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Weekend constraint payments record

Constraint payments to wind farms in the United Kingdom totalled £7.12m over the weekend, 28–29 July 2018, making it the most expensive weekend to date and well above the previous record of £5.87m for 24-25 June 2017. Constraints on Saturday the 28th of July amounted to £4.41m, and on Sunday the 29th to £2.71m.

The total volume of electricity curtailed was also a UK weekend record at 81.51 GWh. That is equivalent to the annual consumption of electrical energy of about 20,000 households.

The number of grid-connected (Balancing Mechanism) wind farms receiving payments for cutting output was also a record at 56 onshore (55 in Scotland and 1 in Wales), and 13 offshore.

When wind farms are constrained, this can be a fraction of the output of which they are capable at the relevant period. Over the last weekend, however, some 67 windfarms were 100% constrained, i.e. were completely shut down, at some time period, mostly between 10pm and midnight (Settlement Periods 44-48) on Saturday night.

Interestingly, while onshore wind in Scotland continued to provide the bulk of these constraints, at 70% of the money and 81% of the energy, offshore wind in England cost the consumer £1.75m to constrain off, accounting for 25% of the UK–wide cost. English offshore wind, however, accounted for only 15% of the energy discarded, reflecting the very much higher prices paid to offshore wind due to the higher lost subsidy, though, as with onshore wind, the constraint payment prices paid actually exceed the lost income by a considerable margin.

Table 1. Onshore wind farms in receipt of constraint payments over the weekend 28–29 July, 2018. Variations in the subsidy per MWh foregone reflect the different RO bands, where older windfarms receive 1 ROC per MWh and new windfarms receive 0.9 ROC per MWh. The value of a ROC is assumed to be £50 per MWh.

Onshore Wind Farm Constraint Payment Energy constrained off (MWh) £/MWh constrained off Subsidy foregone £/MWh
Clyde £758,113 10,911 £69 £50
Whitelee £535,231 7,802 £69 £50
Crystal Rig II £261,373 3,044 £86 £50
Kilgallioch £201,482 1,501 £134 £45
Griffin £196,971 2,914 £68 £50
Fallago £194,552 3,003 £65 £50
Dunmaglass £132,162 2,116 £62 £45
Arecleoch £131,120 1,983 £66 £50
Aikengall £123,019 1,267 £97 £45
Bhlaraidh £120,359 1,927 £62 £45
Brockloch Rig £110,463 1,293 £85 £45
Farr £108,740 1,528 £71 £50
Black Law £103,571 1,522 £68 £50
Strathy North £102,271 1,637 £62 £45
Beinneun £96,757 996 £97 £45
Baillie £94,467 972 £97 £50
Camster £94,090 1,009 £93 £50
Kilbraur £92,903 1,253 £74 £50
Pauls Hill £91,356 1,050 £87 £50
Hadyard Hill £74,391 1,191 £62 £50
Galawhistle £68,421 846 £81 £45
Rothes £67,237 773 £87 £50
Dersalloch £66,791 1,075 £62 £45
Millennium £63,965 863 £74 £50
Lochluichart £62,988 806 £78 £45
A'Chruach £62,449 774 £81 £45
Andershaw £60,617 621 £98 £45
Black Law Ext. £55,953 901 £62 £45
Blackcraig £52,385 537 £98 £45
Moy £50,818 651 £78 £45
Auchrobert £47,733 641 £74 £45
Whiteside Hill £46,066 525 £88 £45
Sanquhar £40,847 411 £99 £45
Mark Hill £38,538 567 £68 £50
Clashindarroch £38,025 481 £79 £45
Burn of Whilk £37,470 470 £80 £45
Edinbane £35,997 436 £83 £50
Ewe Hill II £35,703 575 £62 £45
Minsca £35,345 429 £82 £50
Carraig £32,665 347 £94 £50
Beinn Tharsuinn £29,787 440 £68 £50
Corriemoillie £29,508 398 £74 £45
Pen y Cymoedd £27,302 275 £99 £45
Foudland £26,216 313 £84 £50
Toddleburn £26,072 384 £68 £50
Dunlaw £25,272 372 £68 £50
Beinn an Tuirc £24,593 363 £68 £50
Corriegarth £23,485 289 £81 £45
Minnygap £21,734 235 £92 £45
Dalswinton £20,547 250 £82 £50
Tullo Ext. £20,332 260 £78 £45
Hare Hill £19,189 309 £62 £45
Freasdail £17,842 216 £83 £45
Tullo £16,425 206 £80 £50
Glen App £16,080 259 £62 £45
An Suidhe £11,285 163 £69 £50
Assel Valley £10,634 143 £74 £45
Crystal Rig III £7,555 88 £86 £45
Clachan Flats £4,531 67 £68 £50


Table 2. Offshore wind farms in receipt of constraint payments over the weekend 28-29 July, 2018. Variations in the subsidy per MWh foregone reflect the different RO bands. See Notes on the Renewable Obligation for the different band values for offshore wind farms. The value of a ROC is assumed to be £50 per MWh.

