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Centrica to use customers’ hot water tanks to stop blackouts

October 1, 2019

By Paul Homewood


h/t Philip Bratby/Joe Public




Centrica, the owner of British Gas, plans to use its customers’ hot water tanks to create a virtual power plant which could help National Grid prevent future blackouts.

The UK’s biggest energy supplier hopes to harness household gadgets with energy capacity equivalent to a large power plant by 2025. The plan could help to balance the energy system without any perceptible impact for British households.

Centrica said it has developed sophisticated software algorithms to harness thousands of smart appliances to respond when the energy system is under stress.

These devices will automatically use electricity when there is ample renewable energy on the grid, and then pause their energy use when National Grid needs help steadying the energy system…..

The home devices will be aggregated alongside Centrica’s existing flexible power supplies, totalling 2.5GW of electricity capacity, mostly from business and industrial customers.


Many have long argued that smart meters will in the future allow energy companies to cut off our appliances, but it has usually been denied.

Clearly this is what they are now planning. Things like hot water tanks will, I predict, just be the thin end of the wedge. Wait till they turn off our heating, computers and TVs.

If they are so desperate to plug shortfalls in supply, they must be in a more dire position than I thought. It would, of course, be much easier just to keep that extra 2.5GW of dispatchable capacity instead of closing it down.

Meanwhile, John Constable has discovered that Hornsea wind farm was paid £202/MWh to reduce output in August, a day after the blackouts they caused:



Maybe the National Grid will use our smart meters to make us use more power than we want, when there is too much wind power on the system!

  1. john cooknell permalink
    October 1, 2019 5:33 pm

    Centrica said it has developed sophisticated software algorithms to harness thousands of smart appliances to respond when the energy system is under stress .

    That should go well!!!!! When the system is under stress, by definition things will not be as normal, how is the software and appliances going to work without malfunctioning.

    What will happen, for safety reasons everything will just go off.

  2. October 1, 2019 5:45 pm

    In the United States, California power company (facing bankruptcy for causing wild fires) has for 4 years used meter devices and software to throttle heavy appliances such as air conditioners and heaters. Since California’s climate is mild, this has not yet caused a serious problem, but someday, some one will freeze or heatstroke to death and I gladly anticipate the following lawsuits. No company should muck with the customers instead of fixing the root problem which is unstable power due to dangerous management and/or lack of maintenance of the power grids.

  3. Joe Public permalink
    October 1, 2019 6:03 pm

    The ‘customers’ hot water tanks’ story. By Jillian Ambrose. in The Graun. That explains it.

    “Centrica’s innovation arm said National Grid had approved its plans to use home water tanks, built by a tech startup from Oxford University, alongside larger industrial equipment to deliver services that could automatically balance the electricity system”

    So these are not customers’ existing normal hot water storage cylinders (those who have HWS cylinders rather than non-storage combi-boilers), but rather new ‘special’ ones to be built by a start-up company.

    So for whom & how will they work?

    Those with a combi have no need for one. Few are likely to have the extra space for one.

    Those with a gas-boiler-heated HWS cylinder will be paying 1/3rd the commodity price for gas rather than electricity, and few have cylinders fitted with an electric immersion heater.

    If Centrica wants a heat-sink into which to dump excess surplus electricity, it persuades gas punters to have an off-peak immersion heater. But then that cuts gas demand, NOT peak-time electricity demand, which is the object of the exercise.

    Silly Jilly is so gullible.

    “Mixergy, the tech company behind the smart hot water tanks, said the technology will help consumers use less energy.

    The tank uses artificial intelligence to learn how much hot water a household uses, and at which times of day, to make sure that it doesn’t waste energy when hot water is unlikely to be needed.”

    Consumers can use less energy by using a combi which stores no hot water, and simply heats the correct amount on demand. Using a commodity 1/3rd the price of ‘leccy.

    • It doesn't add up... permalink
      October 2, 2019 11:07 am

      I recall the geysers in my grandmother’s house – one over the kitchen sink and one over the bath. Instantaneous gas fuelled water heaters were common before central heating became the norm, with individual gas fires to main rooms used by the family. It took some time to run a bath.

  4. MrGrimNasty permalink
    October 1, 2019 6:26 pm

    “..without any perceptible impact for British households….”

    Except enormous cost and a ridiculously complicated energy supply/distribution/control system that will inevitably be extremely fragile. A robust electricity supply system needs to be cheap and as simple as possible – kind of like what we used to have!

    • Paul Reynolds permalink
      October 1, 2019 6:40 pm


  5. October 1, 2019 6:46 pm

    Reblogged this on Climate-

  6. October 1, 2019 9:05 pm

    Not much smart about the National Grid. Papering over the cracks is masquerading as a policy.

