AGL's biggest shareholder, billionaire businessman Mike Cannon-Brookes, has not ruled out taking a shot at another takeover bid for the energy giant.

He has also said the company's transition away from coal-fired power generation needs to happen faster than planned if the nation's power supply is to be more stable and prices are to sink.

On Monday, AGL Energy dumped its plans to demerge its coal-focused generation business, saying it had insufficient shareholder support to meet the 75 per cent approval threshold needed for the demerger to go ahead in June.

The decision was made amid continued opposition from major investors, including Cannon-Brookes's private investment firm Grok Ventures.

Some have speculated that Mr Cannon-Brookes has been agitating for the demerger to be blocked so he can return with a lower-priced takeover bid.

AGL Energy earlier this year rejected an $8 billion takeover bid by Mr Cannon-Brookes and Canadian asset manager Brookfield to accelerate the closure of AGL's major coal-fired power stations.

Speaking to ABC's The Business program, Mr Cannon-Brookes said his mission was never to drive down the price of a possible takeover, but also did not rule out taking another shot at one.

"We're entirely focused on the demerger, and then the board renewal and rebuilding [the] company."

AGL's share price fell almost 2 per cent on Monday after the company announced the demerger was off the table.

Asked whether there was any merit in that idea that he was pushing the share price lower, making it a cheaper takeover target, Mr Cannon Brookes responded: "Absolutely none."

"As the largest shareholder in the business, that'd be a pretty silly thing to do," he said.

"People said we wouldn't actually have the shareholding — we have the shareholding. [They said] we wouldn't actually put up the cash. But we put up the cash.

"We continue to believe the opportunities for this company are very large. That is why we are here."

He said Grok Ventures had put $650 million on the table as part of his 11.3 per cent stake, making him the biggest AGL shareholder.

"We've said that we clearly want a Paris-aligned plan, we believe that's the best outcome as a shareholder," he said.

"We've said we want board renewal as a shareholder. And as the largest shareholder, we believe we have some say in that."

Call to transition away from 'unreliable' coal-power generation faster

The AGL board has committed to the closure of its Bayswater power station in 2035 and Loy Yang power station in 2045.

Mr Cannon-Brookes said when those assets cease to be profitable for the company, "significantly faster than those 2035 and 2045 dates, they start losing significant amounts of money".

"So that transition needs to be proactive and needs to be managed. It needs to be very carefully planned.

"And it needs to make sure that we are continuing to provide the lowest-price power to the customers of the company.

"I think we can do that significantly faster than those dates, for sure."

Some have warned that if coal-fired power stations are brought offline too soon, there is a risk of pushing up energy prices in the short term.

But Mr Cannon-Brookes said that would be unlikely to happen as long as there were alternative sources of supply via renewable energy.

He said energy costs were currently high because the price of coal and gas was at all-time highs and that the old coal-generated power plants were "very unreliable".

"These are very old assets that are very hard to run and run reliably," he said.

But according to Australia's electricity market operator, the nation's energy grid will require at least $10 billion for new transmission lines in the near term to handle output from solar and wind farms.

Mr Cannon-Brookes said: "I think we have to be clear that this is an investment".

He said while there would be an up-front cost, Australia could save a lot of money over the long term.

"They will save consumers significant amounts of money, and they are eminently financial over a long period of time," he said.

"So as an investment, it brings people's power bills down."

"There's no doubt that a renewable grid, if we were 100 per cent renewable-powered by, say, 2030 — which is a significantly achievable target – that we would have much lower power prices for consumers than if we have a fossil-fuel-powered grid."

AGL needs a new plan in sync with the Paris agreement

Mr Cannon-Brookes said that was a view that AGL shareholders agreed with since 53 per cent of them voted for a Paris-aligned decarbonisation plan at the company's AGM last year.

"Having that will unlock financing and also have a lower cost of capital for the company, as ESG [environmental, social and governance] investors will come back to the company as well as banks and other companies who lend money."

AGL on Monday said it would undertake a strategic review and AGL's chief executive Graeme Hunt and chairman Peter Botten will leave the company.

Non-executive directors Jacqueline Hey and Diane-Smith Gander will also resign.

Mr Cannon-Brookes has asked for two seats on AGL's new board but is not guaranteed them.

"The first step is board renewal," he said.

"The second step is a clearly Paris-aligned plan that meets the science targets because that will unlock financing and lower cost of capital, so that that has to be done, for sure."