Contrasting Energy Storage Systems for Small-Scale Isolated Grids

Abstract

The goal of this article is to examine the best electricity storage methods, both in terms of technology and economics, for tiny, independent electrical grids that are integrated with power plants that generate renewable energy sources (RES). As case studies, three autonomous Greek is-lands—Symi, Astypalaia, and Kastelorizo—with yearly and approximately for our work is peak demand of 3.9 MW, 2.1 MW, and 0.889 MW, respectively, are examined. Every island under inves-tigation has exceptional solar and wind potential, and their locations are perfect for the installation of seawater PHS (pumped hydro storage). Regarding the energy storage facilities, two distinct strat-egies are examined: PHS systems (for the two largest islands) and electrochemical storage, which is another name for lead acid or lithium-ion batteries. Potential RES units include photovoltaic instal-lations and wind farms. The analysed plants' dimensioning is optimised with a shared goal in mind: achieving an annual percentage of RES penetration above 69.9% while keeping the selling price of energy below the current specific production cost. The analysis is combined with the systems under examination's economic assessment. It is demonstrated that wind-PHS is still a competitive alterna-tive for Symi and Astypalaia given the proper land morphology for PHS installations, while a wind-p/v-batteries features as the best choice for Kastelorizo. Only with PHS support can 99.9% annual RES penetration be attained; with electrochemical batteries, annual RES penetration can range from 79.9 to 91.1%. Electricity selling prices between 199 and 349 €/kWh, which result in payback periods between five and nine years, ensure the economic viability.