J. M. Valverde

Universidad de Sevilla | US · Faculty of Physics

Nanosilica coatings are considered a simple physical treatment to alleviate the effect of cohesion on powder flowability. In limestone powders, these coatings buffer the rise in cohesion at high temperatures. Here, we investigate the role of particle size in the efficiency (and resilience) of these layers. To this end, this work examines a series o...

Although calcium-based materials are the most promising adsorbents used in calcium looping process for carbon dioxide removing, their CO2 capture capacity decaying besides poor fluidization, still are the important challenges. In the present investigation, eggshell as a cheap, easily available and unpolluted source of calcium carbonate was used for...

The reduction, storage, and reuse of greenhouse gas carbon dioxide (CO2) is a crucial concern in modern society. Bio-waste adsorbents have recently aroused the investigator's attention as auspicious materials for CO2 capture. However, the adsorption capacity decaying and poor fluidizability during carbonation/calcination cycles of all natural adsor...

Steam injection has been proposed to attenuate the decay of CaO reactivity during calcium looping (CaL) under operating conditions compatible with carbon capture and storage. However, it is yet unknown whether the perceived advantages granted by steam hold under the distinct operating conditions required for the integration of the CaL process as a...

Fine granular media are pivotal in thermochemical energy storage technology. Reactors based on granular materials store the heat using reversible reactions at high temperatures. Yet, powders become increasingly cohesive in those conditions. The rise of powder cohesion at high temperatures is one of the most irksome phenomena still limiting the scal...

Thermochemical energy storage (TCES) has attracted interest in the last years due to the possibility of attaining high energy densities, seasonal storage capacity and greater efficiencies than currently commercial thermal energy storage systems using molten salts. This work analyses the potential of an ultra-high temperature TCES system based on th...

The Calcium-Looping (CaL) process, based on the multicyclic calcination-carbonation of CaCO3/CaO, is considered a promising Thermochemical Energy Storage (TCES) technology to be integrated into Concentrating Solar Power (CSP) plants. This work proposes a novel CaL integration that operates at low-pressure calcination under pure CO2 and a moderated...

This work demonstrates the first proof-of-concept of Multi-Phase Flash Sintering (MPFS). This novel technique essentially consists of applying a rotating electric field to the sample by means of a multi-phase voltage source as furnace temperature increases. Several ceramic materials with different types of electrical conductivities are sintered wit...

Large-scale thermochemical energy storage (TCES) is gaining relevance as an alternative to current thermal energy storage systems in Concentrated Solar Power plants. Among the different systems, the reversible reaction between CaO and CO2 stands out due to the wide availability and low cost of the raw material: limestone. Direct solar absorption of...

This study explores the effect of steam addition during carbonation on the multicyclic performance of limestone under calcium looping conditions compatible with (i) CO2 capture from postcombustion gases (CCS) and with (ii) thermochemical energy storage (TCES). Steam injection has been proposed to improve the CO2 uptake capacity of CaO-based sorbent...

Due to its technological applications, such as CO2 capture, CaO carbonation kinetics has been extensively studied using a wide array of methods and experimental conditions. A complete understanding of carbonation kinetics is key to optimizing the operating conditions as well as to correctly design the carbonation reactor. However, there is yet no c...

This work reports a novel in situ XRD analysis on the multicycle calcination/carbonation of natural limestone and dolomite at relevant conditions for thermochemical energy storage (TCES) in concentrated solar power (CSP) plants. The experiments allow analysing noninvasively the time evolution of the different phases involved in the Calcium Looping...

The present work proposes integrating a high-temperature thermochemical energy storage cycle to boost the solar contribution in solar combined cycles. The main feature of the plant is the possibility of storing solar energy at a very high temperature and releasing it on demand to drive the combined cycle in the absence of solar radiation. Based on...

Fine powders are the cornerstone of new energy storage solutions to assist concentrated solar power plants. Though, their ability to behave like fluid can be seriously affected at high temperatures. This work investigates the use of nanosilica in fine limestone (calcium carbonate, CaCO3) powders to mitigate the promotion of cohesion forces at high...

