International audienceThe upcoming depletion of fossil fuels calls for the development of alternative energies produced from renewable resources. Particularly, energy valorisation of agriculture and food processing wastes is one of the most promising tools for renewable energy production. The amount of food wastes is rapidly increasing due to urbanisation, industrialisation and population growth worldwide. They consequently represent a widely available resource, and their use as a raw material allows reducing the environmental cost associated with their disposal. These resources usually have high moisture content, making dry valorisation processes unattractive because of a costly drying step prior to conversion. Hydrothermal processes are conversely particularly well suited for the valorisation of wet organic wastes in an economical way, since they use water as the reaction medium. More specifically, liquid fuels can be produced using hydrothermal liquefaction (HTL). The process converts wet biomass into a crude-like oil with higher heating values up to 40 MJ/kg using subcritical water (T=250-370 degrees C, P=10-30 MPa). Though this is an active research area, the mechanisms of hydrothermal liquefaction still remain unclear today. Some processes have already been developed at the pilot scale for valorising food processing wastes. However, the development of HTL processes at industrial scales is facing technological and economic challenges. This paper discusses the two main issues to address for development of the process at large scales. On the one hand, hydrothermal conversion of food processing residues and model compounds is necessary to better understand the fundamentals of hydrothermal liquefaction. As well, technological and process integration issues have to be addressed to ensure economic viability of commercial HTL processes

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International audienceThere are many different ways to convert biomass into liquid fuels, mostly referred to as bio-oils. This paper presents the analysis of bio-oils produced by hydrothermal liquefaction and fast pyrolysis of beech wood. Both processes have a wide panel of parameters that can be optimised influencing the oil quality. Results of the analysis show that both oils have high acidities. Iodine values indicate a high degree of unsaturations. These two qualities seem to be inversely proportional in the case of pyrolysis oils. In the case of hydrothermal conversion, additives to adjust the pH such as sodium hydroxide increase oil yields, lower its viscosity but do little to further improve the quality of the oils. For pyrolysis oils, increasing the severity does reduce acidity but at the expense of more unsaturations and a loss in yield. The results show that without extensive upgrading or refining, commercial fuel standards cannot be met. Specific norms and standards are being elaborated for pyrolysis used in specific installations. This paper shows how detailed analysis can help to optimise process parameters with an objective that goes beyond the mass or energy yield. (c) 2016 Elsevier Ltd. All rights reserved

International audienceBio-oils obtained from hydrothermal liquefaction of biomass are black viscous fuels with good heating values. This paper presents results of physical and chemical characterization of bio-oils produced by hydrothermal liquefaction of blackcurrant pomace. The oils are analyzed with standard normalized tests and compared to specifications required by commercialized biofuels and conventional fuels. Iodine value and total acid number are determined, showing relatively high values. GC/MS analysis demonstrates that bio-oil recovery by solvent extraction followed by subsequent evaporation of the solvent leads to the loss of some volatile compounds in the bio-oil. Thermogravimetric analysis are performed to study the volatility of HTL bio-oils, as well as to evaluate the carbon residue after evaporation. The viscosity of a bio-oil recovered by ethyl-acetate extraction was measured with a rotational viscometer at 25 degrees C, leading to a viscosity of 1.7 Pa.s. The results show furthermore that adding sodium hydroxide to the reaction medium has a limited influence on the properties of bio-oils. The choice of extraction solvent has conversely a significant influence on the quality of the produced oil. We demonstrate in this paper how standardized tests can be applied to hydrothermal bio-oils, to compare them with commercial fuels and evaluate the need for upgrading

