• Energy Research
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For reasons of environment protection and energy security, the share of renewable resources in the global energy supply is now rising at an overwhelming rate. The European Commission has set the target to reach a 20% share of energy from renewable sources by 2020 and further increases of this already ambitious objective will follow. A large fraction of this growth is to come from wind power. The production of electricity from this resource is both spatially distributed and highly dependent on atmospheric conditions and thus intermittent in nature, leading to challenging planning and risk management problems for the stakeholders of the wind energy industry. These new challenges, in particular, those related to investment planning and grid integration under the conditions of large-scale wind generation, call for better understanding of the spatial and temporal distribution of the wind resource and wind power production via precise statistical and probabilistic models. Besides, recent advances in climatology show that it may be possible to develop medium and long-term (seasonal to decadal) probabilistic forecasts of the wind power output with a better performance than that of forecasts based on climatological averages, leading to improved risk management tools for wind power producers and grid operators. The project FOREWER aims to address these crucial issues through a synergy between the statistical and probabilistic methodology and the modern meteorological models. This multidisciplinary public-private partnership brings together mathematicians working on stochastic modeling and risk management, statisticians, and meteorologists from the academic community as well as engineers from the key players of the renewable energy industry. Our goal is first of all to develop reliable theoretical and numerical models and scenario generators for the wind resource distribution and power output at various spatial and temporal scales with a focus on medium to long term (seasonal to decadal). We shall then evaluate the potential of these tools for solving the forecasting and risk management problems relevant for the industrial partners of the project, such as the evaluation of the sensitivity of a proposed wind farm to climate variability and optimal placement of wind farms, determination of the required capacity of back-up generators and optimal operation of these assets, and integration of renewable power sources into the grid. On the one hand, state of the art statistical and probabilistic modeling tools (wavelets, stochastic processes) will be applied to the historical weather simulations performed at LMD (consortium partner), in order to understand the multiscale behavior of the wind resource, analyze its variability modes and identify the predictable components of the distribution. On the other hand, powerful statistical learning methods, developed by the statistics group at LPMA (coordinating partner) will be adapted to identify the salient predicting features as well as the connections between renewable power production and the meteorological variables. The statistical forecasting methodology successfully used by LPMA to predict the power consumption curve will be adapted to obtain seasonal and decadal projections of these relationships and produce reliable probabilistic forecasts of the renewable power production taking into account the climate non-stationarity. The major innovations of the proposed project are - Analysis of the medium and long-term probabilistic predictability of the wind resource using state-of-the-art statistical tools. - The end-to-end approach, which consists in considering the whole chain of wind power production from the modeling and prediction of the renewable resource to the management of the associated risks. The predictive power of our models will be analyzed in case studies with our industrial partners.

Concerted research of 4 research groups involving chemical synthesis, laser spectroscopy, electrochemistry, and theory will be aimed at demonstrating the suitability of new heteroleptic copper(I) complexes for solar energy conversion schemes. While the area of photochemistry is dominated by ruthenium(II) polypyridine complexes, little attention has been paid to copper(I) complexes. One particularly significant driving force of this program lies in the lower cost, higher abundance and lower toxicity of copper compared to ruthenium. New heteroleptic copper complexes will be prepared and investigated with respect to advancing two areas: (i) novel photo- and electro- active rod-like molecular arrays of the general type Donor-Sensitizer-Acceptor in view of long range photoinduced charge separation and (ii) photo-electrochemical devices based on the sensitization of p-type semiconductor (NiO). Synthesis, characterizations and theoretical research will be twinned aiming at a rational design of the complexes in view of the envisioned function. The expected results are the synthesis and the discovery of new copper(I) complexes with useful photophysical properties, which will in turn lead to new breakthroughs in the rational design of copper complexes for long-range photoinduced charge separation and for photoelectrochemical devices, where traditional ruthenium complexes are used. All this will be of fundamental importance for establishing new materials for solar energy convsersion.

