This is shaping up as a record day for solar and wind production compared with coal, aided by the lower level of demand on the weekend. Black coal is possibly at the lowest level ever at 7.2GW and brown coal is down to 2.6GW. In the last couple of years black coal has moved between 8.2 and 16.1. Brown coal has been up to 4.7 but normally it is stable in the vicinity of 4 while black coal ramps up and down along with hydro and gas to compensate for the coming and going of the sun and wind. This is the picture this morning.
RE is up to 50% of demand and the solar component often improves after lunch. Wind is operating over 40% of capacity and contributing just over 3GW that is somewhat better than the average of 2.5. The maximum observed so far is 5GW so if the wind picks up to that level today the champions of RE will be doing handsprings.
Now for the warning. The choke point factor dictates that the grid has to have 100% of supply continuously to avoid blackouts. The sustainability of the system in the absence of coal is limited by the lowest level of RE supply – because the lights start to go when the RE supply (plus hydro and gas if gas is allowed) is less than the demand at the time.
The supply of RE at any point in time is very different from the installed capacity and it is also very different from the average (29% of installed wind capacity). The worst possible case is the limiting factor and the worst possible case is a windless evening just after dark at dinnertime (peak demand.) As any serious wind watcher knows, the worst possible case is effectively zero RE, with the sun in bed and the wind down to 2 or 3% of installed capacity. The wind is often below 10% of installed capacity for periods over 10 hours and up to 32 hours in June and July this year.
So we will need conventional power to be available to supply 100% of demand until the very distant time (if ever) when there is a solution to the problem of feasible and affordable mass power storage.