Origin Energy’s giant Eraring coal power station in NSW produced at its highest level for five years in 2023-24, exposing the market’s heavy reliance on the generator that made its planned closure in 2025 unfeasible.

But the difficulties involved in running the 2880-megawatt generator – the biggest power station in the country – were also highlighted in Origin’s quarterly report on Wednesday, in which the electricity and gas supplier revealed a jump in coal costs that was double what some analysts expected.