By Richard D. Patton
South Australia (SA) is the smallest state in Australia and its government has made a goal of being a leader in renewable energy production. As a consequence, it has a large amount of installed wind and solar generation. After a series of blackouts in 2016, the Australian Energy Market Operator (AEMO) placed strength limits on solar and wind generation, making sure that there was enough backup so that there was not a repeat of the blackouts.
In the 3rd quarter of last year, here is a graph of the curtailment of wind and solar power generation.
Source: AEMO 3rd quarter report 2018
The curtailed power (non-synchronous means wind and solar power) represented 10% of all of the electricity generated in the quarter. It was 150 GWh, so the total generation potential was 1500 GWh, and 1350 GWh was actually used. Over 91 days, this is an average of 618 MW.
There is an interconnector between SA and Victoria. During this time, exports, driven by wind and solar averaged 150 MW out of SA and into Victoria. This was mostly due to wind power. Finally, the average demand of SA was 1465 MW. This can be combined into the following table:
|SA Demand (MW)||Wind and Solar (MW)||Exports (MW)||Used in SA (MW)||Percent of demand from renewables|
This is a higher result than I would have expected. The renewable generation is bumping up against the intermittency constraint. For the comparable quarter last year, the curtailment percentage was 5.9%, so the amount of curtailed power is going up. More installations, especially of wind, will probably push up the curtailment and contribute little to satisfying actual demand.
Australia is in the southern hemisphere, so the 3rd quarter (July, August and September) is the winter there, and winds are usually highest in winter. There is also continued installation of wind and solar power. Comparable numbers for other quarters are:
|3rd quarter 2017||4th quarter 2017||1st quarter 2018||2nd quarter 2018||3rd quarter 2018|
|% curtailment in SA||5.9%||2.3%||1.2%||4.8%||10%|
In the 2nd quarter, 2018, the average demand was 1500 MW and the renewable generation was only 480 MW. The export flow from SA to Victoria was 80 MW. This gives a renewable portion of SA demand of 26.7%. 1st quarter 2018 was similar. Renewables generated 500 MW and there were exports of 80 MW, so renewables were 28%.
In the 4th quarter 2017 there was an anomalously large export figure of approximately 220 MW which probably should be ignored as a special circumstance since it does not occur in any other quarter. Renewables generated 470 MW and demand was static at approximately1500 MW.
None of these figures take into account demand suppression due to home photovoltaic (PV) installations. The PV installations do not go onto overall demand, since that is demand for large generators. These penetration figures would be higher if home PV were considered.
Probably new wind generation in SA will add more to the curtailed energy than to electricity supply in SA. There is more room for growth in PV since PV output rises during the day and that is when demand is highest. SA is a desert. Adelaide, its chief city, is fairly close to the equator at 35o S latitude so it has good solar resources.
It is interesting that my last article showed that Germany appeared to be bumping up against a soft limit of 12.5% for wind and solar, but South Australia is up in the high twenties to low-thirties – almost 2.5 times the penetration. It is not possible to generalize from one case. Each case is different, but probably it depends on both population density and the quality of the wind and solar resource.
AEMO quarterly reports 4th quarter 2017 to 3rd quarter 2018