A storm headed over our country at the end of last week. That inevitably means advocates of wind energy praising how wonderful wind energy is doing and how much electricity was produced by wind. That is exactly what happened and apparently we even have a new record…
It was Chris Derde (manager of energy provider Wase wind) who broke the news. He tweeted that wind energy had a “new record production of 3 GW” and that nuclear power plants lowered “their production by 0.5 GW”. This was one of the two images that accompanied the tweet, illustrating the record:
This is a graph from the Elia website (our grid manager) depicting the Belgian wind production of the previous day (thin orange line) and the projected production of the day of the tweet (thick green line). The thick orange line is the actual measured wind energy production of the same day (until the moment he took the screenshot).
It was not really clear from the screenshot, but looking at the Elia website I found confirmation that electricity production from wind energy almost reached 3 GWh around midnight and was projected to stay close to that value until noon. That is impressive, considering that the previous records had a timespan of (less than) 15 minutes, but nevertheless this is still an exceptional situation.
He also mentioned later in a comment what his motive was to tweet about the record (translated from Dutch):
At the time of the message, a 3 GW wind power capacity was operational. New wind turbines are added regularly; when there is a lot of wind and wind turbines produce at full capacity, it is a new production record.
Of course it is. Capacity is indeed gradually increasing and more capacity will generate more electricity. When it is very windy, like in a storm, records will be broken, no doubt about that. But I fail to see why this is so important in the workings of our current grid.
Here is an overview of a couple days before the record (from the Elia website, but added some arrows to highlight some interesting values):
The first arrow indicates a very low wind power production of 39.95 MWh (June 5 at 16:15). Total monitored capacity is 3,667.385 MW, meaning a capacity factor of just 1.1%. I initially assumed that this was the lowest value of the stretch, but looking at the numbers, there was an even lower value on June 9 at 12:00 (third arrow). Production was 19.8 MWh, meaning a capacity factor of just 0.5%.
By the way, this 0.5% value is not even the lowest value this year. On February 22 at 16:15, there was production of 1.23 MWh which was 0.04% of the wind capacity at that time.
The second arrow is the record production of 2,966.83 MWh (June 8 at 13:45), meaning a capacity factor of 81%.
If we look at the last two arrows, then production ranged between 0.52% and 81% within 12 hours. That is less joyful, that is even a bit scary because this distance will get larger when capacity increases.
There are two things playing here:
At low production something else will have to kick in, some dispatchable backup needs to be available to fill in the gap. This could well be a time of high demand, like the first arrow that coincides with the start of the evening peak.
The same with the low value in February. This happened on a Friday, just before peak hour when the sun was already setting. The contribution of wind (and solar) in peak demand was therefor almost non-existent. At 16:15, there was a demand of 11,162.91 MWh and a solar production of 283.88 MWh, meaning 10,877.80 MWh short. That is 97.45% of production that needs to be filled in by something else.
At the peak we have a sudden burst of electricity production, meaning other (dispatchable) energy sources need to scale back. This could get rather difficult when capacity of intermittent energy sources increases (not only wind, but also solar which can also amplify the effect). The lowest demand in Belgium is still well above 3 GWh, but when our capacity doubles or triples, then there is no room to scale back and other strategies have to be used like curtailment (wasting resources), export the problem (but all other countries are moving in the same direction, so probably will have the same problem) or storage (expensive).
The reaction time of the backup also will need to be quicker, because the higher the increase, the steeper the lines get.
Balancing the two could prove challenging. The lowest production shows how much backup is needed, but this low value will not change much when capcity increases. For example, on June 9, there was a production of 19.8 MWh, therefor a shortage of 8,737.68 – 19.8 MWh = 8,717.88. When doubling the current capacity, only 39.60 MWh would have been producted and still 8,737.68 – 39.60 = 8,698.08 MWh short. Tripling the capacity (as expected by 2030) would only would have produced 59.40 MWh and a shortage of still 8,737.68 – 59.40 = 8,678.28 MWh.
Even multiplying by an insanely high number will not help much (in theory, it would need 441 times the current capacity to satisfy the demand on that day at that time).
At peak production, trouble is looming. There was a production of 2,966.83 MWh on June 8 at 13:45. Doubling the capacity would get 5,933.66 MWh, which is already somewhat below the demand at that moment. Tripling would result in 8,900.49 MWh, which is higher than the demand of that moment. Multiplying by double digit numbers would probably fry the grid.
This is the situation when doubling and tripling the current production:
At peak production, there is a rapid increase that will reach the value of demand (8,737.68 MWh) before even tripling the current capacity (3,667.38 MW). At low production, the double and even triple values are virtually indistinguishable from the base line.
Zooming in on the last day would make the difference clear. Look carefully below right (the gradation is even exaggerated, I used the smallest white space possible, but at this magnification there is in fact no distinction between the three tick marks):
That is the part of the story that doesn’t get told. Only record highs are proclaimed. Because the capacity increases on a regular basis, we are bound to hear many of these records over time and this could give the false impression of a steady progress. The ever increasing distance between highs and lows tell us a different, less optimistic, story and points to challenges that lie ahead.