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This study introduces an innovative solution to address the challenges arising from the volatile natural gas market and the growing integration of renewable energy sources within the industrial sector. The research strives to confront this challenge by including renewable methanol (CH3OH) and converting it into methane (CH4), with an intermediate step involving synthesis gas (CO/H2) by using concentrating solar power. This approach provides a sustainable and adaptable solution to reduce dependence on natural gas. The process entails a methanol decomposition reaction at moderate temperatures (<350 °C). Subsequently, the synthesis gas is compressed to 40 bar, stored, and discharged through a methanation process that can be conducted at high temperatures (>500 °C). The resulting methane is used as fuel for gas turbines and can also serve as feedstock in the chemical industry. The simulations were conducted in ASPEN HYSYS and yielded overall system efficiencies exceeding 29% and roundtrip efficiencies of 44%. Through techno-economic optimisation of the reaction conditions, competitive levelized fuel costs (LCOF) of €172/MWh and future LCOE values of €145/MWh were achieved. These findings present an innovative strategy for integrating gas turbine cycles and additional conversion pathways for green methanol.

Among the portfolio of energy systems for local power generation, Organic Rankine cycles (ORCs) for residential applications are an opportunity for local cogeneration based on synergies with existing thermal heating and storage systems. They can be highly competitive for isolated installations and the refurbishment of existing solar heating installations based on solar domestic hot water. This article evaluates the potential for hybrid solar ORC integration in residential buildings. The analyses focus on the annual yields of a domestic 1 kW ORC cycle to assess the advantages and disadvantages of the variation of demand and the availability of solar resources. The models are developed, integrating TRNSYS and EES to allow a detailed evolution characterisation. Performance and impact of CHP adaptation are considered based on demand, storage volume-collectors area ratio, and production strategies. The analysis is completed with a thermo-economic analysis under different ranges of thermodynamic parameters. Positive IRR results of 8.61% are obtained for the installation located in Seville, Spain, operating the ORC 15% of the year. It also reduces the overheating associated with the lack of heat demand and excess solar irradiation in the solar system for the warm months by 20%.

With the increasing volatility in natural gas markets and the need for residential heat, research for alternative fuels is necessary for several regions. This paper presents a high-duration thermochemical energy storage system (TCES) based on methanol, evaluating its integration with district heating networks, offering a renewable solar-based storage solution and low-temperature heat generation from the exothermic discharge reaction heat. The system eliminates greenhouse gas emissions by using concentrated solar thermal energy to decompose methanol into synthesis gas. Applying the optimised operational thermodynamic parameters, it is possible to satisfy the thermal demand of 892 households in Spain through 12 MW of concentrated solar energy supported by 10 hours of energy storage. Storage efficiencies exceeding 30% and chemical conversion efficiencies exceeding 65% have been demonstrated, resulting in a combined efficiency of 55% for the heating network and methanol TCES. The results show a levelized cost of storage (LCOS) highly competitive with other storage systems (<100 €/MWh), given the simplicity and flexibility of the proposed system.

This work presents a tool for developing competencies in sustainability, focusing on evaluating the environmental impact and carbon footprint in schools. The tool is based on sustainability indicators and follows a methodology derived from the ClimAct and ECF4CLIM projects. It is conceived as a support for the users and the schools to identify and evaluate the relative impact of different actions and measures, to engage them in a sustainable pathway to low-carbon schools supporting their decision-making at the different levels of users. The areas are transport, waste, green procurement, green spaces, energy, water, and indoor air quality. The tool aims to support users and schools in identifying and evaluating the impact of various actions and measures, facilitating decision-making for a sustainable and low-carbon school environment. To quantify sustainability performance, Key Performance Indicators (KPIs) have been established for each area. The results from schools that tested the tool revealed low scores in green procurement (0.59/5) and water (2.03/5), while achieving higher scores in green spaces (3.46/5) and indoor air quality (3.92/5). These findings highlight the areas where improvement is needed and provide a basis for targeted interventions. Developed on the PowerApps platform, supported by Microsoft, the tool allows access to users of different ages and knowledge levels. It has been successfully tested in six schools in Andalusia, Spain, obtaining relevant results in the seven sustainable areas defined. Based on the results, this tool will be used within co-creation and co-implementation processes for more sustainable schools and competencies acquisition by the participants.

The widespread use of renewable energy requires the support of high-capacity energy storage systems. This work proposes a thermochemical energy storage system for concentrated solar power plants based on the reversible hydration/dehydration process of the calcium hydroxide. It is a single fluidised bed reactor concept with alternating dehydration-hydration processes, charging and discharging alternating reactions, with superheated steam as fluidising agent. The system has been modelled using Aspen Plus™, including equilibrium data and hydrodynamic performance of the reactor. The model has been used to evaluate the effect of different parameters of the reactor, such as geometry, average particle size, or inlet streams conditions, on the performance of the reactor and the system. The thermal integration of the system was optimised using pinch analysis. For the proposed layouts, round-trip efficiencies values of 68 % are obtained. The economic analyses show specific investment costs between 4170 $/kWe and 3250 $/kWe for plants in the range of 31 MW to 45 MW, which are competitive with those expected for plants with storage of molten salts in this power range. LCOE values between 67 $/MWh and 83 $/MWh were obtained. The analyses show how these values highly depend on the fresh material replacement requirements related to the deactivation of the material and operational strategies. The results show the interest in further developments of this concept for concentrated solar power plants.

