Gridwatch UK December 2014

This is the first in what I hope will become a monthly series chronicling the UK generation statistics from BM reports and Gridwatch that will be archived on the main menu bar above. As the database grows it will become possible to identify seasonal and temporal, policy driven, changes to the UK grid. But for now I will let the charts speak for themselves. Note that if you click on the charts you will get a very large version that opens in a separate browser window.

Figure 1 Coal, gas, nuclear, wind and imports kept the UK lights on in December. See Figure 3 for the vital statistics. The story is fairly simple. Nuclear provided a very stable base load averaging 7.6 GW. Coal was the biggest producer in Bright Green Britain averaging 12.8 GW and absorbing some of the load following strain, gas averaged 8.6 GW absorbing most of the load following strain including the diurnal demand and wind variance, wind averaged 3.9 GW and the wind blew quite consistently through the month and electricity imports via inter-connectors averaged 2.3 GW.

Peak demand was 51.8 GW early evening on 4th, 8th and 15th December. Minimum demand was 24.5 GW during the night on 22nd December. Peak was 2.1 times greater than minimum.

Figure 2 This rather busy chart shows the contributions to the UK grid in December described in the caption to Figure 1. Wind provided electricity but no control. Its main contribution is to undermine the commercial viability of those generators that provide the essential control.

Figure 3 The vital generating statistics. I still need to find out what the installed capacities are in order to work out load factors. [Dave Rutledge pointed out an error in the GWh total column that was corrected 08:50 on 16th Jan].

Figure 4 A pie chart visualising what I’ve already said. 

And so to complete the picture a quick comparison with France. The main puzzle here is that France continues to produce electricity from gas and hydro at night, even when there is no demand for it, and at times when they are using nuclear surplus to pump hydro. Fritz?

Figure 5 French electricity supply from Gridwatch France. Net exports and pumping water are deducted from the nuclear base load. 

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18 Responses to Gridwatch UK December 2014

  1. Joe Clarkson says:

    I notice that in France nuclear does a fair bit of load following, whereas in the UK it does virtually no load following. I had been under the impression that nuclear was almost always operated more like the UK, at base load with little variation. Anyone care to explain how the French dial their reactors up and down on a diurnal basis? Do they all vary just a little, or do they have some special reactors that can change output dramatically?

  2. Euan: Some light on the French hydro cycling question. To get the correct numbers you have to add the pumped hydro – which is always negative, i.e. it shows only when water was being pumped uphill – to the hydro, which includes the power generated when it came back down again. This is the result:

    Hydro was in fact cycled quite rapidly in a load-following mode, sometimes by more than 10GW in a day. Output even reached zero a couple of times.

    And almost all the water pumped uphill was pumped uphill at night. Maybe they kept the nukes running to power the pumps. 😉

    • Hi All

      When have a very large direct electrical heating demand which is why they show a very much lower day to night variation, as well as smoothing their load curve (and thus Nuc Output) with considerable Hydro & P/S capacity. However, their daytime load can jump significantly when it gets really cold and exceed the generation capability, even with P/S and Hydro flat out. On 8/12/12 demand got to 100GW, the following Wednesday down to 82GW. Thus they have to import or curtail demand. On 8/12/12 we exported flat out at the evening Peak with both France and Germany importing.

      More recently, with GB capacity reduced and a fair amount of GB and Irish Wind overnight. We Import from Europe and Ireland imports from us during the day. Then overnight Ireland goes export to us and, depending on Wind output, we export to Europe…..

      Euan, you might like to show Gridwatch I/C data going both ways, either separately or on the bottom of the stacked graph…..

      A lot more complicated issues can arise when analysing System behaviour with prices, both internal across Interconnections

  3. clivebest says:

    It is notable how the French diurnal variation is only half that in the UK. Excess nuclear generation at night can be used to light motorways, for example across Belgian, cutting cutting down road accidents. It also enables extended industrial production shifts and cheaper heating for buildings.

    Why also is peak UK demand so low compared to both France and Germany and clearly falling? The populations are similar and 10 years ago UK demand was over 60GW. Is this a sign of industrial decline ? Is it because all rail transport across France and Germany is electrified ? DECC appear to consider the fall in UK consumption as a triumph of energy saving policy!

