Actually SM each hydro needs two large storages, one above the generator
and one below it, unless you are going to throw the water into the sea.
Regarding batteries, maybe if they can also fix the self discharge rate.
Such batteries would cost about the same as the windfarms that generate
the charge put into them.
I think we will be looking at some form of miracle to get batteries that good.
Geothermal must be our best non nuclear hope. The only problem I was
able to find out about was corrosion, presumably in the pipes going
down to the granite. It is a pity, but I think that perhaps it is
one of those projects that government money should be used.
There is probably enough heat down there to supply us for 1000 years.
What is the half life ? Is it some thousands of years ?
I know some half lifes are 100,000 of years but I do not know what
isotopes are in the granite.

Aiden,
the reason 7 is used as an approx point is because that is where
the net energy curve goes almost vertical.

Shadow, some of what you think are facts are highly dependent on assumptions. Others are merely descriptions of the current situation.

Though the network itself does not store power, there are things on the network that do (for example the pumped storage at Bogong). Some places overseas store power in flywheels to provide network stability. Others use vanadium batteries (an Australian invention). Those are expensive so scientists are trying to find a way to use iron instead of vanadium.

Most customers have annual contracts at the moment – most do not even have the option of paying based on the wholesale price. That's something that can easily be changed.

In the absence of subsidies, the competitiveness of wind power depends on the interest rate. But because wind power's on whenever the wind blows, it drives down the cost of electricity more than coal can.

Solar thermal is more expensive than wind, but it's dispatchable so its output is more lucrative. And there's great potential to combine it with those ceramic fuel cells that Rhosty's so mad keen on.

Currently we're not making anywhere near as much use of hydro's dispatchability as we could with the existing dams.

I'm not aware of geothermal power being scrapped because of "technical" and commercial problems. Do you have a link?

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Bazz,
"the reason 7 is used as an approx point is because that is where
the net energy curve goes almost vertical."

That's a lie!

How is it possible solar heat in ocean algae is not part of the discussion on this thread?

http://www.climatecentral.org/news/algae-accelerate-arctic-warming-18929

How will CO2 emissions reduction and trading reduce sewage nutrient overload from feeding algae?

Aidan,

As I am an electrical engineer having designed, built, and maintained generation plant and minor networks, my assumptions are based on physics and maths and I challenge you to provide a smidgen of evidence that any one of them is incorrect.

This explains the demise of Geothermal power generation

http://reneweconomy.com.au/2012/australian-geothermal-stuck-between-a-rock-and-a-hard-place-86327

The geothermal plants don't generate enough power to pay its staff let alone repay the steep construction costs

Shadow,

Rhosty, I think you misunderstand about assumptions. Most of them are nothing to do with physics; they're about what the conditions are and will be. For instance you assume that most users will remain on fixed price contracts. That's nothing to do with physics and maths!

You make assumptions about the commercial viability of renewable energy (and indeed of batteries) but you seem to ignore how sensitive it is to the cost of finance. I don't think you've even done the maths!

You claim that if all SA's generation failed, it would "simply draw off the Aus network", then you expect me to believe you're an electrical engineer!

And your link doesn't provide any evidence of geothermal power having been scrapped because of commercial and technical problems. In no cases were they scrapped – there were never any definite plans to begin with, and the original objective remains an objective albeit on a longer timescale.

(Sorry, the above post was directed at Shadow Minister; I don't know why I mentioned Rhosty.)