La situación energética actual es insostenible tanto desde un punto de vista ecológico, ya que actualmente la mayoría de la energía producida proviene de la combustión de hidrocarburos con la contaminación inherente que conlleva, y el otro punto de vista es que es un recurso finito y cuyo fin no parece tan lejano. Actualmente, el mundo necesita combustibles nuevos, estos deben cumplir una serie de condiciones para que puedan ser considerados el combustible definitivo, en primer lugar, deben ser abundante en cualquier parte del mundo y por otra parte, deben ser respetuoso con el medio ambiente; de estas dos premisas aparecen los “Solar Fuel”, que son obtenido de la energía solar, además usan otros recursos abundantes y respetuosos con el medio ambiente como pueden ser el agua, el aire, el CO2, etc. El problema de la obtención de estos combustibles suelen estar asociados a problemas de distinta índole: Limitaciones de la tecnología actual, obtención posible pero económicamente inviable, etc. En este trabajo se desea analizar concretamente la obtención de amoniaco mediante el uso de recursos naturales: aire y agua además de analizar las distintas variables con el fin de obtener conclusiones sobre las distintas configuraciones y tecnologías disponibles para obtener conclusiones sobre la obtención del NH3 de la manera mas responsable.

La transición energética ha tomado las energías renovables como pilar, a pesar de las restricciones de variabilidad climática con las que cuenta. El uso de sistemas de almacenamiento termoquímico se plantea como una opción de vital interés para escenarios futuros de gestión de la demanda y el suministro de energía eléctrica a red. En este trabajo se plantea el estudio de un sistema basado en metanol altamente flexible que hace uso de reacciones de metanación y desplazamientos para la producción de gas natural sintético. Se propone también un modelo basado en la conversión de metano a metanol, para completar el ciclo. En ambas rutas se podrá extraer potencia a partir de la combustión del gas natural producido a partir de un ciclo Joule-Brayton, así como aprovechar la potencia procedente de las reacciones exotérmicas en ciclos orgánicos de Rankine regenerativos. Se obtienen así rendimientos globales de conversión del 50 % para la ruta CH3OH-CH4 y del 43 % en la ruta CH4-CH3OH, a partir de ocho horas de almacenamiento en cada caso. Los costes nivelados de energía resultan de 0.10 €/kWh y 0.15 €/kWh, respectivamente. La integración del bloque de potencia con la configuración propuesta indica rendimientos para una turbina de gas de 100 MW del 35 % y del 10.5 % para ORC de 450 kW que usa Tolueno como fluido de trabajo., Energy transition has taken renewable energies as a pillar, despite the constraints of climate variability. The use of thermochemical storage systems is considered as an option of vital interest for future demand and supply management scenarios of electricity to grid. This work studies a highly flexible methanol-based system that makes use of methanation reactions and shifts for the production of synthetic natural gas. A model based on methane to methanol conversion is also proposed to complete the cycle. In both routes, power can be extracted from the combustion of natural gas produced from a Joule-Brayton cycle, as well as recovering residual energy from the exothermic reactions in regenerative organic Rankine cycles. Overall conversion efficiencies of 50 % for CH3OH-CH4 route and 43 % for CH4-CH3OH route are obtained, from eight hours of storage in each case. The levelised energy costs are 0.10 €/kWh and 0.15 €/kWh, respectively. The integration of the power block with the proposed configuration indicates efficiencies for a 100 MW gas turbine of 35 % and 10.5 % for a 450 kW ORC using toluene as the working fluid.

This work explores the use of open-pore, inert ceramic foams with different pore sizes as particle abatement systems in small biomass combustion systems. Porous foams made of silicon carbide with pore sizes 10 to 60 pores-per-inch were installed in an in-house designed combustion unit operated with wood pellets. Their effects on the temperature distribution inside the chamber, particulate and gases emissions were studied using different airflow rates in the reaction-limited regime (low equivalence ratio) to minimise stoichiometric factors. The influence of pore size, foam position with respect to the flame and space velocity were assessed. The confinement of the flame with inert foams was found to substantially modify the temperature distribution in the combustion chamber, improve the air-fuel mixture, and favour the thermal decomposition of the pellet, leading to a reduction in particulate emissions when compared to free-flame combustion at the same experimental conditions. In general, the amount of particulate matter was found to decrease by up to one order of magnitude as the pore size of the foam was reduced, while the temperature gradient in the combustion chamber was increased. Nitrogen oxides and carbon dioxide emissions were essentially unchanged, irrespectively of the pore size of the foam. It is expected that these values will be improved with longer residence times, as happens in operations with reduced excess air ratios. These results suggest that it is possible to control pollutants derived from domestic heating within the most restrictive current regulations on particulate emissions by integrating flame confinement designs with better operating practices and efficient abatement systems.

