Power outage fuels Aussie energy debate

A power outage during a searing heat wave in South Australia state has worsened a row with the federal government over energy security and the state's heavy reliance on wind and solar power.

Australia's energy market operator cut power to about 40,000 homes and small businesses in the state for about half an hour on Wednesday when it was 41 C as electricity use spiked up as people returned home from work, but the wind died down.

The incident came just months after a major blackout hit the state, which is heavily dependent on wind and solar power, and followed a string of smaller outages and power price spikes which have sparked reviews of the national electricity market and Australian energy policy.

The federal government blames South Australia for failing to secure reliable power supplies while it has rushed into promoting renewable energy, putting major businesses at risk.

BHP Billiton's Olympic Dam copper mine, the state's biggest power user, was forced to stop production for two weeks in September after the statewide blackout, while Alcoa's Portland aluminum smelter was recently crippled by a power outage.

"We can't afford to go the way South Australia has, which has the most expensive and the least reliable electricity in Australia. Bad for jobs. Bad for business. Bad for families," Prime Minister Malcolm Turnbull said on Thursday.

Wind drives more than a third of South Australia's electricity supply.