Spare grid capacity down to 4%
29 Oct 2014
National Grid yesterday warned that the UK’s spare electricity generating capacity this winter will be as low as 4.1% during peak demand of what it describes as an Average Cold Spell (ACS).
The grid operator blamed the decline from last winter’s 5% peak demand capacity margin on planned generator closures, breakdowns such as the fire at Didcot B last week, and new plant not coming online as quickly to replace them.
In response, National Grid is finalising contracts with three power stations to provide additional reserve capacity: Littlebrook oil-fired power station in Kent, Rye House CCGT in Hertfordshire and Peterhead CCGT in Aberdeenshire.
The electricity margin has decreased compared to recent years
National Grid’s Cordi O’Hara
The grid operator’s Winter Outlook Report 2014/15, published yesterday, says that when combining these three plants’ capacity with the capacity offered by major energy users such as process plants in its Demand Side Balancing Reserve (DSBR) scheme, an additional 1.1 GW of capacity will be available, increasing the margin from 4.1% to 6.1%.
“The electricity margin has decreased compared to recent years, but the outlook remains manageable and well within the reliability standard set by Government,” said National Grid director of Market Operation Cordi O’Hara.
“As System Operator, we have taken the sensible precaution to secure additional tools to bolster our response to tighter margins.We will continue to keep a close watching brief across both electricity and gas throughout the winter so that we’re strongly placed to respond to any unanticipated events.”
In National Grid’s Winter Outlook report, the mid-winter generation capacity is assumed to be 71.2 GW, which when taking into account availability and historic performance is de-rated to 58.2 GW for margin analysis.
Taking into account historical weather patterns, National Grid forecasts peak electricity demand for this winter to be 53.6 GW. The more arduous ACS electricity demand, which is demand conditions with a 50% chance of being exceeded, is expected to be 55 GW this winter.
This means electricity generating capacity is just 4.1% above ACS peak demand.
Meanwhile, the Winter Outlook also reports that gas supplies are in rude health, with storage facilities well stocked.