Heating decarbonisation through electrification requires the development of novel heat batteries. They should be suitable for the specific application and match the operation conditions of domestic renewable energy sources. Supercooled liquids, often considered a drawback of phase change materials, are among the most promising technologies supporting heating decarbonisation. Although some studies have shed light on stable supercooling, the fundamentals and stability remain open problems not always accompanied by relevant experimental investigations. This research critically analyses the physic and chemistry of sodium acetate (SA, NaCH3COO) aqueous solution, a low-cost, non-toxic, and abundant compound with stable supercooling for long-term heat storage. It has an appropriate phase change temperature for high-density heat storage using heat pumps or solar thermal technologies in residential applications. The existing discrepancies in literature are critically discussed through a systematic experimental evaluation, providing novel insights into efficient material design and appropriate boundary conditions for reliable material use in long-term heat batteries. Despite previous studies showing that the thermal reliability and stability of sodium acetate aqueous solution as a supercooled liquid for heat storage cannot be guaranteed, this study demonstrates that through an appropriate encapsulation and sealing method, the peritectic composition of sodium acetate solution (p-SA 58 wt%) can be used as a supercooled liquid for long-term heat storage with a stable melting temperature of 57 °C, appropriate for domestic heat technologies. It is demonstrated that energy storage efficiency can be maintained under cycling, with a constant latent heat storage capacity of 245 kJ/kg and a volumetric storage density of 314 MJ/m3. It was confirmed that the material should achieve a fully-melted state for stable supercooling. Finally, local cooling and retaining seed crystals through hi

El crecimiento de la demanda eléctrica y térmica en el sector residencial se debe principalmente a un estado de bienestar cada vez más exigente. Dentro de la cartera de sistemas energéticos para la generación de energía local, los ciclos orgánicos de Rankine son una oportunidad de sinergias con los sistemas de calefacción y almacenamiento térmico existentes. Los sistemas ORC en el sector residencial son de especial interés para instalaciones aisladas y para la rehabilitación de instalaciones de calefacción solar basadas en agua caliente sanitaria (ACS). Este tipo de instalaciones está muy extendido en algunas regiones del sur de Europa como España. Este trabajo evalúa el potencial de la integración solar híbrida ORC en edificios residenciales. Los análisis se centran en los rendimientos anuales de un ciclo ORC de 1-3 kW en combinaciones de los dos sistemas: Solar con y sin Almacenamiento. Los modelos se desarrollan integrando TRNSYS y EES para permitir una caracterización detallada de la evolución. El rendimiento y el impacto de las integraciones se consideran en función de la integración, las características de los componentes, el fluido de trabajo y las estrategias de control para un conjunto de zonas climáticas diferentes. Los análisis se completan con un análisis económico basado en las demandas características para diferentes características de la demanda integrada (edificios residenciales, bloques y edificios terciarios). Los resultados obtenidos muestran los rangos de viabilidad para diferentes escenarios de costes de sistemas y zonas climáticas., The growth in electricity and thermal demand in the residential sector is mainly due to an increasingly demanding welfare state. Among the energy systems portfolio for local power generation, Organic Rankine Cycles are an opportunity for synergies with existing thermal heating and storage systems. ORC systems in the residential sector are of particular interest for isolated installations and the refurbishment of solar heating installations based on solar domestic hot water (SDHW). This kind of installations is widely extended in some regions of southern Europe like Spain. This paper evaluates the potential for hybrid ORC solar integration in residential buildings. The analyses are focused on the annual yields of a 1-3 kW ORC cycle in combinations of the two systems: Solar with and without Storage. The models are developed, integrating TRNSYS and EES to allow a detailed evolution characterisation. The performance and the impact of the integrations are considered as a function of the integration, components characteristics, working fluid and control strategies for a set of different climatic zones. The analyses are completed with an economic analysis based on the characteristic demands for different integrated demand characteristics (residential buildings, blocks, and tertiary buildings). The results obtained show the viability ranges for different systems costs scenarios and climatic zones.

Modelado del sistema híbrido de una instalación fotovoltaica con almacenamiento de energía a base de hidrógeno, considerando datos meteorológicos y variables eléctricas para evaluar los sistemas en términos de carga, niveles de capacidad de almacenamiento y costos de dos procesos electroquímicos diferenciados, electrólisis de agua y electrólisis de reformado de etanol. Análisis de costos para evaluar la viabilidad de ambos sistemas, dimensionados para producir la misma cantidad de hidrógeno almacenado acumulado (SOC), operando en el punto de máxima potencia (MPP). El sistema híbrido con electrólisis de reformado de etanol tiene un mayor costo de inversión inicial y mayores costos anuales, debido a los requisitos de una mayor superficie de electrodo, así como al consumo de etanol. Sin embargo, el proceso convencional requiere un tamaño mucho mayor de la instalación fotovoltaica como consecuencia de sus tensiones más elevadas. Análisis de sensibilidad en un intento de optimizar la configuración en el acoplamiento PV-EL, el tamaño, la eficiencia y los costos de los componentes del sistema. Se puede concluir que el criterio de optimización más importante es la reducción del tamaño del electrolizador, debido al costo de los componentes y al voltaje característico del electrolizador. Los sistemas híbridos PV-H2 pueden desempeñar un papel eficaz en la implementación de una fuente de alimentación distribuida autónoma en aplicaciones que requieren almacenamiento a largo plazo con dispositivos compactos., Hybrid system modeling of a photovoltaic installation with energy storage based on hydrogen, considering meteorological data and electrical variables to evaluate the systems in terms of load, storage capacity levels and costs from two differentiated electrochemical processes, water electrolysis and ethanol reforming electrolysis. Cost analysis to evaluate the viability of both systems, sized to produce the same amount of accumulated stored hydrogen (SOC), operating at the point of maximum power (MPP). The hybrid system with ethanol forming electrolysis has a higher initial investment cost and higher annual costs, due to the requirements for a larger electrode surface, as well as consumption of ethanol. However, the conventional process requires a much larger size of the photovoltaic installation as a consequence of its higher voltages. Sensitivity analysis in an attempt to optimize the configuration in the PV-EL coupling, the size, efficiency and costs of the system components. It can be concluded that the most important criterion for optimization is the reduction of electrolyzer sizes, due to the cost of the components and the characteristic voltage of the electrolyzer. Hybrid PV-H2 systems can play an effective role in implementing an autonomous distributed power supply in applications requiring long-term storage with compact devices.

