It is generally accepted that we will lose up to 15GW or 60% of our coal power by 2040, and maybe sooner if the states and Zali Steggall have their way. It is supposed to be replaced by some 30GW of new RE capacity.
Simple arithmetic based on readily available information on the supply of sun and wind indicates that the plan cannot work. At the inevitable low (choke) points of supply 30GW of RE capacity delivers practically zero electricity.
Yesterday was a particularly good day for the RE enthusiasts. The wind blew between 30 and 40% of capacity all day and at noon 2.3GW of wind plus field solar approaching 2GW and rooftop PV at 5GW delivered 37% of the demand on the grid. In the chart below the rooftop PV is white for contrast. None of the minor players were contributing enough to be visible.
There are two points to draw from this exercise, one is the need to look past the high points to find the low points of RE supply. The second – do we need the RE that we have at present?
First, looking low instead of high.
37% is a very gratifying number for RE enthusiasts but the measure of the capacity of RE to replace conventional power sources is not the high points of supply but the low points, in fact the very lowest point, unless we are prepared to put up with regular power failures if we try to get by with with less than 100% of conventional power available for the times when there is effectively no input from the sun and the wind.
The AEMO warned that we had virtually no spare capacity after Hazelwood closed, so what happens when Liddell goes in 2023 as planned and we have 1.8GW less capacity in the system?
Ignoring solar power that is not available most of the time, how much wind capacity is required to guarantee 1.8GW of power 24 hours a day, 365 days a year (and 366 in leap years)?
Will it work to double the current 7GW of wind capacity to 14GW? At the average of 30% that is 4.2GW that is more than 1.8 but we know that the fleet performs under 10% of capacity several times a month, and some of those dips go as low as 2% in my experience and veteran wind watchers have (very rarely) seen next to no wind for days on end.
So what is the AEMO plan for the green energy transition, given the stark reality of the choke point problem?
Second, what is the use of the RE we have at present?
37% of the power, some 9+GW looks like a great contribution but is it necessary? Consider the unused conventional power capacity at noon yesterday when black coal was running at 9.2GW, brown at 4.0, gas and hydro each below 1GW. 7GW of coal capacity was not being used. Both gas and hydro can run up to 5GW although presumably not for long periods.
On those numbers the RE in the system is surplus to requirements but putting it on line has cost many billions in subsidies, doubled the price of power and driven coal stations out of business, with more to follow.
One more thing. The high points of solar power are doing more harm than good in the smaller grids in WA and the Northern Territory where voltage fluctuations have emerged as a major issue. The same problem applies here but not yet to the same extent.
Wind power has become Australia’s primary source of renewable energy after it produced more electricity in 2019 than hydro capacity for the first time.