Solar technology has shown a keen interest in thermochemical storage to extend its operational timespan beyond a daily basis. Thermochemical solutions are operated by fine powders. Unlike regular granular media, fine powders become cohesive. However, despite the paramount importance of controlling powder flowability to integrate these solutions in...

In the present work, we explore the use of steam in the CaCO3 calcination step of a calcium looping process devised for integration into a thermochemical energy storage process (CaL-TCES). Steam produces a double benefit: firstly, it fastens the calcination, allowing a reduction of the temperature needed to attain full calcination in short residenc...

The integration of Concentrating Solar Power (CSP) in combined cycles is a subjects of increasing attention. Combined cycles require high temperature at the gas turbine inlet (typically over 1000 °C), which hinders plant operation in the absence of direct solar radiation using currently commercial storage technologies based on molten salts (with a...

The Calcium-Looping (CaL) process has emerged in the last years as a promising technology to face two key challenges within the future energy scenario: energy storage in renewable energy-based plants and CO2 capture from fossil fuel combustion. Based on the multicycle calcination-carbonation reaction of CaCO3 for both thermochemical energy storage...

The Calcium Looping performance of limestone for thermochemical energy storage has been investigated under novel favorable conditions, which involve calcination at moderate temperatures under CO2 at low pressure (0.01 and 0.1 bar) and carbonation at high temperature under CO2 at atmospheric pressure. Calcining at low CO2 pressures allows to substan...

The present work reports an in situ XRD analysis on the calcination of natural dolomite under a pure CO2 atmosphere. A main goal is to provide an insight on how calcination kinetics and the crystal structure of the calcination byproducts are affected by the addition of H2O to the calciner at a very low concentration. The working conditions are rele...

This manuscript presents a general model for the fluidized bed carbonator reactor of the Calcium Looping (CaL) process based on bed hydrodynamics, kinetics and sorbent properties. The model proposed relies on the Kunii–Levenspiel theory for circulating fluidized beds in the fast fluidization regime and considers recent findings on the CO2 capture p...

The commercial deployment of calcium looping (CaL) based technologies relies on the availability of non-toxic, widely available and cheap CaCO3 rich materials. Biomineralized CaCO3 from waste amply fulfil the aforementioned requirements. In the present work, we study the performance of eggshell and snail shell from food waste as CaO precursors for...

Calcium looping (CaL) process offers a promising option to boost the energy efficiency and dispatchability in concentrated solar power (CSP) plants. Backed by ample experience on lime and cement industry, the CaL integration in CSP plants could be not only a feasible and reliable technology for energy storage but also a low-cost choice based on the...

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 enc...

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...

Thermal Energy Storage (TES) using granular solids is gaining momentum in the last years. With no degradation up to very high temperatures and very low price the use of some granular materials such as sand or SiC would be feasible for storing sensible heat at large scale. A further step beyond TES is thermochemical energy storage (TCES) wherein the...

Correction for ‘Limestone calcination under calcium-looping conditions for CO 2 capture and thermochemical energy storage in the presence of H 2 O: an in situ XRD analysis’ by Jose Manuel Valverde et al. , Phys. Chem. Chem. Phys. , 2017, 19 , 7587–7596.

The calcium looping process, based on the reversible reaction between CaCO3 and CaO, is recently attracting a great deal of interest as a promising thermochemical energy storage system to be integrated in Concentrated Solar Power plants (CaL-CSP). The main drawbacks of the system are the incomplete conversion of CaO and its sintering-induced deacti...

Dispatchability is a key issue to increase the competitiveness of concentrating solar power plants. Thermochemical energy storage systems are a promising alternative to molten salt-based storage because of the higher energy storage density and the possibility of increasing the storage period. Among possible thermochemical systems, the Calcium-Loopi...

Energy storage based on thermochemical systems is gaining momentum as a 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...

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 intrinsi...

In the last years the CaL process has come into scene as a promising alternative to molten salts for storing energy in concentrated solar power (CSP) plants through the calcination/carbonation reaction of CaCO3/CaO. Natural CaCO3 resources such as limestone are wide available, very cheap and non-toxic. A caveat however is that fine CaCO3 powders mu...

