her research explores the transition to sustainable systems for biowaste valorization in the urban context. Her broader research interests include the transitions to sustainable cities and bioeconomies and the development of transdisciplinary collaboration towards such goals.

Daniel Ddiba

Daniel Ddiba is a Research Fellow at the Stockholm Environment Institute in Sweden working on the Sanitation and Health research area. He holds a PhD from the Department of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology. His research focuses on sanitation, waste management and integrated natural resource management.

Dilip Khatiwada

Dilip Khatiwada is an Associate Professor at the Division of Energy Systems, Department of Energy Technology, KTH Royal Institute of Technology. His research provides insights into the sustainability of renewable energy, decision support tools such as life cycle assessment (LCA), energy systems optimization, and their potential roles in the mitigation of climate change, improved energy security, and sustainable development in different development contexts, as well as methodological contributions for assessing the sustainability in connection with energy and climate policies.

Viktoria Martin

Viktoria Martin is a Professor in Energy Technology at the Division of Energy Systems, Department of Energy Technology, KTH Royal Institute of Technology. Her research addresses renewable energy implementation and related technologies like thermal energy storage, heat driven heat pumping technology, district heating and cooling, cogeneration/polygeneration, techno-economic systems modelling and optimization to aid planning and policy development.

Rebecka Ericsdotter Engström

Rebecka Ericsdotter Engström is a Post-doctoral researcher at the Viable Cities Programme hosted by KTH Royal Institute of Technology. She works on exploring and conceptualizing how cities can demonstrate systemic change in the energy system beyond pilot and demo projects - for example in system demonstrators - and how their transformative potential can be evaluated along the way. She also builds on her previous research on how climate adaptation, resilience and risk perspectives can be built into the transition work in cities from different perspectives.

Maryna Henrysson

Maryna Henrysson is an Assistant Professor at the Division of Energy Systems, Department of Energy Technology, KTH Royal Institute of Technology. Her research interests lie in sustainability transformations, specifically at the intersection of climate action, energy systems, and governance. She explores how socio-ecological and socio-technical systems respond to unsustainable production, consumption, and investment patterns, investigating drivers of transformation, resistance to change, and necessary shifts for societal alignment.

Katia Lasaridi

Katia Lasaridi is a Professor in Environmental Management and Technology at the Harokopio University, Athens, Greece. She works on all aspects of waste management in the context of Circular Economy with emphasis on food waste prevention, valorization and treatment, WEEE management, and Extended Producer Responsibility (EPR), where she has extensive research and consultancy experience. She has served as President of the Board of the Hellenic Recycling Agency, and in Harokopio University as member of the Governing Board, Deputy Rector, and Head of the Geography Department. She is currently member of the Scientific Committee of the Hellenic Institute of Local Authorities.