Renewable Energy Foundation

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Paying Wind Farms to Stop Generating in 2018

Constraint payments to wind farms, that is payments to stop generation, mostly in Scotland, reached record levels in 2018, with the total reaching £124,649,106, as compared to the total in 2017, of £108,247,860.

Of this, £115,716,335 was paid to Scottish wind farms, and nearly all of that, £115,313,091 went to onshore wind farms. These costs are, of course, passed through to consumers in their bills.

The new record data generated a number of stories in the press including the Sunday Times, the Times and the Scottish Daily Mail.

Of particular interest is that behind this record lies the fact that many wind farms received constraint payments for the first time in 2017 and 2018, as shown in the map below, including some such as Stronelairg that began to be constrained off (28 December 2018) within weeks of being connected to the system.

Windfarms First Constrained 2017 2018

Figure 1: Newly constrained wind farms in 2017 (Green dots) and 2018 (Red dots)

There is a growing suspicion that the probability of major constraints is a factor in site selection, since it increases the average earnings per MWh generated as a result of the scale of compensatory constraint payments allowed, which are, and we think unjustifiably, well above lost income. Constraints can account for a substantial part of the potential output of a wind farm.

It is possible from market data to produce reasoned estimates of the fraction of output that is discarded. The following table lists the wind farms with the highest proportion of constrained off energy, which ranges from just below 30% to around 15%. These are high fractions, and, given that constraint payment compensation, which averages £70/MWh, is over 50% in excess of the lost income (£45/MWh) make a material difference to the annual income of the site.

These matters are not at present adequately addressed in the planning system, but clearly should be. Decisions makers should be aware that a site may have been chosen precisely because it lies behind a constraint, and in spite of other material considerations, such as local environmental impacts.

Table 1. Estimated proportion of total generation in 2018 that received payments through the Balancing Mechanism not to be generated. For example, Bhlaraidh generated approximately 192 GWh in 2018 and a further 80 GWh was constrained resulting in the 29% figure in Table 1.

Onshore Wind Farm First Constraint Date % Constrained 2018
Bhlaraidh 10/08/2017 29%
Strathy North 23/07/2015 25%
Dunmaglass 23/09/2016 24%
Fallago 29/04/2013 24%
Black Law I 30/05/2010 24%
Dersalloch 21/11/2016 21%
Hadyard Hill 01/04/2011 21%
Arecleoch 10/09/2011 20%
Griffin 09/11/2012 20%
Harestanes 11/08/2014 19%
Whitelee 30/05/2010 19%
Beinn Tharsuinn 05/10/2010 19%
Farr 05/04/2011 19%
Ewe Hill II 16/05/2017 18%
Black Law II 09/09/2016 17%
Kilbraur 16/05/2011 16%
Gordonbush 06/06/2012 16%
Hare Hill 28/06/2017 15%
Clyde 09/11/2012 15%
Beinn an Tuirc 30/06/2013 15%


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