The interaction between magnetic particles in a bed fluidized by a gas is determined by the magnetizing action of an externally applied magnetic field. As the strength of the field is increased there comes a point at which the bed transits from a fluidlike to a solidlike stable state. Interparticle attractive forces induced by the applied field cau...

Rheological properties of xerographic liquid inks of different concentrations of solid particles have been tested. Generally we have found that viscosity decreases with increasing shear rate, i.e. the system is pseudoplastic as corresponds to the break down of aggregated particles by the applied shear. The viscosity of inks may vary in orders of ma...

High energy density, cycling stability, low cost and scalability are the main features required for thermochemical energy storage systems to achieve a feasible integration in Concentrating Solar Power plants (CSP). While no system has been found to fully satisfy all these requirements, the reversible CaO/CaCO3 carbonation reaction (CaL) is one of t...

[Full text only version: https://rdcu.be/bjHJj] The results of laboratory-scale experiments with ignimbrite material are reported and discussed. The ignimbrite material contained in a rotating drum is subjected to mechanical vibrations, simulating particle agitation at the base of a pyroclastic flow propagating on an irregular substrate. It is obs...

In this work, the multicycle activity of natural CaO precursors (limestone and dolomite) and Ca-based composites (Ca3Al2O6/CaCO3 and ZrO2/CaCO3 mixtures) has been studied for Thermochemical Energy Storage (TCES) in Concentrated Solar Power (CSP) plants by means of the Calcium-Looping process (CaL), using two integration schemes proposed elsewhere t...

In this work we investigate the fluidization behavior and mechanical properties of granular beds of fine magnetite beads as affected by an increase of temperature and the application of a magnetic field. In the range of temperatures tested (up to 200°C) the cohesiveness of the bed is decreased with temperature whereas it is enhanced by the magnetic...

CaO-based materials have been identified as promising sorbents for highly efficient pre-combustion and post-combustion CO2 capture in fluidized beds operated at high temperatures by means of the Calcium Looping (CaL) process. However, Ca-based sorbents suffer from a decline of the capture capacity over multiple sorption/desorption cycles, mainly du...

The potential of controlled rate thermal analysis (CRTA) for studying high‐pressure gas‐solid processes has been evaluated. CRTA is a type of smart temperature program based on a feedback system that uses any experimental signal related to the process evolution for commanding the temperature evolution. In this work, an instrument that uses the grav...

Over the last 40 years different thermal energy storage materials have been investigated with the aim of enhancing energy efficiency in buildings, improving systems performance, and increasing the share of renewable energies. However, the main requirements for their efficient implementation are not fully met by most of them. This paper develops a c...

In this work, we analyze the crystallographic transformations that take place during the carbonation of Na2CO3 into NaHCO3 and the reverse decarbonation reaction at relevant conditions in the dry carbonate process. This process has been recently proposed and tested at the pilot scale to capture CO2 from fossil fuel power plants. However, the mechan...

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 CaCO3 stands as a main candidate due to the high energy density ac...

This work is focused on the use of the Calcium-Looping process (CaL) in Concentrated Solar Power (CSP) plants for Thermochemical Energy Storage (TCES). Cheap, abundant and non-toxic natural carbonate minerals, such as limestone and dolomite, can be employed in this application to store energy through the cyclic calcination/carbonation of CaCO3. In...

The Calcium-Looping process is a promising thermochemical energy storage method based on the multicycle calcination-carbonation of CaCO3-CaO to be used in concentrated solar power plants. When solar energy is available, the CaCO3 solids are calcined at high temperature to produce CaO and CO2, which are stored for subsequent utilization. When power...

This work analyzes the relevant influence of milling on the CO2 capture performance of CaO derived from natural limestone. Diverse types of milling mechanisms produce contrasting effects on the microstructure of the CaO formed after calcination of the milled limestone samples, which affects crucially the kinetics of carbonation at conditions for CO...

