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Numerically literate folk to the fore please

Batteries will be able to suck up excess power generated by wind farms off the coast – and dispense it when the turbines aren’t spinning. The Heysham site will be able to hold 200 megawatts of electricity.

Is this a lot or a little? I’ve simply no idea, no instinctive feel, for whether this is a mosquito fart in a thunderstorm or something useful?

But while the batteries themselves could be up and running as soon as next year, Kona will have to wait another two years for them to be connected to the grid.

And there’s the other thing of course. None of those grid costs are being included in the calculations of how cheap renewables are, are they?

49 thoughts on “Numerically literate folk to the fore please”

  1. Unfortunately the quote doesn’t even make sense. 200MW is a power (how much electricity is going past each second) we should have been told an energy capacity in MJ or MWH.
    It’s like getting asked “how far away is your house?” and being told “6 miles per hour”

  2. Who knows? 200mW isn’t a number one can work with. 200mW/H? 200mW/M? 200mW/S? 200mW/F(ortnight?) 200mW/zS might be an AAA, so you could have it in your pocket. (zeptosecond – requires 20 zeros)
    Struck by the arts graduates again.

  3. Watts (and so megawatts) are a measure of rate, not capacity.

    They are saying something analogous to “this car has a range of 80km/h”. Equally nonsensical that is

    Presumably the original information before it got the PR treatment was it can supply _at a rate_ of 200MW… Which might be a sensible measure for a (small) generator capable of continous output, but somewhat incomplete information for an energy storage system.

    By way of example/comparison for Dinorwig pumped hydro storage, Wikipedia claims:

    “The scheme can supply a maximum power of 1,728 MW (2,317,000 hp) and has a storage capacity of around 9.1 GWh (33 TJ)”

    Which would suggest Dinorwig may at best be able supply at a rate of 1728MW for about 5 hours before its output falls to zero

    So they have approx 1/9th the max output of Dinorwig with no stated capacity. Might be 5 minutes, 5 seconds, a femtosecond…

  4. Journalists writing about battery capacity really need a basic primer on energy vs power before they beclown themselves like this guy.

    Something akin to the previous Guardian staff advisory – ‘silicon = computer chips, silicone = breast implants’

  5. Kind of meaningless as others have said,that’s just an expression of power available, but for how long?

    Coal burning power stations are in the order of around 500MW I think, but of course can supply that for extended periods. 200MW is about enough for about 100,000 kettles instantaneously.

  6. The press release says it’s about the same size as the other biggest ones in Europe – which would be 200MW maximum for about 30-40 minutes iirc.
    Based on the maths being easier if it’s 30 minutes, then energy stored is maximum 0.1 GWh.
    1/90th of a Dinorwig.
    And Dinorwig can be recharged in two ways – rainfall or pumping it up.

  7. The depressing thing is that the somewhat meaningless “200MW” is directly taken from the press release written by Krona Energy.

  8. The FAQ on Kona’s website says 2 to 4 hours endurance. A 2 hour endurance feeding 200 MW implies a capacity of 400 MWh. However by the nature of such installations it will have a fluctuating input and output, so I very much doubt it could supply 200 MW continuously for 2 hours, or accept 200 MW from the windfarms. The batteries would get pretty damned hot!

  9. There’s an amount of moaning going on about time to connect such schemes … given the trivial capacity I’m not at all sure the investment in connection makes sense…

    But what puzzles me is, if the numbers stack up on these relatively small scale storage wheezes, why the “renewable” generators aren’t adding them themselves directly at their point of connection , to capture that gain?

    I can imagine why for storage scale larger than individual generator output that might not fly (although there’s possibly something there), but at this small scale?

  10. If we are going to be using the energy from bird choppers to power the grid and eliminate fossil fuel and nuclear, where is this “excess power” going to come from?

    As I’ve said before, you can’t supply demand and charge up batteries at the same time.

    Germany has 60GW of installed wind turbines. A few days ago they were generating 1GW…..

  11. So far these battery schemes are minuscule in comparison to the normal demand, so they don’t contribute useful storage as such. If you look at the first major one, the Musk one in Sarf Oz, then it’s real forte was balancing and fine frequency control, and the contract they had meant it made a lot of money doing that.

    A few similar ones spread out across the UK would be sufficient to do a similar job here, and valuable for that purpose. However to cast them as storage is something of a con. Perhaps the boosters need to tell porkies like that to get investors in. And government mugs!

