Are renewables cheaper than nuclear?
The most-asked question in Australian energy policy has a short, honest answer — it depends entirely on what you count. Here it is, in four moves, with links to the deep-dive trackers for anyone who wants the full working.
1 · The short answer: it depends what you measure
At the plant gate — the levelised cost of energy, or LCOE — wind and solar are the cheapest new generation available, and that is true. CSIRO GenCost puts bare solar and wind well below nuclear's A$173–288/MWh, and that number is not manufactured. But LCOE prices one thing only: a megawatt-hour at the moment it leaves the turbine or panel. It says nothing about what it costs to turn that variable output into a reliable, 24/7 grid.
2 · LCOE vs whole-system cost
The moment you add what a reliable grid actually needs — storage, backup, the transmission to connect remote wind and solar zones, and a shorter asset life that means rebuilding sooner — the gap narrows and becomes genuinely contested. GenCost itself is the source of the firmed-renewables figure above, and it is transparent about the assumptions driving the nuclear number: a 30-year asset life (versus the 60–80 years US reactors are licensed for), a capacity-factor floor benchmarked to Australian coal dispatch rather than nuclear's ~90% norm, and a first-of-a-kind cost premium of 120% for a standing-start build. Move those assumptions to a defensible mature-fleet case and the number moves too.
GenCost's assumptions are contested, not fabricated — CSIRO shows its working. Source: CSIRO GenCost 2024-25 Final Report (CSIRO/AEMO).
3 · The honest verdict
The cheapest input is not automatically the cheapest system. LCOE under-counts the value of firm power — a plant that can run whenever the grid needs it, not just when the weather cooperates — and that under-counting is exactly the gap a whole-system comparison tries to close.
The fair rebuttal, stated: nuclear is genuinely expensive and slow to build in Australia, and that is a real cost, not a smear — a first Australian reactor could not deliver power for 15+ years after any ban is lifted, at a first-of-a-kind price premium GenCost itself flags. The comparison hinges entirely on what you count and which build scenario (first-of-a-kind vs mature fleet) you price. Neither side gets to quote only its best number.
4 · Go deeper
The numbers, as they move
A short, sourced brief when the figures shift — a GenCost update, a build-cost revision, a milestone. No spam, no hype, just the receipts.