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In the present work, the supercritical water gasification (SCWG) of biomass is analyzed with a view to outlining the possible thermodynamic constraints that must be taken into account to develop this new process. In particular, issues concerning the formation of solid carbon and the process heat duty are discussed. The analysis is conducted by means of a two-phase non-stoichiometric thermodynamic model, based on Gibbs free energy minimization. Results show that char formation at equilibrium only occurs at high biomass concentrations, with a strong dependence on biomass composition. As regards the process heat duty, SCWG is mostly endothermic when biomass concentration is low, although a very small amount of oxidizing agent is able to make the process exothermic, with only a small loss in the heating value of the syngas produced.

fragmentation of solid fuels under severe heating conditions. The devise is a modified heated strip reactor, capable to reach 2000°C in less than 0.2s. Particles are laid on the strip and pyrolysed under inert or moderately oxidizing conditions. The char particles and their fragments, generated upon pyrolysis, can be recovered and analysed to assess the fragmentation propensity of the fuel. Some preliminary experiments have been carried out on two biomass samples in order to assess the temperature time history of particles in the experimental apparatus. In particular biomass particles of approximately 2-3 mm have been used. The temperature of the heated strip reactor in such preliminary tests was varied between 1000 and 1600°C, while the strip nominal heating rate was kept at 104°C/s and the holding time was set at the value of 10s. A near infrared fast camera (38000 frames/sec) has been used to measure the temperature of the heated strip and of the particles during the tests. A heat up model was developed and validated against experimental results. The model was then used to estimate the temperature gradients across particles of biomass and of coal as well. Results show that the strip of the reactor reaches the set temperature in less than 0.2s. When particles are laid on the strip, their bottom surface, which is in physical contact with the strip, immediately reaches the set temperature value. For 1mm coal particles the upper surface can be considered at the same temperature as well. Under the most severe conditions tested (strip temperature of 1600°C , biomass particles of 2mm thickness) the temperature difference between the bottom and the upper face is 200°C after 3s and drops to 100°C after 10 s. On the whole the experimental apparatus simulates uniform heating of the particles with reasonable approximation. In the next future the apparatus will be further upgraded to operate at pressures up to 20 bar.

Wild microalgae (prokaryotic and eukaryotic photosynthetic microorganisms) - phytoplankton - is at the base of the food chain, supporting aquatic primary production. Microalgae are an ideal platform for the large-scale production of biomass because they are fast-growing, solar-powered 'biofactories' with low nutrient requirements. The variety of high-value bioproducts comes from microalgal species due to their wide physiological and functional diversity. Over the last 60 years, microalgal biotechnology has shown a range of applications: from the traditional extensive biomass production in human and animal nutrition, soil conditioning in agriculture, technologies for waste-water treatment, products for cosmetics and pharmacy, and most recently to the possible production of a 'third' generation of biofuels.

Abstract In its 2016 Heating and Cooling Strategy, the European Commission (EC) highlighted the strategic importance of heating demand for the energy demand reduction, and further noted that District Heat Networks (DHN) can play an important role in decarbonising this sector. This study applied a thermal atlas approach to map the potential for district heat networks in Switzerland. It extended existing methods with a novel approach to estimating linear thermal demand density in DHN at a national scale. DHN potential for current-generation high temperature networks as well as cutting-edge low temperature networks were compared for current building space heating and hot water demand as well as for two demand reduction scenarios. The method was tested by comparing its results to those of a local engineering study conducted for a Swiss municipality (Brig-Glis). The potential percentage of demand supplied by high temperature DHN was shown to decrease from 66% to 41% with energy saving while the potential for low temperature systems increased significantly from 2.1% to 42%. The percentage of heat demand covered by heat networks decreases less than the percentage of buildings covered, reflecting the strength of heat networks for supplying large fractions of thermal demand in geographically confined areas.