  12. Theophrastus (2066)

    If it’s 200MW/h, then possibly enough to meet the electricity demands of 40,000-80,000 UK homes (without heat pumps and EVs)…

  13. I’m gonna guess that they mean 200MWh because Wh is the normal unit that batteries are measured in (as opposed to cells which tend to be measured in Ah). 200MWh would make it a big grid-scale battery but certainly nowhere near the biggest in the world, so this all rings true.

    Systems like this tend to be able to charge/discharge at 10C* for short periods of time, with a sustained rate of around 1.5-2C — 10C in such a scheme would be 2GW which it could theoretically maintain for 6 minutes, but would start having heat issues way before then (plus capacity is reduced at high charge/discharge rates); the sustained rate would be somewhere between 300MW for the thick end of 40 minutes or 400MW for a bit under 30.

    From the numbers above, these numbers work when such a battery is filling in gaps while other generation methods are brought online. It takes around 30s to get a large diesel genset from cold to stable production, so a battery like this could prevent a grid restart event by filling in until emergency generation comes online. It’s really difficult to restart the grid after an outage because inductive loads (e.g. motors, switch-mode power supplies) that turn on as soon as the supply is reconnected can destabilise the grid and cause it to fall over again, so if the grid has actually gone down those gensets might not be able to restart it even if they could have kept it running.

    The other thing that big batteries like this can do is react really fast. A battery like this can shove 2GW — probably more in these really small timeframes — onto the grid for controlled single-digit milliseconds. If grid frequency goes to pot, some generators will have to disconnect to protect themselves which can potentially cascade into a complete outage, so being able to essentially brute-force frequency correction can be useful way beyond the nominal capacity of the battery itself. While grid instability on the supply side is hindered by having a large number of small generators (as opposed to a few massive spinning steam turbines that will maintain 3,000rpm due to the sheer rotating mass involved), on the demand side the ratio of inductive to resistive loads has increased significantly.

    *One Coulomb equates to fully charging or discharging in one hour

  14. How long before these things need replacing given the charge/discharge cycle?

    And, is this large scale battery farm the right way to go in the first place? There is someone working on this, forgotten who, but there are god knows how many broadband/wifi routers knocking around the country, using something like 20W 24/7/52. Which is a load that didn’t exist 20 years ago. So, how long would that type of device run on a mobile phone battery?

    How many other bits and pieces could you easily do that with?

  15. Everyone loves Dinorwig 🙂

    The problem with it is that there are so few suitable sites, and the best one’s already being used. A battery bank can be put pretty much anywhere. Close to where there are already grid connections and/or demand, say. One of the purposes of Dinorwig was explicitly that it can manage a grid restart. One battery bank this size might struggle to do a full grid restart, but a few of them together — yup.

    Dinorwig can start in seconds and generate for hours; a battery bank can start in milliseconds and generate for minutes; enough battery banks and you can have hours. The cost of Dinorwig was £425m, taking inflation into account, thats about £4bn today, and with a capacity of ~9,100MWh that works out at £440k per MWh inflation adjusted. The costs of producing grid scale batteries should be in the region of £120k per MWh. Add ancillaries, installation, etc. and we should still be comfortably under £250k per MWh, so around half the price.

    Of course, what this doesn’t even start to solve is the levels of intermittency that relying on wind and solar would induce. But to even out demand against a constant nuclear baseload? Quite feasible.

  16. Never mind “numerically literate” (or numerate): someone who can write “Batteries will be able to suck up excess power” attributes to batteries the properties of blotting paper and is obviously talking nonsense.

  17. Wait till the wind has died down and instantaneous energy prices are peaking then sell the 200MW [sic] at vast profit using you existing transmission infrastructure. With the “right” wind conditions this could make more money than the wind farm.

  18. The answer is obvs. A new law will say that whenever a battery electric car is not being driven around it must be connected to a charging point which will, in future, be capable of drawing power from the car’s battery and crediting some cash to the owner’s account. (Or maybe not: maybe it would happen in place of car tax or fuel tax – but anyway that’s a second order consideration.)

    And thus lots of battery capacity will be made available. Just like that! Unfortunately the amount available might be rather small at rush hour, but little steps, eh? At least it would cover for the lack of solar at night.

  19. “And thus lots of battery capacity will be made available. Just like that! Unfortunately the amount available might be rather small at rush hour, but little steps, eh? At least it would cover for the lack of solar at night.”

    Hmm, so you plug your electric car in at 6pm, and when you go out at 8am to drive to work, or take the kids to school, or whatever, the battery is empty because the grid has drained it overnight as the bird mincers weren’t turning.

