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In the quest for more efficient solar thermal systems, accurately determining the thermal emittance of low-emissive materials is crucial in determining the power losses. This paper describes the calorimetric method designed to precisely measure the thermal emittance of Selective Solar Absorbers (SSAs) to be used in High Vacuum Flat Plate Collectors (HVFPCs). The method’s capability is demonstrated through the successful correction of thermal emittance values for copper samples of varying sizes, including dimensions down to 49 cm2. Results highlight the method’s potential to significantly reduce measurement errors associated with small-size and/or low-emittance samples, providing a path forward to improve the design and efficiency of SSAs. This research marks a significant step in advancing solar thermal technology by enabling emittance measurements with a precision better than 0.003, which is essential for the development of high-performance solar thermal absorbers. The method has also been applied to correct the thermal emittance value of SSA measured in previous measurement campaigns, and it allows a better estimation of the SSA efficiency conversion curve.

Around 600 million m3 of wastewater and 6 million tonnes of leather solid wastes, are generated annually worldwide, with a chromium content of 1 to 4 %. In this context, the thermochemical valorisation of tannery sludge (TS) by hydrothermal liquefaction (HTL) process represents a promising route both for the reduction of the material to dispose in landfill and for the production of an energy carrier. HTL process produces bio-crude from wet biomasses in a hot pressurised water environment, thus avoiding the energy-intensive drying step commonly associated to other thermochemical processes. Moreover, HTL, not aiming at the complete oxidation of the organic component, potentially avoids the oxidation of Cr in its harmful hexavalent form. In this study, a TS was investigated as solid waste for HTL carried out in a 500 mL batch reactor to obtain a bio-crude for energy purposes. Results show that, under the best operating HTL condition (350 °C and 10 min), the H/C ratio of bio-crude was similar to that of starting biomass while the O/C ratio was about three times smaller than in the parent TS. The bio-crude yield was about 25–30 % on dry and ash-free basis, with an associated energy recovery of about 40–45 %. NMR analysis of bio-crude revealed that it is a complex mixture mainly constituted by aliphatic units. Moreover, ICP-MS, atomic absorption and UV–visible spectroscopy analyses proved that inorganic elements are mainly retrieved in the solid residue, and that Cr was present in its starting trivalent form.

Green hydrogen is a promising energy carrier for the decarbonization of hard-to-abate sectors and supporting renewable energy integration, aligning with carbon neutrality goals like the European Green Deal. Iceland’s abundant renewable energy and decarbonized electricity system position it as a strong candidate for green hydrogen production. Despite early initiatives, its hydrogen economy has yet to significantly expand. This study evaluated Iceland’s hydrogen development through stakeholder interviews and a techno-economic analysis of alkaline and PEM electrolyzers. Stakeholders were driven by decarbonization goals, economic opportunities, and energy security but faced technological, economic, and governance challenges. Recommendations include building stakeholder confidence, financial incentives, and creating hydrogen-based chemicals to boost demand. Currently, alkaline electrolyzers are more cost-effective (EUR 1.5–2.8/kg) than PEMs (EUR 2.1–3.6/kg), though the future costs for both could drop below EUR 1.5/kg. Iceland’s low electricity costs and high electrolyzer capacity provide a competitive edge. However, this advantage may shrink as solar and wind costs decline globally, particularly in regions like Australia. This work’s findings emphasize the need for strategic planning to sustain competitiveness and offer transferable insights for other regions introducing hydrogen into ecosystems lacking infrastructure.

Climate change is expected to alter the population dynamics of pioneer tree species and their planned use in sustainable forest management, but we have a limited understanding of how their demographic rates change in response to climate changes during ecological restoration. Based on 12 years of demographic data for a pioneer tree species (Pinus massoniana) censused in three plots that correspond to three stages of ecological restoration in southeastern China. We built integral projection models (IPMs) to assess vital rates (survival, growth, reproduction) and population growth in each plot, then evaluated demographic changes to simulated changes in seasonal mean temperature and precipitation in the current and previous census period. The plot representing the medium restoration stage had the highest population growth rate (λ = 0.983). Mean population survival probability increased with ecological restoration, and reproduction probability was significantly suppressed at the high restoration stage. Survival is always the most important vital rate for λ, and climate affects λ primarily via survival at each restoration stage. The current spring temperature was the most critical climate variable for λ in the low and medium restoration stages, and previous summer temperature was most critical in the high restoration stage. Simulated warming leads to a decrease in the stochastic population growth rate (λs) of P. massoniana in every stage. These findings suggest that during ecological restoration, P. massoniana responds to habitat change via modified demographic performance, thus altering its response to climate change. Despite diverse responses to climate change, the persistence of P. massoniana populations is facing a widespread threat of warming states at each restoration stages.

