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The Arctic climate system is in great distress, warming faster than the rest of the world and transforming more rapidly than previously anticipated. Sustained and harmonized multidisciplinary observations at key locations are needed to fill knowledge gaps and evaluate the ongoing climate change impacts on the complex Arctic marine system. For more than a decade, the Distributed Biological Observatory (DBO) has functioned as a “detection array” for ecosystem changes and trends in the Pacific sector of the Arctic Ocean. This long-term collaborative initiative builds on active involvement of scientists conducting in situ observations within marine disciplines to systematically document how the arctic marine ecosystem is transforming with environmental change. The DBO concept is currently being expanded into other sectors of the Arctic, including Davis Strait and Baffin Bay, the Atlantic Arctic gateway area, and the East Siberian Sea. Through increased collaboration and joint practices, findings from these regional areas can leverage to pan-Arctic perspectives and improve our understanding of the entire Arctic Ocean. Common practices are now being developed, including key phenomena and relevant indicators to study. Also, we strive towards harmonized routines for sampling, analysis and data sharing to increase the comparability across both disciplines and regions, and to improve the usability of our in-situ observations also for the modelling and remote sensing scopes. An ambition is, moreover, to expand from today's predominantly open-sea coverage towards coastal regions, to the benefit of both local communities and researchers. The process of establishing a pan-Arctic DBO network is to a large part facilitated by the EU Horizon project Arctic PASSION (2022-2025). Here, we present the latest developments and shared priorities, as well as our vision of how to incorporate our efforts into other parallel processes aiming to strengthen the pan-Arctic observing system towards, during and beyond the upcoming IPY.

The Arctic climate system is in great distress, warming faster than the rest of the world and transforming more rapidly than previously anticipated. Sustained and harmonized multidisciplinary observations at key locations are needed to fill knowledge gaps and evaluate the ongoing climate change impacts on the complex Arctic marine system. For more than a decade, the Distributed Biological Observatory (DBO) has functioned as a “detection array” for ecosystem changes and trends in the Pacific sector of the Arctic Ocean. This long-term collaborative initiative builds on active involvement of scientists conducting in situ observations within marine disciplines to systematically document how the arctic marine ecosystem is transforming with environmental change. The DBO concept is currently being expanded into other sectors of the Arctic, including Davis Strait and Baffin Bay, the Atlantic Arctic gateway area, and the East Siberian Sea. Through increased collaboration and joint practices, findings from these regional areas can leverage to pan-Arctic perspectives and improve our understanding of the entire Arctic Ocean. Common practices are now being developed, including key phenomena and relevant indicators to study. Also, we strive towards harmonized routines for sampling, analysis and data sharing to increase the comparability across both disciplines and regions, and to improve the usability of our in-situ observations also for the modelling and remote sensing scopes. An ambition is, moreover, to expand from today's predominantly open-sea coverage towards coastal regions, to the benefit of both local communities and researchers. The process of establishing a pan-Arctic DBO network is to a large part facilitated by the EU Horizon project Arctic PASSION (2022-2025). Here, we present the latest developments and shared priorities, as well as our vision of how to incorporate our efforts into other parallel processes aiming to strengthen the pan-Arctic observing system towards, during and beyond the upcoming IPY.

Germanium is a low-cost alternative to the highly expensive III-V semiconductors commonly used on thermophotovoltaic (TPV) devices. Despite efficiencies up to 16.5 % having been theorized in previous works, no experimental efficiencies have been reported so far for germanium-based devices. In this work, we present the first experimental germanium TPV cell efficiency measured under high view factor and high temperature irradiance conditions. Efficiencies and electric power densities up to 11.2 % and 1.43 W/cm2 have been obtained using a graphite emitter heated at 1440ºC.

Germanium is a low-cost alternative to the highly expensive III-V semiconductors commonly used on thermophotovoltaic (TPV) devices. Despite efficiencies up to 16.5 % having been theorized in previous works, no experimental efficiencies have been reported so far for germanium-based devices. In this work, we present the first experimental germanium TPV cell efficiency measured under high view factor and high temperature irradiance conditions. Efficiencies and electric power densities up to 11.2 % and 1.43 W/cm2 have been obtained using a graphite emitter heated at 1440ºC.

