The Liddell power station will be switched off after more than 50 years of service to NSW and the national electricity grid.

Thousands of locals have worked at the site over the years and many are gathering to farewell the plant that they refer to as “the old girl”.

Although activists are celebrating the demise of the coal-fired “clunker”, critics are concerned shutting down the Muswellbrook plant in the Hunter region will remove 10 per cent of the state’s power.

Owner AGL Energy insists the lights will stay on and says it’s been preparing for the closure for the past seven years by adding more wind and solar.

Once powering the equivalent of more than one million homes, the carefully engineered shutdown that began a year ago will end with the last of Liddell’s units switched off on Friday.

More than 90 per cent of the materials in the plant are expected to be recycled during demolition, including 70,000 tonnes of steel — more than the total weight of steel works for the Sydney Harbour Bridge.

Demolition will begin in 2024 and take approximately two years.

Boilers, chimneys, turbine houses, the coal plant and various buildings will go and the site will be levelled with crushed concrete.

But transmission connections will be retained as the site gears up to become an industrial energy hub, equipped with a grid-scale battery.

As Australia’s largest electricity generator and biggest emitter, AGL faced government pressure and a shareholder revolt led by billionaire Mike Cannon-Brookes for going too slow on exiting coal and gas.

Under new management, AGL pledges to be “net zero” from operations with all of its coal-fired power stations to close by 2035 — including Loy Yang, which provides almost a third of Victoria’s power.

AGL’s gas-fired Torrens Island power station, also more than 50 years old and South Australia’s largest plant, is getting a makeover as an industrial hub as well.

Still up in the air is the future of Australia’s biggest coal-fired power station Eraring, which is owned by Origin Energy and located north of Sydney on the shores of Lake Macquarie.

Government briefings suggest the closure of Eraring is more risky than Liddell’s closure, and would leave a supply gap.

-AAP