Comparative study regarding the global influence of energy storage medium on autonomous hybrid systems for a building with economical energy consumption GHEORGHE BADEA, RALUCA - ANDREEA FELSEGHI, TEODORA M. ŞOIMOŞAN, DAN MUREŞAN, FLORIN BADEA, GEORGE NAGHIU Building Services Engineering Department Technical University of Cluj-Napoca Boulevard December 21, no. 128-130, 400604, Cluj-Napoca ROMÂNIA gheorghe.badea@insta.utcluj.ro; http://instalatii.utcluj.ro/ Abstract: - The efficient and rational use of produced energy with the help of unconventional sources is one of actual energetic problems, with stress upon the aspects regarding stocking the energy in excess and deficiencies caused by intermittencies in producing energy caused to weather conditions. The success of renewable energy depends greatly upon the optimization of storage methods of energy excess with its returning in the system whenever necessary, and also upon the technological solutions which will be adopted to cover the intermittencies in producing energy and satisfaction of energy necessities of “peak load”. The batteries could seem to be the right choice, also globally, the development of energetic systems based upon the use of hydrogen as a tampon medium of energy storage, is the central point of different demonstrative projects which will allow validation of these technologies for energy storage as an alternative to classic ones. In the present paper the global influences upon the systems are analyzed, in which the two energy storage methods are integrated – batteries, respectively hydrogen produced from the excess of energy by electrolysis and reintroduced in the system by the fuel cell. The storage mediums serve an autonomous hybrid system, having an economical energy consumption and placement in Cluj - Napoca, Romania. Key - Words: autonomous hybrid system, energy storage medium, hydrogen, fuel cell, batteries, renewable sources of energy. 1 Introduction Hybrid systems of producing electrical energy can be defined as autonomous systems of producing electrical energy which comprise more than one source of energy, and which operates along with the auxiliary equipment, including storage, to supply electrical energy to network or place of interest. By this integration of different sources of energy in one supply system, the technology of hybridization offers the possibility of local usage of renewable sources of energy by supplying electrical energy, in places far from the network. The hybrid systems’ technology covers mainly autonomous systems, and also isolated networks with short coverage and medium voltage, energetic independent [10]. In all cases, the hybrid systems of producing electrical energy contain two or more sources of producing electrical energy to be able to balance the weak points and strong points of each [12]. The present article presents the results of a comparative study that was performed after the simulations using genetic algorithms [7]. Two scenarios have been simulated. In the first one, the hybrid system has as main elements of producing energy photovoltaic panels, wind turbines, and as main storage medium of excess energy it was considered hydrogen obtained by electrolysis, which will return as energy in the system by the fuel cell. The second hybrid system put to analysis has as main elements of producing energy identical with the first one (photovoltaic panels, wind turbines), and for storage medium batteries were used. Simulations on the above mentioned hybrid systems have as results the following aspects: a) technical and environment: the energetic balance of analyzed hybrid system, the excess of energy obtained by the system, the CO2 emissions resulted from the process; Computer Applications in Environmental Sciences and Renewable Energy ISBN: 978-960-474-370-4 209