Offshore Wind Farm Constraint Payment Energy constrained off (MWh)

£/MWh constrained off

Subsidy foregone £/MWh
West of Duddon £1,005,892 6,817 £148 £100
Ormonde £225,341 1,757 £128 £100
Robin Rig East £209,695 1,384 £152 £100
Walney Ext. £166,588 1,012 £165 £90
Robin Rig West £156,866 1,339 £117 £75
Walney £141,517 851 £166 £100
Thanet £72,807 542 £134 £100
Race Bank £40,758 283 £144 £90
Barrow £37,413 434 £86 £50
Humber Offshore £34,814 223 £156 £100
Lincs £15,742 100 £158 £100
Gwynt y Mor £5,752 36 £159 £100
London Array £4,047 27 £151 £100
Westermost £3,393 19 £179 £100
Greaater Gabbard £2,258 14 £159 £100


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Interconnector problems mean wind farm constraint payments continue

Over the last few days REF has been delving into the wind constraint payments data to assist an investigation by the Scotsman newspaper into ongoing problems with the Western Link HVDC Interconnector, a 2.2 GW, £1 billion subsea cable from Hunterston to Deeside expressly built to carry Scottish renewable electricity to English and Welsh consumers.

The story, by the political affairs correspondent Tom Peterkin, was published on Sunday, 29 July 2017.

The Western Link was expected to be ready in late 2015, but did not go live until December 2017, and only then at half capacity. It immediately experienced problems, undergoing repairs in early 2018 in preparation for full commissioning in June. However, the link tripped as soon as it was turned on after the repairs. It remains out of service, and is not now expected to try for full operation until September 2018, according to an update posted on the Western Link website.

The commercial pressures on the partners in the project, Scottish Power Transmission and National Grid, are very considerable, since Ofgem has reportedly not permitted any payments during the over-run period. What is in effect a 2.5 year delay is a serious matter for a £1 billion investment. We imagine that Western Link will try for an earlier recommissioning if at all possible.

Interestingly, in response to the Scotsman’s questioning Western Link revealed, for the first time as far as we know, that the current problem is in Liverpool Bay, so presumably subsea. The bay is shallow and should not be too difficult a place in which to work, though it is littered with wrecks, mostly shipping sunk by enemy action during the two world wars. It would be interesting to know precisely what the problem is and why SPT and NG, hardly amateurs in this field, are having such difficulty in getting the link to work.

Meanwhile, constraint payments to wind continue apace. Of course, that may actually be a blessing in disguise, since it may well be true that constraining wind off is cheaper than paying for the grid to carry the excess energy away. The Western Link is likely to cost consumers about 5 per cent of the capex per year (roughly £50 million) for the approximately 30 year life of the asset.

Of course, the consumer would have been best served if the overbuild of wind power in Scotland had been avoided in the first place.

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Early Rooftop Solar PV Adopters Get Lion’s Share of the FiT Subsidy

As is well known, the generous subsidies given initially to small scale solar PV under the UK Feed-in Tariff resulted in unexpectedly high levels of adoption. Government quickly reduced subsidies for new installations, but did not feel able to retrospectively cut the arguably excessive support for early adopters. Consequently, even today, in 2017, nearly one quarter of the total annual cost of the scheme is being paid to the small-scale rooftop panels erected in the first two years of the scheme, 2010–2012.

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The Total Cost of Subsidies to Renewable Electricity in the United Kingdom: 2002–2016

REF is often asked about the total cost of public support to renewable electricity generators, both annually and since the subsidies began.

The following table gives aggregate figures for the administrative years 2002–2003 to 2015–2016. Administrative years run from the 1 April to 31 March the following year.

