Planning to fail: how 'percent renewables' policy threatens the energy transition

For simplicity let's assume an average Australian thermal conversion efficiency of 40%. In 2022 Australia's total fossil fuel consumption, rounded, was 5250 PJ. Some of that went into generating 666.3 PJ electricity – that's the official fossil fuel electricity figure for that year. If all available fossil fuels had been consumed just in electricity generation at the same 40% thermal efficiency the output would have totalled 2100 PJ.

In this "educated guess" 2100 PJ electricity becomes the bare minimum for a fully electrified economy replacing fossil fuels. Why a minimum? Because anything less means that the sum of all new electrified process routes would consume less electricity than we could generate right now from fossil fuels. Unfortunately that's something only a wild optimist could hope. While not a strictly scientific explanation it's realistic. And if it turns out to be wrong everyone should be happy.

The above calculation is not complete. We still need to add the 2022 clean (from non-fossil fuel sources) generation figure of 318 PJ (rounded). The total electrification target then becomes 2418 PJ, or about 2.5 times total electricity generation for 2022.

In other words electrification of all fossil fuel usage calls for at least 2.5 times, or 250% of, present generation of electricity.

So it's easy to show that "100% renewables" cannot possibly be the correct target. The real target cannot be less than 250%. 100% looks no more than a fraudulent self-serving slogan.

To avoid ambiguity clean energy policy needs a clean electricity target defined as a quantity of electrical energy. It is helpful to see that quantity as the product of today's total electricity generation, from fossil fuel and all other sources, and a "multiplier". That multiplier is the key parameter. It will be derived using comprehensive knowledge of future electricity requirements. Today's best guess for the multiplier is 2.5. That is, if we could switch from a mixed electricity/fossil fuels economy to a fully electrified one we will need 2.5 times more electricity than we use now, plus of course a swag of new technologies.

The 2.5 multiplier must still be refined and confirmed. It won't be less than 2.5 and may well turn out higher than 3. It's very important to get it right. All clean energy planning will depend on it.

One thing is clear. The current "100%" policy metric has helped to flatter clean energy progress. For example with a target of 2418 PJ for 2022 as estimated above, the "percent renewables" performance indicator drops from 32.3% to 13.1 %. That's quite a difference.

With numerical targets and growth rates we can calculate how long it will take to reach policy objectives. For example, clean electricity output in 2022 was 317.5 PJ. With a target of 2418 PJ, the gap to be filled would be 2100 PJ. At the present average output growth rate of 35 PJ per annum it would take 60 years to reach the target!

The numbers are clear. Present growth in clean electricity output is far too slow for reaching fossil fuel abatement ambitions. There will surely be a need for additional clean electricity sources if the real objective is zero fossil fuels. The obvious candidate is nuclear energy.

Australia should drop its objections to nuclear, make it legal, and join the global growth of nuclear energy. One traditional 1 gigawatt nuclear power stations, like its coal counterpart, produces about 30 PJ clean electricity per annum. That's about the output of all solar and wind now installed in Australia. If smaller nuclear units gain in popularity, more will obviously be needed.

In summary Australia is using a defective performance measure in its clean energy policy that completely ignores the total picture for eliminating fossil fuels by means of clean electricity. Clean energy policy needs to be overhauled if the necessary targets are to be reached in any sensible period.

It is hard to see how the obvious deficiencies in the current "% renewables" measure were overlooked in policy setting. Policymakers, regulators, energy lobby groups, energy academics, the electorate, the energy industry, should all share the blame. Whatever the explanation, "100% renewables" must now be abandoned as a policy objective and replaced by a well-defined numerical clean electricity target.