Biogas is mostly composed by CH4 and CO2 generated in the anaerobic digestion of organic matter. However, other compounds present in lower amounts should be also taken into consideration during biogas exploitation since they may cause operational problems. This is the case of siloxanes, which decompose at high temperature generating silicates and SiO2, causing abrasion and leading to the failure of equipment. Thus, biogas cleaning and upgrading constitutes the key challenge of the biogas supply chain. Chemical Looping Combustion (CLC) would allow direct use of biogas without prior cleaning, with significant energy and economic advantages. In CLC, the oxygen required for combustion is supplied by an oxygen carrier (metal oxide) that circulates between two reactors. In the reduction reactor, the fuel is supplied and oxidized to CO2 and H2O while the oxygen carrier is reduced. In the oxidation reactor, the reduced oxygen carrier is re-oxidized in air. Thus, CO2 capture is intrinsic to the process. The objective of the present work was to analyse the possible effects of siloxanes in biogas CLC processes by studying the reactivity and physicochemical changes of selected oxygen carriers during combustion in a batch fluidized bed reactor. Two representative oxygen carriers based on CuO and Fe2O3 were chosen considering the high reactivity in the combustion of methane of Cu-based oxygen carriers and the resistance to sulphur deactivation of Fe-based oxygen carriers. Hexamethyldisiloxane (L2) was selected as siloxane model compound. It was found that siloxane decompose to produce a gaseous fraction and Si-based particles that interact with the oxygen carrier. Part of the Si in these particles was concentrated in the surface of the oxygen carrier particles in the form of SiO2 and silicates/aluminosilicates. This may have some implications on the reactivity of the carriers and their fluidization properties; however, no operation problems would be expected for the oxygen carriers tested in this work in a continuous combustion CLC unit operated with real siloxane concentration. This work was supported by the European Regional Development Fund (ERDF) under the program "Programa Operativo FEDER Aragón 2014-2020 - Construyendo Europa desde Aragón. Proyecto BiosinCO2 (LMP180_18), and by the CO2SPLIT project, Grant PID2020-113131RB-I00, funded by MICIN/AEI/10.13039/501100011033. 3 figures, 4 tables.-- Work presented at the Fluidized Bed Conversion Conference - FBC2024, 8-11th May 2022, Chalmers University of Technology (Sweden). Peer reviewed

Biogas is mostly composed by CH4 and CO2 generated in the anaerobic digestion of organic matter. However, other compounds present in lower amounts should be also taken into consideration during biogas exploitation since they may cause operational problems. This is the case of siloxanes, which decompose at high temperature generating silicates and SiO2, causing abrasion and leading to the failure of equipment. Thus, biogas cleaning and upgrading constitutes the key challenge of the biogas supply chain. Chemical Looping Combustion (CLC) would allow direct use of biogas without prior cleaning, with significant energy and economic advantages. In CLC, the oxygen required for combustion is supplied by an oxygen carrier (metal oxide) that circulates between two reactors. In the reduction reactor, the fuel is supplied and oxidized to CO2 and H2O while the oxygen carrier is reduced. In the oxidation reactor, the reduced oxygen carrier is re-oxidized in air. Thus, CO2 capture is intrinsic to the process. The objective of the present work was to analyse the possible effects of siloxanes in biogas CLC processes by studying the reactivity and physicochemical changes of selected oxygen carriers during combustion in a batch fluidized bed reactor. Two representative oxygen carriers based on CuO and Fe2O3 were chosen considering the high reactivity in the combustion of methane of Cu-based oxygen carriers and the resistance to sulphur deactivation of Fe-based oxygen carriers. Hexamethyldisiloxane (L2) was selected as siloxane model compound. It was found that siloxane decompose to produce a gaseous fraction and Si-based particles that interact with the oxygen carrier. Part of the Si in these particles was concentrated in the surface of the oxygen carrier particles in the form of SiO2 and silicates/aluminosilicates. This may have some implications on the reactivity of the carriers and their fluidization properties; however, no operation problems would be expected for the oxygen carriers tested in this work in a continuous combustion CLC unit operated with real siloxane concentration. This work was supported by the European Regional Development Fund (ERDF) under the program "Programa Operativo FEDER Aragón 2014-2020 - Construyendo Europa desde Aragón. Proyecto BiosinCO2 (LMP180_18), and by the CO2SPLIT project, Grant PID2020-113131RB-I00, funded by MICIN/AEI/10.13039/501100011033. 3 figures, 4 tables.-- Work presented at the Fluidized Bed Conversion Conference - FBC2024, 8-11th May 2022, Chalmers University of Technology (Sweden). Peer reviewed

