The Calcium-Looping (CaCO3/CaO) Process for Thermochemical Energy Storage in Concentrating Solar Power Plants

Articulo aceptado por la revista. * No publicado aún [28-06-2019]Energy storage based on thermochemical systems is gaining momentum as potential alternative to molten salts in Concentrating Solar Power (CSP) plants. This work is a detailed review about the promising integration of a CaCO3/CaO based system, the so-called Calcium-Looping (CaL) process, in CSP plants with tower technology. The CaL process relies on low cost, widely available and non-toxic natural materials (such as limestone or dolomite), which are necessary conditions for the commercial expansion of any energy storage technology at large scale. A comprehensive analysis of the advantages and challenges to be faced for the process to reach a commercial scale is carried out. The review includes a deep overview of reaction mechanisms and process integration schemes proposed in the recent literature. Enhancing the multicycle CaO conversion is a major challenge of the CaL process. Many lab-scale analyses carried out show that residual effective CaO conversion is highly dependent on the process conditions and CaO precursors used, reaching values as different as 0.07-0.82. The selection of the optimal operating conditions must be based on materials, process integration, technology and economics aspects. Global plant efficiencies over 45% (without considering solar-side losses) show the interest of the technology. Furthermore, the technological maturity and potential of the process is assessed. The direction towards which future works should be headed is discussed.Ministerio de Economia y Competitividad CTQ2014-52763-C2, CTQ2017- 83602-C2 (-1-R and -2-R)Unión Europea Horizon 2020 Grant agreement No 727348, project SOCRATCES

The mOxy-CaL Process: Integration of Membrane Separation, Partial Oxy-combustion and Calcium Looping for CO2 Capture

CO2 capture and storage (CCS) is considered as a key strategy in the short to medium term to mitigate global warming. The Calcium-Looping process, based on the reversible carbonation/calcination of CaO particles, is a promising technology for post-combustion CO2 capture because of the low cost and non-toxicity of natural CaO precursors and the minor energy penalty on the power plant in comparison with amines capture based technologies (4-9 % compared to 8-12 %). Another interesting process to reduce CO2 emissions in power plants is oxy-combustion, which is based on replacing the air used for combustion by a highly concentrated (~95 % v/v) O2 stream. This work proposes a novel process (mOxy-CaL) for post-combustion CO2 capture based on the integration of membrane separation, partial oxy-combustion and the Calcium-Looping process. An oxygenenriched air stream, which is obtained from air separation by using highly permeable polymeric membranes, is used to carry out partial oxy-combustion. The flue gas exiting partial oxy-combustion shows a CO2 concentration of ~30 % v/v (higher than 15 % v/v typical in coal power plants). After that, the flue gas is passed to the CaL process where the CO2 reacts with CaO solids according to the carbonation reaction. Thermogravimetric analysis show that the multicycle CaO conversion is enhanced as the CO2 concentration in the flue gas stream is increased. Process simulations show that the mOxy-CaL process has a high CO2 capture efficiency (~95%) with lower energy consumption per kg of CO2 avoided than previously proposed post-combustion CO2 capture technologies. Moreover, the overall system size is significantly lower that state-of-the-art CaL systems, which allows for an important reduction in the capital cost of the technology

2012 un año de ajuste en el empleo: análisis de coyuntura del mercado de trabajo en el primer trimestre de 2012

En artículo analiza de forma sistemática la evolución de la oferta, demanda y desempleo del mercado de trabajo en España y Andalucía referida al primer trimestre de 2012.La situación económica y de mercado de trabajo de los países europeos no contribuye a la recuperación de la economía y el empleo en España. A principios de 2012 se anuncia una nueva fase recesiva en el ciclo económico por lo que se parece que se mantendrán las tendencias de destrucción de empleo y aumento del desempleo que se han puesto de manifiesto desde el comienzo de la crisis. Por su parte, la oferta de trabajo en España se mantiene en un ligero crecimiento basado fundamentalmente en la incorporación de la mujer al mercado laboral. Por ello, en el primer trimestre de 2012 se han alcanzado cifras record en lo referido al total de personas desempleadas.The paper analyses the situation of the Spanish and Andalusian labour market in the first term of 2012. It is organized as follows. Firstly, we present the economic situation in Spain in relation to the rest of the European countries. Section 2, 3 and 4 are devoted to the analysis of labour supply, demand and unemployment in Spain. Finally, section 5 pays attention to the main labour variables in Andalusia which mainly follows tendencies of the Spanish labour market. The economic situation and the labour market evolution in the majority of the European countries are not helping the recovery of economic growth and employment in Spain. A new period of economic recession appears in the first quarter of 2012 and growth of unemployment and massive destruction of employment is expected in the next terms in a similar way to what happened at the beginning of the crisis. On the other hand, Spanish labour supply grows at a small but steady rate. In this term, Spain has reached a new record in the number of unemploye

