Bazz: " No, I was just talking about the size of the battery."

I know you were, that's what my post is about. Battery capacity is measured in the amount of available energy it stores not its power output.
The SI units of energy are Joules [J] (SI is the "International System of Units"). And a Watt [W] is defined as a Joule per second, which is the SI unit of power.
But since the energy supplied is equal to the integration of the power it delivers over the time it delivers it, the units of energy can also be written as a unit of power multiplied by a unit of time:
eg1: in SI units: Watt times second, [Ws], or some multiple of this using metric prefixes if more convenient: [MWs], [GWs], etc,. Note that 1Ws=1J since [W * s] = [J/s * s] = J.
eg2: if you allow the use of non-SI [h] for an hour, ie:1h=3600s, then you can use Watt times hour, [Wh], as an energy unit. Or some multiple of this using metric prefixes: [kWh], [MWh], [GWh], etc,. Note that 1 Wh = 3600Ws = 3600J = 3.6kJ. And that 1MWh = 3,600,000,000Ws = 3.6GJ.

So a battery with 1400MWh would supply 1400MW for 1 hour, or equivalently 700MW for 2 hours, or 100MW for 14 hours, etc.

-- continued below --

-- from above --

Now in your original post you wrote: "So the correct description of the battery would be 1400 Mwatt/hrs. If it really is 700 Megwatt/hr then it will deliver 700Mwatt for 1 hour."
And my post was just a minor technical correction to this. A figure such as your "700Megwatt/hr" would be used to describe a rate of change power but NOT an amount of energy.
eg: if a generator started up and went from 0MW to a final steady 700MW and it took 1 hour, then its average rate of increase in power output over the start-up would be 700MW/h. However this number tells us nothing at all about the amount of energy that the generator supplied during the start up; it could have supplied any amount from just above 0J to all the energy available in the world's fossil fuel reserves*, we simply don't know.

However besides this technicality, overall I believe your post does convey the message you wish get across.

*:Well I'm obviously exaggerating a bit here- it would have to be using some extremely uncommon physics to supply this much energy.

Bazz,
>I am well aware that my little battery would not produce 700Mw in practise.
So you were well aware that you were lying?

Maximum output (MW) and storage capacity (MWh) are both important. Your dismissing the former as meaningless is IMO worse than the failure to report the latter you're criticising.

>The blackout problem cannot be blamed on coal fired stations.
The problem cannot be blamed on what caused it? Seriously?

>They had enough backup installed anyway. So station going off line was always taken up by the others.
It's one thing to have backup installed, but quite another to have it actually running.

I suspect you have a selective memory on this. I remember blackouts used to be quite frequent in SA, and reliability was a key consideration in the decision to build a link to the Victorian network. But not long after that link opened, a fault on it caused a major blackout when SA was utilising Victorian power and IIRC it took about 45 minutes for SA to ramp up its own output to replace it.

Nowadays batteries respond instantly, giving SA the most reliable power supply in the nation.

>Of course it does ! We would not be playing with renewables if it wasn't for AGW activists !
Firstly, it's likely we would be (for economic reasons)
Secondly, AGW is occurring because of changes to the composition of our atmosphere, not because of activists.
Thirdly, our use of renewables has very little bearing on the reliability of supply.

>We will never be able to afford enough distributed renewables all
>connected by the $1Trillion grid including WA.
The Eurasian Supergrid may well have a trillion invested in it over the coming years, including a connection to Australia. It doesn't mean Australia's paying that much!
Nuclear power is the expensive option - solar plus storage is far better value.

Your link is paywalled, but The Australian has long been biased against renewables.

It really is so simple.

We should give any generator a contract to supply a certain amount of power 24/7 for a period. This could be a year or many years. It would then be the responsibility for the generator to decide how this was organised. Wind & solar would be suppliers could chose batteries, pumped hydro, gas, coal or nuclear generation as back up, but it would be their responsibility.

Any failure to supply would attract instant cancellation of the contract.

This would get rid of the get rich quick subsidy farmers, & the ratbag greens, & give us a reliable power supply system, probably with very little wind or solar involved.

Hasbeen,
That's a recipe for high electricity prices, as the threat of immediate loss of contract means a lot of commercial risk (so high insurance costs). It also makes it very easy for the generating companies to quit if their activities turn out not to be profitable (so it wouldn't deliver the reliability you expect). And why the baseload fetish? Don't you realise how idiotic it is to buy a fixed amount all the time regardless of demand?

AEMO does engage in supply contracts rather than just relying on the spot market. But when they do, it's for a few days in advance, taking account of expected demand in order to get the best deal. Whereas your preferred course of action ignores demand and tries to distort the market to favour baseload suppliers, to the detriment of electricity consumers.

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Fester,
>For starters you will need six to eight times the generating capacity to guarantee
>supply, meaning that over 80% of the power generated will go to waste.

That's a very illogical claim: not only does it rely on the peculiar assumption that the output from renewables is near its maximum most of the time, but also you're assuming the excess power has to go to waste rather than be put to productive use.

Why are you so desperate to believe renewables can't do the job?

Aidan, I am trying to make economic sense of renewable energy, but there is none to be made. Considering capacity factor alone it makes no sense, and the European energy link I gave would suggest that a real world capacity factor for wind/solar is about 11%. The other thing about capacity factor is that for conventional power generation, the downtime is predictable, whereas for renewables it is random.

As for why I think that up to 80% of renewable power generation would go to waste, consider which factory might be more profitable: A factory running 24/7 on cheap predictable energy, or a factory running intermittently on expensive renewable power?

As for undersea power cables transferring thousands of gigawatts around the world, consider that a 700mw power cable between Morocco and Spain, running under about 30km of the Mediterranean, costs about $150 million US. So hundreds of thousands of kilometres of undersea cables carrying thousands of gigawatts of power around the world will cost about a trillion dollars? Hahahahaha! That sounds like a job for Captain Underpants.