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UK Power Industry - a turning point?

Discussion in 'Speaker's Corner' started by PlacidCasual, May 12, 2016.

  1. Werewolf

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    They built a big Li-ion bank near one of my old schools, it's about the size of a supermarket and IIRC can supply average power usage to several thousand homes for a few hours.
    Apparently it was built largely because the town needed more incoming capacity as it was expanding and regularly nearly hitting the limit of the supply, if not tripping the safetoes, and it was faster to build the facility than do the upgrades, I think there was also an element of it being a good candidate for it as a test location.

    Given the size, cost and limits of it I can see exactly why it's not practical on a larger scale to give it enough capacity to provide for the whole town for several days of more discharge than recharge you'd likely need something around 100 times larger (think Tesla car battery vs 1650).

    I think they've been upgrading the incoming primary power lines as well, but that's a much longer term project.
     
  2. PlacidCasual

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    Capital costs, energy density and storage capacity are the big problems for battery storage. Even if they come down in price significantly the amount required even for a few hours demand is very high. The politicians will get round this by mandating the requirement to us and spreading the cost. But heaven help the poor when heating, water and gas are required to be carbon free. The UK housing stock is simply incapable of the efficiency required to make that an economic prospect.

    The hair shirt approach to this problem is very frustrating. The anti nuke bias which is killing new fission technologies at birth is going to be very costly.
     
  3. Werewolf

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    Aye I did some checking the one near my old school apparently cost ~£19 million, and can provide power for 6000 homes at peak consumption for about 90 minutes.
    I make that about £150 million to provide a days storage for 6000 homes, probably around 90 million allowing for the difference between peak and average demand (I'm guessing average works out at about 60% of peak), which works out at about 15k per home.
    I suspect nuclear works out far cheaper given you still need the actual generating capacity on top of that.

    Admittedly it was a test of the idea so additional ones/increasing the capacity would probably be a bit lower, but I suspect that is more than offset by the fact the land it was built on had been owned by the network for50 odd years and due to flooding was only useful otherwise for allotments (to the point the electricity distributor allowed local residents to use it for that for a token amount).
    To get it to a day's worth of storage for just 6k houses would likely require it to be the size of a major supermarket, and I suspect the idea doesn't scale up well as at a guess taking the high voltage incoming down to what is used by the batteries, then taking it back up again for long distance distribution would likely be far less efficient than dealing with it entirely at the substation level (so you probably cannot keep the costs down by using out of town locations, as most substations are in built up areas).
     
    Last edited: Mar 15, 2019
  4. Orionaut

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    I have always wondered how much energy could be stored in super-flywheels?

    Rotational storage is already used to some extent, even if only in the spinning machinary of the turboalternators.

    One of the reasons why the original JET was built in the UK was that the nature of the UK national grid enabled it to handle the sudden surges in demand that the machine would generate better than anywhere else in Europe at that time.
     
  5. Angilion

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    And it's still not good enough - JET has 2 big flywheels for that reason. They are extremely big, weighing ~775 tonnes each, so they could reasonably be the "super-flywheels" you refer to. They can store 3.75GJ each. That's a lot, but if my rough off the top of my heads maths is right that's a little over 1000 KWh. UK electricity consumption is in the region of 300,000,000,000 KWh per year. You'd need an awful lot of extremely big flywheels to store enough energy to make a functional national grid from renewables even if generation was from large power stations with some degree of centralised control. With massively distributed generation with no central control, you'd need even more. I think it's not possible.

    EDIT: I just did a bit of reading and discovered two other issues I should have realised already but didn't.

    1) Flywheels continously waste energy because moving parts have friction, so they're not well suited to storing energy for any length of time.

    2) If a flywheel fails, the energy is released. The more energy it's storing, the more destructive the release of that energy. It takes a lot to contain the release of gigajoules of energy...and as shown above, gigajoules is nowhere near enough to stablise a grid. You'd need hundreds of megajoules stored just to power a single car!
     