Operating a reliable electricity system requires strict safety and security criteria such as avoiding grid congestion, minimum levels of inertia, maintaining voltage levels, and minimum adequacy reserves. However, large scale integration of intermittent renewables, namely inverter-based resources (IBR), is creating operational challenges. When operational security criteria are not met, system operators use ancillary services (redispatching) to activate or curtail scheduled units to manage the flows. In Spain, the volumes and costs of redispatching have multiplied by two and nine times between 2019 and 2023, respectively. In 2023, the total costs amounted to 2 b€, for curtailing 3 TWh wind and 0.9 TWh photovoltaics. A similar picture is emerging in other countries. This is the first study to examine the determinants of network constraints associated with redispatched volumes at country level. We use the seasonal autoregressive ARIMA time-series estimators with hourly operational and market data (2019–2023). Results show that actions to alleviate grid bottlenecks amount to one-third of the volumes, and increasing every year with addition of wind, photovoltaics and thermosolar generation. Volumes for solving voltage issues (reactive energy needs) represent one-half. Scheduled MWh from IBR (wind and photovoltaics) increases volumes for voltage problems (+0.05 MWh) and congestion issues (+0.01 MWh). Scheduled MWh from CHP contributes to congestion issues (+0.18 MWh), while thermosolar to grid reliability (N-1) problems (+0.25 MWh). The day-ahead and intraday markets can make economically efficient allocation of units, but massive connection of renewables requires increasing actions by system operators. Operational and regulatory decisions must be taken in advance to avoid the issue in the future.

Novel fire regimes are emerging worldwide and pose substantial challenges to biodiversity conservation. Addressing these challenges and mitigating their impacts on biodiversity will require developing a wide range of fire management practices. In this paper, we leverage research across taxa, ecosystems and continents to highlight strategies for applying fire knowledge in biodiversity conservation. First, we define novel fire regimes and outline different fire management practices in contemporary landscapes from different parts of the world. Next, we synthesize recent research on fire use and biodiversity, and provide a decision-making framework for biodiversity conservation under novel fire regimes. We recommend that fire management strategies for preserving biodiversity should consider both social and ecological factors, iterative learning informed by effective monitoring, and developing and testing new management actions. An integrated approach to learning about fire and biodiversity will help to navigate the complexities of novel fire regimes and preserve biodiversity in a rapidly changing world. This article is part of the theme issue ‘Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks’.

ABSTRACTFreshwater ecosystems face significant threats, including pollution, habitat loss, invasive species, and climate change. To address these challenges, management strategies and restoration efforts have been broadly implemented. Across Europe, such efforts have resulted in overall improvements in freshwater biodiversity, but recovery has stalled or failed to occur in many localities, which may be partly caused by the limited dispersal capacity of many species. Here, we used a comprehensive dataset comprising 1327 time series of freshwater macroinvertebrate communities ranging from 1968 to 2021 across 23 European countries to investigate whether dispersal capacity changes with the ecological quality of riverine systems. Sites experiencing improvements in ecological quality exhibited a net gain in species and tended to have macroinvertebrate communities containing species with stronger dispersal capacity (e.g., active aquatic and aerial dispersers, species with frequent propensity to drift, and insects with larger wings). In contrast, sites experiencing degradation of ecological quality exhibited a net loss of species and a reduction in the proportion of strong dispersers. However, this response varied extensively among countries and local sites, with some improving sites exhibiting no parallel gains in macroinvertebrates with higher dispersal capacity. Dispersal capacity of the local species pool can affect the success of freshwater ecosystem restoration projects. Management strategies should focus on enhancing landscape connectivity to create accessible “source” areas and refugia for sensitive taxa, especially as climate change reshapes habitat suitability. Additionally, biodiversity initiatives must incorporate adaptive decision‐making approaches that account for the site‐specific responses of macroinvertebrate communities to changes in ecological quality.

This deliverable documents the establishment of the HEPHAESTUS Green Living Lab (HGLL) on Bornholm, Denmark. It outlines the conceptual foundations, co-creation processes, stakeholder engagement, implementation activities, and evaluation framework used to develop the Living Lab. Guided by New European Bauhaus values and Living Lab principles, the HGLL connects craft heritage with circular economy experimentation, positioning Bornholm as a “test island” for sustainable innovation in the craft sector.