The calcium looping (CaL) process, based on the cyclic carbonation/calcination of CaO, has come into scene in the last years with a high potential to be used in large-scale technologies aimed at mitigating global warming. In the CaL process for CO2 capture, the CO2-loaded flue gas is used to fluidize a bed of CaO particles at temperatures around ~...

An ever more environmentally conscious society demands the use of green, sustainable and high-efficiency renewable energy resources. However, large-scale energy storage remains a challenge for a deep penetration of power produced from renewables into the grid. The Calcium-Looping (CaL) process, based on the reversible carbonation/calcination of CaO...

The Calcium Looping (CaL) process, based on the carbonation/calcination of CaO, has been proposed as a feasible technology for Thermochemical Energy Storage (TCES) in Concentrated Solar Power (CSP) plants. The CaL process usually employs limestone as CaO precursor for its very low cost, non-toxicity, abundance and wide geographical distribution. Ho...

This work reports the Calcium-Looping (CaL) multicycle performance under energy storage and CO2 capture conditions of different Al-composites prepared by milling mixtures of nanoalumina and natural limestone powders. The micro- and nanostructure of the composites have been analyzed by X-ray diffraction, scanning electron microscopy and high-resolut...

Buildings are responsible for one-third of the world's energy consumption, of which 60% is due to heating and cooling. To accomplish the low-carbon energy goal in the building sector, thermal energy storage offers a number of benefits by reducing energy consumption and promoting the use of renewable energy sources. This manuscript reviews recent ad...

Thermochemical energy storage in Concentrated Solar Power plants by means of the Calcium-Looping process is a promising novel technology that would allow for a higher share of renewables. A main benefit of this technology is the use of widely available, non-toxic and environmentally friendly calcium carbonate minerals as raw materials to store ener...

The present work is focused on thermochemical energy storage (TCES) in Concentrated Solar Power (CSP) plants by means of the Calcium-Looping (CaL) process using cheap, abundant and non-toxic natural carbonate minerals. CaL conditions for CSP storage involve calcination of CaCO3 in the solar receiver at relatively low temperature whereas carbonation...

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 unde...

Dynamical weakening of dense granular flows plays a critical role on diverse geological events such as seismic faulting and landslides. A common feature of these processes is the development of fluid-solid relative flows that could lead to fluidization by hydrodynamic viscous stresses. Volcanic ash landslides (pyroclastic flows) are characterized b...

This paper proposes a novel CO2 capture technology from the integration of partial oxy-combustion and the Calcium-Looping capture process based on the multicycle carbonation/calcination of limestone derived CaO. The concentration of CO2 in the carbonator reactor is increased by means of partial oxy-combustion, which enhances the multicycle CaO conv...

The Calcium Looping (CaL) process, based on the cyclic carbonation/calcination of CaO, has emerged in the last years as a potentially low cost technique for CO2 capture at reduced energy penalty. In the present work, natural limestone and dolomite have been pretreated with diluted acetic acid to obtain Ca and Ca-Mg mixed acetates, whose CO2 capture...

This work reports an in situ XRD analysis of whether the calcination/carbonation behavior of natural limestone (CaCO3) is affected by the addition of H2O to the calciner at a very low concentration under relevant Calcium-Looping (CaL) conditions for CO2 capture in coal fired power plants (CFPP) and Thermochemical Energy Storage (TCES) in Concentrat...

Thermochemical energy storage (TCES) is considered a promising technology to overcome the issues of intermittent energy generation in Concentrated Solar Power (CSP) plants and couple them with yearly electricity demand. The development of this technology could favor the commercial deployment of CSP, which is considered as a key factor for new chall...

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....

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...

The share of renewable energies is rapidly growing partly in response to the urgent need of mitigating CO2 emissions from fossil fuel power plants. However, cheap and efficient large-scale energy storage technologies are not yet available to allow for a significant penetration of renewable energies into the grid. Recently, it has been proposed a po...

This work reports an in situ XRD analysis of whether the calcination/carbonation behavior of natural limestone (CaCO3) is affected by the addition of H2O to the calciner at a very low concentration under relevant Calcium-Looping (CaL) conditions for CO2 capture in coal fired power plants (CFPP) and Thermochemical Energy Storage (TCES) in Concentrat...