    Last edited: Mar 21, 2019
  6. Werewolf

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    Aye, I remember reading about the potential use of flywheels in data centres 20 odd years ago (in Computer Shopper back in the 400-500 page days;)), where they were suggested as a replacement for battery UPS's but as you say they aren't efficient in terms of storage, they require maintainance (which is expensive/requires heavy plant equipment), and if something goes wrong you have rather a large issue...

    Anyone who has ever seen the damage a CD could do to a 32x or higher CD-rom drive, or a grinding disc when they fail will have an idea of what can happen, but imagine tens or hundreds of tons rather than a few dozen grams.
     
  7. shroomz

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    The consensus where I am is that within the next 5 years we'll be building gas turbine power plants again. Battery, flywheel and pumped hydro storage just aren't enough to deal with baseload. There are a number of projects that are currently shelved (because the capacity market is skewed towards solar pv or at most, small banks of reciprocating engines)but have had a lot of the initial design work done. Once some nuclear power plants go offline, the conversation will change.
     
  8. b0rn2sk8

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    It’s interesting that there is so much talk about baseload here. I listened to an interview with someone involved with the Australian grid, they are doing the exact opposite and are moving away from it to distributable capacity.

    They have a very interesting grid, it’s very long, thin and ‘c’ shaped around the coast of the country. They also have one of the cleanest grids in the world with something like 50% renewable in certain provinces (mostly wind).
     
  9. Werewolf

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    I suspect Austrailia is quite lucky in regards to green generating capacity as they've got a relatively small population, and vast spaces in which to put in the wind/solar farms which is a good combination.
     
  10. Rroff

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    Also angle to the sun in Australia helps I suspect though not checked that.
     
  11. PlacidCasual

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    There are modern flywheels that rotate at 10,000’s of rpm and can store impressive amounts. They’re relatively small obviously because of the centrifugal forces but have been considered for providing very high surges rather than long term large scale storage.
     
  12. Angilion

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    The same fundamental problems apply, albeit with a few differences in detail. As you say, they're not even being considered for large scale storage because flywheels simply aren't suited to that. Whether it's a massive flywheel rotating slower or a lighter flywheel rotating faster the basic principles and the basic problems are the same. The scale isn't possible and the risk climbs rapidly with scale. A flywheel storing gigajoules of energy is inherently dangerous and you'd need at least many millions of them to stablise a grid based on renewables. Flywheels have been considered for cars because energy can be put into them far faster than it can be put into batteries. It would be possible to build a car with electric motor(s) to drive the car, a flywheel to store energy and a system to convert kinetic energy from the flywheel to electricity to power the motor(s) that drive the car. It would even be quite efficient. The unsolvable problem is that a wildly impractical amount of armour would be required to prevent any fault in the flywheel destroying the car, killing everyone in it and everyone nearby. The car would be too heavy to drive. There are other problems, since a flywheel storing enough energy would have a very strong gyroscopic effect and that's rather less than ideal unless you only want to drive in a straight line, but apparently those are at least theoretically solvable. The armour required to contain the sudden release of hundreds of megajoules of kinetic energy is not. Well, it is, but the weight is ludicrous. And that's a flywheel for a car, "just" hundreds of megajoules. Anything of any use in stablising a grid powered by renewables would require storing billions of times as much energy. It could theoretically be done with enough space for many, many flywheels, but maintainance would be impractically difficult and you'd run the risk of a cascade failure as one failing flywheel causes damage to another and another and another and...you have the sudden release of enough energy to level a city. Stored energy is almost always very dangerous and storing it as kinetic energy is definitely always dangerous.

    As you say, the use of flywheels is for surges in demand. Small local surges, to be precise. Sure, the 1GW potential (and extremely brief) peak requirement of JET is a lot, but in comparison to the routine second to second use of even a small national grid like ours it's a trifling amount. JET can pull 575MW from the grid, so those vast flywheels are for the remaining 425MW plus a safety margin. 1550 tonnes of flywheels for seconds of power delivery.
     
  13. satchef1

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    Might want to double check what was said in that interview. Australia definitely does not have one of the cleanest grids in the world. Their main power source is still Coal. Among developed countries, and accounting for population size, they remain one of the worst polluters.

