Storage Systems for Renewable Energies
Renewable Energies Context
Energy Storage Systems (ESS)
The energy storage systems (see Fig 1) allow conserving excess electricity and releasing it when necessary. This presents several advantages:
- The reduction of the huge differences in the demand curve, thus achieving greater quality in the supply of power, greater stability of the system and avoiding over-dimensioning.
- The development of smart grids, which allow the bi-directionality of electricity (distributed generation), thus being able to supply energy to the grid or receive it.
- The integration of renewable energy sources, allowing their use without the presence of generation.
Storage systems have important features that solve many shortcomings in generation. However, like any technological development they have certain limitations or disadvantages, which are related to:
- The cost: Although costs have reduced, there is still a limitation when considering their use, due to the number of batteries needed to have an appropriate level of generation against other options that can currently be cheaper.
- The dimensions: The size of the batteries, especially when the arrangement has a considerable number of batteries it becomes a problem for its implementation given that a large space specially conditioned for that purpose is necessary.
- Lifespan: Even if all specifications are respected; depth of discharge, cycles of use, environmental conditions and maintenance, the batteries have a relatively short life with respect to the elements of generation and must be replaced periodically.
Therefore to choose the system that best suits the installation of a user, the following factors should be taken into account:
- Energy: Storage device performance, system life (number of cycles of loading and unloading), utility (storage system outlet installed), amount of energy required to store and storage time (short or long term).
- Economic: Price per kW of the storage and transformation system.
- Environmental: Impact on the environment, either by its manufacture or by its installation and use.