The mixed group of shareholders, customers and environmentalists presented a petition signed by almost 12,000 people urging the company to close the Hunter Valley plant, ahead of Wednesday's AGM in Melbourne.

"AGL is Australia's biggest climate polluter and if it is to address climate change then the company needs to get out of coal," Nature Conservation Council campaign director Daisy Barham told Fairfax Media.

"They need to close Liddell, we can't rely on this clunker of a power station to keep the lights on."

The Nature Conservation Council said the estimated $1 billion required to keep Liddell open beyond its scheduled closure in 2022 should be invested in new clean energy generation.

The group urged the company's board to keep to its earlier plan to shutter the operation.

"We know the board is coming under pressure from the Prime Minister, but they are also under pressure from shareholders to close Liddell and get out of coal," Ms Barham said.

"We think it is unfair Prime Minister Malcolm Turnbull has asked for a solution, yet the government has not made a plan to fix the energy problem either, we need Mr Turnbull to make a plan too."

She called on the government to "stop bullying the company into keeping the power station open beyond 2022".

Shareholder Anne Long told Fairfax Media she originally invested in AGL because she believed it was a company dedicated to making a difference.

"We bought into AGL after they released their rehabilitation statement demonstrating that they were committed to greener energy," Mrs Long said.

"It was an ethically motivated investment."

She called on AGL to stay the course on its earlier business decision to expand its renewables portfolio

AGL has approximately 70 days left to formulate plan responding to Mr Turnbull's request to extend the life of Liddell, or plan for the expected energy shortfall following its shutdown.

AGL's annual general meeting on Wednesday is one of the most anticipated of the year, and although the 90-day deadline for a definitive response to government requests to extend the plant's life beyond 2022 is still some ways out, a direction from the board may be forthcoming at the event.

To date, AGL chief executive Andy Vesey has stuck fast to the line that Liddell needs to close, however, ongoing pressure from the government may still see the plant remain open beyond the scheduled closure date, depending on the AGL board response.

AGL's shares were down 0.1 per cent on Monday morning.