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The present paper makes a comparative analysis of the outdoor culture of H. pluvialis in a tubular photobioreactor and a bubble column. Both reactors had the same volume and were operated in the same way, thus allowing the influence of the reactor design to be analyzed. Due to the large changes in cell morphology and biochemical composition of H. pluvialis during outdoor culture, a new, faster methodology has been developed for their evaluation. Characterisation of the cultures is carried out on a macroscopic scale using a colorimetric method that allows the simultaneous determination of biomass concentration, and the chlorophyll, carotenoid and astaxanthin content of the biomass. On the microscopic scale, a method was developed based on the computer analysis of digital microscopic images. This method allows the quantification of cell population, average cell size and population homogeneity. The accuracy of the methods was verified during the operation of outdoor photobioreactors on a pilot plant scale. Data from the reactors showed tubular reactors to be more suitable for the production of H. pluvialis biomass and/or astaxanthin, due to their higher light availability. In the tubular photobioreactor biomass concentrations of 7.0 g/L (d.wt.) were reached after 16 days, with an overall biomass productivity of 0.41 g/L day. In the bubble column photobioreactor, on the other hand, the maximum biomass concentration reached was 1.4 g/L, with an overall biomass productivity of 0.06 g/L day. The maximum daily biomass productivity, 0.55 g/L day, was reached in the tubular photobioreactor for an average irradiance inside the culture of 130 microE/m2s. In addition, the carotenoid content of biomass from tubular photobioreactor increased up to 2.0%d.wt., whereas that of the biomass from the bubble column remained roughly constant at values of 0.5%d.wt. It should be noted that in the tubular photobioreactor under conditions of nitrate saturation, there was an accumulation of carotenoids due to the high irradiance in this reactor, their content in the biomass increasing from 0.5 to 1.0%d.wt. However, carotenoid accumulation mainly took place when nitrate concentration in the medium was below 5.0mM, conditions which were only observed in the tubular photobioreactor. A similar behaviour was observed for astaxanthin, with maximum values of 1.1 and 0.2%d.wt. measured in the tubular and bubble column photobioreactors, respectively. From these data astaxanthin productivities of 4.4 and 0.12 mg/L day were calculated for the tubular and the bubble column photobioreactors. Accumulation of carotenoids was also accompanied by an increase in cell size from 20 to 35 microm, which was only observed in the tubular photobioreactors. Thus it may be concluded that the methodology developed in the present study allows the monitoring of H. pluvialis cultures characterized by fast variations of cell morphology and biochemical composition, especially in outdoor conditions, and that tubular photobioreactors are preferable to bubble columns for the production of biomass and/or astaxanthin.

In this work we present the manufacturing processes and results obtained from the characterization of heterojunction with intrinsic thin layer solar cells that include a heavily Ti ion implanted Si absorbing layer. The cells exhibit external circuit photocurrent at photon energies well below the Si bandgap. We discuss the origin of this below-bandgap photocurrent and the modifications in the hydrogenated amorphous intrinsic Si layer thickness to increase the open-circuit voltage.

Trabajo presentado en el 4th Colombian Conference on Automatic Control (CCAC), celebrado en Medellín (Colombia), del 15 al 18 de octubre de 2019 Given the need of implementing methodologies in industry for the reduction of the energy consumption costs, it is required to create modelling methodologies that, together with the use of new technologies, will allow identifying energy consumption models based on input-output data. These models will later be used to design a suitable model-based control strategy. In this paper, a subspace identification algorithm based on the RQ decomposition approach has been reported, which is both implemented and validated on a test-bench that emulates the energy consumption of an industrial machine within a manufacturing process. Subsequently, the resultant model fitting when using the proposed modelling methodology has been compared with different identification routines included into the MATLAB System Identification Toolbox¿, showing, in general, better results for the proposed methodology in this paper, with up to almost 80% of fitting in some cases. This work has been funded by the project IKERCON (ref. C10683).

The thermal reactivity and kinetics of five coal chars, a biomass char, and two coal/biomass char blends in an oxy-fuel combustion atmosphere (30%O2–70%CO2) were studied using the non-isothermal thermogravimetric method at three heating rates. Fuel chars were obtained by devolatilization in an entrained flow reactor at 1273 K under N2 and CO2 atmospheres. Three nth-order representative gas–solid models – the volumetric model (VM), the grain model (GM) and the random pore model (RPM) – were employed to describe the reactive behaviour of the chars. The RPM model was found to be the best for describing the reactivity of the high rank coal chars, while VM was the model that best described the reactivity of the bituminous coal chars, the biomass char and the coal-biomass blend char. The kinetic parameters of the chars obtained in N2 and CO2 in an oxy-fuel combustion atmosphere with 30% of oxygen were compared, but no relevant differences were observed. The behaviour of the blend of the bituminous coal (90%wt.) and the biomass (10%wt.) chars resembled that of the individual coal concealing the effect of the biomass. Likewise, no interaction was detected between the high rank coal and the biomass chars during oxy-fuel combustion of the blend. This work was carried out with financial support from the Spanish MICINN (Project PS-120000-2005-2) co-financed by the European Regional Development Fund (ERDF). M.V.G. and L.A. acknowledge funding from the CSIC JAE-Pre and CSIC JAE-Doc programs, respectively, co-financed by the European Social Fund. J.R. acknowledges funding from the Government of the Principado de Asturias (Severo Ochoa program). Peer reviewed

