Optimal fuzzy multi-objective design of a renewable energy system with economics, reliability, and environmental emissions considerations

Besides economical issues, reliability and environmental emissions have become major concerns whenever an energy system is designed. The objective of this study is to design both an autonomous and non-autonomous hybrid green power system (HGPS) to supply a specific load demand considering economics, reliability indices, and environmental emissions. The HGPS includes wind turbine (WT), photovoltaic (PV) array, fuel cell, and the actual data used for simulation which are annual solar irradiation and wind speed for the state of Illinois. For reliability analysis, it is assumed that only WT, PV, DC/AC convertor, and electrical network might have failure in supplying power. To evaluate the actual reliability level of the HGPS equipments, all possible conditions should be considered and for each one of them, the reliability indices are estimated by determining the quantity and probability of load demands not supplied. However, in this study, an approximate model is utilized to examine the reliability indices. In the approximate model, the average power generation of WT units and PV array is utilized (instead of considering the outage of each WT unit and PV array separately) and then the mathematical expectation of reliability indices is calculated. The results show that the reliability indices are activated when there is no backup (electrical network) for the HGPS. The utilization of HGPS in parallel with electrical network, when cost is given the highest importance, leads to the purchase of all power from the electrical network. However, when emission is considered as the second objective function in the fuzzy multi-objective problem; the degree of importance given to each function (total cost and emission) plays a major role in the optimal design of HGPS. (C) 2014 AIP Publishing LLC.