Energy company AGL to mothball half of SA's Torrens Island power plant

Dozens of jobs are under threat at Adelaide's Torrens Island power station with operator AGL announcing it will close half the plant in 2017.

AGL said four of the older generating units, known collectively as A-station, would be taken out of service.

The company said the move had been prompted by rising gas prices and an increasing shift to renewable energy, however it said energy supply and power prices would not be affected by the shutdown.

"Based on the current market outlook AGL has decided that the Torrens Island A-station will be mothballed in 2017," AGL group general manger Anthony Fowler said.

The gas-fired power station has been in operation since the 1960s and currently employs about 180 people.

About 50 of those work on A-station, but the company said it was too early to determine exactly how many jobs would go.

John Adley from the Communications, Electrical and Plumbing Union said the unions will be talking to AGL in the new year about their ongoing operational requirements and the impact that may have on employment.

"It certainly doesn't help the uncertainty that we're facing in SA," Mr Adley said.

"With the cloud over ASC and the closure of Holdens, we've got foundries closing. It's not a good situation."

AGL said the South Australian market was becoming increasingly reliant on renewable energy, reducing the demand for the kind of conventional power generated in the State.

Mr Fowler said the four A-station units were taken out of service between July and September this year without any effect on supply.

"This decision will be reviewed if market conditions change materially," he said.