To John Daysh
and what I'm simply asking is that the government decide on what you call 'policy choices' so that a single ultimate final cost can be determined by the CSIRO and AEMO and then communicated to the people of Australia so that we know what it's going to cost us to achieve Net Zero.

and you seem to be defending the CSIRO and AEMO by saying they model multiple scenarios but they don't produce a costing for of the scenarios, so what are they hiding, I wonder? I suspect it's a cost of about one trillion dollars, with much of this amount to be paid by taxpayers, either through their purchase of domestic solar panels and batteries or through subsidies to industry or both.

Bernie,

It appears you've collapsed fully into conspiracies, motive-hunting, and citing invented numbers.

Governments do make policy choices, and those choices are then modelled in detail. That modelling doesn't happen in GenCost because GenCost isn't a system-design exercise, it's an input-cost study. Whole-of-system scenarios, including reliability standards and total system costs, are produced through AEMO's Integrated System Plan and related modelling, where assumptions are explicit and alternatives are compared side-by-side.

It's simply incorrect to say that scenarios aren't costed. They are. What doesn't exist is a single, immutable "ultimate final cost of Net Zero", because costs vary with demand growth, technology mix, reliability settings, fuel prices, financing assumptions and time horizon. Change those inputs and the total changes materially.

Again, presenting one number without locking all of that down would be misleading, not transparent.

Jumping from that complexity to claims that costs are being "hidden", or asserting a trillion-dollar figure without a model, assumptions or source, isn't analysis. It's speculation. If there's a specific scenario you think governments should commit to, the productive way forward is to specify its assumptions and cost that system, not to infer concealment from the absence of a single headline number.

To John Daysh
You wrote "GenCost isn't a system-design exercise, it's an input-cost study" yet Bowen happily quotes the GenCost reports, saying that renewables are the cheapest way to produce electricity. Why does the federal government not direct AEMO or whoever is responsible for energy-related studies to produce a design of the full system and then direct CSIRO to assess the cost of the complete package of input measures? Answer: because the cost will be a trillion dollars or more, as implied in the 2024-2025 GenCost report.
I'm not sure why you are trying to defend the indefensible.

Bernie,

You're still conflating three different things: political messaging, input-cost studies, and system-design modelling.

When Bowen quotes GenCost to say renewables are the cheapest generation technology, that's political messaging based on a generation-only metric. I've never defended that simplification, and I've explicitly said it's misleading when treated as a whole-system answer.

GenCost itself is not pretending to be a full system design, and it does not "imply" a trillion-dollar cost. It provides technology input costs. Full system design and costing is done through AEMO's Integrated System Plan and related scenario modelling, where assumptions are explicit and alternatives are compared.

That work already exists.

What you keep demanding is a single, authoritative "final cost of Net Zero" detached from assumptions about demand growth, reliability standards, technology mix, financing and time horizon. That number does not exist in any serious modelling framework, and inventing one while accusing others of concealment isn't analysis.

Disagreeing with political spin is reasonable. Replacing it with an unsupported trillion-dollar figure and claims of bad faith is not.

If there's a specific system design you think governments should commit to, the intellectually honest step is to specify its assumptions and cost that system, not assert that everyone else is hiding the answer.

To John Daysh
You wrote: "....detached from assumptions about demand growth, reliability standards, technology mix, financing and time horizon. That number does not exist in any serious modelling framework, and inventing one while accusing others of concealment isn't analysis." So what you're really saying is that the federal government, using taxpayer money, should be free to build a new electricity-production system in Australia for an unknown cost without any plan that outlines what reliability standards will be applied or or what the technology mix etc will be. Do you not understand how irresponsible such a process is for a government when the cost is almost certainly going to be hundreds of billions of dollars and in my view close to one trillion dollars? I say again: committing Australia to such a course of action is highly irresponsible. It is extremely poor governance,

Bernie,

No, that is not what I am saying. In fact, I've made a conscious effort not to say anything like it.

Governments do not build electricity systems "without a plan", and no one is proposing that reliability standards, technology mix or time horizons be left undefined. Those things are set through policy, regulation and planning processes, and then modelled through AEMO's ISP and related work. That is how system planning is actually done.

What I'm pushing back on is the idea that there exists, or should exist, a single, definitive "ultimate final cost of Net Zero" that can be published independently of those choices. Costs are produced after assumptions are specified, not before. Change the assumptions and the total changes. That isn't irresponsibility, it's how large infrastructure systems are planned.

Calling that complexity "unknown cost" or "no plan" is simply wrong. And repeatedly asserting trillion-dollar figures without a defined system, assumptions or source doesn't make the governance argument stronger, it replaces it with conjecture.

If you want to argue that a particular set of policy choices is irresponsible, then the argument has to be about those choices. It can't rest on inventing a single headline number and treating its absence as proof of negligence.