World's biggest battery

Tesla: World's biggest battery half-built

The plan to build the 100MW (129MWh) lithium battery grew out of a Twitter bet between Tesla boss Elon Musk and Australian software entrepreneur Mike Cannon-Brookes.

Mr Musk said Tesla would build the wind-charged battery in 100 days or the state would not have to pay for it.

It is designed to help prevent power cuts that regularly hit the region.

Critics have said the area's reliance on renewable energy sources has left it vulnerable.