Characterisation of Vanadium Batteries

The objectives of the project are

• Get first hand experience of the operation of the vanadium battery
• Experimentally establish the operating characteristics such as efficiencies, charge and discharge response times etc.
• Assess the perspectives of the use of vanadium batteries in the Danish electricity supply system

Vanadium battery technology
Vanadium batteries are so-called redox-flow batteries. Redox because of the chemical reaction in the battery i.e. the ions in the electrolyte are reduced or oxidised (change in valence) and flow because the electrolyte is pumped through the a cell stack where the electrolyte is separated by a membrane. Particularly for the vanadium battery the electrolyte is the same on both sides of the membrane.

Schematic of vanadium battery

Features of a vanadium battery
Independent sizing of energy and power capacity. The size of the storage tanks define the energy capacity and the membrane area defines the power capacity.
High efficiency. The cycle efficiency power to power is 80-85%
Fast response. Response time as low as 20ms
Life time. Since the electrodes are not participating in the process life time is determined by the membranes and is expected to be more than 10 years.

Test system
A test system is being acquired from VRB power systems. It will be a 15kW/120kWh battery. It will be installed as part of SYSLAB at Risoe National Laboratory. The test system will allow for direct control of active power and reactive power

Vanadium battery under construction

Perspectives of use of vanadium batteries

• Easier and improved integration of wind energy
• Improved utilisation of the electricity infrastructure
• Possibility for improved power quality

Partners

Risø National Laboratory
PA Energy A/S
OI-electric A/S

Project period: 2004 - 2007