    Having a cheap constant source of generation like Nuclear must be an advantage in the future if electrical power is to replace burning oil for transport.

    I get more or less the same figures for fuel contribution to peak UK demand over the last 30 days.

    • Leo Smith says:

      One of the reasons is that the UK climate is simply more equable, being maritime. We don’t get the extreme heat nor the extreme cold that central Europe does. Another reason is the heavy use of gas for heating – because it (used to be) cheap.

      We also do less heavy industry and more service industry.

  4. Leo Smith says:

    There is one associated point that is worth making: From an engineering and economic standpoint there is a rule-of-thumb in large engineering projects

    “profit comes form average returns, capital cost is 90% about meeting exceptional conditions”

    That is: an aircraft say costing one tenth as much to build and fly would stay in the air nearly all the time. Unfortunately it would not have enough safety margin to stay in the air all the time.

    Meeting worst case conditions adds considerable weight and expense, making the aircraft more fuel hungry and more capital expensive.,

    Exactly the same is true of the grid. Having excess plant to meet contingencies costs in terms of capital and in terms of maintenance, but there is no excess product flow generated by it to pay for it.

    Renewable energy of the intermittent kind simply increases the need for low average output standby plant that generates little income.

    Hence the deployment of massively fuel inefficient, but low capital and maintenance, diesel generators for STOR.

    Pumped storage is great, because it can absorb night time surplus and feed the daytime peaks. The same is true of a hydro plant that isn’t full of rainwater. Water can be conserved until the high earning peak times so although its not pumped, the economics dictate that when say half full water can be used to maximise profit by feeding peak demand.

    Sadly renewable energy of the intermittent kind is truly worse than useless. It simply becomes a wildly fluctuating (and less predictable) component of the grid needing even more dispatch to smooth out the flow. The cost of this is not borne by the renewable companies: It is displaced to (largely) the gas operators who then need to raise prices to accommodate the same costs of maintenance and capital investment, for less average output, their market having been ‘stolen’ by renewables.

    When you look at the UK grid holistically it is clear that diversification of a certain sort does help reduce costs. In the absence of nearly enough hydro to balance peak demand, we have to use gas as an intermediate dispatchable technology, with coal and nuclear providing the most cost effective base-load. That is the optimal mix. Adding renewables – solar and wind – simply cuts into the profits of the gas operators, and adds expensive electricity of its own,. There is in a purely economic sense, no place for these renewables in the UK grid at all, all they are adding is cost and unreliability, and due to the fact they displace the more efficient gas generation, not the coal, and they reduce the generation efficiency of that gas, it is arguable that they do not even reduce CO2 emissions either.

    In short you pay three times for renewables: Once because they are inherently more expensive than the alternatives, and again because of the cost of keeping unprofitable plant and over specified grid links available for when they fail to turn up, and thirdly because they impose additional stop start costs (increased fuel burn and wear and tear) on whatever is in fact being used to balance them.

    The conclusion has to be that renewable energy contributes little or nothing to CO2 reduction and massively to energy costs.

    We would all be better off without it. Except Samantha Cameron’s daddy of course…

    • clivebest says:

      “The conclusion has to be that renewable energy contributes little or nothing to CO2 reduction and massively to energy costs.”

      Yet politicians live on another planet. They never seem to learn their lesson

      Ed Davey July 2014:

      We’re driving investment in our energy security, and our plans have made us number one in the world for investment in offshore wind energy

    • John Williams says:


      Admirably clear and concise summary. I think I will quote it (if I may) at the start of every wind farm application objection we write as an introduction. Given the flood of applications in the Borders, that will be pretty frequently.

      I will leave out the dig at the end, although it speaks volumes. Milliband has also been assuring the renewables industry that Labour will keep on approving further applications.
      As Clive says “they never learn”.

  5. Jacob says:

    It would be interesting to compare the data also to Germany, you can find the data at the Agora site. They are more similar in the supply mix to Britain, much less nuclear than France, much more wind and sun than Britain, and using coal for balancing rather than gas.

  6. Have you seen this nonsense report produced for RenewableUK “The Impact of Wind Energy on UK Energy Dependence”? There’s a complete lack of understanding of our electricity supply – but it was written for RenewableUK by a very young economist.

    Of course the BBC environment reporter is heavily supporting it.

  7. Joe C says:

    Outstanding post Leo.

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