(Since this note was written the UK has seen 4 hours of zero coal generation. Between midnight and 4am on Tuesday 10th May, no coal-fired power station was working on the UK grid. As far as I can see, this has never happened before. A highly symbolic event).
At about 15.30 on Sunday afternoon (8th May 2016), the only coal power station working on the UK grid throttled back its operations. The 400 megawatts or so being generated fell to around 280 megawatts for about half an hour. The reason was probably that the system electricity price had declined to about minus £30 a megawatt hour. It made sense not to generate at all but coal-fired power stations take some time to reduce or increase their output.
At coal’s minimum generation, it was producing about 1.2% of all grid-generated UK electricity. If we included in the wind and solar not on the high voltage National Grid, the figure would have probably been below 1%. 1.2% is the lowest figure ever recorded in the UK since the dawn of the electricity age.
The chart below shows how coal has declined dramatically in importance over the past year and a half. From nearly 50% of generation in early 2015, the average figure this spring has been little more than a tenth of this. More wind, more PV and low gas prices are pushing coal out of the generating mix. Whatever else is going wrong, this is very good news indeed.