Utilización de carburo de silicio biomórfico como sustrato en filtros de flujo de pared en motores diésel. La presente invención se refiere a un filtro para partículas liberadas tras la combustión en motores diésel que comprende un filtro de flujo de pared de carburo de silicio biomórfico. El resultado es un nuevo filtro cerámico cuya microestructura jerarquizada depende de la selección de un precursor vegetal óptimo. Siguiendo el diseño y la geometría habitual de los filtros de flujo de pared, se favorece una mejora de las especificaciones técnicas de eficiencia y de pérdida de carga. La presente invención es de aplicación al sector automovilístico e industrial, en particular a la eliminación de partículas y purificación de gases residuales en procesos de combustión.

Instalación de almacenamiento de energía termoquímica-mecánica y procedimiento de almacenamiento de energía. La instalación de almacenamiento de energía comprende un bloque endotérmico con un reactor endotérmico (1) configurado para recibir una corriente de metanol y calor a media/baja temperatura (2) y producir un gas de síntesis (3) por descomposición térmica del metanol. Comprende también un bloque exotérmico con un reactor exotérmico (5) configurado para recibir una corriente de gas de síntesis proveniente del bloque endotérmico y producir una corriente de gas rica en metano (6), a alta presión y alta temperatura, por metanación; y un motor térmico (7) configurado para recibir la corriente rica en metano (6) y generar energía mecánica. El procedimiento de almacenamiento de energía se lleva a cabo en dicha instalación.

New and improved energy storage technologies are required to overcome non-dispatchability, which is the main challenge for the successful integration of large shares of renewable energy within energy supply systems. Energy storage is proposed to tackle daily variations on the demand side, i.e., storing low-price energy during off-peak or valley periods for utilization during peak periods. Regarding electrical energy storage, several technologies are available with different potentials for scalability, density, and cost. A recent approach for grid-scale applications is based on transcritical carbon dioxide charge and discharge cycles in combination with thermal energy storage systems. This alternative to pumped-hydro and compressed air energy storage has been discussed in scientific literature, where different configurations have been proposed and their efficiency and costs calculated. The potential of the concept has been demonstrated to be an economical alternative, including hybrid concepts with solar thermal storage. Even at low temperatures, the addition of solar energy has proved to be cost effective. This paper explores the effect of introducing solar-based high temperature heat on the performance of different configurations of “Transcritical carbon dioxide ‒ thermal energy storage system” cycles. A base-cycle with 8-hour discharge time is compared with different layouts. Discussions include details on the models, parametric analyses -including solar technology alternatives-, and simulation results. Round trip efficiency of the base case, without solar support and at pressure ratio of 9.4, is 52%. When solar input is considered, the efficiency is above 60%, increasing the turbine inlet temperature to 950 K. Estimated levelized cost of electricity values are in the range of pumped hydro and compressed air energy storage, 90-140 USD/MWh in agreement with other works on this thermal storage technology. The global analysis shows clear advantages for advancing in t

Solar photovoltaic plants are today a competitive alternative to power plants based on fossil fuels. Cost reduction in photovoltaics modules, scalability and ease of installation of these plants are enabling a rapid worldwide expansion of the technology. Nevertheless, dispatchability still remains as the major challenge to overcome due the intrinsic variability of solar energy. Most of the current solar photovoltaic facilities at large scale lack energy storage while those with storage systems rely on expensive batteries. Batteries are based on elements such as nickel, lithium or cadmium whose scarcity hinder their sustainability for storing energy in the large scale. This manuscript presents a novel concept to integrate thermochemical energy storage in photovoltaic plants. Furthermore, the concept is also directly adaptable to wind power plants to store surplus energy. The paper analyses the suitability of the Calcium-Looping process as thermochemical energy storage system in solar photovoltaics plants. The system works as follows: part of the power produced in the solar plant provides electricity to the grid while the rest is used to supply heat for calcination of calcium carbonate. After calcination, the products of the reaction – calcium oxide and carbon dioxide- are stored separately. When power production is required, the stored products are brought together in a carbonation reactor wherein the exothermic reaction releases energy for power production. The overall system is simulated to estimate the process behaviour and results show that storage efficiencies of ∼40% can be achieved. Moreover, an economic analysis is developed to compare the proposed system with batteries. Due to the low price of natural calcium oxide precursors, such as limestone, and the expected longer lifetime of equipment as compared to batteries, the Calcium-Looping process can be considered as a potential alternative for improving dispatchability in solar photovoltaic plants.

