Redox battery promises to hold many megawatts

Unlike conventional batteries that store reactive materials in cells, a flow battery stores electrolytes in tanks, one for positive reactions and another for negative. To make a utility-scale system, the standard 7 kW-rated VRB cell stacks are assembled to build 200-kW modules which in turn are scalable up to 10-MW  systems.

The Vanadium Redox Battery (VRB) is a patented advanced, energy-storage system that is said to be safe, environmentally friendly, and can operate at the lowest cost of any flow battery technology. It is:

• An electrochemical system that efficiently converts chemical energy to electrical energy, and vice versa
• A ‘flow battery’ that rapidly charges and discharges
• A patented process based on the reduction and oxidation of different forms of the element Vanadium
• An on-demand energy storage system in which the electrolyte never wears out and overall maintenance costs are extremely low. Energy (electricity) can be stored in liquid form, at room temperature, almost indefinitely, and customers do not have to buy more capacity than they immediately need, and can easily add energy and power in modular fashion over time.

The vanadium redox battery has three main parts:

• A stack in which the conversion of electric energy and chemical energy takes place
• Tanks to hold liquid electrolytes
• Power conversion equipment

Unlike conventional batteries that store their reactive materials within the cells, a flow battery stores electrolytes in tanks, one for positive reactions and another for negative. These electrolytes get pumped through the cells when electric current flows – and return to the same tanks. The positive and negative electrolytes do not actually mix together because a thin membrane separates them – only selected ions “flow” through the cells.

In the VRB, a high number of charges and discharges can occur without significant decrease in capacity. This enormous cycling capability exists partly because the electrodes – where the reactions take place – are made of a stable, porous carbon material that does not get altered physically or chemically when the dissolved salts contact it.

Flow batteries are also unique in their ability to meet specific energy and power demands of almost any size. If you were to connect a long series of conventional (e.g., lead-acid) batteries, that string will inevitably be weakened by the differing energy levels within each independent cell. A flow battery, on the other hand, contains cells with nearly identical characteristics, because they all share the same energy-bearing electrolyte. This makes the upper limit of the energy-to-power ratio of a flow battery almost unlimited.

Prudent’s VRB is distinct from hybrid flow batteries (such as zinc-bromine or sodium-sulfur, for example) which have one reactive electrode and therefore suffer from the degradation drawbacks of conventional batteries. Using only Vanadium in the electrolyte – as opposed to a blend of electrochemical elements – gives Prudent Energy’s advanced battery systems the most competitive advantage in terms of operating cost, system life, maintenance, and safety.

Prudent Energy

www.pdenergy.com