Climate activism and shareholder unrest is pushing power giants such as AGL to speed up the shift to renewable energy.

Electricity giant AGL says its remaining coal-fired power plants cannot continue operating long enough for them to be replaced by nuclear reactors, as proposed in the federal opposition’s energy policy, without raising the risk of higher prices for consumers and more sudden outages.

The Coalition is promising to cut short Australia’s renewable energy rollout target and build a fleet of government-owned nuclear generators across the mainland if it wins this year’s election, starting with two plants from 2037 and reaching seven by 2050.

But the timelines of its so-called “coal-to-nuclear” policy, which depends on coal-fired generators staying in the grid until nuclear facilities are up and running, clashes with the closure plans of many of Australia’s coal plant operators who want to retire their ageing generators by no later than 2035.

AGL chief executive Damien Nicks on Wednesday said the company’s two remaining coal-fired power plants – the Loy Yang A generator in Victoria’s Latrobe Valley, and Bayswater in NSW – would both be 50 years old by 2035, putting them among the oldest power stations anywhere in the world.

“Around the world only 1 per cent of plants over 50 years of age are still operating on coal,” Nicks said. “That tells you a lot.”

The Dutton-led opposition has earmarked two of AGL’s sites, including Loy Yang A, among seven locations where it wants to construct nuclear power plants. The Coalition favours nuclear technology as an emissions-free source of energy, and argues that baseload power from either a coal or nuclear plant must be a crucial part of a “balanced energy mix” that would also include renewables, batteries and gas.

However, many industry leaders, experts and top energy officials have cautioned that nuclear is a “comparatively expensive” power source that would take too long to deploy in time to replace ageing coal.

The Albanese government, meanwhile, has targets to double the share of renewables to 82 per cent by 2030. It follows the advice of the Australian Energy Market Operator, which determines that the best and lowest-cost transition from coal is to develop a grid dominated by renewables, supported by storage assets such as batteries and hydroelectric dams, and fast-response gas-powered generators.

Nicks said AGL, which supplies energy to more than 4 million customers, did not intend to participate in any proposal for its site to house nuclear energy, and was “not entertaining the idea” of coal plant extensions. He pointed to the deteriorating reliability of its Liddell coal-fired power station in NSW, which became increasingly breakdown-prone before it was decommissioned in 2023.

“If you have too many outages over a hot summer period or in winter, when there is also high demand, it creates market issues that none of us wants to see,” Nicks said.

“I certainly don’t want to be sitting here relying on coal in 10 years time.”

Opposition energy spokesman Ted O’Brien was contacted for comment.

Although AGL remains eastern Australia’s biggest coal-fired electricity supplier, the 180-year-old utility is working to replace its coal plants with cleaner sources, spending billions of dollars building 12 gigawatts of firmed renewables in time for its planned exit from coal in 2035.

It is also advancing a strategy to transform its retiring fossil fuel sites into lower-carbon industrial energy “hubs” spanning renewables, grid-scale batteries and the manufacturing of green technologies that could help reduce Australia’s emissions.

On Wednesday, AGL outlined a new target to greenlight investments in 1.4 gigawatts of new grid-scale batteries, which can soak up surplus renewable energy and inject critical discharges when needed, within the next 12–18 months.

It came as AGL posted a slump in its half-year profit to $97 million on Wednesday, however, AGL’s underlying earnings for the period exceeded analysts’ forecasts by more than 20 per cent, partly driven by earnings from its first two big batteries at Torrens and Liddell.

UBS analyst Tom Allen described the result as a “big beat” to first-half underlying earnings expectations, while noting the significant contribution from AGL’s batteries.

AGL shares closed the day 0.2 per cent stronger at $11.73.