This paper presents the results of a preliminary experimental study to assess the performance of biomorphic silicon carbide when used for the abatement of soot particles in the exhaust of Diesel engines. Given its optimal thermal and mechanical properties, silicon carbide is one of the most popular substrates in commercial diesel particulate filters. Biomorphic silicon carbide is known for having, besides, a hierarchical porous microstructure and the possibility of tailoring that microstructure through the selection of a suitable wood precursor. An experimental rig was designed and built to be integrated within an engine test bench that allowed to characterizing small lab-scale biomorphic silicon carbide filter samples. A particle counter was used to measure the particles distribution before and after the samples, while a differential pressure sensor was used to measure their pressure drop during the soot loading process. The experimental campaign yielded promising results: for the flow rate conditions that the measuring devices imposed (1 litre per minute; space velocity = 42,000 L/h), the samples showed initial efficiencies above 80%, pressure drops below 20 mbar, and a low increase in the pressure drop with the soot load which allows to reach almost 100% efficiency with an increase in pressure drop lower than 15%, when the soot load is still less than 0.01 g/L. It shows the potential of this material and the interest for advancing in more complex diesel particle filter designs based on the results of this work

Solar photovoltaics (PV) plants are today a competitive alternative to power plants based on fossil fuels. Cost reduction in PV modules, scalability (from kW to MW) and ease of installation of PV plants are enabling a rapid expansion of the technology throughout the world. Nevertheless, PV dispatchability still remains as the major challenge to be overcome due to intrinsic variability of solar energy. Most of the current PV facilities lack energy storage while those with storage systems rely on expensive batteries. Batteries are based on elements such as nickel, lithium or cadmium whose scarcity hinder the sustainability of batteries for storing energy in the large scale. This manuscript presents a novel concept to integrate thermochemical energy storage in PV plants. Furthermore, the concept is also directly adaptable to wind power plants in order to store surplus energy. In particular, this paper analyses the suitability of the Calcium-Looping (CaL) process as thermochemical energy storage system applied to large scale PV facilities. The PV-CaL integration works as follows: a part of power produced in the PV plant provides electricity to the grid while the rest is used to supply heat to carry out the calcination of CaCO3. After calcination, the products of the reaction (CaO and CO2) are stored separately. When power production is required, the stored products are brought together in a carbonation reactor wherein the exothermic reaction releases energy for power production. The overall system is simulated in order to estimate the process behaviour and results show that storage efficiencies of ~40% can be achieved. Moreover, an economic analysis is developed to compare the proposed system with batteries. Due to the low price of natural CaO precursors such as limestone and the longer lifetime of equipment than batteries, the CaL process can be considered as a promising alternative to increase dispatchability in PV plants. Moreover, limestone is abundant and nontoxic

Capture and sequestration of CO2 released by conventional fossil fuel combustion is an urgent need to mitigate global warming. In this work, main CO2 capture and sequestration (CCS) systems are reviewed, with the focus on their integration with renewables in order to achieve power plants with nearly zero CO2 emissions. Among these technologies under development, the Dry Carbonate Process shows several advantages. This manuscript analyses the integration of a CO2 sorption-desorption cycle based on Na2CO3/NaHCO3 into a coal fired power plant (CFPP) for CO2 capture with solar support for sorbent regeneration. The Dry Carbonate Process relies on the use of a dry regenerable sorbent such as sodium carbonate (Na2CO3) to remove CO2 from flue gases. Na2CO3 is converted to sodium bicarbonate (NaHCO3) through reaction with CO2 and water steam. Na2CO3 is regenerated when NaHCO3 is heated, which yields a gas stream mostly containing CO2 and H2O. Condensation of H2O produces a pure CO2 stream suitable for its subsequent use or compression and sequestration. In this paper, the application of the Dry Carbonate CO2 capture process in a coal-based power plant is studied with the goal of optimizing CO2 capture efficiency, heat and power requirements. Integration of this CO2 capture process requires an additional heat supply which would reduce the global power plant efficiency by around 9–10%. Dry Carbonate Process has the advantage compared with other CCS technologies that requires a relatively low temperature for sorbent regeneration (< 200 °C). It allows an effective integration of medium temperature solar thermal power to assist NaHCO3 decarbonation. This integration reduces the global system efficiency drop to the consumption associated with mechanical parasitic consumption, resulting in a fossil fuel energy penalty of 3–4% (including CO2 compression). The paper shows the viability of the concept through economic analyses under different scenarios. The results suggest the interes

La integración de sistemas termoquímicos de energía en plantas CSP está ganando interés en los últimos años. De entre los posibles sistemas termoquímicos, el proceso de Calcium-looping (CaL), basado en la calcinación/carbonatación multicíclica de CaCO3, está considerado como uno de los más prometedores. Tras la aparente sencillez del proceso se encuentran una serie de retos que deben ser resueltos para que la tecnología pueda alcanzar una escala comercial. En el presente trabajo se muestra un análisis crítico del estado actual de la tecnología con el objetivo de evaluar los retos y oportunidades que presenta la integración del CaL como sistema de almacenamiento termoquímico en plantas CSP. El proyecto SOCRATCES, financiado dentro del programa H2020, tiene como principal objetivo desarrollar un prototipo a escala piloto de la integración CSP-CaL en Sevilla (España)., Thermochemical energy storage is gaining attention in last years to be integrated in CSP plants. Among the various possibilities, the Calcium-looping (CaL) process, based on the multicyclic calcination/carbonation of CaCO3, is considered as one of the most promising systems. However, for a commercial deployment of CSP, several challenges must be solved. This work presents a critical analysis on the status of the technology with the aim of evaluating the main challenges and opportunities of the CSP-CaL integration. The SOCRATCES project, founded from the European Union’s Horizon 2020 research and innovation programme, aims to develop a CSP-CaL prototype at pilot scale in Seville (Spain).