    It's currently quite a hot topic in Oz, hence all the protests and the furore over kids skipping school to join climate marches etc.
     
    Last edited: Mar 23, 2019
  14. b0rn2sk8

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    Your right, they were only referring to South Australia rather than the whole thing, slightly different but still pretty good going by any measure.
     
  15. ubersonic

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    Three points worth remembering here:

    1: The worst power station disaster in history occurred at a hydro plant (Shimantan Dam), the death toll was nearly 3000x that of Chernobyl. In fact when you look at power station disaster deaths there aren't even any nuclear accidents in the top 5.

    2: A disaster on that scale isn't just unlikely it's actually impossible today, the disaster wasn't just caused by human error but by the humans overriding the safety systems to allow them to make that error. The systems in a modern power station simply will not let the humans do something like that.

    3: Actually it has happened at Sellafield, back in 1957 when the plant was called Windscale the UK was attempting to produce it's first nuclear bomb (not to be confused with the atom bombs it had built previously). Winston Churchill announced this publicly as a PR stunt then gave the UK's nuclear weapons program an impossible deadline in which to produce the Tritium required (there wasn't enough time to build a research reactor capable of doing it).

    This left them with only one option (besides say no), in layman's terms they had to overclock an existing reactor and hope it didn't blow up. They chose Windscale (Sellafield) and got to work, safety systems offline, all good, until it caught fire and nearly exploded. To put in perspective how close it came, the reactor had reached 1400°c when they went for their last gasp attempt to put it out (and obviously succeeded).
     
  16. nkata

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    If you need short term surge capacity, the Dinorwig scheme in North Wales has produced this for decades. A lake at the top of the mountain and one at the bottom connected by tunnels with turbines. Using low demand periods, water is pumped up hill and then released back down through the turbine hall when everyone switches the kettle on at half time. Completed in 1985 and still in use 30 years later.
     
  17. Angilion

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    That's true (and Dinorwig has been mentioned a number of times because it's a particularly well implemented example of pumped water storage) but it's irrelevant to the main reason why renewables can't be the solution - load balancing. Supply and demand must be matched at all times. When the supply can't be controllably varied by enough and quickly enough to match variations in demand, electricity storage is required. The more renewables (inherently uncontrollable) are used for generation, the more electricity storage is required. Electricity needs to be moved in and out of storage in huge quantities at high speed as both supply and demand fluctuate constantly. Pumped water storage can't provide even a tiny fraction of the scale or speed required to do that. It's not meant to. It's a solution to a different problem.
     
  18. PlacidCasual

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    Dinorwig was explicitly built to accommodate a trip of the largest nuclear generating units in the UK and allow time for a thermal station to be brought on line instead. It's all about grid stability.

    If a Sizewell B unit trips that's 1200MW gone in seconds. Historically the combined steam inventory and mechanical momentum of the 500MW coal fleet would be able to accommodate the loss of the Sizewell B unit for 30's or so before the grid frequency dropped too far. The Dinorwig generators would be run up to speed using air (if memory serves) whilst the water valves open and be on load in 30's and rapidly ramping up. In addition most of the coal stations had Olypmus or Trent derivative open cycle gas turbines that triggered on low frequency and could be at full load in 30's until Dinorwig was at full load. Dinorwig can supply about 1700MW for 4 hours and half that for another 4 then it's done. This was plenty of time to bring on a few oil units and increase load on coal stations to make up the shortfall. Dinorwig isn't really used for load balancing more fast emergency reserve.

    The old system was very well thought out with well specified and balanced components distributed in a rational fashion. Bit more of a buggers muddle these days.
     
  19. satchef1

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  20. Angilion

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    Reading it even superficially is useful. Even the very quickest skim reading shows a few problems:

    1) They haven't even looked at any of the alledgedly suitable sites, let alone done any sort of meaningful analysis of them.
    2) They haven't considered safety.
    3) They haven't meanigfully considered environmental impact - the only consideration they gave to it was whether or not the site required dams on existing rivers.
    4) They haven't considered cost.

    Interesting? Maybe. Useful? No.