Premio extraordinario de Trabajo Fin de Máster curso 2023/2024. Máster Universitario en Tecnologías Avanzadas de Materiales para la Construcción Sostenible. The construction industry faces a growing challenge in balancing resource consumption with environmental sustainability. This research investigates the potential of utilising biomass bottom ash (BBA), a by-product of renewable biomass energy generation, as a partial replacement for sand and cement in construction mortars. By incorporating BBA, this study aims to achieve a threefold benefit: reducing reliance on natural resources like virgin sand, mitigating CO2 emissions associated with cement production, and diverting waste from landfill sites. This study explores the use of olive and eucalyptus BBA as a partial replacement material at percentages of 25% and 50% for sand and 25% for cement in mortars. Additionally, the influence of a carbonation treatment on the properties of BBA and its subsequent effect on the mechanical performance of the resulting mortars is investigated. The research employs a combination of material physical and chemical characterisation techniques, mechanical testing, and leaching analysis to assess the suitability of BBA for sustainable construction applications. The findings demonstrate that BBA can achieve acceptable mechanical performance of mortars in some cases. However, limitations have been identified, requiring further research to optimise its use. Overall, the results suggest that BBA has promising potential as a sustainable construction material, although factors like biomass type and replacement ratio need careful consideration. The research also highlights the potential benefits of carbonation treatment, though its effectiveness appears to be dependent on both BBA type and replacement level. This study contributes to the development of sustainable construction practices by promoting the utilisation of by-products and reducing the environmental impact of the industry. By overcoming current limitations and fostering further research, BBA has the potential to play a significant role in transitioning the construction sector towards a more environmentally friendly future. La industria de la construcción se enfrenta a un creciente desafío para equilibrar el consumo de recursos con la sostenibilidad ambiental. Esta investigación analiza el potencial del uso de cenizas de fondo de biomasa (CFB), un subproducto de la generación de energía a partir de biomasa renovable, como reemplazo parcial de la arena y el cemento en morteros de construcción. Al incorporar CFB, este estudio apunta a lograr un triple beneficio: reducir la dependencia de recursos naturales como la arena natural, mitigar las emisiones de CO2 asociadas con la producción de cemento y desviar residuos de los vertederos. Este estudio explora el uso de CFB de olivo y eucalipto como material de reemplazo parcial en porcentajes de 25% y 50% para arena y 25% para cemento en morteros. Además, se investiga la influencia de un tratamiento de carbonatación en las propiedades de la CFB y su efecto posterior sobre el comportamiento mecánico de los morteros resultantes. La investigación emplea una combinación de técnicas de caracterización física y química de materiales, ensayos mecánicos y análisis de lixiviación para evaluar la idoneidad de la CFB para aplicaciones de construcción sostenible. Los resultados demuestran que la CFB puede lograr un comportamiento mecánico aceptable de los morteros en algunos casos. Sin embargo, se han identificado limitaciones que requieren investigaciones adicionales para optimizar su uso. En general, los resultados sugieren que la CFB tiene un potencial prometedor como material de construcción sostenible, aunque factores como el tipo de biomasa y el porcentaje de sustitución deben considerarse cuidadosamente. La investigación también destaca los posibles beneficios del tratamiento de carbonatación, aunque su efectividad parece depender tanto del tipo de CFB como del nivel de sustitución. Este estudio contribuye al desarrollo de prácticas de construcción sostenible fomentando la utilización de subproductos y reduciendo el impacto ambiental de la industria. Al superar las limitaciones actuales y fomentar la investigación adicional, la CFB tiene el potencial de desempeñar un papel importante en la transición del sector de la construcción hacia un futuro más ecológico.

