In accordance with various studies, the building sector requires more and more energy in summer for space cooling. This is also closely linked to the now well-proved rise in outdoor air temperatures due to climate change that provokes extreme hot events in summer even in moderate climates. To approach these new needs and challenges, it is essential to invest to lower overall demand, to increase energy conversion efficiencies and to replace fossil fuels with renewable energy sources (RES), in addition to the reduction of the summer peak of electric consumption for space cooling, also moving to sustainable heating and cooling technologies. In fact, currently, buildings heating is largely supplied by fossil-fueled individual heating solutions (e.g., natural gas boilers), while cooling is mainly provided by electric appliances such as individual cooling machines. In many cases, the traditional district heating system allows to heat buildings efficiently, but without solving the problem of summer cooling. In this framework, the PhD research here presented deals with new energy goals for the rational and sustainable use of thermal renewable sources in Europe. In particular, it will focus on the technology of shallow geothermal district heating applied to new and innovative District Thermal Systems (DTS), also called 5GDHC. The expression DTS has been adopted instead of District Heating (DH) and/or District Cooling (DC), indicating a system of pipes connected one side to final users (that can be also a prosumer) for thermal demands and other side to available heat sources, regardless of their level of temperature, size and complexity. Shallow geothermal energy applied to 5GDHC is one of the domains that can support in moving from fossil-based to sustainable cooling and heating solutions. Even though this kind of application is at the moment poorly diffused and neither studied in Europe, the establishment of scenarios with high amounts of DTS by 2050 would be in line with the current urbanization trend. Since geothermal 5GDHC (here named Geo-5GDHC) implies big investments, it is fundamental to have a systematic frame of analysis in order to guide their evolution and penetration effectively, underlying strength and weaknesses. This PhD investigates whether a Geo-5GDHC system can be cost-effective in different climatic contexts, where buildings have different heating and cooling demands, considering also different insulation levels and the presence of PVT panels (integration of photovoltaic and thermal technology). Through the definition of different scenarios and the use of a software (PILEDHC) appositely developed to couple a Geo-5GDHC energy assessment model with an economic analysis, the research highlights results and guidelines to provide common solutions for new and innovative geothermal district thermal systems, considering both the energy and the economic aspect and different contexts and conditions.
Secondo diversi studi, il settore edilizio richiede sempre più energia in estate per il raffreddamento degli ambienti. Ciò è strettamente legato anche all'ormai comprovato aumento delle temperature dell'aria esterna dovuto al cambiamento climatico, che provoca eventi di caldo estremo in estate anche in climi moderati. Per far fronte a queste nuove esigenze e sfide, è fondamentale investire per ridurre la domanda complessiva, aumentare l'efficienza di conversione dell'energia e sostituire i combustibili fossili con fonti energetiche rinnovabili, oltre a ridurre il picco estivo di consumo elettrico per il raffrescamento degli ambienti, passando anche a tecnologie di riscaldamento e raffrescamento sostenibili. Attualmente, infatti, il fabbisogno di riscaldamento degli edifici è in gran parte coperto da soluzioni individuali alimentate a combustibili fossili (ad esempio, caldaie a gas naturale), mentre il raffrescamento è fornito principalmente da apparecchi elettrici come le macchine frigorifere individuali. In molti casi, i sistemi di teleriscaldamento tradizionali consentono di riscaldare gli edifici in modo efficiente, ma senza risolvere il problema del raffreddamento estivo. In questo contesto, la ricerca di dottorato qui presentata si occupa di nuovi obiettivi energetici per l'uso razionale e sostenibile delle fonti rinnovabili termiche in Europa. In particolare, si concentra sulla tecnologia del teleriscaldamento geotermico a bassa profondità applicata a nuovi e innovativi sistemi termici di quartiere (District Thermal System, DTS), chiamati anche 5GDHC. L'espressione DTS è stata adottata al posto di District Heating (DH) e/o District Cooling (DC), indicando un sistema di tubazioni collegate da un lato all'utenza finale (che può essere anche un prosumer) per le domande termiche e dall'altro alle