Smart energy grids and renewable multi-generation systems

The current carbon-based energy system is undergoing a deep transformation, mostly aimed at reducing the energy-related emissions of carbon dioxide and other air pollutions. The evolutionary trend of such transition is toward smart energy networks, combining several energy technologies for energy production, storage and utilization, and including a plurality of energy producers, users and prosumers (i.e., producers and users at the same time). The main goal of this work is to explore a series of possible solutions addressing the development of sustainable smart energy networks, analyzing pros and cons of different layouts and technologies from energy, environmental and economic viewpoints, and providing criteria and guidelines for designers, stakeholder and policy makers. Note that the researches described within this thesis are based on researches published on peer-reviewed journals, which was coauthored by the author of this thesis. The studies are based on the use of a dynamic simulation approach. Dynamic simulations can mimic the real performance and behavior of the systems under evaluation, providing crucial information about such systems; this way, it is possible to evaluate their economic profitability and their capacity to reduce fossil energy consumptions and CO2 emissions, with respect to conventional systems. TRNSYS suite is adopted for carrying out such analyses and simulations. TRNSYS is a well-known and reliable tool, widely adopted in academic and commercial applications. Note that TRNSYS environment comes with a large library of components experimentally validated. Moreover, TRNSYS allows the user to adopt in-house and user-developed models. This tool exhibits high accuracy and reliability for the calculation of the dynamic performance of several solar systems. In addition, this software proved high accuracy and risibility in simulating building energy performance. Private mobility is the first sector analyzed in the thesis; in fact, it is currently recognized as one of the most important source of energy consumptions and related CO2 emissions. Different solutions to couple electric vehicles and renewable energy technologies were proposed and analyzed, highlighting that layouts including electric vehicles, residential buildings and renewable energies can be profitably included into smart energy networks. The second chapter is devoted to polygeneration systems. Such systems manage several energy sources, vectors and final users and energy vectors, and are therefore especially attractive for the development of smart energy networks. Polygeneration systems fed by renewables can produce several energy vectors with a very limited consumption of fossil energy. In particular, geothermal and solar energy were considered in the case studies developed and analyzed; such energy source, in fact, are largely available in Campania (South of Italy), where most of the systems evaluated are located. The production of freshwater through reverse osmosis driven by photovoltaic panels was also considered, aiming to match most needs of a given residential district. In addition, reverse osmosis can exploit the excess of photovoltaic power production, avoiding the problems related with the unbalancing of the local electric grid. Moreover, the coupling of photovoltaic energy and reverse osmosis is useful for reducing the dependence on water supply shipped by the mainland, in many isolated islands of the Mediterranean Sea. In Chapter 3, several layouts involving different energy networks were developed and analyzed, also coupling the energy demands of a residential district and that related to private mobility. A further smart energy network able to simultaneously provide thermal energy, electricity and drinkable water was assessed. Finally, the case of a micro energy network was also considered, referred to a hospital facility. Hospitals are highly energy intensive buildings and represent an important candidate for inclusion within a smart micro energy network: in fact, they are usually located nearby residential areas, and their energy facilities can be easily connected or expanded to the energy network serving such residential area. In this framework, several micro energy networks based on cogeneration internal combustion engine were analyzed. A hybrid layout based on photovoltaic and cogeneration was analyzed, too