The previous post dealt with the precarious nature of the electricity supply in the state of South Australia, especially from 2018. In this post I describe how to obtain some early warnings of power outages due to high demand; this is most likely to occur towards the end of summer heatwaves that don’t end during weekends or holidays.
This post deals mainly with monitoring demand, and knowing when to worry about it; later posts will deal with monitoring the available supply.
Probably the best way to predict electricity demand in the near future is to look at recent demand, the weather forecast, the dates of weekends and holidays, and at what happened at roughly the same time in recent years. The following figure shows Adelaide maximum temperatures (blue curve) and South Australian electricity demand (red curve) at 17:30 EST (close to the time of peak summer demand) during the months of November and December 2015:
The main driver of fluctuations in peak electricity demand is the temperature, though humidity, cloudiness and wind speed and direction are probably also involved. It can be seen that the electricity demand (red) has roughly the same times of peaks and troughs as the maximum temperature (blue). Heatwave duration also plays a role, generally with peak demand rising as the heatwave progresses.
A key secondary influence on peak electricity demand is the time within the working week, with lower demand during weekends (probably including half-day Friday to some extent) and public holidays. Peak electricity demand in December 2015 occurred on Thursday 17th at just under 3000 MW, but it is likely that demand would have risen significantly above 3000 MW if the maximum temperature of 43.2C at the end of the heatwave had landed on a working day, rather than on Saturday 19th December.
The South Australian electricity system (including interconnectors) can currently meet peak demands actually or might-have-been seen in the recent past (several instances between 3000 and 3400 MW), but will not be able to do so reliably from the summer of 2017/18. Early warning of high demand can be obtained by looking at forecast temperatures during working days, and then checking demand data from recent days and past years.
Some people may be surprised that there will be a problem with inadequate electricity supply in South Australia, given the amount of money that has been spent in recent years on solar and wind power. The remainder of this post deals with the current realities of wind power, with more to come in later posts.
In the previous post there is a plot produced by the AEMO of wind power generated in South Australia in 2011, showing its almost total absence at certain times, a feature that is still present in 2016:
See below for the source of the figure above, useful for checking the current and recent availability of electricity in Australia.
Maximum temperature data for Adelaide Kent Town from: http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=122&p_display_type=dailyDataFile&p_startYear=2015&p_c=-106646410&p_stn_num=023090
Electricity demand data from: http://nemweb.com.au/Reports/ARCHIVE/Operational_Demand/ACTUAL_HH/
Current and recent electricity production can be seen in plots generated here: http://energy.anero.id.au/