With the newspapers again talking about the increased risk of blackouts in UK, I thought it was relevant to revisit the article that I wrote on 6th October, 2014.
As traditional power stations close due to old age and more stringent pollution regulations and the UK gradually gets more of its energy from renewable sources, the ratio between peak demand for power and the maximum that can be generated (the capacity market) is expected to shrink for a few years. While the National Grid has been planning for the change for some years, this year has seen several unexpected events such as the fires at Ironbridge and Ferrybridge coal-fired power stations and the recent fire at Didcot B gas-fired power station. Taking into account all the recent problems, the Grid says there is a 4.1% margin between available capacity and peak demand.
Let’s now talk figures. The National Grid expects peak demand to be 53.6 gigawatts if we have an average winter rising to 56 gigawatts if we have an exceptionally cold spell. The UK grid has a total generating capacity of more than 71 gigawatts if all the power stations are running at their full capacity while the expected capacity is nearer to 58.2 gigawatts during periods of peak demand. 0.9 gigawatts of available capacity must be held in reserve in case of sudden changes leaving an available capacity to meet demand of 57.3 gigawatts. So the 4.1% margin equates to 2.3 gigawatts above a cold winter demand of 55 gigawatts and therefore the margin would be halved if we get a very cold winter.
This method of calculating whether we have enough capacity is now seen as being outdated and the Government has introduced a new standard called “loss of load expectation” or LOLE. This is the number of hours each year during which the Grid would have to take action to ensure supplies continue. With the switch to variable power sources such as renewables, LOLE makes better use of the information available – for example the variation between the amount of power created by a wind farm on a windy day vs a calm day is enormous.
But whether we refer to capacity margins or LOLE, is UK at risk of having blackouts this winter? One surprising fact is that although the National Grid has based its figures on peak demand remaining the same in fact electricity demand in UK has been falling consistently since 2005. However even if the electricity demand in UK remains the same rather than decreasing, the National Grid has several contingency plans in place:
These Schemes will run for the next few years until the Government’s capacity market starts. As Ed Davey said in an interview with the Sunday Telegraph “We have extra contingencies on top of the caution and extra contingencies on top of the contingencies.”
Adapted from an article written by Christian at Carbon Brief on 30.10.14