In this 36 months material-modeling project, we aim at providing through a theoretical design a new generation of nano-objects able to convert sunlight into energy and store it in an efficient fashion. To this end we will make use of the so-called Molecular Solar Thermal (MOST) process, where the irradiation of an organic photochrome with solar light permits the switching to a second isomer, higher in energy (energy storage step), while the return to the most stable isomer with the help of a less energetic external stimulus induces the energy excess release as heat (energy release step). In the FALCON project, we propose to go beyond the current state of the art of MOST process in solution and use the functionalization of metallic NanoParticle (NP) has a mean of attaining optoelectronic nanomaterial with superior solar energy storage abilities. Coating NPs with organic photochromes will indeed permit a fine control of the molecules density, a critical parameter in the energy storage mechanism, and potentially enhance the switching process of the molecule due to the effect of the Localized Surface Plasmon Resonance (LSPR) of the NP. To reach this goal, the FALCON project is dedicated to the in-silico design of NP-photochromes solar thermal fuel devices with the help of atomistic modelling. The development of a theoretical approach is crucial as it will permit an in-depth understanding of the non-trivial interactions between the two parts of the device, that are today yet to be fully rationalized with quantum chemistry models. It will also save precious time, raw material and human resources prior to the experimental device fabrication. This computational design is however by definition a challenge for fundamental research, as one would need quantum mechanics model to describe the electronic interactions in the device up to a very large scale, much larger than the consideration of a sole molecule. So far, no computation method has been able to provide an atomic quantum description to contribute to the development of hybrid nanomaterial. The FALCON project aims at fulfilling this blank with the help of computations based on the Density Functional Tight Binding (DFTB) model, as it allows a quantum description of the electrons at a very low computational cost, once correctly parameterized. We thus propose to set up a specific DFTB protocol able to fully describe the ground state and excited states of these nano-objects, granting access to i) the description of the photochromic process of the molecules onto the NP, under the LSPR influence, ii) the quantity of energy stored during this process, and ultimately iii) the design of new devices with optimized properties. To achieve this goal a large part of the project is dedicated to the construction of a new DFTB parameterization able to describe accurately both the metallic NP and the organic photochromes properties. Once correctly set up, the second half of the project applies this theoretical tool to explore the photochromic and energy storage capabilities of various NP-photochromes hybrid systems, to establish general design rules and finally propose more efficient systems. The success of this fundamental project will permit to speed up the fabrication of complex functional nano-objects, in future large-scale experience/theory collaborations, in the critical field of renewable energy. Furthermore, DFTB computational schemes constructed during this project will be a real breakthrough for the material modeling community and will permit subsequent functionalized NP modeling for other applications.

Inorganic thin film photovoltaics (PV) are mainly based on CdTe, amorphous Si or CIGS. In the most recent times, hybrid organo-metal halide perovskites have emerged with the highest conversion efficiencies reported of 20.1 %. However, these materials present stability, reliability, scalability and toxicity problems. Of course, research in this area is focusing hard on these challenges, but success is not guaranteed. Alternative inorganic oxides could offer significant advantages. The ideal bandgap of an active photovoltaic layer for the solar spectrum is around 1.3 eV. However oxides with low bandgaps are scarce. One of the most studied oxides as an active photovoltaic layer to date is cuprous oxide, Cu2O. Its bandgap is around 2.1 eV and so it is not ideal for the solar spectrum. Its conversion efficiencies do not generally exceed 4%. In this project we propose to study an emerging type of solar cells that is based on ferroelectricity. In this type of solar cell, a p-n junction is not necessarily needed, as opposed to conventional cells. Interesting efficiencies start to be obtained with this type of solar cells (up to 8.1 %, in 2015), yet the mechanisms are still not well understood and there are several materials and engineering issues to be tackled. The objective of this project is to initiate a game-changing photovoltaic technology based on new multifunctional inorganic oxide materials with suitably low bandgaps. These oxides are stable, non-toxic, abundant and processable by a range of scalable methods. Radically enhanced performance is certainly possible through incorporating multifunctionality into them. There are five highly structured WPs in this project which when put together will ensure the greatest chance of success. We aim to synthetize ferroelectric materials that absorb a large part of the solar spectrum and have reduced bandgaps. We will explore four types of materials with promising properties: BiMnO3, doped BiFeO3, Bi2FeCrO6, and doped TbMnO3. For these materials, the project will consist in growing thin films and assess their structural, optical and electrical properties to better understand these materials. Then, the most promising materials will be integrated into all oxide solar cells and their potential for photovoltaics will be evaluated.