Abstract Silicon carbide-based filter elements were catalytically activated to provide filter elements for catalytic tar removal from biomass-derived syngas. The filter element support was coated with CeO 2 , CaO–Al 2 O 3 and MgO with a specific surface of 7.4, 15.9 and 21.9 m 2 /g synthesized by exo-templating with activated carbon. Doping of a MgO coated filter element with 60 wt% NiO has led to an increase of the specific surface from 0.15 to 0.21 m 2 /g, whereas in case of a MgO–Al 2 O 3 coated filter element a decrease from 1.18 to 0.91 m 2 /g was found. An increase of the NiO loading from 6 to 60 wt% on a MgO coated filter element resulted in an increase of the naphthalene conversion from 91 to 100% at 800 °C and a face velocity of 2.5 cm/s at a naphthalene concentration of 5 g/Nm 3 in model biomass gasification gas. In case of a MgO–Al 2 O 3 coated filter element with 60 wt% NiO in addition to complete naphthalene conversion in the absence of H 2 S, a higher conversion of 66% was found in the presence of 100 ppmv H 2 S compared to 49% of the MgO–NiO coated filter element. After scaling up of the catalytic activation procedure to a 1520 mm long filter candle, which shows an acceptable differential pressure of 54.9 mbar, 58 and 97% naphthalene conversion was achieved in the presence and absence of H 2 S, respectively. The calculated WHSV value of 209.6 Nm 3 h −1 kg −1 indicates the technical feasibility of a further increase of the catalytic performance by an increase of the NiO loading.

Biomasa je obnovljivi izvor energije, koji bilježi rast upotrebe prije svega zbog ekoloških utjecaja. Nije je potrebno dodatno preraditi kako bi se koristila kao izvor za proizvodnju električne energije. Dakle, koristi se u svome prirodnom obliku. U radu će se pojasniti sam pojam biomase i način iskoristivosti iste za proizvodnju električne energije. Između ostalog, korištenje biomase za proizvodnju električne energije donosi niz prednosti u ekonomskom statusu države, regija i gradova, otvaranjem novih radnih mjesta u poljoprivredi, šumarstvu i pogonima za proizvodnju električne energije (kogeneracijskim elektranama). Biomass is a renewable energy source, which records an increase in use due to environmental impacts. No further processing is required to be used as a source for elektricity generation. So it is used in its natural form. The paper will explain the concept of biomass and the way it can be used for electricity production. Among other things, the use of biomass for electricity production brings a number of advantages in the economic status of the state, regions and cities, by creating new jobs in agriculture, forestry and electricity generation plants (cogeneration power plants).

The cleaning of syngas is one of the most important challenges in the development of technologies based on gasification of biomass. Tar is an undesired byproduct because, once condensed, it can cause fouling and plugging and damage the downstream equipment. Thermochemical methods for tar destruction, which include catalytic cracking and thermal cracking, are intrinsically attractive because they are energetically efficient and no movable parts are required nor byproducts are produced. The main difficulty with these methods is the tendency for tar to polymerize at high temperatures. An alternative to tar removal is the complete combustion of the syngas in a porous burner directly as it leaves the particle capture system. In this context, the main aim of this study is to evaluate the destruction of the tar present in the syngas from biomass gasification by combustion in porous media. A gas mixture was used to emulate the syngas, which included toluene as a tar surrogate. Initially, CHEMKIN was used to asses...

This study investigates the environmental improvements associated to the integration of a microalgae unit as a side-stream process within an existing municipal wastewater treatment facility in northern Italy. Microalgae are fed on the centrate from sludge dewatering, rich in nutrients, and on the CO2 in the flue-gas of the combined heat and power unit. The produced biomass is recirculated upflow the water line where it settles and undergoes anaerobic digestion generating extra biogas. A life cycle assessment was performed collecting primary data from an algal pilot-scale plant installed at the facility. Fifteen environmental indicators were evaluated. Compared to the baseline wastewater treatment, the new algal configuration allows an improvement for 7 out of 15 indicators mainly thanks to the electricity savings in the facility. Some recommendations are provided to improve the performance of the algal system in the scaling up.