Thermochemical processes are promising ways for energy valorization of biomass and waste, but suffer from a lack of predictability. In this work, we focus on using model molecules to model the behavior of wet organic residues during hydrothermal liquefaction (HTL), a process used to produce bio based liquid fuels from wet biomass. Monomeric and polymeric model molecules were used as modelling tools to study HTL of real resources. Experiments with model mixtures and four food processing residues (blackcurrant pomace, raspberry achenes, brewer's spent grains, grape marc) were conducted at 300°C, 60 min holding time and a dry matter concentration of 15 wt%. To elaborate model mixtures, four model monomers (glucose, guaiacol, glutamic acid, linoleic acid) and two model polymers (microcrystalline cellulose, alkali lignin) were selected from characterization of blackcurrant pomace. HTL of model mixtures reproduced HTL of blackcurrant pomace with acceptable representative ness, but results showed that model mixtures should include polymers to represent the fiber content of the resource. Results of HTL of model compounds were used to elaborate poly nomial correlations able to predict experimental yields as a function of the initial biomass composition. Calculations were within-8.0 to ?4.8 wt% of experimental yields obtained by HTL of real food processing residues, showing a good accuracy of the correlations. These expressions also showed good agreement with HTL results reported in the literature for other resources, and could be useful to assess the potential of various kinds of bioresources for HTL. Keywords Hydrothermal liquefaction Á Model compounds Á Food processing residues Á Bio oil Á Polynomial regression Á Mixture designs Electronic supplementary material The online version of this article (

International audienceHydrothermal liquefaction (HTL) of wet organic waste is a promising technology for producing renewable liquid fuels. However, implementation of the process at commercial scales must overcome several challenges. Efficient management of the contaminated aqueous phase generated after the conversion is necessary to limit water treatment expenses. In this study, we suggest the, direct recycling, of the aqueous phase at the inlet of the HTL process. The purpose is to evaluate the effect of recycling the process water on the bio-oil recovery and quality. HTL of blackcurrant pomace was performed in a batch autoclave, at a temperature of 310 degrees C, with a holding time of 10 min, and a dry biomass concentration of 14.5 wt %. The influence of recycling the process water at the inlet of the process was evaluated for five recycle rounds. Recycling the process water has a positive effect on the bio-oil recovery, with the bio-oil yield increasing from 26 wt % to 31 wt % after five recycles. The energy recovery respectively increased from 48% to 57%, mainly because of the better bio-oil yield. Along the recycling experiments, the aspect of the,raw organic residue recovered from the, reactor changed, from an oily :solid to a free-flowing organic residue. Analytical results (total organic carbon, thermogravimetric analysis, and gas chromatography mass, spectroscopy (GC-MS) analysis) suggest that the improvement of the bio-oil yield is mainly due to the saturation of the aqueous phase with light-polar organics, which contribute to bio-oil formation by condensation reactions. Especially, products from the Maillard reaction could play an important role

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Alterations in seagrass epiphytic communities are expected under future ocean 21 acidification conditions, yet this hypothesis has been little tested in situ. A Free Ocean Carbon 22Dioxide Enrichment (FOCE) system was used to lower pH by a ~ 0.3 unit offset within a 23 partially enclosed portion (1.7 m 3 ) of a Posidonia oceanica meadow (11 m depth) between 21 24June and 3 November 2014. Leaf epiphytic community composition (% cover) and bulk 25 epiphytic mineralogy were compared every four weeks within three treatments, located in the 26 same meadow: a pH-manipulated (experimental enclosure) and a control enclosure, as well as a 27 nearby ambient area. Percent coverage of invertebrate calcifiers and crustose coralline algae 28 (CCA) did not appear to be affected by the lowered pH. Furthermore, fleshy algae did not 29 proliferate at lowered pH. Only Foraminifera, which covered less than 3% of leaf surfaces, 30 declined in manner consistent with ocean acidification predictions. Bulk epiphytic magnesium 31 carbonate composition was similar between treatments and percentage of magnesium appeared 32 2 to increase from summer to autumn. CCA did not exhibit any visible skeleton dissolution or 33 mineral alteration at lowered pH and carbonate saturation state. Negative impacts from ocean 34 acidification on P. oceanica epiphytic communities were smaller than expected. Epiphytic 35 calcifiers were possibly protected from the pH treatment due to host plant photosynthesis inside 36 the enclosure where water flow is slowed. The more positive outcome than expected suggests 37 that calcareous members of epiphytic communities may find refuge in some conditions and be 38