Approach and measures

Approach

Every box uses a measure to help understand the scale, the measure is Eraring, Australia’s largest coal-fired power station. It has four units and can deliver 2,880 megawatts at full power or 25.2 terawatt-hours. In the year to 30 June 2025 it generated 14.2 terawatt-hours, about one-fourteenth of the electricity traded in the east-coast grid.

Where a box says, “one Eraring”, it means that year’s output of 14.2 terawatt-hours. A megawatt is a rate of delivery, like the width of a pipe. A megawatt-hour is a quantity delivered, like the water that came through it. One thousand megawatts make a gigawatt; one million megawatt-hours make a terawatt-hour.

A figure marked “estimate” is the author’s calculation based on a stated assumption. Three agencies run our electricity system. AEMO is the Australian Energy Market Operator, which runs the east-coast grid and writes its plan; the AER is the Australian Energy Regulator, which sets what networks may charge; the CER is the Clean Energy Regulator, which counts rooftop systems and certificates.

Five things are kept apart in every box and never added: what is operating, what is under construction, what is approved but unbuilt, what is merely proposed, and what AEMO says will be needed. A hosting target is not a project. A turbine number in a consent is a ceiling. Rooftop solar is a separate fleet from grid-scale solar. A battery’s megawatts and its megawatt-hours measure different things. Where a figure is an estimate, the assumption is in the note.