Vanadium battery prototype for large-scale electrical energy storage

The prototype, a 10 kW redox flow battery demonstrator, paves the way towards a 50 kW flow battery. It has been developed by CSIC's PTI TrasnEner+ Interdisciplinary Thematic Platform, which is working to develop large-scale energy storage technologies for stationary applications.

This battery prototype, with 10 kW of power and 20 kWh of energy, allows electrical energy to be stored for stationary applications, such as energy storage in homes or small businesses.A team of CSIC researchers has developed a 10-kilowatt (kW) vanadium redox flow battery prototype to demonstrate its viability as a large-scale electrical energy storage system, especially for renewable energies. This prototype, with 10 kW of power and 20 kWh of energy, allows electrical energy to be stored for stationary applications, such as energy storage in homes or small businesses. 

This is a first step towards the goal of obtaining a 50-kilowatt battery, which will enable this technology to be introduced into the industrial sector.

The prototype is the result of the work of the CSIC's PTI TrasnEner+ Interdisciplinary Thematic Platform, which is pursuing the stationary storage of electrical energy on a large scale, with the aim of achieving greater integration of renewable energies, overcoming their intermittency problems and accelerating the energy transition.

The project is coordinated by Ricardo Santamaría, researcher at the Institute of Carbon Science and Technology (INCAR), with the participation of groups from the Laboratory for Research in Fluid Dynamics and Combustion Technologies (LIFTEC), the Institute of Chemical Technology (ITQ), the Institute of Robotics and Industrial Informatics (IRI), the Institute of Carbochemistry (ICB), the Institute of Materials Science of Madrid (ICMM), the Institute of Materials Science of Barcelona (ICMB) and the Institute of Polymer Science and Technology (ICTP).

Redox flow batteries are highly flexible devices in which the energy is stored in electrolytes, which contain the electroactive vanadium species. The electrolytes are in external tanks and flow through the action of hydraulic pumps inside the battery cells where the electrochemical oxidation-reduction reactions take place.

Facilitating the transition towards clean energy

The main advantage of these batteries is their versatility: the power and energy of the system can be independently adapted by increasing the active surface of the electrodes, the number of cells and the volume of electrolyte. They also have a long life cycle that can exceed 20 years, making them excellent candidates for stationary and heavy-duty applications where other technologies such as lithium batteries cannot compete, and they could facilitate the market penetration of renewables.

"One of the great advantages of redox flow batteries is that they can be sized in power and capacity, therefore they can be connected directly to generation plants and in turn connected to distribution grids but also they can be installed near energy consumption centres," says Santamaria.

The prototype is made up of 4 stacks of cells, similar to those that will be incorporated in the 50 kW battery.

The design of all the battery elements, the technology of the sealing and closure systems, and manufacturing and assembly processes are work of the LIFTEC research group led by researcher Félix Barreras. The INCAR research group has modified the carbon electrodes to improve their electrochemical properties. On its turn, the ITQ group, led by Antonio Chica, has been in charge of the membranes and the electrolyte.

The team has developed also an energy management system, based on operating protocols compatible with industrial standards, which allows the permanent control of the status of the battery.

Similarly, the IRI research group, led by Ramón Costa, is collaborating with the LIFTEC group for creating a telemetry system to operate remotely the battery and to monitor all operating variables in real time. They are also working on the implementation of techniques for the prediction of the state of charge to enable an efficient management of energy flow and to extend the useful life of the device.

A wide range of applications

The 10 kW prototype could cover the growing needs for self-consumption of energy in isolated buildings as well as in small neighbourhood communities, or even for small commercial consumers.

However, the ultimate goal of the project is to validate the 50 kW prototype by connecting it to a renewable energy generation plant, such as a solar field. To this end, a smart microgrid has been developed, consisting of the 10 kW flow battery, a solar field and several programmable loads and sources that allow different consumptions to be simulated.

As Félix Barreras points out, "this installation will allow us to study realistic scenarios, with a modular power architecture that allows the battery to be used in stand-alone mode or connected to the grid, either in alternating or direct current".

 "We think this technology can help companies to achieve a relevant position in the European environment in the challenge of maintaining energy supply in a decarbonised system based on renewable energies," says Clara Blanco, coordinator of the PTI-TransEner+.

This initiative receives funds from the Next Generation EU Funds through the Recovery, Transformation and Resilience Plan, specifically Component 17, Institutional reform and capacity building of the national science, technology and innovation system.