  7. October 1, 2019 9:26 pm

    Big brother will not only be watching you, but also interfering in your life. We need to drain the swamp and install a whole new political system.

  8. October 1, 2019 9:44 pm

    We are buying a generator. Got the room for one that will power all we need.

    • Stephen Bazlinton permalink
      October 1, 2019 10:28 pm

      Trouble with a generator is that they will ban or ration fossil fuels……………

      • HotScot permalink
        October 1, 2019 11:03 pm

        I’ll use vegetable oil then. Already cheaper than diesel in some cases.

    • HotScot permalink
      October 1, 2019 11:01 pm

      My intention is to build a house when I retire in 2 years time.

      It will have an eff off big diesel generator as a back up.

  9. October 1, 2019 11:12 pm

    Big brother is not watching you, big brother actually makes all decisions for us. Eat now, drink now, sleep now, squat because brown substance is going to drip from your buttocks. But judging how much of their personal lifes people already give up to Social Media, maybe thats not so much of a change. To me, it will. Besides, utilities must be desperate when they resort to such measures. Stable electricity has value. Flicker electricity much less so.

    • Duker permalink
      October 2, 2019 1:12 am

      Its a very old concept which has been used in my country for decades. We mostly use electricity for hot water heating. The heating element was connected to a ripple control device at the meter board. During time of peak demand , signals sent over the power network lines tell the controller to turn off or on, and the thermostat at the tank will turn to heating element off or on as required by the tank temperature.
      The main reasons are for local load spreading and of course national supply constraints.
      They seem to have a better control now with smart meters as you individuals ask their supplier for continuous supply , but at a premium price. The old ripple control would work by
      the whole neighbour hoods.
      Ask modern hot water heaters use a 3kW element , its a load reduction method that is well worth doing.
      It doesnt make any sense to build a grid and local network just to be able to supply all users all the time when peaks could be only a few hours a few times a year

      • HowardP permalink
        October 2, 2019 5:31 am

        I wonder how many homes in the UK actually use an electric immersion heater now, except where there is no alternative? When I lived there, it always seemed just a quick and efficient way of draining my bank account.

      • It doesn't add up... permalink
        October 2, 2019 11:00 am

        I know in Australia water heating is often on a timed basis running overnight after 11 p.m. when demand is otherwise low. It creates a demand surge at 11 p.m. as all the water heaters switch on. It’s similar in principle to the UK white meter scheme which offers a lower price for overnight use but a higher price for daytime use.

      • A C Osborn permalink
        October 2, 2019 12:04 pm

        You seem to forget that the CUSTOMER pays for the privilege of having Electricity when they want it and as much as they want.
        A proper profit making organisation would be supplying them with as much as they are prepared to use.
        Rationing is for 3rd world countries, which is where we are heading.

  10. Tim the Coder permalink
    October 2, 2019 10:50 am

    What a load of Little Jilly’s tosh.
    Hot water tanks: has she (or Centrica) never heard of a thermostat?

    Mine, like every other one I’ve ever seen, holds water at a temperature limited by the thermostat. So no way of heating it more, without exceeding the temperature and creating dangerously hot domestic water. Scalded kids, what green fun.

    What this really means is that if you use any hot water, Centrica will control when you are allowed any more. But they daren’t say that.

    I worked on a bid for ‘Smart Metering’, glad to say we lost it. Phew. And yes, it is all about remotely turning off your power if your face doesn’t fit. The public description is “Demand Management”. Join the Party if you want to wash. Or stop shivering.

  11. swan101 permalink
    October 2, 2019 12:07 pm

    Reblogged this on ECO-ENERGY DATABASE and commented:
    N.B. You have been warned……….

  12. It doesn't add up... permalink
    October 2, 2019 12:44 pm

    For those homes that have a hot water tank, a typical size is 120 litres. At 4.2kJ/kg/K, heating up from cold feed at 10C to hot at 60C (hotter is unsafe given risk of scalding) consumes 4.2*50*120/3600 or 7kWh. So that is the maximum they could dump e.g. from a solar surplus if you start with a cold tank. Heaters typically consume 3kW so it takes about 2 hours 20 minutes to heat a tank from cold. Compare with electric showers, which offer a tepid or low flow output at 9kW, and a better one at 13.5kW. Demand management during your shower could be an unpleasant shock.

