- Spanish electricity data with hourly resolution is presented for the months of September and October. Two months that were marked by periodically wind free conditions in northern Europe.
- Spain has 22.9 GW installed wind capacity. This produced a maximum 14,552 MW and minimum 301 MW in the period, load varying from 1.3 to 63%. A colossal dynamic range of 48.
- Wind in Spain is balanced mainly by varying coal output with a little help from gas and a tiny amount of help from hydro. Imports and exports are not used at all in the gross balancing exercise.
- Hydro is used to balance solar and to follow diurnal demand.
- The Green fantasy of using grid interconnectivity and hydro to balance variable wind is not being put into practice in Spain.
Figures 1 and 2 September (top) and October (bottom) based on data downloaded from Red Eléctrica de España. The data are archived one day at a time on this site and so it is a little cumbersome to download. The source data has 10 minute resolution and I have averaged that to 1 hour to make the data file size more manageable. XL does not manage negative numbers (exports) well in these stacked area charts. Hence I have added / deducted exports / imports from the Cogeneration data. That slice is therefore corrupted. Click charts for very large high resolution versions (10*50 cm) that will open in a new browser window.
[The wind capacity in Spain was wrongly stated as 27,480 MW when this article was published. It was brought to my attention in comments that the correct figure is in fact 22,845 MW and the text has been corrected accordingly.]
Red Eléctrica de España is Spain’s electricity grid operator. My quest for pan-European wind data during The Big Lull took me to their website (thanks to Paul-Frederik Bach for the link) where I was able to download all the generating data for September and October. The primary objective was to access the wind data but since Spain has one of the most progressive and diversified renewable energy grids in the world I will first present an overview of the generating philosophy. “Wind not Blowing in Spain Either” will have to wait till later in the week.
Spain has Europe’s second largest wind park after Germany with 22.9 GW installed capacity. The charts show (I hope) that when the wind huffs and puffs in Iberia that other generators must take the strain. It should be self evident from the charts (Figures 1 and 2) that coal is one of the main generators providing load balancing service, contracting when the wind blows hard. Nuclear by and large just hums along providing base load as does thermal renewable generation. But it’s not so easy to see what is going on with the other generating sources. That is because there are two variables at work – variable but predictable demand and variable uncontrollable wind.
Green Energy literature is full of fantasy about inter connectors and hydro being used to balance variable wind power. So one would think that Spain, connected to France and Portugal and owner of a sizeable hydro suite would be putting this fantasy into practice. Figures 3 to 6 show the correlations between wind and coal, gas, hydro and imports.
Figure 5 Note that hydro spans positive and negative numbers the latter being pumping that is relatively minor. See also Figure 8.
Figure 6 Positive numbers are imports and negative numbers are exports. The pattern of exports and imports is following a diurnal cycle (Figure 7).
Figure 7 Cross border electricity trade is cyclical and presumably following daily pricing patterns. There is no coherence with wind.
As expected following inspection of Figures 1 and 2, coal is negatively correlated with wind (R^2 = 0.42, Figure 3). Gas (CCGT) also shows a negative correlation (R^2 = 0.22, Figure 4) though not so strong as coal. As we will see below, this is because gas plays a dual role balancing wind and following the daily demand load. Hydro also shows a rather weak correlation (R^2 = 0.14) the reason for this being that hydro is used mainly to balance solar and to follow the daily demand load. This is discussed in greater detail below. Imports and exports show no correlation with wind at all with R^2 = 0.018. The reason for this is quite simple. When the wind blows in Spain, it also blows in Portugal and France and there is either surplus or scarcity everywhere. It is also evident that Spain manages to absorb all of its wind production when it blows and to cover demand from nuclear, coal, gas and hydro when it doesn’t.
Figure 8 shows the stacked output for gas, hydro and solar. Solar has the virtue of being on during the day, coincident with peak demand. But it does not follow demand. The chart shows how dispatchable hydro provides the bulk of the demand following service while at the same time is fine tuned to balancing solar (you must click on chart to be able to see this). Gas also provides some of the demand following service and a close examination of the peak tops shows they are ragged from which I conclude that gas also provides fine tuning.
Figure 8 Stacked load-following generation.
Figure 9 The pattern of hydro production mainly follows daily demand minus solar. There is only occasional coherence with wind during two storms where hydro production was stopped and some minor pumping was deployed. It is not clear if water conserved has any real value.
Figure 9 provides a clearer picture of what is going on between wind and hydro. As already stated, hydro use is dominated by following the diurnal demand and solar curves. During periods of high wind, for example 13, 16, 17 September and 4, 5, 6 October, hydro production does make way for wind and some surplus power is used for pumping (negative hydro). Both these events span the weekend. It is not clear whether or not the water saved serves any future purpose. A look at Figure 1 shows that on Sunday 13th September, when demand was low and the wind was strong that everything else was switched off apart from a little coal and nuclear. It seems that hydro had to be switched off to avoid abating excessive wind. A similar situation occurred on Sunday 4th October (Figure 2). This perhaps provides further clarity on why Spain abruptly stopped expanding its wind fleet. When the wind blows hard it can barely cope with all the power produced.
Pumping picks up towards the end of October with short bursts in the early hours of the morning not clearly linked to wind and this represents conventional diurnal pumping employing nuclear base load at night.
The expansion of renewables in Spain came to an abrupt halt in 2012. The main reason normally given is that the cost of subsidies was bankrupting the country and that may well be true. But Figures 1 and 2 show that on occasions when the wind blows hard Spain already generates most of its electricity from hydro, wind, solar and nuclear power. I suspect the country is at the limit of renewables it can sensibly manage.
The relatively large hydro suite that provided up to 6 GW of power during September and October offers great flexibility in following diurnal load and balancing solar but is barely used to balance variable wind.
Coal is the main loser when the wind blows hard. The 8, 9 and 10 of September were relatively wind still (Figure 1) and coal ran as stable base load for three days with mean output of 8144 MW. Had coal ran as such for the whole month, 5.86 TWh would have been produced. Because of curtailment to make way for wind 4.63 TWh were produced instead. That is a 21% decline that should presumably translate to 21% less coal burned. I wonder if the Spaniards feel this has been worth the cost?