“Vanadium reflux flow battery” experiment

A remote wind farm on the Scottish island of Gigha is to be connected to seven shipping container-sized vanadium redox flow batteries, a new class of device that could revolutionise renewable energy

SYSTEM SET-UP

Stored energy: 1.68MWh

Battery array: Seven shipping containers house batteries. Eighth container controls system

Control unit

Container: Holds four battery units

6m Cost: $5m

Electrolyte: Solution separated into half-cells

Cell stack: Divided by membrane

Cell stack: Battery “engine”

Half-cells: One side negative, other positive

Discharged system (flat)

Wind turbine: 330kW

Power: Electricity harvested from wind  turbine

Cell stack membrane

Electrons

Redox reaction

On discharge reaction is reversed. Electron flow becomes electric current

Charging: Vanadium electrolyte pumped through cell stack. Electrons pass through membrane

SCOTLAND

Edinburgh

GIGHA

GIGHA ISLAND

Dancing Ladies of Gigha windfarm

2km 1.2 miles

Sources: redT Energy Storage, Windpower Monthly, Financial Times

Picture: Vestas