    With these basic parameters we can see that if we fitted the system to all 28 million homes it could store 28*7 or 246 GWh which is less than a quarter of a typical day’s current electricity demand in winter, and barely 5% of daily combined electricity and gas use in a cold spell. It is not going to bridge over days of low renewables output, since you will use the hot water, and cold water replacing the hot will reduce the tank temperature by convection and conduction, and even modern lagged tanks cool over a couple of days. Typical hot water use is 50 litres per person per day (soon to be rationed?) So for 66 million people using electric water heating daily use would total 192.5 GWh. Most of this is currently met by gas. Converting to electricity will add to demand and compete with recharging your EV. Do you want a shower, or to get to work in the morning?

    • Duker permalink
      October 3, 2019 1:22 am

      ” cold water replacing the hot will reduce the tank temperature by convection and conduction,”
      Hot water rises to the top – cold doesnt. Its a very slow change to to ‘average’ the whole tank temperature, maybe 12+hours
      The cuts in practice in my instance are mostly short , maybe 15 min at a time, and are rotated around different neighbour hoods in urban areas.
      The advantage is for reducing the daily peaks, not to make people wait till the middle of the night.
      A friend told me about the 1950s when supply was really limited and a switch above the stove meant you could have electric heating or electric stove operating , not both

      • It doesn't add up... permalink
        October 3, 2019 3:36 pm

        Peak demand is in the 5:30-6:00p.m. slot. That is not when immersion heaters are typically being run.

        As hot water is drawn down, there is a flow of cold water into the tank from near the bottom, and inevitably there is some mixing arising from the flow. A static tank not being drawn on will not mix as rapidly. Better still are tanks with internal baffles that prevent most of the conduction and convection flows.

  13. It doesn't add up... permalink
    October 2, 2019 4:40 pm

    I suppose I ought also to comment on the potential role for grid stabilisation and the sudden loss of generation or interconnector supply such as that which caused the August 9th blackouts. At 3kW per heater that is switched on, you need 333,333 per GW of switchable supply. The cumulative loss on 9th August was some 1.878GW, which would require some 626,000 heaters to be switched off for up to 15 minutes to match. Now, perhaps at 4 a.m. when households want their water heated prior to taking morning showers and baths there might be little problem in finding enough switched on heaters to switch off for a few minutes while other generators ramped up to replace missing supply. But that is much less likely to be the case if instead the event occurs at 4 p.m.

    Additionally, simultaneous switching can create transients on local portions of the distribution system. Transients can trigger trips and localised blackouts. Large industrial consumers are usually required to ensure that such transients are smoothed out by reactive response (e.g. capacitor banks protecting large motor loads) or by ramping rather than instantaneous switching. This can be fixed, might it might involve additional electronics at the local transformer if there were many connected homes tied into the scheme – which of course adds to the cost and complexity. There is little proof that this is a cost effective way of dealing with grid stability issues.

    • Duker permalink
      October 3, 2019 1:28 am

      You keep forgetting about hot water storage… 300l ( a medium sized tank)will give all the hot water you need if the suplly is turned off while under the shower.
      I only have my hot water on for a fixed time early in the morning and then off all day, provides plenty of hot water for showers during that time . Cold water stays at bottom, while hot water comes out of top, where is hottest by convection, during the time 3kW element is turned off. if you have a family you have a bigger tank or have longer period element is on – maybe 2 hrs max.

      • It doesn't add up... permalink
        October 3, 2019 3:40 pm

        I did a whole post about water tanks just above. Now you may have 300 litre tanks, but in the UK those are rare, and only found in the largest older houses. Many newbuild homes do not even have 120 litres of tankage – and are not large enough to spare the space for one.

  14. Mike Higton permalink
    October 5, 2019 3:56 pm

    HW tank cpacity can be enhanced by raising the temp and fitting a thermostatic blender on the outlet to reduce the supply temp to safe levels.

  15. Mike Higton permalink
    October 5, 2019 4:06 pm

    IDAU: “Converting to electricity will add to demand and compete with recharging your EV. Do you want a shower, or to get to work in the morning?”

    This scenario is being touted as a feature in a full-page ad by the Campaign for a Smarter Britain. Under a sub-heading “Innovation” they say they are trialling “outcome-based services” where “Customers will be able to choose an outcome (for example, a fully-charged electric car or a warm home) and it will be up to providers to make this happen in the cheapest and greenest way”.

    They don’t say what happens if the customer wants both, plus power for cooking, hot water, etc.. Obviously the aim is to ration power.

    This is all going to be enabled by smart meters…….reinforces my intention to avoid having one.

  16. October 7, 2019 5:51 am

    Give y’all one guess how this will usually be used.

    “These devices will automatically use electricity when there is ample renewable energy on the grid, and then PAUSE THEIR ENERGY USE…”

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