In the present work, the individual or synergistic effect of Ni-based catalysts (Ni/CeO₂, Ni/Al₂O₃) and an eutectic carbonate salt mixture (MS) on the CO₂ gasification performance of olive kernels was investigated. It was found that the Ni/CeO₂ catalyst presented a relatively superior instant gasification reaction rate (Rco) compared to Ni/Al₂O₃, in line with the significant redox capability of CeO₂. On the other hand, the use of the binary eutectic carbonate salt mixture (MS) lowered the onset and maximum CO₂ gasification temperatures, resulting in a notably higher carbon conversion efficiency (81%) compared to the individual Ni-based catalysts and non-catalytic gasification tests (60%). Interestingly, a synergetic catalyst-carbonate salt mixture effect was revealed in the low and intermediate CO₂ gasification temperature regimes, boosting the instant gasification reaction rate (Rco). In fact, in the temperature range of 300 to 550 °C, the maximum Rco value for both MS-Ni/Al₂O₃ and MS-Ni/CeO₂ systems were four times higher (4 × 10⁻³ min⁻¹ at 460 °C) compared to the individual counterparts. The present results demonstrated for the first time the combined effect of two different Ni-based catalysts and an eutectic carbonate salt mixture towards enhancing the CO production rate during CO₂ gasification of olive kernel biomass fuel, especially in the devolatilization and tar cracking/reforming zones. On the basis of a systematic characterization study and lab-scale gasification experiments, the beneficial role of catalysts and molten carbonate salts on the gasification process was revealed, which can be ascribed to the catalytic activity as well as the improved mass and heat transport properties offered by the molten carbonate salts.

Micro-enterprises are vital to the European economy, including in Croatia, where they make over 88% of the total number of businesses. Despite their significance, they face substantial energy vulnerability due to factors like small size, limited financial resources, and high energy costs. This paper investigates the determinants of energy vulnerability among Croatian micro-enterprises, employing a survey of 470 micro-enterprises. The study covers firms across all Croatian NUTS2 regions and ensures geographic and sectoral representativeness. Key findings reveal that enterprises with higher energy expenditures relative to revenue are most susceptible to energy vulnerability, which is aligned with our assumption. On the other hand, businesses that own their premises, have more employees, and have been operational longer are more likely to invest in energy efficiency measures, thereby reducing vulnerability. Notably, a significant proportion of micro-enterprises report that energy costs adversely affect their household finances, highlighting the nature of business and personal economic stability. The paper underscores the need for targeted policies and support mechanisms to enhance the energy-related resilience of micro-enterprises, considering their unique structural and financial constraints.

This article examines Greek households’ energy and transport poverty and vulnerability, two concepts often intertwined in policy, making use of both single and composite indicators. The methodology employed aligns with the European Social Climate Fund regulation, using household income from economically active members and the share of expenditures on fossil-based energy use in buildings and transport, as well as the required investment costs in energy efficiency improvements for dwellings or transport decarbonization measures. Through these indicators, the proportion of energy-vulnerable households in Greece ranges from 19% to 40%, while transport vulnerability varies between 22% and 43%. Notably, the analysis reveals that households in higher income categories can still be highly vulnerable, depending on household size, composition and dependency, which impact energy and transport needs. As such, the research findings reveal that the current legislative frameworks may not fully capture the vulnerability of certain demographic groups in the event of additional costs of fossil fuels due to new climate policies. Therefore, it is strongly recommended that policymakers adjust criteria to better target vulnerable households based on their unique characteristics and needs, and use improved data collection systems to monitor energy and transport poverty and vulnerability.

Achieving a climate-neutral and circular built environment in Europe requires policy frameworks supported by robust data infrastructures, transparent governance models, and validated approaches that integrate circular technologies into renovation and construction practices. In that framework, the present paper presents a policy-oriented synthesis of the findings of two Horizon Eu-rope projects, DeCO2 and CRedIBlE, that operationalise whole-life carbon assessment, circular resource management, and interoperable building data systems along with harmonised data architectures with the aim to create the necessary conditions for policy instruments, that rely on accurate stock-level information. Specifically, in the framework of those two projects, the paper will present a parametric evaluation of renovation measures to support the identification of cost-effective interventions compatible with circular design strategies. That framework can assist building users and managers in deciding on the best possible renovation strategies, material-reuse schemes, and carbon-reduction path-ways grounded in verifiable, comparable data. These capabilities are essential for implementing key policy levers, such as minimum energy performance standards (MEPS), digital building logbooks, and pre-demolition audit requirements. All in all, the research presents a technically rigorous yet policy-relevant framework for accelerating circular, low-carbon transformation across the European built environment.

Positive Energy Districts (PEDs) represent a pivotal evolution in urban energy performance, expanding the ambition from individual buildings to entire neighborhoods and wider urban systems. While much attention has been devoted to their technological dimensions, successful PED development equally depends on sustained citizen engagement, inclusive governance and community-driven co-creation. This study brings together nine EU-funded projects — InterPED, TIPS4PED, ARV, COMMUNITAS, PEDvolution, Citizen-led Renovation, NEUTRALPATH, ASCEND, and LEGOFIT — to present and compare their approaches to citizen and stakeholder engagement in PED planning, design, and implementation. Drawing on contributions prepared for a dedicated workshop at the Sustainable Places 2025 Conference, this paper identifies five cross-cutting themes: partnership-based engagement models, digital tools and platforms for co-creation, energy communities as governance frameworks, participatory monitoring and living lab methodologies, and gamification and innovative facilitation. The projects collectively demonstrate that the energy transition is not merely a technical challenge but a fundamentally societal one, and that citizens can play an active role as co-creators in PED development processes. The findings highlight the importance of inclusivity, adaptive engagement frameworks, energy literacy, and long-term governance structures in enabling PEDs that are equitable, resilient, and scalable across diverse European urban contexts.