Cheap, Reliable, and Renewable: July 2022

Some more plots from the National Electricity Market (NEM) for the month of July to illustrate the problems we continue to face. Figures 1 and 2 are updates of similar figures from June, but Figures 3 and 4 are new and hopefully show the problem even more clearly.

Figure 1: July consumption: all sources (Gigawatts)

Note the dip in consumption every weekend is even more marked than in June.

Figure 2 shows the relative contribution of all major sources, (but including battery, if you can see it).

Figure 2: July consumption as a percentage of total: all sources

Coal usage increased mid month to provide over 60% of all electricity.  The contrast with all other sources is obvious.

For the next plot I calculated anomalies from the monthly means of all energy sources. I have calculated totals for Renewables (Wind and Solar) and for Coal, Gas, and Hydro- the main sources we rely on to keep our electricity system stable. To allow for days when total consumption was up or down, I subtracted Total energy anomalies from Coal, Gas, and Hydro.

Figure 3: July consumption anomalies: renewables and non-renewables

Figure 4 shows how Non-renewables are controlled by Renewables:

Figure 4: Coal, Gas, and Hydro as a Function of Renewables

Wind and solar can sell to the market as much energy as they produce, so on days (and hours) when they can supply more, coal, gas, and hydro must cut back. However, at those times when the sun doesn’t shine and the wind is not as strong, the shortfall has to be made up by non-renewables- and with gas in short supply, that means higher costs.

The average daily price in July was $376.73.

(P.S.- Hydro is normally included as a renewable, but really it isn’t. In drought years, there’s not enough water to power the turbines, and in wet years- like 2022- water release through the turbines causes downstream flooding, so needs to be curtailed.)

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