Guest Post by John Morgan. John is Chief Scientist at a Sydney startup developing smart grid and grid scale energy storage technologies. You can follow John on twitter at @JohnDPMorgan.
A lot of ink is spilled on wind intermittency, and not necessarily based in data. So I have extracted and analyzed a high resolution dataset of a year’s worth of Australian wind power for a number of interesting properties. I previously wrote about the capacity factor as a limit to the share of electricity that wind and solar can acquire, so I also ask how wind capacity factor changes with time, place and season. In particular, how does it change during sunlight hours and what does it mean for the capacity factor limit on renewable energy penetration?
Australian wind fleet data
The Australian Energy Market Operator (AEMO) publishes data on all generators connected to the National Electricity Market (NEM) grid, which covers the eastern states including Tasmania, but excludes Western Australia and the Northern Territory. The data includes power generation every five minutes for every generator for the last year, their capacities as registered with the grid operator, and more. It is not very accessible, being in the form of thousands of SCADA data files, many of which contain errors. But with a bit of work the data can be extracted. Here, for instance, is the output of all grid-connected wind farms at five minute resolution over one year:
Wind capacity factor
Here is the top level summary of the Australian wind farm fleet over the last year:
The nameplate capacity is the total capacity of all wind farms – 3753 MW. But the whole fleet only manages 3238 MW at peak.The whole is less than the sum of its parts – half a gigawatt less in this case. Why is this?
The fleet is comprised of wind farms distributed over a large area of eastern Australia. To achieve maximum theoretical power the wind would have to be blowing at the optimum speed for each wind farm, at all wind farms, simultaneously. This is a statistical improbability and quite possibly a hydrodynamic impossibility, as it would require a high velocity correlated flow field over very large distances.