Nikolaos Koukouzas

Coal-dependent regions face a multidimensional transition challenge that extends beyond energy substitution and requires coordinated transformation of industrial systems, landscapes, infrastructure, governance and local economies. Using a structured narrative review and framework-building approach, this paper develops a systems-based framework for sustainable post-lignite transition, using Western Macedonia as the main integrated case and Megalopolis as a comparative Greek lignite region. The proposed approach integrates four interrelated domains: subsurface and geological potential, industrial decarbonisation pathways, post-mining land and infrastructure reuse, and socio-economic and governance transition. Particular emphasis is placed on the role of carbon capture, utilisation and storage (CCUS), low-carbon industrial technologies, renewable energy integration, energy-storage options, land rehabilitation, heritage valorisation and place-based development strategies. The analysis highlights that successful post-coal transition depends not only on the availability of individual technological solutions, but also on their spatial, environmental, economic and governance compatibility within the regional system. By aligning geological knowledge, engineering innovation, environmental management and just-transition planning, the paper proposes an integrated planning framework intended to structure the consideration of multiple forms of evidence in former lignite regions. The framework is broadly consistent with the Sustainable Development Goals, particularly those related to clean energy, resilient infrastructure, sustainable communities, responsible land reuse, climate action and ecosystem restoration, and offers transferable insights for European coal regions seeking resilient, diversified and low-carbon development pathways.

Background Exploration of subsurface gases such as hydrogen, helium, methane, and carbon dioxide can be achieved by integration of geological framework, hydrogeochemistry, and isotope analysis to understand generation, migration, and trapping mechanisms. A focused hydrogeochemical survey for the aforementioned gases was conducted in West Macedonia (Greece) to identify potentially suitable locations for geological reservoirs, gas sources and gas migration routes based on previous research. West Macedonia (Greece) is characterised by ophiolitic complexes, sedimentary basins, and active fault systems. This presents favourable geological conditions for investigating potential gas reservoirs and migration pathways. Methods The investigation presented in this study deployed sequential spring and borehole water sampling for geochemical analysis of trace elements and gas analysis for hydrogen, helium, methane and carbon dioxide to identify and characterise gaseous geological reservoirs. The investigation extended into isotope studies for d 13C TDC, δ 13C CH 4 , δ 13D CH 4 , δD H 2O, δ 18O H 2O. Results The analysis provided evidence for the existence of helium, biogenic methane, carbon dioxide and traces of hydrogen that need to be further investigated for validation and better understanding of the gas generation and migration routes. Variations in dissolved ions and gas composition largely reflect enrichment of resident groundwater by meteoric recharge and subsequent water–rock interaction. Fault-controlled pathways appear to facilitate multi-gas signatures in specific locations. Conclusions The data suggests the existence of helium, methane, carbon dioxide and validated trace concentrations of hydrogen from previous studies in the wider area. Isotopic analysis provides strong evidence for biotic generation of methane, whereas helium comes from a deeper source. Hydrogeochemical controls, structural features, and lithological variability collectively influence gas occurrence. This preliminary investigation indicates the existence of multiple gas generation and migration mechanisms and provides a scientific basis for further targeted exploration of natural hydrogen and associated gases.

Media coverage plays a pivotal role in shaping public perception of the energy transition. This study provides a comprehensive analysis of how the lignite phase-out is represented in Greece, both by national and regional media, with a specific focus on the impacted region of Western Macedonia. Using data from the Leipzig Corpora Collection and regional news portals from 2013 to 2022, the analysis reveals significant divergences between media levels. While both show synchronized peaks for key terms like “Climate change” (2019) and “Western Macedonia” (2021), regional media addressed the direct impacts of the transition earlier and more intensely, with terms like “post-lignite” and “de-lignification” peaking in 2020 following the announcement of the Master Plan. National media framed the transition within a broader, top-down policy context, often with an optimistic tone, reflecting EU directives. In contrast, regional media provided a community-centric perspective, highlighting concerns over job losses and the preservation of local identity. The findings underscore a clear tension between official narratives of progress and local-level concerns, demonstrating that media discourse is a critical, multi-faceted component of just transition processes that policymakers must consider.

Closed and abandoned coal mines are increasing globally, leading to a growing emphasis on their transition into sustainable post-mining areas. This focus marks the era of just transition, highlighting the importance of equitable reclamation efforts. The complexity of mining landscapes makes them susceptible to multiple hazards, which can occur simultaneously or successively, a concept known as multi-hazard. This study emphasizes the need for a comprehensive approach to multi-hazard analysis, which is an essential part of the sustainable reclamation and safety of post-mining areas, directly impacting the safety and well-being of communities. The research compares four widely employed semi-quantitative multi-hazard methodologies: the Analytic Hierarchy Process (AHP), the Entropy Weight Method (EWM), the partial multiplication factor method, and the spatiotemporal method. Each method's strengths and limitations are evaluated by applying it to a specific post-mining area, incorporating an innovative multi-hazard scenario assessment. The implementation and comparison of the methods revealed that each one has particular advantages: AHP is widely used with supporting background, EMW is straightforward to implement, the partial multiplication factor method demonstrates more precisely multi-hazard principles, and the spatiotemporal method is the only one that considers temporal frequency. However, none of the methods accounts for the sequence of hazards within scenarios. While AHP and EWM provide consistent rankings, the partial multiplication factor and spatiotemporal methods show greater variability in multi-hazard index (MHI) values, highlighting the influence of both hazard intensity and interactions.

