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Abstract In case of a core melt-down accident in a light water nuclear reactor, hydrogen is produced during reactor core degradation and released into the reactor building. This subsequently creates a combustion hazard. A local ignition of the combustible mixture may generate standing flames or initially slow propagating flames. Depending on geometry, mixture composition and turbulence level, the flame can accelerate or be quenched after a certain distance. The loads generated by the combustion process (increase of the containment atmosphere pressure and temperature) may threaten the integrity of the containment building and of internal walls and equipment. Turbulent deflagration flames may generate high pressure pulses, temperature peaks, shock waves and large pressure gradients which could severely damage specific containment components, internal walls and/or safety equipment. The evaluation of such loads requires validated codes which can be used with a high level of confidence. Currently, turbulence and steam effect on flame acceleration, flame deceleration and flame quenching mechanisms are not well reproduced by combustion models usually implemented in safety tools and further model enhancement and validation are still needed. For this purpose, two hydrogen deflagration benchmark exercises have been organised in the framework of the SARNET network. The first benchmark was focused on turbulence effect on flame propagation. For this purpose, three tests performed in the ENACCEF facility were considered. They concern vertical flame propagation in an initially homogenous mixture with 13 vol.% hydrogen content and different geometrical configurations. Three blockage ratios of 0, 0.33 and 0.6 were considered to generate different levels of turbulence. The second benchmark objective was the investigation of the diluting effect on flame propagation. Thus, three tests performed in the ENACCEF facility using the same blockage ratio of 0.63 and three different initial gas compositions (with 10, 20 and 30 vol.% diluents) have been considered. Since ENACCEF runs at ambient temperature, a surrogate to steam was used consisting of a mixture of 0.6He + 0.4CO 2 on molar basis. This paper aims to present the benchmarks conclusions regarding the ability of LP and CFD combustion models to predict the effect of turbulence and diluent on flame propagation.

District heating is a network of pipes through which heat is delivered from a centralised source. It is expected to play an important role in the decarbonisation of the energy sector in the coming years. In district heating, heat is traditionally generated through fossil fuels, often with combined heat and power (CHP) units. However, increasingly, waste heat is being used as a low carbon alternative, either directly or, for low temperature sources, via a heat pump. The design of district heating often has competing objectives: the need for inexpensive energy and meeting low carbon targets. In addition, the planning of district heating schemes is subject to multiple sources of uncertainty such as variability in heat demand and energy prices. This paper proposes a decision support tool to analyse and compare system designs for district heating under uncertainty using stochastic ordering (dominance). Contrary to traditional uncertainty metrics that provide statistical summaries and impose total ordering, stochastic ordering is a partial ordering and operates with full probability distributions. In our analysis, we apply the orderings in the mean and dispersion to the waste heat recovery problem in Brunswick, Germany.

Access to reliable and affordable energy is vital for sustainable development. In the off-grid areas of developing countries, decentralized energy solutions have received increasing attention due to their contributions to reducing poverty. However, most of the rural population in many developing countries still has little or no access to modern energy technologies. This paper assesses the factors that determine the successes and failures of decentralized energy solutions based on local harmonized case studies from heterogeneous contexts from Asia, sub-Saharan Africa, and South America. The case studies were analyzed through the coupled lenses of energy transition and the Water–Energy–Food Security (WEF) Nexus. The findings indicate that access to modern decentralized energy solutions has not resulted in complete energy transitions due to various tradeoffs with the other domains of the WEF Nexus. On the other hand, the case studies point at the potential for improvements in food security, incomes, health, the empowerment of women, and resource conservation when synergies between decentralized energy solutions and other components of the WEF Nexus are present.

Unequivocal change in the climate system has put coastal regions around the world at increasing risk from climate-related hazards. Monitoring the coast is often difficult and expensive, resulting in sparse monitoring equipment lacking in sufficient temporal and spatial coverage. Thus, low-cost methods to monitor the coast at finer temporal and spatial resolution are imperative for climate resilience along the world’s coasts. Exploiting such low-cost methods for the development of early warning support could be invaluable to coastal settlements. This paper aims to provide the most up-to-date low-cost techniques developed and used in the last decade for monitoring coastal hazards and their forcing agents via systematic review of the peer-reviewed literature in three scientific databases: Scopus, Web of Science and ScienceDirect. A total of 60 papers retrieved from these databases through the preferred reporting items for systematic reviews and meta-analyses (PRISMA) protocol were analysed in detail to yield different categories of low-cost sensors. These sensors span the entire domain for monitoring coastal hazards, as they focus on monitoring coastal zone characteristics (e.g., topography), forcing agents (e.g., water levels), and the hazards themselves (e.g., coastal flooding). It was found from the meta-analysis of the retrieved papers that terrestrial photogrammetry, followed by aerial photogrammetry, was the most widely used technique for monitoring different coastal hazards, mainly coastal erosion and shoreline change. Different monitoring techniques are available to monitor the same hazard/forcing agent, for instance, unmanned aerial vehicles (UAVs), time-lapse cameras, and wireless sensor networks (WSNs) for monitoring coastal morphological changes such as beach erosion, creating opportunities to not only select but also combine different techniques to meet specific monitoring objectives. The sensors considered in this paper are useful for monitoring the most pressing challenges in coastal zones due to the changing climate. Such a review could be extended to encompass more sensors and variables in the future due to the systematic approach of this review. This study is the first to systematically review a wide range of low-cost sensors available for the monitoring of coastal zones in the context of changing climate and is expected to benefit coastal researchers and managers to choose suitable low-cost sensors to meet their desired objectives for the regular monitoring of the coast to increase climate resilience.