    That’ll do wonders for the sales of electric cars……

  20. To give you a sense of how that sort of output compares, Tim, try

    Fancy technological thingy at the bottom of the page gives the current output of Drax and the approximate percentage of the GB grid demand.

    At time of writing – 1860MW, 5.93% of demand
    200MW from the batteries? Pfft. A whole 0.66% of grid demand on a not very cold Friday midday.

    I’m sure we’ll all join in with a big… whoopdie fucking do.

  21. “That’ll do wonders for the sales of electric cars”

    ^ This.

    Plus the additional battery cycles shortening the life and/or range. nope.
    I’m happy to go for a PHEV for my next car, but full EVs just don’t cut it for the times you need to do something a little out of the ordinary.

  22. I’m happy to go for a PHEV for my next car, but full EVs just don’t cut it for the times you need to do something a little out of the ordinary.

    I don’t see why PHEVs aren’t the goto option for the car industry.
    Short distance/slow urban driving – electric power only.
    Long distance/green laning out in the sticks driving – dinosaur juice power.

    Everyone’s happy. No range problems, cleaner driving in cities, reduced grid demand.

    Of course, it should be up to the individual as to what they want, but I can’t see many downsides of PHEV from a fuel/energy persepective.

  23. ‘… to suck up excess power generated by wind farms off the coast…’

    If those windmills are powering the grid in place of gas and nuke, which is the intention, there will be little or no excess power to recharge batteries.

    The rationale for batteries is to provide power when windmills cannot provide it when needed, so exactly the same problem will apply to battery recharge, no wind power available to recharge them when needed. Presumably the solution is to have other batteries ready to recharge the exhausted batteries when wind power is not in excess.

    It helps to realise all the people caught up in this nonsense have mental health problems and are quite mad.


    Of course, when it comes to a) price and b) operational wear and maintenance, batteries do very badly. Back in 2009, some idiot decided EV’s could back up the grid, and it even made it into government position papers, despite the difference in duty cycles required and the fact that at the time li-ion batteries wear out after 600 charge/discharge cycles

  25. Chernyy Drakon

    The problem with PHEVs is:
    1) when not charged they are heavier and therefore consume a lot more fuel
    2) most people don’t charge them because they don’t really care, it’s not worth the hazzle and/or they just have a PHEV for personal/corporate greenwashing reasons (the old revealed preferences thing)

  26. “That’ll do wonders for the sales of electric cars……” Since they will be the only sort of car on sale this may not matter.

  27. The lithium ion batteries have charging cycles in the thousands of you keep the state of charge between 20% and 80%. Grid stabilization puts very little stress on the batteries.

    The big problem with intermittent (non-dispatchable) power sources is reliability. The Independent System Operators (ISO) are tasked with maintaining grid reliability and running the power marketplace. This is fundamentally at odds with the goal of the green power producers.

    The goal of the green power producers is to sell every last watt when their systems are producing power. They have no responsibility for reliability or dispatchability. So they will lower their price to sell every watt, when they are producing. This comes at expense of the base load producers. Some ISOs are required by the government to prioritize buying green energy, which completely shuts down the the base load producers when green power production is high.

    Unfortunately the ISOs have no way to mandate reliability and despatchability. So the true cost of green energy does not fall on the producers. This is a fundamental market failure of our current energy markets.

  28. Bloke in North Dorset

    A couple of points to add to the excellent ones above:

    That 200MW(h) is likely to be the maximum but nobody in their right minds discharges to zero if they want to use the batter again, let alone start a fire.

    As a general rule batteries are designed to discharge quickly eg provide despatch power (start a car) don’t charge as efficiently from a trickle charger, which is what will be happening in some of the scenarios discussed above.

  29. “Dinosaur juice power. Everyone’s happy”

    Not the Greens – they REALLY don’t want anyone* using proper energy…

    *Except themselves, of course!

  30. Presumably the solution is to have other batteries ready to recharge the exhausted batteries

    Great batteries have little batteries upon their backs to charge ’em,
    And little batteries have lesser batteries, and so ad infinitum.
    And the great batteries themselves, in turn, have greater batteries to go on;
    While these again have greater still, and greater still, and so on.

    Apologies to Augustus de Morgan

  31. Peak grid load in winter is around 45GW (45,000 MW) so more than 2,000 times the “200MW” of this baksheesh merchant.
    But the gas grid supplies some 7x this, in winter, and transport fuel (ships, road vehicles, planes) another 7 times. And the brainless politicos plan to convert all this to electrical source also, either via batteries or green hydrogen.