Nowadays, the impacts of construction on environment and health became major stakes. Problems linked with the indoor air quality are considered to be an important risk factor for human health. The current trend tends to improve environmental quality of buildings, dealing with thermal performances, hygrothermal comfort and the use of materials with low impacts. For various reasons (patrimonial, environmental, economic…), there is a resurgence of interest in materials used by human since centuries, as earth and bio-based materials (wood, plant fibres and aggregates). Earth is said to improve moisture regulation into the buildings and consequently users’ comfort. Earth is commonly reinforced or lightened with plant matters. However, under some conditions, development of moulds was observed on the surface of these materials raising many questions as for their use. The BIOTERRA project aims to identify, characterize and offer one (or more) solution(s), with low environmental impact, to the microbial proliferation on earth bio-based products (bricks and plasters) used for construction and restoration of health and durable buildings. This project also aims to develop and validate innovative methodologies for the identification of the microbial strains and the study of their proliferation on building materials. BIOTERRA project is articulated around 4 technical tasks and 2 additional tasks on project management and valorization of the results. The first task will concern mostly the choice of raw materials (earth and plant aggregates), the fabrication of materials of study (bricks and plasters) and the identification of microbial strains present in earth building heritage and in the raw materials used for the study. The second and third tasks will be carried out in parallel and will be strongly interdependent. Task 2 will concern the functional properties of studied materials; in particular, their hygrothermal properties which impact comfort and microbial proliferation studied in task 3. The use of modeling will allow dealing in depth with the experimental results. The main objective of the third task is the study of microbial proliferation and their influent parameters for identified and isolated strains during task 1. Furthermore some solutions to limit proliferation will be evaluated (various recommendations and biological control in order to limit the impact on health). The identification of microbial strains (task 1) and the study of their proliferation (task 3) will be based on the development of innovative methodologies. Lastly, task 4 will concern the validation of tasks 2 and 3 on a large scale with, in particular, the monitoring of offices in building equipped with removable partition-walls made with materials of the study. This highly multi-disciplinary project brings together 9 partners including 5 laboratories: the “Laboratoire Matériaux et Durabilité des Constructions” (LMDC), the project coordinator, the “Laboratoire Génie Civil et Bâtiment” (LGCB), the “CETE of Lyon”, the “Laboratoire de Génie Chimique” (LGC) and the “Laboratoire de Recherche en Sciences Végétales” (LRSV). The “Centre Technique de Matériaux Naturels de Construction“ (CTMNC) reinforces this consortium. Finally, three other industrial partners will participate in this project: Agencement-structure, Agronutrition et les Carrières du Boulonnais.

The CNRS / Université de Pau et des Pays de l'Adour, in collaboration with the world's leading producer of organic solar cells, OPVIUS GmbH, and local politicians and artisans in the Vic-Montaner region, has recently demonstrated that it is possible to produce large-scale (1.5 x 0.7 m) organic solar panels (OSPs), that are lightweight (10.2 kg) and have robust polycarbonate encapsulation. The project attracted a great deal of attention in the press (google Baylère, Hiorns, Vic-Montaner, Sud-Ouest for example) and in local communities. Importantly, unlike perovskite-based devices, these panels are non-toxic and fully recyclable. They are installed with minimal effort on public buildings for on-site use of generated electricity, even in restricted zones areas due to their colour adaptability. This is an important step in the industrialization of OSPs. Silicon solar cells should be placed directly facing the sun to give their maximum efficiency, otherwise they lose up to 50% of their power output depending on the angle of the sun. This is not the case for OSPs. They work at all angles, just as well. This opens up a vast area that is available on the walls of private and public buildings. For example, lightweight and ergonomic, our polycarbonate panels are easy to install. It should also be noted that local laws (in France imposed by Bâtiments de France) restrict the implantation of silicon cells in villages. However, we have already negotiated with them locally to ensure that OSPs are now accepted within 500 m of sacred and culturally important buildings. These two elements open up a large market for OSPs in France. However, the daily power of the OSPs is still less than that of silicon cells. Therefore, we will build a project to close the efficiency gap between the power produced by silicon cells and OSPs. This project will be called "Increasing the efficiency of large-scale photovoltaic panels" (ELEVATE). It will aim to improve the efficiency of OSPs so that they are equivalent to Si-based panels on vertical walls. To achieve this objective, ELEVATE will need to bring together the key, highest quality teams from across Europe working in the following fields: i) macromolecular chemistry, ii) physics of devices and modules, ii) polymer processing, iv) physical characterization, and v) modelling that will deliver: new materials; new module architectures; new film processing techniques; depth characterization of materials; and predicting the best macromolecules and understanding their behaviour. ELEVATE will call on the world-leading OSP manufacturers, OPVIUS, and will integrate the leading manufacturers of semi-conducting materials. To solve the challenge of high-performance OSPs, we will rely on the leading academics in each relevant area from across Europe. While France has exceptional talents, ELEVATE would not be possible at a national level alone due to the extremely diverse and cross-science level of industrial and academic expertise required. To build ELEVATE will be a project in itself. For this reason, this project, called INFO was developed to finance project construction meetings, determine working groups, decide on milestones and deliverables, and take into account the needs of public interactions. Given the high public profile of the project ELEVATE, particular attention will be given to fostering open scientific activities with scientific communities, the general public and schools throughout the world.

