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Can we afford a renewables-only power supply?

By Geoff Carmody - posted Wednesday, 4 April 2018

The SA intermittency effects measured by the AEMO (eg, for solar, 15% 'efficiency' in 2016-17) are an 'on average' measure for the financial year as a whole. Through the year, there will be substantial variations around that average (season- and weather-related). Reliability requires sufficient generation and storage capacity to deal with these variations around the average as well as year-average intermittency.

Uncertainty is not about averages. It's about the spread around them. Pluses and minuses around the average don't cancel out. They increase total required renewables capacity for reliability.

We know there will be long periods (eg, during tropical storms, cyclones, etc) when the sun will not shine for days or even weeks, as well as heatwave conditions, again for days or more. Prolonged periods of little or no wind (even too much) are common. Droughts are a cyclical Australian feature.


Long periods of no renewables supply, or too much, threaten power reliability. As RETs head towards 100%, using renewables as back-up requires (i) even more generation capacity (to generate more power in 'good' times), and (ii) even more storage capacity (to hoard more power for 'bad' times). Both add yet more to renewables' costs relative to fossil-fuel generators delivering the same reliable power.

What's the cost of reliability-equivalent renewables versus fossil-fuel plant? We're not told. For now, politicians rely on fossil-fuel, rationing, and hope, as back-up. Their 'power' concerns are more personal.

I'm no renewables fan. I'd like to see all support – Federal and State – abolished ASAP. They're ineffective, inefficient, costly, unreliable, and unfair to the poor (see my OLO Power Failure piece of 30 January 2018).

It's incumbent upon die-hard fans of up to 100% renewables to respond publicly to the multiplied generation and storage capacity arithmetic outlined above. Are these multiples right or wrong? If wrong, why? If right, what will they cost? If they continue to ignore these questions, why? More dissembling and dishonesty?

Most politicians, incumbent governments and other, give lip-service to power affordability and reliability, and to renewables. OK. Tell us what happens in the power end-game where we have 100% renewables. Tell us what 100% reliance on renewables requires in multiplied generation and storage capacity.

And tell us the bill we'll cop for that.


Wither (the spelling is deliberate) affordable, reliable, power?

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About the Author

Geoff Carmody is Director, Geoff Carmody & Associates, a former co-founder of Access Economics, and before that was a senior officer in the Commonwealth Treasury. He favours a national consumption-based climate policy, preferably using a carbon tax to put a price on carbon. He has prepared papers entitled Effective climate change policy: the seven Cs. Paper #1: Some design principles for evaluating greenhouse gas abatement policies. Paper #2: Implementing design principles for effective climate change policy. Paper #3: ETS or carbon tax?

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