A discussion of possible approaches to the integration of thermochemical storage systems in concentrating solar power plants

One of the most interesting perspectives for the development of concentrated solar power (CSP) is the storage of solar energy on a seasonal basis, intending to exploit the summer solar radiation in excess and use it in the winter months, thus stabilizing the yearly production and increasing the capacity factor of the plant. By using materials subject to reversible chemical reactions, and thus storing the thermal energy in the form of chemical energy, thermochemical storage systems can potentially serve to this purpose. The present work focuses on the identification of possible integration solutions between CSP plants and thermochemical systems for long-term energy storage, particularly for high-temperature systems such as central receiver plants. The analysis is restricted to storage systems potentially compatible with temperatures ranging from 700 to 1000 ◦C and using gases as heat transfer fluids. On the basis of the solar plant specifications, suitable reactive systems are identified and the process interfaces for the integration of solar plant/storage system/power block are discussed. The main operating conditions of the storage unit are defined for each considered case through process simulation

Investigation into the Coupling of Micro Gas Turbines with CSP Technology: OMSoP Project☆

Abstract Solar power generation has been gaining worldwide increasing interest by virtue of its ability to meet both the growing energy needs and the increasing concerns on the carbon dioxide emissions. One of the most promising Concentrated Solar Power (CSP) technologies under development uses a parabolic dish to concentrate solar power into a focal point, raising thetemperature of a working fluid which is then used in a thermodynamic cycle to generate electricity. In the OMSoP project, funded by the European Commission, it is proposed to use a Brayton cycle in the form of a micro-gas turbine (MGT), which replaces the more conventional Stirling engine,with the aim of increasing the ratio of the electric power generated to the solar energy collected and improving the operability in relation to solar energy short time fluctuations. To achieve these objectives, research and development will be conducted in all aspects of the system leading to a full scale demonstrative plant to be located at the ENEA Casaccia Research Centre.The present work deals with the activities carried out so far by ENEA, which is principally involved in the development and experimental characterization of the dish component, and in the integration of the complete system, both in terms of modelling and realization

Calcium Looping for Thermochemical Storage: Assessment of Intrinsic Reaction Rate and Estimate of Kinetic/Transport Parameters for Synthetic CaO/Mayenite Particles from TGA Data

Mayenite-supported CaO represents an affordable and safetycompliant candidate material for thermochemical storage processes. We here analyze the thermogravimetric analysis (TGA) performance of synthetic CaO/mayenite micrometric powder under carbonatation/calcination looping and develop a model to interpret and analyze the experimental results. In the experimental campaign, calcination is run at 900 degrees C, while the carbonatation temperature is varied between 600 and 800 degrees C. For the carbonatation reaction, a generalized shrinking core model assuming a thermodynamically consistent first-order kinetic and a conversion-dependent diffusivity of CO2 inside the porous CaCO3 layer is validated through TGA carbonatation tests conducted with CO2/N-2 mixtures at different compositions. Interestingly, the kinetic constant of this reaction is found to be relatively insensitive to the temperature in the interval considered. In contrast, diffusion-limited regimes are never found for the calcination reaction so that this phase of the cycle can be predicted based on a single kinetic constant of the heterogeneous reaction. This constant is found to follow the typical Arrhenius-type dependence on temperature. Sizably different kinetic and transport parameters are obtained in the first carbonation performed on virgin CaO/mayenite particles with respect to those associated with subsequent cycles. When different parameters are afforded for the first and following cycles, the shrinking core model proposed closely predicts the TGA data over five CaO/CaCO3 cycles. The results found constitute an essential preliminary piece of information for designing equipment geometry and operating conditions of industrial-scale reactors. In this respect, knowledge of the parameters defining the intrinsic reaction rates and diffusive transport is essential in defining the optimal conversion of the material associated with minimal looping time

A Quasi-Steady State Model of a Solar Parabolic Dish Micro Gas Turbine Demonstration Plant

