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International audience; Molten salt pyrolysis driven by concentrated solar radiation is well positioned to utilize solar energy and lignite effectively. This study focused on the effects of temperature (500, 600, 700 and 800 °C) and molten carbonate salt (Li2CO3-Na2CO3-K2CO3) on properties of char obtained from lignite pyrolysis, as well as gas and tar products for revealing their formation mechanism and transformation process. Molten salt pyrolysis of HulunBuir lignite produced more gas products and less char compared to conventional pyrolysis owing to the enhanced heat transfer and catalytic effect of molten salt. The char yield decreased from 58.4% to 43.4%, and the gas yield (especially CO2, H2 and CO) increased from 28.3% to 46.1% at 800 °C. CO2, CO and H2 production increased about 60.43%, 103.42% and 65.2% at 800 °C, respectively. Additionally, the presence of molten salt improved the tar quality with more hydrocarbon content (maximum increase of 5.8%) and less oxygenated compounds. The structure and reactivity relationship of char was characterized by XRD, BET, SEM, FTIR, Raman spectroscopy and TGA. Molten salt generated char had a higher reactivity due to the increase of disorder, surface area, microporosity (maximum of 71.74%) and active sites.

International audience; The solar gasification system (SGS) and traditional system are modeled by Aspen Plus. And their energetic, economic as well as ecologic (3E) performance are compared. The effects of different feedstocks and Direct Normal Irradiance (DNI) to the productivity and efficiency of SGS are also carried out. The results show that a biomass-based, solar-assisted liquid fuel production system offers a productivity increasing potential of 49.44% more refined syngas and 65.74% more liquid fuels due to its higher utilization of feedstock. And for the same reason, the energetic performance of SGS increases from 40.22% to 40.66% for thermal efficiency and from 38.35% to 41.35% for exergy efficiency compared with those of reference system. The final price of products in SGS could only be equal to that of reference system when the carbon tax is under considering, while both of them shows no superiority to that of petroleum products. SGS has a better ecology performance contributed by less total carbon and water footprints which are only 55.27% and 61.34% of those of the reference system.

International audience; Solar pyrolysis of raw and heavy metals (HMs) impregnated willow was performed at different temperatures (600, 800, 1000, 1200, 1400 and 1600 °C) with heating rate of 50 °C/s. CHNS, ICP-OES, SEM-EDX and BET were employed to investigate the effects of temperature and HMs contamination on char properties. The results indicated that a more ordered and aromatic char was formed with increasing pyrolysis temperature. Char carbon contents increased from 70.0% to 88.4% while hydrogen and oxygen contents declined. Char BET surface area firstly increased from 5.3 to 161.0 m2/g with rising the temperature from 600 to 1000 °C, then decreased at higher temperatures due to plastic deformation. Pyrolysis caused alkali and alkaline-earth metals (A&AEMs) enrichment in char as temperature increased from 600 to 800 °C, then their content decreased at higher temperatures. The presence of Cu or Ni led to the decrease of hydrogen and oxygen contents and significant increase of Ni or Cu in char compared with those in raw willow char. Besides, Raman and BET analysis showed that contaminated willow char had a higher ratio of G band area to the integrated area (IG/IAll) and bigger BET surface area than raw material indicating a more organized and porous structure of the char.

International audience; This paper presents a new model and optimization procedure for off-grid hybrid PV (photovoltaic)/Diesel systems operating without battery storage.The proposed technico-economic model takes into account the variability of both the solar irradiation and the electrical loads. It allows optimizing the design and the operation of the hybrid systems by searching their lowest LCOE (Levelized Cost of Electricity). Two cases have been investigated: identical Diesel generators and Diesel generators with different sizes, and both are compared to conventional standalone Diesel generator systems. For the same load profile, the optimization results show that the LCOE of the optimized batteryless hybrid solar PV/Diesel (0.289 €/kWh for the hybrid system with identical Diesel generators and 0.284 €/kWh for the hybrid system with different sizes of Diesel generators) is lower than the LCOE obtained with standalone Diesel generators (0.32 €/kWh for the both cases). The obtained results are then confirmed by HOMER (Hybrid Optimization Model for Electric Renewables) software.

International audience; An exergy-based analysis applied to ideal thermochemical dipoles allowed to design an original process that could use low-grade energy, produced from a thermal solar collector at around 70 °C, to provide low-temperature cold, below −23 °C, in order to store deep-frozen food. The ideal coefficient of performance (COP) of this system is 0.5 and the exergetic yield is 1. Taking into account the process enthalpies and the sensible heat of the reactants, the COPthermo is 0.17. The process functioning is described in this paper. It alternates between a regeneration mode during daytime and cold production mode during night-time. An experimental prototype was designed and built. It proved the feasibility of the concept and showed an experimental COP of about 0.06, which is similar to the up-to-date solar cooling systems, but at higher cold temperatures. The mean annual exergetic yield of the process is about 0.06.

International audience; A solar deep-freezing process has been designed. It aims at cooling down a cold box to about −20 °C, using simple flat plate solar collectors operating at 70 °C. This original process involves two cascaded thermochemical systems based on the BaCl2/ammonia reaction. Its working mode is discontinuous as it alternates between a regeneration mode during daytime and a cold production mode during nighttime. A global dynamic model involving the various system components allows the simulation of the process; it predicts the evolution of the components temperatures and the rates of chemical reactions of the system. It also allows the dimensioning of the system components to maintain a 500 l cold box at −20 °C during the 6 sunniest months of the year under typical Mediterranean weather conditions and provide over 80% of the total yearly cooling needs of this box. This requires a solar collector area of 5.8 m2 and 39 kg of reactive salt. The predicted coefficient of performance (COP) is about 0.1 over the year, and the net solar COP, taking into account the collector efficiencies, is 0.05.