A Bank for the Wind

An island off Australia is innovating with a new way of storing excess power from wind turbines and solar arrays, at the same time providing a vital backup store for when the sun doesn't shine and the wind doesn't blow. The storage method is 'flow batteries' which work by using excess power to extract (and store) energy rich chemicals from the battery and injecting fresh chemicals to absorb more charge. Once the renewable generators stop generating, the flow is reversed and the energy-rich chemicals release their charge.

Expansion is as easy as adding bigger tanks and more chemicals, but the technology is more complex as it requires sophisticated pumping mechanisms to provide the flow. There is also the leakage problem common to virtually all rechargable battery systems. However they do deliver 80% of the charge injected into them, and can provide this level of efficiency for many years.

The installation on Kings Island, Australia, consists of 70,000L of vanadium sulphate solution as the battery electrolyte, and is capable of delivering 400kW for a two-hour stretch. This might not sound long, but on the island the proportion of wind-derived electricity has risen from 12% to 40%.

A Canadian company, VRB Power Systems, is installing a 12MWh system in southern Ireland, at Sorne Hill in Donegal. This should allow a guaranteed provision of wind-generated electricity, plus extra income from the sale of any excess that gets sold to the Grid.

Source: New Scientist