The EU has set clear targets regarding energy conservation of buildings and heavily supports activities towards achieving these targets on a European scale. The Green Deal, renovation wave, Energy Performance of Buildings Directive (EPBD) and Energy Efficiency Directive (EED) are some examples of EU's actions. For more than a decade, Energy Performance Certificates provide detailed data about the current energy needs of a building/building unit as well as information about the building construction and systems. A Building Renovation Passport (BRP) has, on a European level lately, been conceived as a tool that can stimulate cost-effective renovation in the form of a long-term basis, step-by-step deep renovation roadmap following defined quality criteria, and outline energy renovation measures that will improve the energy performance of the building. A Digital Building Logbook (DBL) is another tool that can serve as an archive where all building information can be stored and continuously updated. In this way, a full record of the building history will be electronically available with data regarding construction plans and permits, maintenance and system replacement activities, energy and heat consumption and production, etc. Building Renovation Passports and the Digital Building Logbook are tools that can help in achieving energy efficiency in existing buildings and contribute to reaching the EU renovation wave goals. The objective of this report is to investigate how the current EPC schemes best make the link towards the BRP and the DBL to further incentivise and stimulate cost-effective deep energy renovations of buildings across Europe. Three surveys were carried out to collect relevant information about the current status of the EPC data records and to identify stakeholders' potential needs, perceptions, thoughts and expectations, regarding a future connection between the EPC and the BRP or DBL. These surveys were prepared in two forms: using an excel file format circulated via email, and through an online questionnaire. Their completion was carried out by 16 countries. Regarding the EPCs, the state or regional energy agencies are the owner of the EPC data records and make full use of them. Their current main usage is for statistical reasons in the majority of the countries and their access is publicly available in half of the responding countries. Many common data is stored in the EPC database which can be linked with other tools (half of the EPC databases are already linked with another source). Regarding the BRP, a review of existing European schemes showed that successful BRPs have combined the renovation advice with financial support, legal requirements and/or communication campaigns. An important factor of the BRP is that it should be issued by a qualified expert and should provide customised measures for the specific building together with the investment costs per renovation measure(s). The DBL analysis showed that it should provide access to building information and contribute to better decision-making for future interventions as well as operation, use and maintenance records. The building owner/user is proposed to have full access to the logbook and provide/input about energy bills and building plans/construction materials info. An important aspect is that every time the building undergoes intervention works, the DBL should be updated accordingly. The most important barrier is the lack of motivation to update the DBL contents followed by the absence of synergies and consistency with other tools. Another interesting finding is that both BRP and DBL should be fed automatically by EPC data without any user interference. There is a clear possible interconnection between EPC data and BRP and DBL future contents. In addition, BRP can be an instrument to increase the renovation rates and DBLs are necessary for the management of buildings' information. The linkage of EPC data and BRP and DBL can be strengthened by introducing BRP and DBL as voluntary schemes under national incentives and should be fully implemented once they have demonstrated acceptance by the stakeholders.

Abstract. The assessment of wind conditions in complex terrain requires the use of Computational Fluid Dynamics (CFD) simulations incorporating an accurate parameterization of forest canopy effects and variable thermal stability effects. This study aims to investigate how incorporating the presence of trees can improve flow predictions. A three-dimensional steady Reynolds-averaged Navier-Stokes (RANS) equations model is set up using OpenFOAM to simulate the flow over a complex terrain site comprising two parallel ridges located near Perdigão, Portugal. A 7.5 km × 7.5 km terrain of the Perdigao site is constructed from elevation data centered around a 100 m met-mast located on the northeast ridge. A 30-min averaged stationary period corresponding to near-neutral conditions on a single met-mast tower is simulated. The impact of incorporating different source terms is studied such as forest canopy, Coriolis forces as well as also buoyancy forces. The prediction capability of the models is analyzed for different groups of towers on the South-West ridge, inside the valley, and on the North-East ridge based on the flow topology. The inclusion of a canopy model is shown to improve predictions close to the ground for most of the towers, while reducing prediction accuracy on top of the ridges, illustrating the need to represent terrain heterogeneity.

Abstract Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are increasingly used to reconstruct mean annual air temperature (MAAT) during the early Paleogene. However, the application of this proxy in coal deposits is limited and brGDGTs have only been detected in immature coals (i.e. lignites). Using samples recovered from Schoningen, Germany (∼48°N palaeolatitude), we provide the first detailed study into the occurrence and distribution of brGDGTs through a sequence of early Eocene lignites and associated interbeds. BrGDGTs are abundant and present in every sample. In comparison to modern studies, changes in vegetation type do not appear to significantly impact brGDGT distributions; however, there are subtle differences between lignites – representing peat-forming environments – and siliciclastic nearshore marine interbed depositional environments. Using the most recent brGDGT temperature calibration (MATmr) developed for soils, we generate the first continental temperature record from central-western continental Europe through the early Eocene. Lignite-derived MAAT estimates range from 23 to 26 °C while those derived from the nearshore marine interbeds exceed 20 °C. These estimates are consistent with other mid-latitude environments and model simulations, indicating enhanced mid-latitude, early Eocene warmth. In the basal part of the section studied, warming is recorded in both the lignites (∼2 °C) and nearshore marine interbeds (∼2–3 °C). This culminates in a long-term temperature maximum, likely including the Early Eocene Climatic Optimum (EECO). Although this long-term warming trend is relatively well established in the marine realm, it has rarely been shown in terrestrial settings. Using a suite of model simulations we show that the magnitude of warming at Schoningen is broadly consistent with a doubling of CO2, in agreement with late Paleocene and early Eocene pCO2 estimates.