Does Australian renewable energy save the earth – or just cost it?

It works now because of the fossil-fuelled base-load/peaking supply system in Australia's east coast grid. Electricity prices are high during peak demand and low during the small hours of the night/morning. We can choose when to dispatch high cost peaking supplies and when to use off-peak to recharge the upper dams.

But what happens in our ACT 'nirvana' world of 100% reliance on intermittent renewables?

I assume dispatching power as it's generated is cheaper than dispatching power that has gone through the full renewable energy generation/storage/draw-down/dispatch process. That means 'pumped hydro' systems would be pumping water uphill when the sun is shining strongly or the wind is blowing strongly (so other renewables are available at lowest cost to power the pumps). Such systems would then be competing to use other renewable energy sources when they are in their own generation/storage phases, conflicting with their generation/storage objectives, in our hypothetical 100% renewables world.

Does 100% reliance on intermittent renewables reduce our ability to choose how we match peak supply with peak demand? Do the sun cycle and the weather determine this instead? Does 'pumped hydro's' cost arbitrage rationale shift it from being a peaking power supply complement (as now) towards a more base-load power demand competitor? If so, does that further magnify the generation/storage multiple inherent in 100% reliance on intermittent renewables?

The nuclear option?

Using renewables to deliver base-load power (and even peaking power) will be expensive because of generation/storage requirements to deal with intermittency. Yet Australia is well-endowed with the resources needed for a nuclear power generation industry. It's ideal for base-load energy supply for a start (as in France).

We have no compunction about exporting some of our resources for this purpose to countries that have not signed the nuclear Non-Proliferation Treaty. What ideological, cultural or other cringe prevents us using our resources for our own peaceful, reliable, low-emissions base-load nuclear power generation? To be sure, this will take time, because so far we've chosen not to have a nuclear power industry. If policy is reversed, we might need to import 'nuclear batteries' for a while. (So be it. SA is importing diesel generators to cover summer blackout risks.)

Resolving the power 'trilemma'

The Government says we face an energy policy 'trilemma'. Policy needs to deliver (i) low emissions, (ii) reliable energy, (iii) low-cost energy.

That's three (conflicting) objectives. Do we really only have one instrument – renewable energy – to deliver them? Is that choice immutable? (SA is using brown coal plus diesel as back-up power.) Renewables advocates should consider the arithmetic implicit in the physics: renewables as our only power supply are very expensive.

Nuclear power might get us close to two objectives (low emissions plus reliable energy). Cost probably will still be an issue (but less than for renewables?). Coal could deliver one objective (reliable energy) or maybe two (lower cost, via stop-gap refurbishment of existing plant?). Low emissions plus cheap energy seems too hard now.

If you sweep nuclear energy or coal off the policy table in favour of renewables, achieving these three conflicting objectives with one instrument is numerical nonsense. A blend of energy sources seems the only way to get a compromise outcome in terms of the three objectives, at least pending some new technological breakthrough. As now, putting all one's eggs in the renewables basket scores renewables = 1, plus achievement of any of the three energy policy objectives = 0. Or worse.

We should control what we can control locally (reliability and cost), and persuade others jointly to control what we jointly affect globally (emissions).

We should not foist any Australian emissions reduction targets solely on electricity, a crucial industrial and household input.

Such targets are globally ineffective, at best, anyway.