Another trip down the rabbit hole

And while wind can run for 24 hours under the right conditions, and solar for 12 hours, the very best batteries can run for four hours, but most can only manage two.

So 9 gigawatts of batteries cannot backup (firm) 23 gigawatts of wind and solar.

Coal and renewables are not equal

In his release announcing the extension of the original scheme Minister Bowen implies that it will replace 26.7 GW of coal-fired power capacity.

But just on the averages, you would need between 61 GW and 107 GW of wind or solar capacity to meet this challenge-plus huge amounts of batteries.

The equation gets worse.

One of the reasons for the revised scheme is that the speed of installation of renewable power has stalled.

The Clean Energy Council reported in August that "investment levels so far this year are 50 percent below the rolling 12-month quarterly average of 699 MW and are a long way off the pace necessary for Australia to achieve an 82 per cent renewable energy share by 2030."

Why is that happening?

One reason is that it is becoming increasingly hard to make money out of renewable energy because it is all available at the same time. When the sun is up, solar panels everywhere are producing power, and when the wind is blowing the same applies to wind turbines over large swathes of the country.

This leads to famine and feast where electricity prices can go from less than -$50 a MWh (it was -$99.99 at one stage in South Australia recently) to $15,500 a MWh (the all-time record).

So here's the problem-the more unreliable renewables you have the worse this gets, unless you have storage capable of soaking it up when the price is low and selling it when the price is high, which we don't.

Mr. Bowen's plan tacitly acknowledges that part of the scheme is for the government to subsidise the losses of the generators when they sell below cost in return for a share of the profits when they sell above a nominated price.