# Ranking of Electricity Accumulation Possibilities: Multicriteria Analysis
## 1 Introduction  
The last decades have seen a purposeful transition in the European energy sector from centralized fossil use to renewable energy source systems. Taking into account the 2030 and 2050 goals set by the European Union in the climate and energy sector, one of the contributions is the commitment to increase the share of renewable energy resources in the total balance of primary energy resources, reduce greenhouse gas emissions and promote energy efficiency [1]. To be able to achieve and stimulate these goals, an integral factor is not only the use of renewable electricity to replace fossil fuel resources, but also the targeted integration of renewable electricity accumulation. Energy storage is a critical enabler of energy transition. The principle is based on the accumulation of excess energy at times when the demand is lower and the efficiency of energy production is higher, but the discharge, i.e., transfer of energy back for consumption, at times when the production volumes are too small as affected by the seasonality of renewable electricity. Energy storage technologies have been recognized and acknowledged for their integral role in providing ancillary services that contribute significantly to power generation, transmission, and distribution. Energy storage technologies serve as security systems inpower grids, providing uninterrupted power supply through peak load balancing and grid support services that enable greater integration of renewable energy sources [2]. There are countless benefits to using renewable electricity, especially when it comes to solar and wind power. The most important aspect is the sustainability of the resource, making it possible to reduce the impact of the energy sector on climate change. No less important are the economic benefits, which can be further increased by directly storing energy. Accumulation of electricity can meet the needs of consumers, which differ both in terms of volumes and loads characteristic of consumption, which are uneven over the course of the year. The benefits of accumulation are to cover the so-called peak hours and to eliminate the impact of seasonality. By accumulating renewable energy, it not only makes it possible to ensure self-consumption, but also gives renewable energy a higher value by selling electricity at a higher price. On a larger scale, it is also an opportunity to postpone expensive investments in transmission and distribution infrastructure, ensuring higher efficiency of existing networks [3]. A study by [4] investigates various aspects of renewable integrated deregulated power systems, with an emphasis on energy storage. The authors delineate the descriptive statistics of energy storage systems while highlighting the most recent technological advancements. The study contends that various optimization techniques should be used to identify the most optimal and suitable system that maximizes system profits while minimizing operation and maintenance expenses [4]. A study by [5] compares the levelized cost of storage (LCOS) for various energy storage technologies, such as lead-acid, lithium-ion, vanadium redox flow batteries, and flywheel, by concentrating on the competitiveness and economic aspects of these technologies. The results demonstrate that the linear electric machine-based gravity energy storage system has a great deal of potential as a cost-competitive technology for primary response grid support, as well as a number of distinct benefits [5]. Ref. [6] summarizes the different parameters of energy storage systems and presents the main classification of energy storage technological solutions. The study concludes that energy storage systems may not always be the optimal and feasible choice among existing alternative storage systems. However, this suggests that despite the possible absence of investment signals regarding flexibility, it is essential to evaluate the long-term potential at the regional and national levels [6].