Australia needs clean nuclear energy

• Based on 40% of fossil fuels going into electricity generation, one can simply multiply these totals by 2.5 to get a sensible minimum for future electricity.
• Prof MZ Jacobson (Stanford University) in his "100% WWS Project" developed roadmaps for infrastructures of 139 countries to be powered entirely by wind, water, and sunlight. In total, Jacobson's electrical energy inputs for 2050 came to about 380 EJ. That's about four times the 2018 global figure.
• In his book Sustainable Energy – without the hot air, the late Prof DJC MacKay (Cambridge University) estimated the 2050 energy needs of a fully electrified UK. With addition of only transportation and heating his result was nearly triple the present UK electricity supply.
• Prof BW Brook (University of Tasmania) arrived (in 2012) at a multiplier of 3.6 for the increase in global electrical energy needs from 2010 to 2060.

To summarise, there's no possibility that "100% renewables" will allow any economy to dispense with fossil fuels. At the very least, 2.5 times present electricity supply will be needed and multipliers in the range 3 to 4 look credible.

Let's take 3.5 as a reasonable estimate. That would mean that for eliminating fossil fuels by 2050 Australia would require around 3300 PJ (electrical) and the world 335 EJ (electrical).

These projections of future clean energy needs are rough but crucial. They need refining. In my view an industry-driven audit of every major industry and supply chain is required. There are always plenty of ideas. Identifying practical routes and solutions needs knowledge and experience.

3. Clean energy progress – the reality.

I have shown that a 100% renewables target that refers only to replacing today's electrical energy consumption falls far short of meeting future needs without fossil fuels. Lower targets mean exaggerated perceptions of progress in the clean energy transition. True progress can only be measured in relation to an electrical energy target that displaces all fossil fuels. For Australia that target is 3300 PJ (electrical).

The Table below relates this target to the latest full-year (2018) renewable energy data for Australia (from BP 2019 Statistical Review of World Energy).

2018 Australian renewable energy data
Electrical output by source and relative to a 2050 target of 3,300 PJ

Solar and wind, the main future clean growth prospects, in 2018 represented just 3.1% of Australia's 2050 requirements. Their combined output would need to increase 32-fold to meet the target. The global picture is similar; world solar output was 2.10 EJ, wind output 4.57 EJ, which are respectively 0.6% and 1.4% of a 335 EJ clean electrical energy target. Clearly there's a long way to go before anywhere near sufficient clean electricity is produced.

There is also a major quality problem. Solar and wind electricity are intrinsically intermittent. Without energy storage they cannot supply electricity meeting the normal expectation of availability on demand. For some reason there's a popular perception that one or more of the many possible energy storage solutions such as pumped hydroelectricity, electrochemical batteries and chemical storage like hydrogen or ammonia will prove to be practical at the required scale. This view is entirely speculative. Underlying concepts are old, the technologies have been maturing for centuries. The barrier is the massive scale needed. No storage technology is in large scale commercial operation with solar- and wind-based power supplies. Fossil fuels presently plug the gaps.

Speculation on storage prospects should carry no weight in public policy formulation at least until there is full scale demonstration of storage in real renewables-based grids.