Background The CO 2 emissions reduction is crucial for the energy transition. New technologies for CO 2 capture and storage are under development, such as CEEGS 1, 2 . Porous media and rock caverns are geological formations of high interest for such technology. Among them, depleted hydrocarbon fields (DHF) gain ground due to existing reservoir knowledge and already established infrastructure which decreases the cost. However, one of the major problems caused during CO 2 storage in DHF is the interactions between the injected CO 2 and the remaining fluids. Methods In this study, the potential CO 2 storage in DHF was investigated. Marismas 3 was used as a hypothetical model area for the examination of CO 2 interactions with a carbonate-silisiclastic reservoir. PHREEQC software 1 was used to investigate reservoir rock/water/remained gas (CH 4) interactions followed by interactions taking place after the CO 2 injection. Different scenarios were used for the CO 2 concentration and behaviour in the reservoir. To make the system more complex and generic, the CMG-GEM software 3 was utilized to examine the long-term sequestration of CO 2 through dissolution trapping, residual trapping, and lateral migration in a reservoir analogue to the Marismas field, but at higher depth, compatible with the CEEGS technology. Results During the CO 2 injection, carbonic acid was formed, causing a dissolution of several minerals, leading to siderite and clay minerals precipitation, which may cause problems to the permeability of the system. The colloidal nature of siderite and the Ca-montmorillonite swelling properties are of high concern for pore throat clogging. The other newly formed mineralogical phases are not threatening the reservoir quality. CMG-GEM validated the critical phase of CO 2 plume establishment. Conclusions The proposed DHF is promising for real-world underground applications fitting to CEEGS technology as the newly formed minerals that could cause failures can be easily controlled by anthropogenic changes in the reservoir parameters.

During surface coal mining, vast amounts of overburden waste materials—called spoils—are excavated and dumped, forming massive heaps, the sustainable exploitation of which is a top priority globally. This study addresses the advanced geotechnical characterization of spoil materials, focusing on lignite mine spoil heaps, which are often ignored due to their highly heterogeneous nature. This research quantifies the spatial variability in spoil materials from a large heap in Greece, highlighting the importance of a robust geotechnical framework for their effective reclamation. Using statistical analysis and variogram modeling, the scale of fluctuation (SoF) was derived for both the vertical and horizontal directions. The SoF values for spoil properties are found to be on the high end of the natural soil range. Vertical correlations are observed for distances over 10 m, occasionally reaching 20 m, indicating significant spatial variability; in the horizontal direction, the SoF reaches up to 285 m. These findings suggest that spoil elements exhibit important spatial dependence, which is critical for their proper design and exploitation. The results provide a basis for future research and the use of advanced numerical tools, such as the random finite element method, to support geotechnical design and the sustainable exploitation of spoil heaps.

This work presents a structured methodology for multi-hazard risk assessment in post-mining coal areas, addressing the complex interactions between natural, mining, and technological hazards. The methodology provides a flexible, semi-quantitative mixed-methods framework designed to evaluate multi-hazard risk scenarios through a seven-step process, which includes identification of hazards, analysis of hazard interactions, and calculation of the Multi-Hazard Index (MHI), Vulnerability Index (VI), and Multi-Risk Value (MRV). The MHI assesses the cumulative intensity of hazard interactions, while the MRV quantifies the socio-economic impacts of various multi-hazard scenarios. The framework also incorporates vulnerability assessments, using social and physical vulnerability indices, to better understand the potential risks to communities. The methodology aims to enhance the safety of post-mining areas by mitigating the cascading effects of hazard interactions and by systematically increasing the knowledge of hazard interdependencies. This approach is adaptable to diverse post-mining contexts, offering a comprehensive framework for assessing and managing multi-hazard risks. It aligns with the broader objectives of the European Green Deal by promoting sustainable land management and addressing the transition of coal regions toward a carbon-neutral economy. It equips stakeholders with necessary tools to enhance resilience and ensure the long-term socio-economic and environmental stability and safety of post-mining areas.

Heritage and culture tourism involve features that commemorate a valued past. Mining heritage tourism allows visitors to experience the past, guided by former mining landscapes and engaging interactively with material artifacts. This paper introduces the CoalHeritage European project, focusing on the promotion of coal mining heritage through the production and design of the European Visual Map Journal (EVMJ). The EVMJ is a user-friendly, web-based, interactive storytelling platform that supports the transfer of industrial and geoheritage from former coal mining areas. It aims to collect and disseminate heritage assets from post-mining coal areas, informing stakeholders and promoting these sites as tourist destinations. To further enhance public awareness, several ESRI StoryMaps web apps are being created to highlight specific features of each case study across Europe. The aim of this work is to introduce coal mining heritage as a new term, present the coal heritage platform and its importance for disseminating coal heritage aspects to the public, describe the methodology used for its design, and provide a brief overview of its evolving content.