The second turbine at Adelaide's Pelican Point gas-fired power station has been unviable for years, its operator says.

The turbine was not operating earlier this month, when temporary load shedding was ordered for 90,000 customers due to insufficient power supply.

That situation prompted the Australian Energy Market Operator (AEMO) to order the station to turn it on the following day to avoid a repeat.

Power company Engie has now appeared before a federal select committee hearing in Adelaide, where it was quizzed over the plant's role in the load shedding.

Head of corporate affairs, Jim Kouts told the committee that the second turbine was mothballed in July 2015.

"Between the years 2013, 14, 15, you could see the losses were increasing. By the time it got to 2015, we'd lost over $17 million that year," Mr Kouts said.

Engie also owns the Hazelwood power station in Victoria, which is scheduled to close in March.

Mr Kouts said that closure does not guarantee Pelican Point will ramp up production, but the company is working on increasing customers, with an aim to firing up the second turbine.

"We need to contract the plant. That's what we want to do. We want to then put that plant back on a commercial footing and return it to full service," Mr Kouts said.

"We are talking to industrial customers, explaining the market conditions."

Engie is also tendering for a South Australian Government contract to provide 75 per cent of its power.

But the company said it could do that without returning Pelican Point to full production, or adding any generation to its operations.

The Government has said that the aim of the tender is to bring more power generation to South Australia, casting doubt on Engie's bid.

AGL misses committee hearing

Another power generator, AGL, was also scheduled to give evidence to the committee, but emailed at the last minute to say that it could not make it.

Greens senator Sarah Hanson-Young said the company had been given several weeks' notice and she was disappointed with the decision.

She said she hoped to question AGL over forced outages at the company's Torrens Island power station.

That had been listed as another factor that led to the load shedding earlier this month.

"We know that the AEMO report has come out saying partly the energy lack of supply issue was because their plants weren't able to operate," Senator Hanson-Young said.

"Now, from what I see, they're refusing to show up. We will contact them and we will require them to appear at our next hearing."

AGL has responded by saying it did not initially make a submission to the committee, which requested it attend the hearing.

It said it was not able to appear today and would provide a written submission shortly.