The issue of climate change was the subject of discussion among leaders from all countries of the world at the Conference of the Parties (COP26) in Glasgow in 2021. To accelerate the achievement of the goals of the previous Paris Agreement, all countries have been invited to commit to securing a global net-zero by mid-century and keep the global average temperature increase significantly below 2 °C, compared to pre-industrial levels by 2050, and more specifically within the upper limit of 1.5 °C. All countries focus their policies on a global energy transition that consists of increased use of renewable sources for electricity generation and direct use of renewable heat and biomass, direct use of clean electricity in transport and heat applications, improved energy efficiency, and increased use of green hydrogen and bioenergy with carbon capture and storage. Currently, the renewable energy sources with the widest range of applications in the industrial sector are hydroelectric, geothermal, biomass, tidal, wind and solar. Solar energy is used to generate electricity using large-scale power plants or building installations, to produce domestic hot water, to supply space heating or cooling to meet the energy demands of both residential and tertiary users, and to desalinate seawater or brackish water. The most widely used solar technologies for electricity generation are Photovoltaic (PV) and Concentrating Solar Power (CSP) systems, both of which convert solar radiation into electricity but exploit different operating mechanisms and have different conversion efficiencies and investment costs. In CSP plants, the solar concentrator essentially consists of a collector, which, through a series of mirrors or lenses, concentrates the collected Direct Normal Irradiance (DNI) onto a receiver, thus obtaining high-temperature thermal energy, which is subsequently converted first into mechanical energy and, then, into electricity. There are four types of solar concentrator systems currently available on the renewable power technologies market, namely: linear Fresnel reflectors, parabolic trough collectors, central solar towers and parabolic dishes (usually equipped with a Stirling engine or a Brayton-cycle micro-turbine). Among all, the dish-Stirling system is the least widespread commercially and the least mature from a technological point of view since, firstly, the installation cost of the parabolic dish concentrator is still too high compared to other CSP technologies suffering the most from the stop of incentives and funding on the renewable energy sector and, secondly, the coupling with a thermal storage system is more difficult to realise. Nevertheless, this technology appears to be the most interesting and promising in terms of high values of solar-to-electric energy conversion efficiency, ease of installation, and modularity and is a viable solution for applications in integrated energy plants. Also, dish-Stirling systems are environmentally reliable not only in terms of emission-free energy generation but also in terms of the level of sustainability observed in the production and installation phases. Research presented in this thesis has been focused on the modelling, optimisation and energy, economic and environmental analysis of dish-Stirling power concentration solar systems, considering the demonstration plant installed within the university campus of Palermo (Italy) as a reference system.
raggiungimento degli obiettivi del precedente Accordo di Parigi, tutti i Paesi sono stati invitati a impegnarsi a garantire l'azzeramento globale entro la metà del secolo e a mantenere l'aumento della temperatura media globale significativamente al di sotto dei 2 °C, rispetto ai livelli preindustriali, entro il 2050, e più precisamente entro il limite superiore di 1,5 °C. Tutti i Paesi stanno concentrando le loro politiche su una transizione energetica globale che consiste nell'aumento dell'uso di fonti rinnovabili per la generazione di elettricità e nell'uso diretto di calore e biomassa rinnovabili, nell'uso diretto di elettricità pulita nei trasporti e nelle applicazioni termiche, nel miglioramento dell'efficienza energetica e nell'aumento dell'uso di idrogeno verde e bioenergia con cattura e stoccaggio del carbonio. Attualmente, tra le fonti di energia rinnovabile con la più ampia gamma di applicazioni nel settore industriale, l'energia solare viene utilizzata per generare elettricità attraverso centrali elettriche di grandi dimensioni o impianti a servizio di singoli edifici, per produrre acqua calda sanitaria, per fornire riscaldamento o raffreddamento degli ambienti per soddisfare la domanda energetica di utenti residenziali e terziari e per desalinizzare l'acqua di mare o salmastra. Le tecnologie solari più utilizzate per la produzione di energia elettrica sono gli impianti fotovoltaici (PV) e quelli a concentrazione solare (CSP), che convertono entrambi la radiazione solare in energia elettrica, ma sfruttano meccanismi di funzionamento diversi e presentano efficienze di conversione e costi di investimento differenti. Negli impianti CSP, il concentratore solare consiste essenzialmente in un collettore che, attraverso una serie di specchi o lenti, concentra l'irraggiamento normale diretto (DNI) raccolto su un ricevitore, ottenendo così energia termica ad alta temperatura, che viene successivamente convertita prima in energia meccanica e poi in elettricità. Esistono