Use of an economic index for optimal storage dimensioning within an autonomous power system

In many European and Asian regions the use of autonomous and semi-autonomous power systems is quite useful. Such systems have local generations which, for the most part, are based on both fossil energy sources and renewable energy sources. In such Energy Storages Systems (ESS) are necessary to ensure the supply to the consumers. Considering economic criteria, an optimal storage capacity for each generation mix can be obtained. This study aims firstly to review the ESS technologies and, secondly, to explain a methodology for designing the optimal storage capacity within an autonomous and semi-autonomous power system. A new economic index has been introduced, which summarizes the discount values for not integrating the power generated by RES into the grid. In balance with this discounted value, the discounted energy storage costs have been considered. The calculation shows that in some cases a semi-autonomous operation is quite favorable from an economic point of view.