La presente invención presenta un sistema integrado de producción de Na2HCO3 a partir del CO2 capturada de industrias o plantas de potencia mediante un proceso de carbonato seco partiendo de trona como materia prima (Na2CO3 · NaHCO3 · 2H2O) y convirtiéndo

Efficient, low-cost and environmentally friendly storage of thermal energy stands as a main challenge for large scale deployment of solar energy. This work explores the integration into concentrated solar power plants of the calcium looping process based upon the reversible carbonation/calcination of calcium oxide for thermochemical energy storage. An efficient concentrated solar power-calcium looping integration would allow storing energy in the long term by calcination of calcium carbonate thus overcoming the hurdle of variable power generation from solar. After calcination, the stored products of the reaction (calcium oxide and carbon dioxide) are brought together in a carbonator reactor whereby the high temperature exothermic reaction releases the stored energy for efficient power production when needed. This work analyses several power cycle configurations with the main goal of optimizing the performance of the overall system integration. Possible integration schemes are proposed in which power production is carried out directly (using a closed carbon dioxide Brayton power cycle) or indirectly (by means of a steam reheat Rankine cycle or a supercritical carbon dioxide Brayton cycle). The results obtained show that the highest plant efficiencies (up to 45–46%) are achievable using a closed carbon dioxide Brayton power cycle.

In this paper, a novel carbon capture and utilization process is proposed. It is based on using a fraction of the captured carbon dioxide to produce sodium bicarbonate, a widely used product in the chemical and food industries. The process couples the Dry Carbonate process for carbon dioxide capture with sodium bicarbonate production. Raw material is trona or sodium sesquicarbonate dehydrate, which is a relatively abundant mineral composed by approximately 46% sodium carbonate and 35% sodium bicarbonate by weight. In the process, trona is firstly converted into sodium carbonate in a fluidized bed reactor operated at 180–200 °C and 1 bar. Heat required in the fluidized bed reactor for decomposing trona can be supplied by renewable sources such as low/medium temperature solar energy or biomass. A fraction of the sodium carbonate generated is recirculated for carbon dioxide capture by means of the dry carbonate process. The rest is converted to sodium bicarbonate in a carbonating tower through the reaction with carbon dioxide and water. After separation of sodium bicarbonate and other salts from water, the sodium bicarbonate produced is suitable for direct sale. The use of renewable sources for supplying the energy required at the sorbent regenerator and for trona decomposition yields a near-zero carbon dioxide emissions global system. As case of study, carbon dioxide capture coupled to sodium bicarbonate production has been analysed for a 15 MWel coal fired power plant. Heat required in the carbon capture process penalizes the global system efficiency by a 10.2%, which is reduced just to the electricity parasitic consumption for solids transport and carbon dioxide compression (∼3%) if renewable energy sources are integrated. From an economic perspective, the penalty in electricity consumption is fully compensated by the new by-product sales. Taking into account the reduction of electricity sales and current prices of trona and sodium bicarbonate a return of investment

El objeto de la invención es la integración de un ciclo de carbonatación-calcinación (Calcium Looping) con un lazo cerrado de potencia por donde evoluciona CO2 o mezclas de CO2 con otros gases para proporcionar almacenamiento termoquímico para plantas de potencias y procesos industriales con calor disponible a media temperatura (por encima de los 550ºC). Esto es de aplicación entre otros a plantas termosolares y procesos industriales. Con el sistema desarrollado se consiguen rendimientos de operación por encima del 46% con una capacidad de almacenamiento con gran desfase entre la carga y descarga de larga duración.

Biomorphic SiC is a biotemplated material fabricated by Si melt-infiltration of carbon preforms from wood pyrolysis. In this work, porous bioSiC ceramics from five different wood precursors, with porosities between 45 and 72% were studied for their feasibility in filtering applications.Gas permeability and mechanical stability were investigated as a function of the microstructure of the starting wood precursor. Air-permeation performance at room temperature was measured for a range of flow rates, and the permeability constants were assessed by fitting of Forchheimer's equation to the experimental data. Darcian permeabilities were achieved in the range 10-10 m, while inertial terms were in the range 10-10 m, showing a correlation with the average pore size and orientation of the larger channels. Regarding the mechanical stability, maximum compressive strength values were reached in the range of 3-115 MPa.These results improve our understanding of the ways in which the microstructure influences permeability and mechanical robustness, enabling the device requirements to be tailored by selecting the wood precursor. It was also shown that these materials are promising for hot-gas filtering applications.

Este artículo analiza las causas de la rotura del cigüeñal de un motor diesel de cuatro tiempos de 16 cilindros en V a 60°, de potencia nominal 1500 k W a 1500 rpm. El análisis se ha desarrollado en tres etapas. En la primera fase se han evaluado con un modelo de elementos finitos las solicitaciones de tipo estático en la muñequilla. La segunda etapa consistió en el desarrollo de un modelo dinámico del sistema cigüeñal -acoplamiento -alternador y en el análisis de las solicitaciones de tipo dinámico. Finalmente se llevó cabo un análisis metalográfico del material. El trabajo ha permitido identificar de forma inequívoca la fatiga como causa de la rotura., This paper analyzes the causes of the breakage of the crankshaft of a four stroke diese! engine with 16 cylinders in V (60°). The nominal power is 1500 kW at 1500 rpm. The analysis has been developed in three steps. A static study through a finite elements program was the first step. The second part consisted in the development of a dynamic model of the crankshaft within the alternator. And finally a metallographic analysis of the material. The work has allowed to identify the fatigue like cause of the breakage.