quattro tipi di sistemi di concentrazione solare attualmente disponibili sul mercato delle tecnologie per l'energia rinnovabile: i riflettori lineari di Fresnel, i collettori parabolici, le torri solari centrali e i dischi parabolici (solitamente dotati di un motore Stirling o di una microturbina a ciclo Brayton). Tra tutti, il sistema dish-Stirling è il meno diffuso commercialmente e il meno maturo dal punto di vista tecnologico poiché, in primo luogo, il costo di installazione di tale tecnologia è ancora troppo elevato rispetto alle altre tecnologie CSP in quanto risentono maggiormente dello stop agli incentivi e ai finanziamenti sul settore delle energie rinnovabili e, in secondo luogo, l'accoppiamento con un sistema di accumulo termico è più difficile da realizzare. Ciononostante, questa tecnologia appare la più interessante e promettente in termini di elevati valori di efficienza di conversione dell'energia solare in energia elettrica, facilità di installazione, modularità della taglia e rappresenta una valida soluzione per applicazioni in impianti energetici integrati. Inoltre, i sistemi dish-Stirling sono affidabili dal punto di vista ambientale non solo in termini di produzione di energia senza emissioni, ma anche per il livello di sostenibilità osservato nelle fasi di produzione e installazione. La ricerca presentata in questa tesi di dottorato si è concentrata sulla modellazione, l'ottimizzazione e l'analisi energetica, economica e ambientale dei sistemi solari a concentrazione di potenza dish-Stirling, considerando come sistema di riferimento l'impianto dimostrativo installato all'interno del campus universitario di Palermo (Italia).
(2022). MODELLING, OPTIMIZATION, AND 3E-ANALYSIS OF DISH-STIRLING CONCENTRATING SOLAR POWER SYSTEMS.
MODELLING, OPTIMIZATION, AND 3E-ANALYSIS OF DISH-STIRLING CONCENTRATING SOLAR POWER SYSTEMS
GUARINO, Stefania
2022-07-01
Abstract
The issue of climate change was the subject of discussion among leaders from all countries of the world at the Conference of the Parties (COP26) in Glasgow in 2021. To accelerate the achievement of the goals of the previous Paris Agreement, all countries have been invited to commit to securing a global net-zero by mid-century and keep the global average temperature increase significantly below 2 °C, compared to pre-industrial levels by 2050, and more specifically within the upper limit of 1.5 °C. All countries focus their policies on a global energy transition that consists of increased use of renewable sources for electricity generation and direct use of renewable heat and biomass, direct use of clean electricity in transport and heat applications, improved energy efficiency, and increased use of green hydrogen and bioenergy with carbon capture and storage. Currently, the renewable energy sources with the widest range of applications in the industrial sector are hydroelectric, geothermal, biomass, tidal, wind and solar. Solar energy is used to generate electricity using large-scale power plants or building installations, to produce domestic hot water, to supply space heating or cooling to meet the energy demands of both residential and tertiary users, and to desalinate seawater or brackish water. The most widely used solar technologies for electricity generation are Photovoltaic (PV) and Concentrating Solar Power (CSP) systems, both of which convert solar radiation into electricity but exploit different operating mechanisms and have different conversion efficiencies and investment costs. In CSP plants, the solar concentrator essentially consists of a collector, which, through a series of mirrors or lenses, concentrates the collected Direct Normal Irradiance (DNI) onto a receiver, thus obtaining high-temperature thermal energy, which is subsequently converted first into mechanical energy and, then, into electricity. There are four types of solar concentrator systems currently available on the renewable power technologies market, namely: linear Fresnel reflectors, parabolic trough collectors, central solar towers and parabolic dishes (usually equipped with a Stirling engine or a Brayton-cycle micro-turbine). Among all, the dish-Stirling system is the least widespread commercially and the least mature from a technological point of view since, firstly, the installation cost of the parabolic dish concentrator is still too high compared to other CSP technologies suffering the most from the stop of incentives and funding on the renewable energy sector and, secondly, the coupling with a thermal storage system is more difficult to realise. Nevertheless, this technology appears to be the most interesting and promising in terms of high values of solar-to-electric energy conversion efficiency, ease of installation, and modularity and is a viable solution for applications in integrated energy plants. Also, dish-Stirling systems are environmentally reliable not only in terms of emission-free energy generation but also in terms of the level of sustainability observed in the production and installation phases. Research presented in this thesis has been focused on the modelling, optimisation and energy, economic and environmental analysis of dish-Stirling power concentration solar systems, considering the demonstration plant installed within the university campus of Palermo (Italy) as a reference system.File | Dimensione | Formato | |
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