How did the UK grid respond to losing a few nuclear reactors? [View all]

[GliderGuider]

How did the UK grid respond to losing a few nuclear reactors?

In the second week of August power company EDF decided to shutdown their reactors in Heysham and Hartlepool. This was a precautionary measure after finding a defect in the boiler of Heysham unit 1. In total 4 reactors that can produce up to 2.6 GigaWatts (GW) of electricity were turned off. On the week they were turned off, the UK used an average of 30 GW.

Some were quick to declare that wind power came to the rescue when nuclear power was proven unreliable (for example Ari Phillips in Thinkprogress, Greenpeace, Giles Parkinson in reneweconomy.com.au...). More recently Justin McKeating from Greenpeace repeated the claim: "...we see a reversal of the view that renewables need to be supported by nuclear power. Although nuclear and wind power do not have the same generation characteristics, nuclear reactors now needing to lean on renewables means the nuclear industry has a big problem." Given that the claim appears unlikely on meteorological grounds and no evidence for it was provided, I felt a more careful scrutiny was called for.

So, did wind power replace missing nuclear capacity? Short answer is, no it did not. Missing nuclear generation was mostly replaced by increasing use of coal.

In Figure 1 I show the output of relevant power sources in the UK between Saturday 8th August and Thursday 14th August. EDF reactors were ramped down during this period and this can be clearly seen in the figure. Equally clear is that when nuclear output was declining, wind power output was declining even more steeply. So rather than coming to the rescue, wind power was unfortunately galloping away when the action started. The reduction in the amount of wind and nuclear power was mirrored by a clear increase in gas and coal power. Contrary to earlier claims, low carbon sources were replaced by fossil fuels.

UK production and demand data suggest common sense relationships. Wind power acts mainly together with gas while missing nuclear reactors were (sadly) mostly replaced by burning more coal. In the long run it might be technically possible to do without coal. This could be done by using electricity storage like batteries or trading between countries, so that times or places where it's windy can export electricity to times or places when it's not. Changing power demand to match supply, so that power-hungry appliances and industries turn on when it's windy could also help. However, it will be some considerable time before wind power has the capacity to take the place of fossil fuels to meet our power needs.