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What happens in an extended wind lull?

Extended Wind Lulls

The intermittency of wind is already a huge problem in GB. It used to be said that "it's always windy somewhere", but that was proved to be untrue a long time ago. Lulls in wind can cover virtually the whole of GB, and can last for hours, days, weeks or even be prevalent over periods of a month or longer.

When total wind power was small this was a problem that could be resolved using "spinning reserves" of fossil fuels, notably gas. However, as total wind power has increased, lulls in the wind have started to cause bigger and bigger gaps to fill. As wind power increases, we will need to use not only gas to fill the gap, but we will be increasingly dependent on interconnectors. By carefully setting our available gas power and managing its use we can help, but we have limited control over interconnectors, both in terms of availability and the source (fossil fuel or otherwise) of the electricity we are importing. And, as the available wind power increases still further and the gaps get larger and larger, we will increasingly not be able to fill the gap and power cuts will become more likely. Other sources - notably nuclear - are to decline, whilst others just will not have enough available power to make up the difference.

This problem will be made even worse by the fact that by 2050 the National Grid figures show that GB electricity demand will have greatly increased.

GB will have an increasing number of power cuts, and they will tend to last longer.

Here is an example of what happens now when there is little wind for a protracted period of time.


March 2021

Throughout the month of March 2021 variation in GB electricity demand was met by CCGT (i.e. gas) with support from interconnectors and biomass. Nuclear provided a base supply. The contribution from wind varied dramatically during that month, outstripping CCGT on some days and contributing almost nothing on others.

Wind Lulls in 2021

If we assume that a wind lull is when wind is supplying less than 5% of demand, the table below shows the extent of wind lulls in 2021.

Incidence of wind lulls in 2021
MonthTotal Hours <5%No. of LullsNo. of Lulls >5 hoursNo. of Lulls >10 hoursMaximum Lull (hours)
January155105
February3411134
March11097443.5
April156137453.5
May177178467
June8996330.5
July314.5965120
August128.5174354.5
September108148518
October93105
November2832114
December8433339.5
TOTAL12531035433 

Wind lulls were much more prevalent in 2021 compared to 2020, with 13 days in total in July when wind contributed very little to the grid. December was also disastrous, with three wind lulls of over 10 hours each following on in quick succession. The overall figures would have been much worse but for October and November being very windy months and including Storm Arwen.

The National Grid’s Future Energy Scenarios (FES) published in 2021 proposes massive increases in operational wind capacity (over six times current capacity in one scenario) through to 2050 with significant reductions in gas (to zero in one scenario) and nuclear.

It is hard to see what GB would have done in 2021 without gas and nuclear, and to contemplate what will happen if any of the scenarios in FES 2021 are adopted.

It is also a rather sobering thought to consider how much storage Great Britain will need to cover these frequent extended periods of low wind.

How will GB cope with low wind days, weeks and months in 2030 and 2050?