This work reports an in situ XRD analysis of whether the calcination/carbonation behavior of natural limestone (CaCO3) is affected by the addition of H2O to the calciner at a very low concentration under relevant Calcium-Looping (CaL) conditions for CO2 capture in coal fired power plants (CFPP) and Thermochemical Energy Storage (TCES) in Concentrat...

Deep penetration of renewable energies into the grid relies on the development of large-scale energy storage technologies using cheap, abundant and non-toxic materials. Concentrated Solar Power (CSP) is particularly suitable to massively store thermal energy for dispatchable electricity generation. This is currently accomplished in a few demonstrat...

The calcium looping (CaL) process, based on the calcination/carbonation of CaCO3 at high temperatures, has emerged in the last years as a potentially low cost technology for CO2 capture. In this work, we show that the application of high intensity sound waves to granular beds of limestone and dolomite in a CaL reactor enhances significantly their m...

Fluidized beds of granular materials can be stabilized by interparticle attractive forces which confer the expanded bed an elastic modulus that stabilizes it against flow perturbations. Stabilization in a structure of enduring contacts is seen to occur naturally due to the universal van der Waals forces for m particle size beds albeit in a quite re...

The multicycle CO2 capture performance of CaO derived from the calcination of ball-milled limestone and dolomite have been tested under “realistic” operation conditions (high CO2 concentration environment and temperature) for the first time. Here it is shown that the CO2 capture capacity of CaO is inversely related to the milling power applied to t...

The multicycle CO2 capture performance of CaO derived from the calcination of ball-milled limestone and dolomite have been tested under “realistic” operation conditions (high CO2 concentration environment and temperature) for the first time. Here it is shown that the CO2 capture capacity of CaO is inversely related to the milling power applied to t...

Limestone (CaCO$_3$) calcination to yield CaO plays a central role on a myriad of natural and industrial processes among which the recently emerged Calcium Looping (CaL) process to capture CO_2 is gaining a great relevance in the last years. A main drawback of this process however is that calcination to regenerate the CaO sorbent particles must be...

Limestone (CaCO3) calcination to yield CaO plays a central role in a myriad of natural and industrial processes, among which the recently emerged Calcium Looping (CaL) process to capture CO2 is gaining a great relevance in the last few years. A main drawback of this process, however, is that calcination to regenerate the CaO sorbent particles must...

A vast number of physical processes involving oscillations of a bounded viscous fluid are relevantly influenced by acoustic streaming. When this happens a steady circulation of fluid develops in a thin boundary adjacent to the interface. Some examples are refracted sound waves, a fluid inside a spherical cavity undergoing torsional oscillations or...

The calcium looping (CaL) process, based upon the dry carbonation/calcination of CaO/CaCO3, is at the center of a potentially low-cost, second-generation technology for CO2 capture. This manuscript analyzes the energy penalty that arises from the integration of the CaL process into a coal-fired power plant using cheap and abundantly available CaO p...

The calcium looping (CaL) process, based on the calcination/carbonation of CaCO3, has emerged in the last years as a potentially low cost technology for CO2 capture. In this work, we show that the application of high intensity sound to limestone and dolomite beds in a CaL reactor enhances significantly their multicycle CO2 capture capacity. Experim...

The multicycle CO2 capture performance of CaO derived from natural limestone and dolomite has been investigated by means of thermogravimetry under realistic Calcium-Looping conditions, which necessarily involve high CO2 concentration and high temperatures in the calcination stage and fast transitions between the carbonation and calcination stages....

One of the major drawbacks that hinder the industrial competitiveness of the calcium looping (CaL) process for CO2 capture is the high temperature (∼930-950 °C) needed in practice to attain full calcination of limestone in a high CO2 partial pressure environment for short residence times as required. In this work, the multicycle CO2 capture perform...

The Ca-Looping (CaL) process is at the root of a promising 2nd generation technology for post-combustion CO2 capture at coal fired power plants. The process is based on the reversible and quick carbonation/calcination reaction of CaO/CaCO 3 at high temperatures and allows using low cost, widely available and non toxic CaO precursors such as natural...