The UK charity REF is today publishing a brief analytic review of the extreme spike in constraint payments to Scottish wind farms during the first two months of the year, when £69 million was put on to consumer bills at an average rate of more than £1 million a day. This is four times greater than the previous most expensive January-February period on record, which was in 2016. The study can be read here.
Constraint payments, which began in 2010, arise when wind power in Scotland exceeds local demand but cannot be exported to England due to insufficient grid infrastructure. A new 2.2 GW subsea cable, The Western Link, running from Hunterston to Deeside was expected to mitigate these problems, and was scheduled to come into service at the end of 2015, but due to construction delays only became operational at the end of 2018.
In 2017 Ofgem reported National Grid’s prediction that the addition of the Western Link would reduce annual wind constraint costs to zero. In fact, payments amounted to a record £130m in 2019, and it seems probable that 2020 will be another record year.
High constraint costs in January and February 2020 were caused in part by the failure of the Western Link, which was out of operation from the 10th of January to the 7th of February, the most recent of several failures since it entered service. However, even after the link was repaired, constraint costs remained as high during the latter part of February as they were during the outage. This was partly because of strong winds, but also because wider network reinforcement is unable to keep pace with wind sector growth in Scotland where government continues to approve wind farms in spite of the constraints.
Specifically, considerations affecting the crucial substation at Harker, near Carlisle, exacerbated by further complications arising from the growth of wind and solar farms near to the Scotland-England boundary, have meant that the transfer capacity over the border to England has been capped, offsetting by fifty per cent the contribution of the Western Link. The Link was expected to increase transfer capacity from 4.4 GW to 6.6 GW, but due to the Harker problems the actual capacity is limited to 5.6 GW, contributing to high constraint payments and falsifying National Grid’s prediction of zero costs.
This mistaken forecast not only throws an unflattering spotlight on the cost-effectiveness of the £1.3 billion Western Link as compared to alternative courses of action, but also raises doubts as to the quality of National Grid’s planning function. This is of acute relevance since Grid is now proposing a further three interconnectors, this time on the East coast, at a cost of £8.5 billion to consumers.
Dr John Constable, director of REF, said: “In spite of expenditure on grid reinforcement and new lines such as the Western Link, the electricity system is failing to keep up with the development of wind in Scotland, resulting in very high costs to consumers. Government both at Holyrood and Westminster must share the blame. Meanwhile, heads or tails, the energy companies win handsomely.”