In the framework of the European Optimised Microturbine Solar Power system (OMSoP) project, a novel energy system for solar electricity production was developed, based on the integration of the solar dish technology with Micro Gas Turbines (MGT). A pilot plant with a capacity of 5–7 kWe was realized and installed at the ENEA Casaccia site (Rome) and went under testing to validate the feasibility of the technology and improve the current design. The present work deals with the development of a quasi-state system model, built in the Engineering Equation Solver environment, composed of different modules that correspond to the main system components. The system model was used to define the optimal system parameters, to help the elaboration on an operational strategy to maximize the overall plant efficiency, and to guide the improvement of the single components in view of their optimised design. From the analysis it emerged that the system in design conditions is able to generate, in nominal conditions, 4.5 kWe instead of the expected 5 kWe due to the limitation of the stator current to 13 A, while maximum levels of 5.6 kW could be achieved by “overcharging” the high-speed generator up to 15 A and operating the MGT at the very high speed of 150 krpm. From the transient simulation of the demo system on an annual basis, the maximum average output power is 3.58 kWe. Regarding the cycle efficiency, the annual averaged value is about 17%, whereas the target value is 21%. The improvement of the generator only does not seem to significantly increase the power output on the annual basis (3.75 kWe vs. 3.58 kWe). Differently, the improvement of the solar dish, with the upgrade of the other system components, would significantly increase the system power output to around ~10 kWe

DTT - Divertor Tokamak Test facility: A testbed for DEMO

The effective treatment of the heat and power exhaust is a critical issue in the road map to the realization of the fusion energy. In order to provide possible, reliable, well assessed and on-time answers to DEMO, the Divertor Tokamak Test facility (DTT) has been conceived and projected to be carried out and operated within the European strategy in fusion technology. This paper, based on the invited plenary talk at the 31st virtual SOFT Conference 2020, provides an overview of the DTT scientific proposal, which is deeply illustrated in the 2019 DTT Interim Design Report

DTT - Divertor Tokamak Test facility - Interim Design Report

The “Divertor Tokamak Test facility, DTT” is a milestone along the international program aimed at demonstrating – in the second half of this century – the feasibility of obtaining to commercial electricity from controlled thermonuclear fusion. DTT is a Tokamak conceived and designed in Italy with a broad international vision. The construction will be carried out in the ENEA Frascati site, mainly supported by national funds, complemented by EUROfusion and European incentive schemes for innovative investments. The project team includes more than 180 high-standard researchers from ENEA, CREATE, CNR, INFN, RFX and various universities. The volume, entitled DTT Interim Design Report (“Green Book” from the colour of the cover), briefly describes the status of the project, the planning of the design future activities and its organizational structure. The publication of the Green Book also provides an occasion for thorough discussions in the fusion community and a broad international collaboration on the DTT challenge

L'impiego dei materiali polimerici nell'imballaggio

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

L'inquinamento acustico prodotto da traffico ferroviario: origine, propagazione e sistemi di attenuazione. Progetto 'Apparati silenti'

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Hybridization solutions for solar dish systems installed in the Mediterranean region

One of the main challenges facing the commercialization of parabolic solar systems is their high initial cost, which is not competitive with the low cost, ease of operation, and reliability of photovoltaic technology. However, one potential solution to maximize their energy producibility and improve their economic profitability is to hybridize the power conversion unit. By enabling reliable power generation and reducing reliance on the availability of solar thermal energy, hybridization can be a valid solution to improve the efficiency and practicality of parabolic dish solar systems. This study aims to assess the energy performance of two hybrid parabolic dish systems: the dish-Stirling system located at the University of Palermo, and the dish-Micro Gas Turbine system located at ENEA Casaccia. Different scenarios were examined by varying the installation site and operational strategy, as well as exploring hybridization solutions of the solar source with conventional fossil fuel or renewable ones. The findings suggest that hybridizing parabolic dish systems with conventional fuels or renewable energies greatly enhances their performance, increasing operational hours and maximizing energy producibility