Los ajustes deprimen el empleo. Análisis de coyuntura del mercado de trabajo en el segundo trimestre de 2012

La economía española ha entrado en recesión en el segundo trimestre de 2012, por segunda vez desde que estalló la crisis económica. La intensa caída de la actividad económica provoca una nueva oleada de destrucción de empleo. Como consecuencia, se ha alcanzado la tasa de paro más alta en un trimestre en la serie histórica de la EPA que ofrece el INE. En el artículo presente se analizan la evolución de las principales variables laborales en el mercado de trabajo español y de Andalucía. Se presta especial atención a la formación de la mano de obra y a la evolución de los diferentes grupos de trabajadores cualificados de acuerdo con la evolución del ciclo económico en el periodo 2008-2012.In the second quarter of 2012, Spanish economy has come into a new recession period for the second time since the beginning of the economic crisis. The big decrease of economic activity is the cause of a new wave of employment destruction. As a result, the highest rate of unemployment in modern Spanish economic history has been reached, according to the data provided by the National Institute of Statistics. In this paper, we analyse the evolution of the main labour indicators in the Spanish and Andalusian Labour Markets. We pay special attention to the impact of economic crisis on different groups of workers according to their educational levels in the period 2008-2012

Instalados en la recesión económica. Análisis de coyuntura del mercado de trabajo en el segundo semestre de 2012

A lo largo de 2012, España experimenta una profundización en la recesión económica que está sufriendo. Durante los cuatro trimestres de este año, no se han visto cifras positivas de crecimiento, sino una caída constante. La misma tendencia se observa en el resto de economías europeas, que en la última parte del año están adentrándose, o van camino de caer, de nuevo en la recesión. Como consecuencia de esta evolución, el deterioro del mercado de trabajo español sigue aumentando. Cae la ocupación y aumenta el desempleo hasta casi seis millones de personas, alcanzándose la tasa de paro más elevada de los registros de la EPA (26,02%). En el presente trabajo se presenta una panorámica sobre la evolución de la economía y el mercado de trabajo en España en el segundo semestre de 2012. El artículo también recoge un epígrafe dedicado al análisis de la evolución de las variables económicas y laborales más relevantes en Andalucía

Desequilibrios crecientes. Análisis de coyuntura del mercado de trabajo en el primer semestre de 2013

A lo largo del primer semestre de 2013, la economía española ha seguido en el proceso de recesión económica, si bien se presentan algunos indicios de que las previsiones para los próximos años pueden mejorar indicando el final de la crisis y el comienzo de la recuperación económica. No obstante, la tasa de paro en España se situó en el 26,26%, y la tasa de empleo en el 43,91%, valores muy alejados de la media de la UE. En el presente artículo se presenta una panorámica sobre la evolución de la economía y del mercado de trabajo en España en el primer trimestre de 2013. En primer lugar se analiza la evolución del cuadro macroeconómico general de la economía española. En las tres secciones siguientes se analizan, respectivamente, la oferta de trabajo, la demanda de trabajo y el desempleo. El artículo concluye con un epígrafe dedicado a la evolución de las variables económicas y laborales en Andalucía en el mismo periodo de tiempo

Carbonation of Limestone Derived CaO for Thermochemical Energy Storage: From Kinetics to Process Integration in Concentrating Solar Plants