Premio extraordinario de Trabajo Fin de Máster curso 2023/2024. Máster Universitario en Tecnologías Avanzadas de Materiales para la Construcción Sostenible. The construction industry faces a growing challenge in balancing resource consumption with environmental sustainability. This research investigates the potential of utilising biomass bottom ash (BBA), a by-product of renewable biomass energy generation, as a partial replacement for sand and cement in construction mortars. By incorporating BBA, this study aims to achieve a threefold benefit: reducing reliance on natural resources like virgin sand, mitigating CO2 emissions associated with cement production, and diverting waste from landfill sites. This study explores the use of olive and eucalyptus BBA as a partial replacement material at percentages of 25% and 50% for sand and 25% for cement in mortars. Additionally, the influence of a carbonation treatment on the properties of BBA and its subsequent effect on the mechanical performance of the resulting mortars is investigated. The research employs a combination of material physical and chemical characterisation techniques, mechanical testing, and leaching analysis to assess the suitability of BBA for sustainable construction applications. The findings demonstrate that BBA can achieve acceptable mechanical performance of mortars in some cases. However, limitations have been identified, requiring further research to optimise its use. Overall, the results suggest that BBA has promising potential as a sustainable construction material, although factors like biomass type and replacement ratio need careful consideration. The research also highlights the potential benefits of carbonation treatment, though its effectiveness appears to be dependent on both BBA type and replacement level. This study contributes to the development of sustainable construction practices by promoting the utilisation of by-products and reducing the environmental impact of the industry. By overcoming current limitations and fostering further research, BBA has the potential to play a significant role in transitioning the construction sector towards a more environmentally friendly future. La industria de la construcción se enfrenta a un creciente desafío para equilibrar el consumo de recursos con la sostenibilidad ambiental. Esta investigación analiza el potencial del uso de cenizas de fondo de biomasa (CFB), un subproducto de la generación de energía a partir de biomasa renovable, como reemplazo parcial de la arena y el cemento en morteros de construcción. Al incorporar CFB, este estudio apunta a lograr un triple beneficio: reducir la dependencia de recursos naturales como la arena natural, mitigar las emisiones de CO2 asociadas con la producción de cemento y desviar residuos de los vertederos. Este estudio explora el uso de CFB de olivo y eucalipto como material de reemplazo parcial en porcentajes de 25% y 50% para arena y 25% para cemento en morteros. Además, se investiga la influencia de un tratamiento de carbonatación en las propiedades de la CFB y su efecto posterior sobre el comportamiento mecánico de los morteros resultantes. La investigación emplea una combinación de técnicas de caracterización física y química de materiales, ensayos mecánicos y análisis de lixiviación para evaluar la idoneidad de la CFB para aplicaciones de construcción sostenible. Los resultados demuestran que la CFB puede lograr un comportamiento mecánico aceptable de los morteros en algunos casos. Sin embargo, se han identificado limitaciones que requieren investigaciones adicionales para optimizar su uso. En general, los resultados sugieren que la CFB tiene un potencial prometedor como material de construcción sostenible, aunque factores como el tipo de biomasa y el porcentaje de sustitución deben considerarse cuidadosamente. La investigación también destaca los posibles beneficios del tratamiento de carbonatación, aunque su efectividad parece depender tanto del tipo de CFB como del nivel de sustitución. Este estudio contribuye al desarrollo de prácticas de construcción sostenible fomentando la utilización de subproductos y reduciendo el impacto ambiental de la industria. Al superar las limitaciones actuales y fomentar la investigación adicional, la CFB tiene el potencial de desempeñar un papel importante en la transición del sector de la construcción hacia un futuro más ecológico.

To address the challenges posed by climate change and global warming, there is a pressing need to utilise renewable materials that can be obtained in a safe and environmentally friendly manner. The utilisation of biomass as a source of chemicals represents a revolutionary methodology with the potential to overcome humanity's reliance on fossil resources. Electrochemical technologies are advantageous in synthesising value-added products from biomass at atmospheric temperature and pressure, utilising water as a solvent and concurrently as a source of oxygen and hydrogen atoms and regulating chemical reactions through the application of electrical potential. In this study, inexpensive materials such as Cu and graphite, with slight modifications of catalytic metals such as Pd, Ag, Ni, were used for the electrochemical production of compounds that are used to produce polymeric materials, biofuels, pharmaceutical industry, etc. Compendi d'articles, Doctorat internacional Programa de Doctorat en Ciències