Solar and wind assisted heat pump to meet the building air conditioning and electric energy demand in the presence of an electric vehicle charging station and battery storage

Abstract

The increasingly widespread use of heat pumps (HPs) for the air conditioning of environments and electric vehicles (EVs) in urban contexts will lead in the short term to an increase in required electricity both on a scale of agglomeration of buildings and of a single building. To address this issue, in this work, an efficient renewable hybrid trigeneration system (RHTS) is analysed to be employed for heating and cooling air conditioning and electricity production. The electric energy is produced by means of an electric renewable hybrid system (ERHS), composed by photovoltaic (PV) and wind systems with a battery storage, which is employed to power the HP, an EV charging station and building electric devices.A methodology that employs different indicators, to be used both in a deterministic and statistical system analysis, was proposed to quantify the average reliability and reliability uncertainty of a hybrid system. In particular, in the statistical analysis, each indicator was subdivided into the average and uncertainty contribution, defined with two different perspectives. The first set of indicators allows quantification of the ERHS capability: to satisfy the overall load by means of the overall PV-wind fraction; to utilize the entire renewable energy produced by means of the utilization factor, to operate in nominal conditions by means of the dimensionless manufacturability; to cover the overall load over time by means of the overall time contemporaneity factor. The second set of indicators permits the comparison of the three different electric loads among them in terms of: renewable energy sent by the ERHS to each load by means of the energy contemporaneity factors; satisfaction of each single load by means of the PV-wind fractions; satisfaction of each single load in relation to the overall load by means of the weighted PV-wind fractions; satisfaction of each single load over time by means of the time contemporaneity factors.For this issue, a dynamic simulation tool, containing sophisticated models and proper algorithms and made up of three subroutines respectively for the building, HP and ERHS systems, was developed. In particular, a new algorithm to simulate the performance of a reversible multi-stage air-source HP was created.By considering an RHTS employed for supplying an office building energy demand located in the Mediterranean area, a weekly deterministic analysis has allowed evaluation of the reliability of the ERHS in the presence and absence of electric storage, while a yearly statistical analysis has allowed the identification of the system configurations with the highest average reliability and lowest reliability uncertainty by varying of the battery capacity, PV and wind power.