The present work analyses the changes in the chemical structure of a perhydrous coal during its thermal evolution at different temperatures in an open-medium pyrolysis system. The results obtained were compared with those described for non-perhydrous coals in order to establish the effect of the substances assimilated by the coal structure (hydrocarbon/oil-like substances) on the thermal evolution of the coal. The transformation ratio at each stage of thermal treatment was determined and the chemical-structural characterisation of the resultant products was performed. Changes in textural and microtextural properties associated with structural modifications during the evolution were also tested. The results obtained show that this perhydrous coal develops a specific evolution pathway different from that followed by non-perhydrous coals with a normal H/C ratio. The substances assimilated by the perhydrous coal cannot be easily and totally released from its structure so that they can be only partially removed after thermal treatment. Thus, the treatment debilitates the interactions between the substances and the coal matrix in addition to weakening and cracking the matrix during the thermal process. The increase in temperature also leads to the conversion of some of the heavy assimilated substances into lighter compounds. However, the assimilated substances are present even at high temperatures of the thermal process, providing hydrogen which has the effect of stabilising the radicals originated during the pyrolysis and improving the fluidity properties in the reacting medium. Financial support for this work was provided through a contract with the European Community (No. 7220/EC-769). Peer reviewed

[EN] It is widely recognised that energy poverty can have serious and detrimental impacts upon multiple aspects of people's well-being and life quality. This paper seeks to provide a multi-dimensional and theoretically-attuned account of the relations between energy poverty and well-being, through the use of the Capabilities Approach and specifically Nussbaum's normative theory of Central Capabilities. Drawing on interviews with 109 households in 4 European countries, we demonstrate how 6 of the 10 Central Capabilities - namely Bodily Health, Emotions, Affiliation, Play, Practical Reason and Senses, Imagination & Thought - can be directly harmed by energy poverty. Our findings strengthen claims that energy poverty should be considered a serious form of (energy) injustice. We conclude by reflecting on the implications of our work for energy poverty research and policy, and the opportunities opened up by adopting the Capabilities Approach. Data collection in Budapest, Gdansk and Skopje received funding from the European Research Council under the European Union's Seventh Framework Programme [grant number FP7/2007-2013]/ERC grant agreement number 313478. We also acknowledge the COST Action "European Energy Poverty: Agenda Co-Creation and Knowledge Innovation" [ENGAGER 2017-2021, CA16232] supported by COST (European Cooperation in Science and Technology - www.cost.eu).This was supported by Ministerio de Ciencia, Innovacion y Universidades.

The application of hydration/dehydration reactions of CaO/Ca(OH)2 to thermochemical energy storage systems can be facilitated by the development of Ca-based materials with improved mechanical properties when compared to the natural Ca-precursor, while maintaining good chemical activity. For this purpose, we are developing composite materials for fluidized bed or fixed bed applications synthesized using sodium silicate to bind fine CaO/Ca(OH)2 particles. In this work, the mechanism of decay in the mechanical properties of the resulting CaO/Ca-silicates composites over hundreds of hydration/dehydration cycles has been investigated. Based on the observed mechanism, improvements to the method of synthesis of the materials have been introduced, in order to retain the original carbonate grain volumes, which are larger than those of the equimolar quantity of the expanding Ca(OH)2 during hydration. A noticeable improvement in the mechanical stability of the resulting pellets was observed when the material was exposed to temperatures of around 880 °C in pure CO2 before calcination in order to avoid the decomposition of CaCO3 during the formation of the hard Ca-silicates that provide mechanical strength to the composite. Further gains in mechanical stability were achieved by avoiding the complete hydration of the CaO grains in the composites. These results confirm the primary role of Ca(OH)2 anisotropic expansion as the main cause of the reduction in crushing strength of the pellets. It can be concluded that the formation of calcium silicates as binders of CaO rich grains is a promising route for the development Ca-based composite materials. However, more effort is still needed to overcome the decay in performance observed after several hundreds of cycles. The financial support provided by the European Commission under the 7th Framework Program (StoRRe Project GA 282677) is acknowledged. Y.A. Criado thanks the Government of the Principality of Asturias for a Ph.D. fellowship (Severo Ochoa Program). Help from Dr. A. Borrego in the microscopic analysis of the samples is also acknowledged. Peer reviewed