Why UK coal use will decrease this year

Carbon Brief today have a good summary of changes in the UK energy mix in 2012. One thing that stands out is that the relative positions of gas and coal have reversed between 2011 and 2012. From their piece

Coal produced 42.8 per cent of the UK’s electricity in 2012, a rather startling rise from 2011, when it provided just 30 per cent. In 2011, gas produced 40 per cent of UK electricity – so gas and coal have basically swapped places in just a year.

On the one hand this is alarming, after all we don’t want coal use to be increasing. (The emissions consequences of this are not clear, however prelimary figures indicated that overall emissions did not rise in the first half of 2012). On the other hand this is going to be a very brief increase, for the simple reason that a large number of coal plants are closing next month.The gist is this: UK coal plant capacity is 23 GW, but 6 GW is being retired next month. Coal capacity has been pretty flat since 2000, so this will mark a pretty sharp decline from 23 to 17 GW [Update: The DECC website I took the 23 GW figure from was somewhat misleading, and didn’t state that it was the total coal capacity from major power producers. The real figure seems to be 28.6. So, the percentage decline in coal output is likely to be slightly lower than this post implies.]

Below is average monthly output from the UK’s coal plants in 2012, with the blue line showing the absolute physical maximum of 17 GW from April 2013 onwards (using data taken from Elexon’s website):

So, clearly the 2012 coal output will not be repeated. How much will it decrease? That is essentially market driven, so I’ll just do a quick illustrative back of the envelope calculations. Below is the average monthly output 2012 would have had if there was a cap of 17 GW of output, but with any output below 17 GW staying the same.

This simplistic scenario results in a decrease in coal use of about 10%. The real figure will probably be higher, but estimating that will involve looking at historic output of the power plants that are and are not being closed, which I may do at some point in the future.