Summer is coming to the state of South Australia, an area located between a furnace (the interior) and a freezer (Antarctica and the Southern Ocean). When the furnace dominates the weather there can be heatwaves lasting several days, with maximum temperatures around 40C, resulting in very elevated demands for electricity, so there is great interest in where that electricity will come from.
This post looks at wind power data from the previous summer (2015/16) to provide a visual assessment of the reliability of its contribution to meeting the highest peak demands. Most of the wind farms in South Australia are in a range of hills to the North of Adelaide, and the following figure shows the total wind power from those wind farms, at 5-minute resolution, for December 2015:
The temperatures in red are the highest daily maxima at Adelaide Kent Town. See the SE AUS WIND POWER page of this blog for the list of wind farms in the area near Adelaide.
The figure above reveals some important characteristics of the summer wind power from that group of wind farms:
- The daily average output is relatively consistent and healthy at around 500 MW, a fact that helps to explain why so many wind farms are to be found in that area
- Unfortunately, for meeting afternoon peak demands, most of the wind power is produced at night, and there is a strong tendency for it to all but vanish in the afternoon. This may be the meteorological phenomenon known locally as “gully” winds, caused by the hilly location.
- There is usually a daily roller coaster ride between maxima as high as 900 MW and minima close to zero, often with wind power falling rapidly at the same time as demand picks up quickly in the morning
- The daily roller coaster is much faster than the coming and going of weather patterns, which raises the question of predictability, a necessary procedure for ensuring that electricity supply matches demand
The wind power pattern of the figure above is found also in the data for January and February 2016, as shown in the following two figures:
The daily roller coaster occurs in all data examined, apart from a few periods where the wind remains strong for several days. The daily roller coaster can be seen also in earlier data produced by the AEMO, in particular in two recent heatwaves, in 2014 and 2011:
In the figure above notice how the white area, representing the wind power, is relatively wide at night and narrow during the daytime.
The figure above also shows that SA wind power was much higher at night than during the day, and that wind power tends to become more consistent towards the end of heatwaves.
SA BLACKOUT RISKS
Wind power is contributing indirectly to blackout risk in South Australia, due to its detrimental effect on the economics of conventional (especially baseload) power stations. On some nights wind power is close to meeting 100% of demand, so any baseload power station is forced to curtail or shutdown its output, leading to a longterm decline in the number of such power stations.
The most likely cause of a summer blackout in the near future might be a breakdown of a conventional power station, or of an interconnector. The data shown above suggests that wind power would not be able to replace the lost power during the afternoon lulls. There is also the possibility of the conventional power stations being unable to cope with the highly variable, and to some extent unpredictable, wind power.