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18 marzo 2024

What Are Vanadium Batteries? Its importance in the energy transition

Vanadium flow batteries promise to be a strong solution for renewable energy on days when weather conditions are not favourable. 

Planta fotovoltaica de Son Orlandis, Mallorca.
Photovoltaic plant in Son Orlandis, Mallorca.

The transition to renewable energies is critical to combating climate change and reducing the use of fossil fuels. Sources such as solar and wind are inexhaustible and clean, but they present the challenge of variability and dependence on climatic conditions.

To address this drawback, energy storage becomes a key factor because it guarantees a constant, reliable energy supply, as endorsed by Nature in its report on vanadium redox flow batteries. 

And what about lithium batteries? They have been essential in the field of energy storage due to their energy density and portability, but they have a clear drawback: They are limited by their life cycle and the environmental impact associated with their extraction. In this context, vanadium emerges as a promising solution.

 

What Are Vanadium Flow Batteries?

Vanadium (V) is a tough, silvery chemical element with atomic number 23. It is used in alloys to strengthen and improve the shock and corrosion resistance of other metals. It has applications in the chemical industry and in storage, as is the case with vanadium flow batteries.

Vanadium flow or BFV batteries are a type of rechargeable battery that uses vanadium in different oxidation states to store energy. They consist of two tanks of liquid solution, separated by a membrane. When the battery is charged and discharged, vanadium oxidises or reduces, enabling electrons to be released and generate electric current. 

Infografía funcionamiento baterias de vanadio

How do vanadium batteries work?

  1. The battery receives energy from the sun and wind. It is this energy that charges the battery.

  2. Charge/discharge occurs by releasing electrons and exchanging protons between both tanks of vanadium electrolyte.

  3. The oxidation and reduction reactions in the stacks (or electrochemical cell) create different electric currents.

  4. The anolyte (Vanadium fluid in negative electrode) releases an electron when the battery discharges and it is absorbed by the catholyte (Vanadium fluid in positive electrode) by means of the electrical circuit that is formed between the two. The reverse process occurs when charging.

  5. When the anolyte releases the electron to balance charges, the sulphuric acid from its solution releases a proton (H+), which crosses the membrane and transforms into water in the catholyte.

  6. The energy obtained in the electrochemical cell is stored in the giant tanks for when it is needed. This brings flexibility to the system, because simply increasing the size or number of tanks increases storage hours.

  7. On days when natural resources are not available, renewable energy can still be used thanks to the vanadium battery. These batteries can store 35% of the total output of a photovoltaic plant.

And how are they different from lithium batteries? The experts in the Innovation Area of Endesa's renewable subsidiary, Enel Green Power, have the answer:

"Vanadium flow batteries store electricity electrochemically, like lithium batteries, but using a different configuration and elements other than lithium, in this case vanadium. Using a component other than lithium enables us to differentiate our portfolio of storage solutions, thus reducing reliance on a single critical material." 

Vanadium provides a storage solution that can compensate for the intermittency of renewable energy, even when demand peaks. This is achieved by storing energy during periods of high production and releasing it when needed. The process makes it possible to reduce dependence on conventional energy sources.

And is the power grid ready to support these batteries? Their flexibility and scalability make them suitable for integration into modern power grids. They ensure that the energy generated can be released in a controlled and precise way, as indicated by MPDI in its Energies study on a comparable circuit model for vanadium redox flow batteries.

 

The first vanadium battery installation in Spain

The commissioning of the largest vanadium battery installation in Europe and the first in Spain, located in Mallorca, represents a milestone in the development and adoption of this technology in Spain.

Planta fotovoltaica de Son Orlandis, Mallorca.
Vanadium battery at the Son Orlandis photovoltaic plant, Mallorca.

The installation in the Balearic Islands was completed in a photovoltaic plant, enabling the production of solar energy to be combined with an innovative energy storage system called VCHARGE±. How powerful is it? 1.1MW with a capacity of 5.5 MVh.

The Son Orlandis storage system consists of a battery that uses vanadium redox flow technology which is very adaptable and has a high capacity. It is a safe solution and not only does it have an almost infinite useful life, it can also be re-used.

Vanadium plays a crucial role in the transition to a more sustainable and resilient energy system. The characteristics of VFBs, including their durability, efficiency and environmental compatibility, make them a key technology in the fight against climate change.

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