Thermochemical energy storage (TCES) is considered as a promising technology to accomplish high energy storage efficiency in concentrating solar power (CSP) plants. Among the various possibilities, the calcium-looping (CaL) process, based on the reversible calcination-carbonation of CaCO stands as a main candidate due to the high energy density achievable and the extremely low price, nontoxicity, and wide availability of natural CaO precursors such as limestone. The CaL process is already widely studied for CO capture in fossil fuel power plants or to enhance H production from methane reforming. Either one of these applications requires particular reaction conditions to which the sorbent performance (reaction kinetics and multicycle conversion) is extremely sensitive. Therefore, specific models based on the conditions of any particular application are needed. To get a grip on the optimum conditions for the carbonation of limestone derived CaO in the CaL-CSP integration, in the present work is pursued a multidisciplinary approach that combines theoretical modeling on reaction kinetics, lab-scale experimental tests at relevant CaL conditions for TCES, process modeling, and simulations. A new analytic equation to estimate the carbonation reaction rate as a function of CO partial pressure and temperature is proposed and validated with experimental data. Using the kinetics analysis, a carbonator model is proposed to assess the average carbonation degree of the solids. After that, the carbonator model is incorporated into an overall process integration scheme to address the optimum operation conditions from thermodynamic and kinetics considerations. Results from process simulations show that the highest efficiencies for the CaL-CSP integration are achieved at carbonator absolute pressures of ∼3.5-4 bar, which leads to an overall plant efficiency (net electric power to net solar thermal power) around 41% when carbonation is carried out at 950 °C under pure CO.Ministerio de Economía y Competitividad CTQ2014-52763-C2, CTQ2017- 83602-C2European Union 72734

Partial oxycombustion-calcium looping hybridisation for CO2 capture in waste-to-energy power plants

The integration of bioenergy and carbon capture and storage (BECCS) presents a great opportunity for power production with global negative CO2 emissions. This work explores a novel synergetic system that integrates membranes, partial biomass oxycombustion and the calcium looping (CaL) process. Polymeric membranes generate oxygen-enriched air (OEA) with an O2 concentration of 40%v/v, which is used for partial oxycombustion of biomass waste. The CO2-enriched flue gas evolves from the waste-to-energy plant to the CaL unit, where CO2 concentration is increased up to 90-95%v/v, ready for purification and sequestration. Compared to only oxycombustion systems, the proposed concept presents fewer technological challenges in retrofitting boilers to waste-to-energy plants. Moreover, this new approach is highly efficient as integrating membranes to produce OEA instead of cryogenic distillation systems significantly reduces energy consumption. A novel integration concept is modelled to evaluate the whole process efficiency and the effect of key parameters on the system performance, such as the temperature of the reactors, the membrane surface area, and the partial oxy-combustion degree. The results show that the novel system has an energy consumption associated with CO2 capture below 4 MJ/kg CO2 (a 31% lower than that for a conventional CaL process), with a higher CO2 capture efficiency than oxycombustion and the CaL process separately. On the other hand, the economic analysis shows a higher CO2 capture cost for the novel configuration than for the typical CaL configuration due to the additional investment cost of the membrane system. Improvements in membrane performance, mainly by increasing its permeance and diminishing the required surface area, would significantly reduce the economic cost of this novel integration. Using membranes with permeance over 400 GPU would boost the competitiveness of the system.Este ítem es la versión preprint del artículo. Se puede consultar la versión final aquí https://doi.org/10.1016/j.jclepro.2023.136776Junta de Andaluci

A new model of the carbonator reactor in the Calcium Looping technology for post-combustion CO2 capture

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

La influencia de la temperatura en la datación de conchas por racemización de aminoácidos de los yacimientos de El Perro y La Fragua (Santoña, Cantabria)

Los yacimientos de El Perro y La Fragua se sitúan en el Monte Buciero (Santoña), separados únicamente por apenas 600 metros, en una zona que presenta un microclima particular que provoca el desarrollo de una vegetación con variedad de especies mediterráneas relictas y otras de carácter más atlántico. Ambos presentan niveles del Magdaleniense, Aziliense y Mesolítico que han sido datados empleando el método del carbono-14. En todos los niveles se encuentran abundantes restos de moluscos, incluyendo representantes del género Patella, que se analizaron mediante el método de racemización de aminoácidos. Las edades obtenidas con este método son superiores a las de radiocarbono y a la atribución cultural de los materiales