Energy storage is the main challenge for a deep penetration of renewable energies into the grid to overcome their intrinsic variability. Thus, the commercial expansion of renewable energy, particularly wind and solar, at large scale depends crucially on the development of cheap, efficient and non-toxic energy storage systems enabling to supply more flexibility to the grid. The Ca-Looping (CaL) process, based upon the reversible carbonation/calcination of CaO, is one of the most promising technologies for thermochemical energy storage (TCES), which offers a high potential for the long-term storage of energy with relatively small storage volume. This manuscript explores the use of the CaL process to store Concentrated Solar Power (CSP). A CSPCaL integration scheme is proposed mainly characterized by the use of a CO2 closed loop for the CaL cycle and power production, which provides heat decoupled from the solar source and temperatures well above the ~550ºC limit that poses the use of molten salts currently used to store energy as sensible heat. The proposed CSP-CaL integration leads to high values of plant global efficiency (of around 45-46%) with a storage capacity that allows for long time gaps between load and discharge. Moreover, the use of environmentally benign, abundantly available and cheap raw materials such as natural limestone would mark a milestone on the road towards the industrial competitiveness of CSP.

The Ca-Looping (CaL) process is considered as a promising technology for CO2 post-combustion capture in power generation plants yielding a minor penalty on plant performance as compared with other capture technologies such as conventional amine-based capture systems. This manuscript presents a new carbonator reactor model based on lab-scale multicyclic CaO conversion results, which take into account realistic CaO regeneration conditions that necessarily involve calcination under high CO2 partial pressure and high temperature. Under these conditions, CaO conversion in the diffusion controlled stage is a relevant contribution to the carbonation degree in the typical residence times. The main novelty of the model proposed in the present work is the consideration of the capture efficiency in the diffusion controlled phase of carbonation. It is demonstrated that increasing the residence time by a few minutes in the carbonator yields a significant improvement of the capture efficiency. Model predictions are shown to agree with experimental results retrieved from pilot-scale tests. The new model allows a more accurate evaluation and prediction of carbonator’s performance over a wider range of residence times. The results obtained may be relevant for the optimization of CaL operation parameters to be integrated in real power plants.

Wastewater treatment stations take advantage of the biogas produced from sludge in anaerobic digesters to generate electricity (reciprocating gas engines) and heat (cooling water and engine exhaust gases). A fraction of this electricity is used to operate the plant while the remaining is sold to the grid. Heat is almost entirely used to support the endothermic anaerobic digestion and a minimum fraction of it is rejected to the environment at a set of fan coolers. This generic description is applicable to on-design conditions. Nevertheless, the operating conditions of the plant present a large seasonal variation so it is commonly found that the fraction of heat rejected to the atmosphere increases significantly at certain times of the year. Moreover, the heat available in the exhaust gases of the reciprocating engine is at a very high temperature (around 650 ºC), which is far from the temperature at which heat is needed for the digestion of sludge (around 40 ºC in the digesters). This temperature difference offers an opportunity to introduce an intermediate system between the engines and the digesters that makes use of a fraction of the available heat to convert it into electricity. An Organic Rankine Cycle (ORC) with an appropriate working fluid is an adequate candidate for these hot/cold temperature sources. In this paper, the techno-economic effect of adding an Organic Rankine Cycle as the intermediate system of an existing wastewater treatment station is analysed. On this purpose, different working fluids and system layouts have been studied for a reference wastewater treatment station giving rise to optimal systems configurations. The proposed systems yield very promising results with regard to global efficiency and electricity production (thermodynamically and economically).

Método para la fabricación de un material acústico a partir del residuo de la fragmentación de vehículos fuera de uso se caracteriza porque comprende, al menos, las etapas de: (i) una primera etapa de trituración y homogenización (1) de los residuos del vehículo fuera de uso, debido a la heterogeneidad del mismo; y (ii) una segunda etapa de mezclado del residuo triturado con un fundente (2) de baja temperatura; en donde el producto resultante se introduce en moldes (3), controlándose la densidad y espesor del producto (4) para posteriormente hornearse (5) a temperatura estable; y donde transcurrido el tiempo de curado, el producto queda listo para su caracterización (6).

A methodology for the estimation of the mean temperature of the cylinder inner surface in an air-cooled internal combustion engine is proposed. Knowledge of this temperature is necessary to determine the heat flux from the combustion chamber to the cylinder wall. Along with the heat transfer coefficient this parameter also allows almost 50% of engine heat losses to be determined. The temperature is relatively easy to determine for water-cooled engines but this is not in the case for air-cooled engines. The methodology described here combines numerical and experimental procedures. Simulations were based on FEM models and experiments were based on the use of thermocouples and infrared thermography. The methodology avoids the use of data or correlations developed for other engines, providing more reliable results than extrapolating models from one engine to another. It also prevents from taking measurements from inside the combustion chamber, reducing invasion and experiments complexity. The proposed methodology has been successfully applied to an air-cooled four-stroke direct-injection diesel engine and it allows the cylinder mean inner surface temperature and cylinder-cooling air heat transfer coefficient to be estimated.