fonti di calore disponibili, indipendentemente dal loro livello di temperatura, dimensione e complessità. L'energia geotermica a bassa profondità applicata al 5GDHC è una delle soluzioni che possono supportare il passaggio da soluzioni di raffreddamento e riscaldamento basate su fonti fossili a soluzioni sostenibili. Anche se questo tipo di applicazione è al momento poco diffusa e studiata in Europa, una forte penetrazione di questa tecnologia entro il 2050 sarebbe in linea con l'attuale tendenza all'urbanizzazione. Poiché la geotermia 5GDHC (qui denominata Geo-5GDHC) implica grandi investimenti, è fondamentale disporre di un quadro di analisi sistematico per guidarne efficacemente l'evoluzione e la penetrazione, evidenziandone punti di forza e di debolezza. Questa ricerca di dottorato analizza dal punto vista economico i vantaggi di un sistema Geo-5GDHC in diversi contesti climatici, dove gli edifici hanno diverse domande di riscaldamento e raffrescamento, considerando anche diversi livelli di isolamento e la presenza di pannelli PVT (integrazione di tecnologia fotovoltaica e termica). Attraverso la definizione di diversi scenari e l'utilizzo di un software (PILEDHC), appositamente sviluppato per accoppiare un modello di valutazione energetica ed economica del Geo-5GDHC, la ricerca fornisce risultati e linee guida per l’applicazione di nuovi e innovativi sistemi geotermici di teleriscaldamento, considerando sia l'aspetto energetico che quello economico in diversi contesti e condizioni.
Energy-economic analysis applied to geothermal district thermal systems
BELLIARDI, MARCO
2021/2022
Abstract
In accordance with various studies, the building sector requires more and more energy in summer for space cooling. This is also closely linked to the now well-proved rise in outdoor air temperatures due to climate change that provokes extreme hot events in summer even in moderate climates. To approach these new needs and challenges, it is essential to invest to lower overall demand, to increase energy conversion efficiencies and to replace fossil fuels with renewable energy sources (RES), in addition to the reduction of the summer peak of electric consumption for space cooling, also moving to sustainable heating and cooling technologies. In fact, currently, buildings heating is largely supplied by fossil-fueled individual heating solutions (e.g., natural gas boilers), while cooling is mainly provided by electric appliances such as individual cooling machines. In many cases, the traditional district heating system allows to heat buildings efficiently, but without solving the problem of summer cooling. In this framework, the PhD research here presented deals with new energy goals for the rational and sustainable use of thermal renewable sources in Europe. In particular, it will focus on the technology of shallow geothermal district heating applied to new and innovative District Thermal Systems (DTS), also called 5GDHC. The expression DTS has been adopted instead of District Heating (DH) and/or District Cooling (DC), indicating a system of pipes connected one side to final users (that can be also a prosumer) for thermal demands and other side to available heat sources, regardless of their level of temperature, size and complexity. Shallow geothermal energy applied to 5GDHC is one of the domains that can support in moving from fossil-based to sustainable cooling and heating solutions. Even though this kind of application is at the moment poorly diffused and neither studied in Europe, the establishment of scenarios with high amounts of DTS by 2050 would be in line with the current urbanization trend. Since geothermal 5GDHC (here named Geo-5GDHC) implies big investments, it is fundamental to have a systematic frame of analysis in order to guide their evolution and penetration effectively, underlying strength and weaknesses. This PhD investigates whether a Geo-5GDHC system can be cost-effective in different climatic contexts, where buildings have different heating and cooling demands, considering also different insulation levels and the presence of PVT panels (integration of photovoltaic and thermal technology). Through the definition of different scenarios and the use of a software (PILEDHC) appositely developed to couple a Geo-5GDHC energy assessment model with an economic analysis, the research highlights results and guidelines to provide common solutions for new and innovative geothermal district thermal systems, considering both the energy and the economic aspect and different contexts and conditions.| File | Dimensione | Formato | |
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Descrizione: PhD thesis - Marco Belliardi
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https://hdl.handle.net/10589/220338