Year RO (£m) FiT (£m) Total (£m)
2002-2003 278 278
2003-2004 416 416
2004-2005 495 495
2005-2006 583 583
2006-2007 719 719
2007-2008 876 876
2008-2009 1,036 1,036
2009-2010 1,119 1,119
2010-2011 1,285 14 1,300
2011-2012 1,458 151 1,608
2012-2013 1,991 506 2,498
2013-2014 2,599 691 3,290
2014-2015 3,114 866 3,980
2015-2016 3,743 1,110 4,853
Total (£m) 19,818 3,338 23,156
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Santa's Christmas present for wind farms

Over the Christmas period, high winds accompanying Storms Barbara and Conor combined with low demand for electricity to deliver a £7 million gift to the owners of wind farms in the form of constraint payments. Constraint payments occur when wind farms are paid not to generate, usually in periods when wind generation is surplus to demand. The bulk of these payments are made when wind generation cannot be used in Scotland, and there is insufficient grid capacity to export the energy to England. The cost of these payments is borne by electricity bill payers throughout the United Kingdom.

The peak payments over the current holiday season were made on Christmas Day, as summarised in the following table drawn from the REF datasets:

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Renewables planning activity in the last six months

As regular users of the REF datasets will know, our EU Target Tracker is updated monthly and based on the government’s Renewable Energy Planning Database (REPD). This month’s update has just been released, and merits a general comment.

As a rule, the totals change little month on month, with the major trends only being visible over longer timescales. Focus on the short term and net changes is a mistake. It is only by studying the changes at the individual planning application level over 6 months or longer that we can see the major trends and the impacts of changes in government policy.

To that end, we have compared the detailed planning data released for April 2016 with that released this week for November 2016. We looked at how many new applications have been submitted in the last half year, how many abandoned, how many were granted or refused planning permission, how many appealed by the developers, and how many have begun construction and operation. Predictably, 80-90% of the activity involves onshore wind, solar photovoltaic and offshore wind.

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New wind farm constrained off grid within days of opening


On the 28th of October, Falk Renewables announced that its newest wind power station, Assell Valley Wind Farm in Ayrshire, had begun generating

Two weeks later, on the 11th of November, Assell Valley wind farm had to reduce output on instruction from National Grid in order to cope with the on-going problem of Scottish wind farms generating surplus electricity which can neither be used in Scotland, because of low demand, nor exported to England because of the limited interconnector capacity between the two countries.

Assell Valley wind farm charged £76/MWh to reduce output, which is approximately twice the subsidy income foregone when the wind farm is constrained off. Further constraint bids from this wind farm were accepted on the 12th and 16th of November at the same price. At the time of this blog (21 November 2016) the total income from constraints to stop generating for this new wind farm amounted to just under £10,000.

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Government Data on Renewable Energy Development is Inconsistent and Unreliable

There are significant inconsistencies between the various sources of Government data on renewable energy deployment which undermine confidence in claims regarding progress towards 2020 targets and firm control of subsidy costs to the consumer. For example, the government’s Renewable Energy Planning Database (REPD) is the principal source for estimates of progress and probable future cost, but is inconsistent with five other data sources published by government, and also with estimates made by National Grid. What cannot be measured accurately cannot be managed adequately. Government needs to get a grip.

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The Increasing Cost of CO2 Emissions Reductions in the United Kingdom

A reduction in the use of coal and a rise of gas for generating electricity has slashed the UK grid emissions factor to around 0.26 tonnes of CO2 per MWh.  This has the economic consequence of increasing the subsidy cost of saving emissions through increased use of renewables.  It now costs around £169 to save a tonne of CO2 through use of onshore wind, and £267 for offshore wind. This is 6-10 times the estimated cost of environmental damage caused by a tonne of emitted CO2 and demonstrates how expensive and ineffective the UK renewables policy is in abating greenhouse gas emissions.

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UK Coal Benefits from Exceptionally High Wholesale Electricity Prices

The unusually hot September weather, and a resulting higher demand from air-conditioning and refrigeration units, over the past week has contributed to very high wholesale electricity prices, with coal stations being the main beneficiary.

Coal appears to have been called upon because several gigawatts of gas generation were offline. Furthermore, generation from the UK’s 14 GW of wind turbines during the period was, as is likely during a hot spell, modest, ranging from a high of 4GW to less than 1 GW, or from 29% to less than 7% of its capacity.

The prices charged by the coal generators during this period were exceptionally high. West Burton coal-fired power station, owned by EdF, charged up to £1,237 per MWh for providing an extra 1.5 GWh of electricity on Wednesday 14th September. This is approximately 30 times the usual wholesale price. Ratcliffe-on-Soar coal-fired power station, owned by E.On, charged up to £1,484 per MWh for providing extra power, earning an extra £6 million for the day.

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