energies Article Integration of Micro-Cogeneration Units and Electric Storages into a Micro-Scale Residential Solar District Heating System Operating with a Seasonal Thermal Storage Antonio Rosato * , Antonio Ciervo, Giovanni Ciampi , Michelangelo Scorpio and Sergio Sibilio Department of Architecture and Industrial Design, University of Campania Luigi Vanvitelli, 81031 Aversa, Italy;
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[email protected]; Tel.: +39-081-501-0845 Received: 31 July 2020; Accepted: 9 October 2020; Published: 19 October 2020 Abstract: A micro-scale district heating network based on the operation of solar thermal collectors coupled to a long-term borehole thermal storage is modeled, simulated and investigated over a period of five years. The plant is devoted to covering the domestic hot water and space heating demands of a district composed of six typical residential buildings located in Naples (southern Italy). Three alternative natural gas-fueled back-up auxiliary systems (condensing boiler and two different technologies of micro-cogeneration) aiming at balancing the solar energy intermittency are investigated. The utilization of electric storages in combination with the cogeneration systems is also considered with the aim of improving the self-consumption of cogenerated electric energy; heat recovery from the distribution circuit is also evaluated to pre-heat the mains water for domestic hot water production. The performances of the proposed plant schemes are contrasted with those of a typical Italian decentralized heating plant (based on the utilization of natural gas-fueled non-condensing boilers).