This innovative system for the management of Vanadium redox flow batteries (VRFB) is designed to increase their efficiency. It can control the temperature of the electrolytes in order to avoid the precipitation of vanadium salts in the solution, which could cause damages or critical situations. The Battery Management System (BMS) can also improve the battery’s response time, which is very useful when VRFBs are used for quick regulation of grid frequency.
Patent status
SUBMITTED
Priority Number
IT102020000005263
Priority Date
11/03/2020
License
INTERNATIONAL
Market
This technology looks to the electrochemical energy storage market, which is closely tied to the production of electricity from renewable resources. Electrochemical energy accumulators are frequently used in various stationary applications such as domestic end-user, microgrids and DSO/TSO distribution grids. In particular, 50% of the flow battery market uses Vanadium Redox Flow Batteries, which in 2020 was worth approximately 194 Million USD and is estimated to grow by a CAGR of 20.9% by 2027 (Global Industry Analysts, Vanadium Redox Battery – Global Market Trajectory & Analytics, (2021).
Problem
Redox Flow Batteries (RFBs) are used to store and generate electricity according to the energy requirements of the industrial power plant, energy distribution grid, or single electrical load. They are especially useful to stabilize the electrical output to end users, independently from the fluctuation of power sources that are intermittent and not programmable, like wind turbines, photovoltaic panels or other generators based on renewable sources.
Such great energy storage capacity occurs because RFBs use high concentrations of reagents (electrolytes). Reversible or irreversible reactions can occur within the electrolyte solutions, especially when the batteries are inactive or in stand- by i.e. when there is neither power intake from a source nor power output from the battery. For example, exothermal self-discharging reactions occur in VRFB batteries during stand by, due to the recombination of the ions normally present in each semi-cell that migrate to the other (crossover effect).
Current technologies limits
At around 50°C the ions present in VRFB batteries begin to crystalize and precipitate within the electrolyte solution. The precipitated salts can also accumulate within the porosity of the electrodes and reduce the capacity to create the redox reactions necessary to generate electricity. Both these phenomenon can cause damage to the battery components and an irreversible reduction of the quantity of energy that the RFB can store.
In order to avoid these events, the cells can be emptied during battery stand-by, but this inevitably causes a delay in the response time when electricity is required, as the cells need to be filled again. Also, the emptying process can cause a depression within the cells: this can favour the entry of air and cause undesired reactions between atmospheric oxygen and the electrolytes. Alternatively, forced ventilation is used to avoid the precipitation of electrolytes but this has proven to be a complex, costly and energy consuming solution.
Killer Application
This innovative battery management system is developed for the management of Vanadium Redox Flow batteries used in energy storage installation of any size, especially on multiple stack installations. It can be applied to:
Technology and our solution
This new battery management system software is capable of interacting with the different hardware elements to which it is connected: signal conditioning system, power management system, hydraulic circuits, stack voltage and current, OCV etc.
By acquiring a multitude of parameters (open circuit voltage OCV, cell and stack voltage, input and output stack temperature, stack current, electrolyte flow rates, stack pressure drops, tank levels, pump power) the patented method behind the BMS can control battery functions, in particular:
Advantages
Compared to existing BMS technology, this patented battery management system can control a redox flow battery in order to:
Roadmap
The current TRL of this technology is 7 since it has been tested on an industrial scale battery set up at the Electrochemical Energy Storage and Conversion Laboratory of the Department of Electronic Engineering of the University of Padua. The invention and the algorithm run on LabVIEW but the software can easily be transferred to industrially relevant PLC with a minimum investment in order to elevate the TRL to 9.
TRL
The team