Homogeneous charge compression ignition (HCCI) engines produce very low NO and soot emissions and alsoimprove engine efficiency when compare to conventional spark ignition engines. The combustion process bases on the self-ignition of a homogenous air-fuel mixture without an external ignition source. The gas temperature is very important to initiate the combustion and to promote the appropriate chemical kinetics. As a result, the heat release rate and heat transfer inside the combustion chamber play a significant role in the HCCI combustion mode. The high relevance of gas temperature on this combustion mode means that heat transferis considered through a dedicated heat transfer model. In this system the forced convection from hot gases to the combustion chamber walls is the dominant heat transfer mechanism. This paper focuses on the relationship between HRR in HCCI combustion mode and the four parameters that are required for an analytical function to model this heat release rate. More specifically, the influences of the fuel-air equivalence ratio, engine speed and EGR on the four parameters that control HRR are examined. The analytical HRR law is validated over a wide range of operating conditions in HCCI combustion mode and shows that these four parameters are directly related to any load condition, including engine speed, fuel rate and EGR. These parameters can therefore be used to characterize this combustion mode.

Se describe una herramienta virtual que permite la simulación detallada del funcionamiento de un motor diesel, así como un análisis paramétrico y de sensibilidad de estos motores. Ello es debido a la continua necesidad para un ingeniero de entender y aplicar modelos matemáticos en la simulación de motores. La herramienta se ha desarrollado en lenguaje MATLAB y el empleo de la herramienta puede ayudar a realizar simulaciones en lugar de ensayos difíciles de llevar a cabo en el laboratorio. El empleo de la herramienta permite entender el funcionamiento de los motores diesel en distintas condiciones operativas. Los resultados de la simulación son visualizados mediante el uso de “graphical user interface (GUI)”. Se han obtenido muy buenos resultados por parte de los alumnos con el uso de esta herramienta, This article describes a virtual instrument that allows a detailed diesel engine simulation performance and parametric analysis of the combustion process. The stimulus for developing this computer-aided educational tool derives from the continuing need of the engineer to understand and apply mathematical models in engine simulation. Common programming language Matlab is selected to develop the software and interfaces. The application of software in teaching internal combustion engines can help students to improve their parametric analysis and make them understand diesel combustion better. Simulation and parametric analysis are visualized on the designed graphical user interface (GUI). The software has been used by students who have achieved excellent results by using this teaching tool.

Homogeneous charge compression ignition (HCCI) engines are drawing attracting attention as the next-generation’s internal combustion engine, mainly because of its very low NOx and soot emissions and also for improvement in engine efficiency. Much research has been carried out in order to go deeper in this combustion process using multizone models or CFD codes. These simulation tools, although they can give a detailed view of the combustion process, are very time consuming and the results depend a lot on the initial conditions. A previous step to be considered in the simulation of the HCCI process is a heat release law evaluated from results of the experiment and a zero-dimensional model. This paper focuses on the development of a new heat release rate (HRR) law that models the HCCI process when the combustion chamber is considered as a homogeneous volume. The parameters of this law have been adjusted through an optimization process that has allowed to fit the combustion chamber pressure. All the engine operative conditions from low to full load have been successfully simulated with this HRR law, with the maximum error in the estimation of combustion chamber pressure less than 2%.

Los ejes cigüeñales son una parte fundamental en el funcionamiento de los motores de combustión interna alternativos y compresores volumétricos alternativos. El fallo de un cigüeñal no es uno de los problemas más frecuentes, sin embargo puede tener consecuencias muy importantes tanto en la integridad del sistema como en la disponibilidad de este, siendo además los costes asociados a su reparación, agravados por su difícil accesibilidad. En el diseño de cigüeñales el principal factor determinante es la torsión del sistema, de manera que debe buscarse que las frecuencias resonantes del sistema se encuentren suficientemente alejadas de las frecuencias principales de la excitación.

En la memoria que se redacta a continuación se recoge la experiencia de un grupo de profesores noveles inscritos en un programa de formación dirigido por un profesor de reconocida experiencia en labores docentes. Se expondrán los objetivos planteados y los métodos empleados para su realización. Tras un análisis de resultados se concluye que existen condicionantes internos y externos que dificultan la aplicación de ciertas técnicas de enseñanza. El escrito finaliza con alguna propuesta de mejora del programa de formación de cara a próximas ediciones del mismo., The work done by a number of unexperienced lecturers under the guidance of a much more experienced professor is shown in this report. Firstly, both objectives and tasks to accomplish them are presented. Afterwards, an analysis of the results reveals that a number of internal and internal facts makes it difficult to apply sorne learning techniques. At the end of the report there are some ideas to improve the course in the future.

En este artículo se analizan las causas de las averías sistemáticas que se producen en un grupo motobomba. Éstas consisten en la rotura de los rotores de la bomba (6 etapas) por la sección de admisión así como del cierre. El análisis se ha desarrollado en tres etapas: a) desarrollo de un modelo dinámico de torsión, b) desarrollo de un modelo dinámico para identificación de velocidades críticas, c) validación experimental y medida de magnitudes instantáneas. El análisis ha permitido identificar de forma inequívoca la operación de la motobomba muy próxima a una resonancia a torsión del sistema, lo que ha provocado un deterioro prematuro del chavetero así como la abrasión de los rotores., In this paper the causes of a pump-engine systematic failure are analyzed. These consist of the breakage of the rotors of the pump (6 stages) by the admission section as well as of the closing. The analysis has been developed in three steps: a) development of a torsion dynamic model b) development of a dynamic model in order to identify the critics speeds, c) experimental validation and measure of instantaneous parameters. The analysis has allowed identifying the operation of the pump-motor system closely to a torsion resonance, which has caused a premature deterioration of the keyway, as well as the abrasion of the rotors.