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Abstract This paper deals with thermal efficiency enhancement analysis of a solar water heating system with a solar tracker. Made at laboratory-scale, an automated mechanical system enables solar panel rotation and inclination. The control system is programmed to place the solar panels facing the sun throughout the day. Its coordinates by means of the solar height and the azimuthal angle will determine the sun position on the celestial sphere. The thermal behaviour of the solar water heating system is developed with energy balance on solar panels, heat exchanger and storage system. The solar irradiation intensity is measured by a pyranometer placed in the plan of the solar panels. Comparison between experimental results obtained for fixed inclinations of solar panels and those obtained with the solar tracker shows a 40% gain of overall stored thermal energy. The energy gain depends on the season. The low inclinations are still favourable in summer while in winter they are higher inclinations are needed.

The Normandy region is prone to gravitational movements of various kinds (mudflows, rockfalls, rotational or translational landslides, etc.). The Pays d'Auge, at the contact between the Armorican Massif and the Paris Basin, is particularly concerned by these processes, due to a wide lithological variability and the sensitivity of materials to the presence of water. Many researches have been carried out in hinterland and coastal areas, contributing to the understanding of the landforms and the processes at work.Within the framework of the ANR RICOCHET program, this PhD thesis aims to provide some answers regarding the hazard assessment, both in terms of predisposing and triggering factors. The studied area extends specifically at the coastal and hinterland fringe of the Pays d'Auge, in the lower valley of the Touques river.Using a multidisciplinary approach combining geomorphology, geophysics, hydrogeology and geotechnics, investigations were carried out on three representative sites of landslide phenomena affecting this territory. By using existing data sets, completed by new acquisitions, this work aims to improve the knowledge of the hydromechanical functioning of each major type of landslide considered. The stability of the sites was assessed using numerical models based on finite element (SLOPE/W®) and finite difference (FLAC®) methods. A spatialized assessment of the susceptibility and hazard is then carried out at a larger scale (1:10,000) by the joint use of (1) a physically based model to simulate the triggering probability (ALICE®) and (2) an empirical model for the propagation (Flow-R®). The landslide sensitivity is highlighted with respect to current forcing, and considering the expected influence of climate change. ; La région Normandie est sujette aux mouvements gravitaires de diverses natures (coulées de boues, éboulements, glissements de terrain rotationnels ou translationnels, etc.). Le Pays d’Auge, au contact entre Massif armoricain et Bassin parisien, est particulièrement affecté par ces ...

In the context of climate change, Arctic marine ecosystems are affected by rapid environmental modifications, whose effects on biotic communities are still debated. The sea-ice decline and the increase in freshwater inputs and turbidity are likely to impact Arctic primary producers, with cascade effects on a key-process in those ecosystems: the trophic relationship between primary producers and benthic consumers (generally referred as “pelagic-benthic coupling”). The direct study of such complex interaction is not straightforward in the Arctic. The biological model of filter-feeding bivalves offers the possibility to get around these problems, allowing to study those ecological processes indirectly. Among the advantages of this model, there is first of all the fact that these organisms record in their shell, in the carbonate layers, some dynamics of their environments. The information recorded in such “bioarchives” are interpreted through the methods of sclerochronology and sclerochemistry and relate to a time window corresponding to the organism lifespan (from some years to more than 500 years). Given that these organisms are primary consumers, another advantage of this biological model is that the study of their diet can provide information about the trophic relationship with primary producers. With the methods of trophic ecology, especially fatty acids and stable isotopes, the study of the tissues allows the investigation of sources assimilated at a timescale of weeks/months.The main objective of this thesis is to test the potential of bivalves Astarte moerchi (borealis complex) as a biological model for the study of marine Arctic ecosystems. A coupled approach is used to combine shell analysis by the methods of sclerochronology and sclerochemistry (elemental ratios) and tissue analysis by the methods of trophic ecology (fatty acids, carbon and nitrogen stable isotopes, compound-specific carbon stable isotopes on individual fatty acids). Two living A. moerchi populations have been studied in two fjords ...

Biofouling is an important factor to consider when calculating the energetic efficiency of tidal farms. Despite the fact that biofouling effects have been widely investigated in the past for naval applications, very few studies concern tidal turbines. This paper proposes a numerical approach to assess the impact of biofouling on tidal turbines, which is efficient for testing many configurations. Two turbulence models are tested (RANS k-ω SST and LES Smagorinsky) for the motionless blade case to validate them. Then we chose to use the Smagorinsky model for the case of a complete tidal turbine rotor with realistically fouled blades. The pressure coefficient is strongly affected by the barnacle in the motionless blade case and the power coefficient is slightly degraded in the complete rotor case. Motionless blade cases do not represent the real biofouling behaviour for two reasons. First, sessile species settle in the down flow part of the chord where their impact is less important. Then, the surrounding turbulence provoked by the blades rotation in the rotor case reduces the impact of biofouling. In the wake, biofouling generates small vortexes that propagate into the larger ones, causing them to spread their energy.

Knowledge of rheological evolution of biomass during dry anaerobic digestion (D-AD) is important in the engineering design, modeling, and operation of D-AD reactors. In this work, two methods of rheological analysis, the slump test and the shear-box, were used to measure the evolution of the yield stress, cohesion and friction angle of the straw-cattle manure (SCM) during the D-AD. Firstly, four 60 L batch leach-bed reactors (LBR) were started in parallel and stopped at different stages of the D-AD process on days 0, 10, 21 and 31. Secondly, a 500 L and 2 m length plug flow reactor (PFR) was operated with 40 days of solid retention time and samples were recovered at different positions. The solid degradation during D-AD process was monitored by analysis of the degradation of volatile solids, the fiber content and the Flash BMP. Similar degradation patterns of SCM and rheological evolution were observed in both reactors type. VS content decreased of 10.7% and 10.2% in 30 days in PFR and LBR respectively. VS degradation in both cases was well explained by hemicellulose and cellulose consuming in D-AD process. Considering the rheological analysis, the results showed that D-AD induced a reduction of the yield stress of 28.1 and 24.2% in 30 days in PFR and LBR respectively. Moreover, a similar evolution of cohesion and friction angle value for samples from both reactors was observed. This study demonstrates the close relationship between the state of degradation of the solid biomass and its rheological properties.

Abstract Energy communities will play a central role in the sustainable energy transition by helping inform and engage end users to become more responsible consumers of energy. However, the true potential of energy communities can only be unlocked at scale. This scalability requires data-driven solutions that model not just the behavior of building occupants but also of energy flexible resources in buildings, distributed generation and grid conditions in general. This understanding can then be utilized to improve the design and operation of energy communities in a variety of real-world settings. However, in practice, collecting and analyzing the data necessary to realize these objectives forms a large part of such projects, and is often seen as a prohibitive stumbling block. Furthermore, without a proper understanding of the local context, these projects are often at risk of failure due to misplaced expectations. However, this process can be considerably accelerated by utilizing open source datasets and models from related projects, which have been carried out in the past. Likewise, a number of open source, general-purpose tools exist that can help practitioners design and operate LECs in a near-optimal manner. These resources are important because they not only help ground expectations, they also provide LECs and other relevant stakeholders, including utilities and distribution system operators, with much-needed visibility on future energy and cash flows. This review provides a detailed overview of these open-source datasets, models and tools, and the many ways they can be utilized in optimally designing and operating real-world energy communities. It also highlights some of the most important limitations in currently available open source resources, and points to future research directions.