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What Happens When The Coal Plants Shut?

December 22, 2017

By Paul Homewood




Coal power generation has been running at 12.8% of UK demand in the last 24 hours, about 5GW.

This has not been untypical so far this month, with the first 19 days averaging 6.8 GW:


The average only tells us so much, however, as coal power has peaked at close to 10 GW on most days.



With wind averaging 13%, most of the rest has come from dispatchable sources, coal, gas, nuclear and bio.


At its peak this month, dispatchable power reached 43.3 GW, still well within capacity.


GW Peak Capacity
Coal 10.1 13.4
Gas 24.3 31.8
Nuclear 6.8 9.5
Bio 2.1 2.8
Total 43.3 57.5


However demand has peaked at 50.4 GW, which would leave things very tight without wind power. There are, of course, the interconnectors, but these have only been running at about 1 GW this month.

So, looking ahead, what happens when all of our coal plants are closed down?


The most recent Capacity Market Auction, held last year and covering the winter of 2020/21, includes 6.1 GW of coal/bio, out of a total auction of 52.4 GW:




We need to take account of a couple of factors though:

1) The capacity required is on a “de-rated” basis. This reflects the fact that generators cannot guarantee to be working at 100% of capacity all the time.

Building in a safety factor of 85%, the figure of 52.43 GW actually requires installed capacity of 61.7 GW.

2) Contracts are awarded to storage projects, even though they can only supply power for a short period, quite likely much less than may be needed.

It would appear that the government is now changing the rules to reflect this. Storage may be useful for short term balancing requirements, but not for stand by capacity.

3) Interconnectors can only guarantee power if surplus power is available across the Channel.

4) Demand Side Response (DSR), as with storage, may not be able to cope with long periods of demand.

All in all, if we look at just the truly dispatchable sources, we find that things look much tighter:



2020/21 De-Rated
GW Auction Capacity
CCGT 22.6 27.0
CHP 4.4 2.8
Coal/Bio 6.1 13.8
Hydro 0.7 1.4
Nuclear 7.9 8.1
OCGT 3.8 1.2
Total 45.5 54.3

Take the current 11.4 GW of de-rated coal capacity out of the mix, and we are down to the bones already, even assuming we can rely on storage, DSR and I/Cs.

There does not appear either to be much existing CCGT capacity waiting to join the Auction either. Although the National Grid do not show it explicitly, nearly all existing CCGT were awarded contracts for 2020/21.

The government hope is that, once all coal plants are shut, new CCGTs will spring up to replace them. But things may not be as simple as that.

Given the unfair competition from heavily subsidised renewables and the promise of rising carbon prices, there is little incentive to build new CCGT plants, even with the subsidy from the Capacity Market, as Trafford Power have found out to their cost.

To make matters worse, many existing CCGTs may not stay open till the mid 2020s, either because of age or economics. The CCC’s Fifth Carbon Budget, for instance, assumed that 6 GW of gas capacity would be gone by 2025, and 10 GW by 2030.

Realistically we need at the very least 60 GW of dispatchable capacity, even without the extra demand from EVs.

Even allowing for Hinkley Point, this would require another 18 GW of new capacity to be built somehow in the next seven years. There is no sign at all of this happening.




All data, unless otherwise stated is from BMRS:

  1. December 22, 2017 12:16 pm

    They get moved to Germany, like when transformers and stuff from Didcot were put in a new German coal power station.

  2. December 22, 2017 12:32 pm

    fortunately for the UK France has decided to not phase out their nukes and invest in new ones. At least that interconnector will stay alive.

  3. Jack Broughton permalink
    December 22, 2017 1:34 pm

    Another complicating factor in the power availability is that the unreliables are increasing the fuel burn in the reliables and greatly increasing the wear an tear on these due to the damaging effects on all power plant of cyclical loads. Thus, availability of the fired stock will reduce and new plant will be needed urgently. Nuclear is also likely to reduce in the 10 year time-frame, even if life-extensions are carried-out.

    In my view the best approach would be to charge unreliables for their unreliability fuel- wastage back-up costs (including wear and tear). Also, the coal power station closure and scrappage policy need to be stopped urgently as these offer fuel flexibility and storage that gas does not offer – (especially without the Rough storage). Apart from LNG the UK seems totally vulnerable to external supply problems and costs.

    • Gerry, England permalink
      December 23, 2017 11:11 am

      As I think has been said before, the thermal plant needs to be kept warm in readiness for use which is a waste of energy – you know, the stuff we are supposed to be saving – and a cost on fossil fuel generators. I worked on a steam turbine generator once and on leaving site it would take 12 hours to bring it up to temperature to run again.

  4. Gerry, England permalink
    December 22, 2017 1:37 pm

    Just need a static high pressure to kill off the wind bringing fog and frost to stop any solar getting through and then out go the lights.

  5. December 22, 2017 2:08 pm

    New nuclear won’t be ready when the last coal plants go out of service, unless they extend the deadline.

  6. December 22, 2017 2:54 pm

    “What Happens When The Coal Plants Shut?” I suspect those of us living in the countryside will find that the lights go out. They won’t dare to let the lights go out in the big cities because there would be civil unrest. The BBC will lay the blame on the big six energy companies (and the Con-servatives), if they bother to report it at all.

  7. Malcolm Bell permalink
    December 22, 2017 6:24 pm

    So what is the problem – just install eight times as many windmills as we already have – one in everyone’s back garden for a start. Then dam all the big estuaries (especially Solway, none of the London Greenies know where it is so it doesn’t matter) and wverything will be fine. No problem – is there?

  8. Bruce of Newcastle permalink
    December 22, 2017 9:28 pm

    Better question is “what happens when the gas runs out?”

  9. December 23, 2017 10:14 am

    Reblogged this on Climate Collections.

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