IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 __________________________________________________________________________________________ Volume: 02 Issue: 11 | Nov-2013, Available @ http://www.ijret.org 462 INNOVATIVE STRATEGIES FOR ENERGY OPTIMIZATION S. Bottillo 1 , L. Cedola 2 , R. de Lieto Vollaro 3 , A. Vallati 4 1 Ph.D. Student, 4 Assistant Professor, DIAEE, Sapienza University of Rome, Rome, Italy 2 Assistant Professor, DIMA, Sapienza University of Rome, Italy 3 Assistant Professor, Department of Engineering, University of Roma Tre, Rome, Italy, simone.bottillo@uniroma1.it, luca.cedola@uniroma1.it, roberto.delietovollaro@uniroma3.it, andrea.vallati@uniroma1.it Abstract Optimization of energy production systems is a relevant issue that must be considered in order to follow the fossil fuels consumption reduction policies and the CO2 emission regulation. Increasing electricity production from renewable resources (e.g. photovoltaic systems and wind farms) is desirable but its unpredictability is a cause of problems for the main grid stability. The multi-energy system represents an efficient solution, by realizing an interface among renewable energy sources, energy storage systems and conventional power generators. Direct consequences of multi-energy systems are wider energy flexibility and benefits for the electric grid. In this study the performances of a multi-energy system in dynamic regime have been evaluated and a comparison with a conventional system has been performed. The results show how this innovative energetic approach can provide a cost reduction in power supply and energy fees of 40% and 25% respectively and CO2 emission decrease attained around 18%. Furthermore, the multi-energy system taken as case of study has been optimized through the utilization of three different type of energy storage (Pb-Ac batteries, Flywheels and Micro-Caes). Keywords: Multi-Energy System, Cost of Energy, Energy Storage ----------------------------------------------------------------------***------------------------------------------------------------------------ 1. INTRODUCTION The rise of CO2 level in the atmosphere is the main responsible for global warming and the international community set a deadline to achieve some targets in the Kyoto Protocol. The European Union accepted the recommendations established in the agreement and it has outlined a strategy in order to achieve three different targets (called 20-20-20) within 2020: the 20% reduction of greenhouse gases emissions, the 20% increase of energy production from renewable sources and the 20% increase of energy efficiency [1-2]. The following guidelines have been outlined: promoting the electricity distribution grid with generators connected, incentivizing the energy production from renewable sources and from CHP systems (combined heat and power) applied in residential, service and commercial sectors, developing the sustainable mobility through the utilization of electric vehicles, promoting a rational use of electricity in order to decrease the energy consumption. For this reason, it is necessary to study multi-energy or hybrid systems: systems which use two or more energy sources, energy converters, fuels [3] in order to meet the energy demand of a user which can be a single building, a group of buildings or a factory. These systems are inherently flexible and allow to exploit the renewable sources in the best way, following thermal and electric demands, increasing the reliability of service continuity through the utilization of CHP generators and reducing operation costs. Multi-energy systems play a crucial role in a political context inclined to the distributed generation. It is possible to control the power production and energy demand providing a valuable contribution to the stabilization of the electric main grid, by including energy storage systems and endothermic generators. It is necessary to communicate with a “smart grid” by exchanging information and by controlling the energy flows, in order to produce: an increase of energy saving, a reduction of pollutant emissions, the possibility of realizes stand-alone systems, relieving congestion in the electric grid during the peak hours of the day [4]. As the technology of electronic devices continue to improve, a perfect management of systems connected to different kind of energy storage (electric and thermal) can be realized. The optimal management of energetic flows in complex systems must be managed by an important device: the energy hub (a smart system used to analyze the situation and manage the components of the plant efficiently). It has been demonstrated that an efficient energy-hub produces a remarkable reduction of costs, greenhouse gases emissions and energy saving [5]. The energy-hub is considered as unit where the energetic flows are converted, conditioned and eventually stored [6]; as input it requires an amount of energy (electric energy from the grid, natural gas, energy from renewable sources) and it ensures the supply for several services, such as: electric and thermal energy, cooling, compressed air, etc. The redundant connections that could be established between input and output inside the energy-hub have two significant consequences: an increase of reliability of