The imminent shutdown of the power station that provides more than 10 per cent of NSW’s electricity may drive up power prices and trigger more frequent squeezes on supply as coal closures accelerate.

When AGL Energy pulls the plug at Unit 4 at its Liddell generator in the Hunter Valley on Wednesday, it will kick off a 10-day process for the shutdown of a power station that has been – as of Monday – eight years in the making.