The aim of the STAID project (Seasonal Thermochemical heAt storage In buildings) is the design and evaluation of a compact seasonal thermochemical heat storage system for building application. The thermal energy storage material is a zeolite/magnesium sulphate composite; one task of the project dealing with the optimization of the material to increase the storage energy density. These materials have been chose because of their low price and low environmental footprint. One key point of the project is the integration of the composite material in the reactor of the thermal energy storage system. Then, the reactor will be design according to the required heating power and energy storage needs. The reactor will be coupled with an air thermal collector. During the sunny days, hot air coming from the collector is passing through the reactor in order to dehydrate the composite material and then to store thermal energy. During the cold days, the moist air coming from the interior of the building is used to release heat in the airflow. The heat is then transferred to the new air from the exterior via a heat exchanger system. The so designed system will allow a long term thermal energy storage without heat losses.

The BAGETE project will focus on the development of nanostructurated metal oxide electrodes for their use as photo-anodes for hydrogen production by Photo-ElectroChemical (PEC) water splitting. This project fits in the frame of the Challenge 2 “Clean, safe and effective energy” for the Young Scientist competition. Solar energy is an attractive renewable energy source with low environmental impact. However, it remains a challenge to produce a continuous flow of usable energy from sunlight, due to the diffuse and fluctuating nature of the solar irradiation. Therefore this project aims at developing new materials that can directly convert solar energy into energetic chemical species, also called “solar fuels”, which can be stored and distributed on demand. The PEC approach combines, in a single structure, a light absorbing material (usually a semiconductor), and a catalytic part for the redox reactions. The principle of PEC cell has been confirmed for production of H2 and O2 by water splitting at the laboratory scale. However among all the different materials and architectures tested, none is totally satisfying yet. This is due to the fact that it is difficult to combine high solar-to-chemical energy conversion efficiency with stability of the semiconducting material toward photo-corrosion. The project will use titanium dioxide as a starting material. TiO2 is known for its good stability for photo-electrochemical applications. However its performances are largely limited by its wide bandgap that only allows absorption of UV light. Therefore in order to improve its performances, this work will focus on developing novel synthesis methods that can modify the morphology and the electronic structure of TiO2. The first objective will be to synthesize 1D aligned TiO2 nanostructures which will improve the photo-generated charge transport. Then, a large part of the project will be devoted to the development of original co-alloyed TiO2 structures. This approach aims to introduce large atomic percentage of cationic and anionic species in substitution of Ti4+ and O2- in the TiO2 lattice. This insertion should be stoichiometric to achieve a balance of the charge between anions and cations. By an appropriate selection of anions/cations pairs, we can modify the electronic band structure of TiO2, with the aim to reduce its bandgap for a better solar light absorption. Furthermore, thanks to the charge balance, the co-alloying approach will provide a more stable crystalline structure with fewer defects than the classical mono-doping approaches. This last point is important to preserve a high mobility of charge carriers and avoid their recombination. Cationic species insertion will be achieved simultaneously with the TiO2 nanotubes growth by an original in-situ method while the anion insertion will be achieved by adapted thermal treatments. Specific characterization methods will be developed to explore the properties of the co-alloyed materials, especially their crystalline structure (TEM with cartography, XRD) and electronic properties (photoluminescence, impedance spectroscopy). Ultimately, the knowledge we will gain on co-alloying method will be used to synthesize TiO2-NTs photo-electrodes with variable co-alloying elements concentrations, in order to absorb photon with different energies gradually in the thickness of the film. We expect these original structures will provide a better light absorption with efficient transport of charge carriers. To further improve the PEC properties of the co-alloyed TiO2 photo-electrodes, we will deposit catalytic nanoparticles on their surface to enhance the charge transfer and the overall efficiency of the reaction. Finally, the modified TiO2 nanostructures will be tested in PEC experiments in different conditions (such as irradiation, electrolyte pH) to identify the best approaches and modifications to reach stable and highly efficient solar-to-chemical energy conversion.