    So the electricity grid, at peak load, is only 6 % of the total energy consumption.

    I agree with John B, most of the advocates of this are mad, but not all of them. Many have just spotted a get-rich-quick trough of tax-payers money to feed on, and some are outright evil.

    Was it Oliver who said: “Kill them all, let God decide!”?

  32. @Emil

    1) when not charged they are heavier and therefore consume a lot more fuel
    I have a 2016 Volvo XC90 PHEV that I bought a couple of years ago. It is heavier than the petrol/diesel versions, by a touch under 200kg (~9%). With the battery depleted it still behaves like a conventional hybrid and gets low-30s mpg on the motorway, high 20s elsewhere. There was a (newer) pure petrol XC90 in the extended family for a while, and that returned low-30s on the motorway and mid-20s off, all running in similar terrain, so the behaviour as a regular hybrid actually more than offsets the additional weight.

    The issues I have with the PHEV powertrain are almost all down to implementation — and this is a pretty early car, later iterations will fix/improve some but not all of them. The biggest deals are the puny 89bhp you get in electric-only mode and the small battery.

    Granted: this is in something that’s porky to start with. I’m sure that smaller/lighter cars will find that having two powertrains has more of an impact as their proportion of total vehicle mass increases, and the extra kit will further eat into cubage. The additional cost when new (£10k or so for mine) is hard to justify given the fuel savings but I got mine 3rd-hand with 90k on the clock, and at that point the difference in price between it and an equivalently-specced petrol or diesel was pretty much negligible.

    2) most people don’t charge them
    Citation needed. Sure, some won’t, but most? Even if electricity and petrol costs were at parity, I’d still charge mine because it drives more smoothly and quietly in electric mode.

  33. “The lithium ion batteries have charging cycles in the thousands if you keep the state of charge between 20% and 80%. Grid stabilization puts very little stress on the batteries.”

    Regardless, who is compensating the car owner for the degradation of their battery over time? Every charge/discharge cycle used by the Grid is one less used by the car owner.

  34. There is a more informative post about the battery story here.

    I did once do a rough calculation and worked out that, if you had a million fully charged Nissan Leaf battery packs, you could power the National Grid for about a hour. That gives a rough idea of how much capacity you would need to cover the eventuality of the wind not blowing for a couple of weeks, about 350 million Leaf batteries and one or two extra windmills to make sure they stayed fully charged until needed.

  35. @BiND,

    For Li-NMC batteries, you can get maybe 700-800 cycles 100-0-100 before significant problems (normally considered to be a reduction to 80% of initial capacity). Charging to >80% or discharging below 10% at high C rates is the issue that will kill them much faster than that. Reducing this to 80-10-80 charging should increase this to multiple thousands of cycles. There are lots of trade-offs with energy/power densities vs. longevity vs. cost, including how much silicon you put in the anode, the thickness of various substrates, how well you do thermal management and the form factor. Li-FePO4 batteries have an inherently lower C rate for both charging and discharging but can maintain that rate up to 90% and down to pretty much 0% with minimal degradation, although again chemistry, cell design, etc. will all play a part in the longevity.

    Most large batteries are specced with “total” and “useable” capacities, the difference being software limits that stop charging/discharging beyond a certain point to protect the cells. I would hope that the 200MWh quoted figure is the “useable” value, although if the journos can’t even get the units right…

  36. If you go to the web site of the people building it:
    it still says 200MW. I think its main purpose is helping to stabilise grid frequency, not to keep the lights on when the wind ain’t blowing and the sun ain’t shining. For that, you need to supply 40GW* -so, for a day’s supply you need 1,000GWh, when the largest battery plants in the world currently operational are ~100MWh (and have a disturbing tendency to ‘go on fire’).

    The idea that batteries can keep the lights on for a two-week period of dunkelflaute, frequently experienced during W European winters, is magical thinking powered by extreme scientific illiteracy.

    * based on current UK grid figures, we’ll need 2-3x that when all vehicles are electric and all homes use heat pumps (currently scheduled for the 12th of Never)

  37. One thing apparent from New Zealand’s flood stricken areas, EV’s would be utterly useless in assisting the clean up let alone rescuing people. None have the endurance and there is no electricity to provide charging stations.

    Fossil fuels to the rescue!

  38. …if the numbers stack up on these relatively small scale storage wheezes…
    if” is doing some heavy lifting there!

    It takes around 30s to get a large diesel genset from cold to stable production…
    Really? That seems remarkably fast to me, but I don’t deal with gensets much. What sort of size are you thinking of Matt? I imagine that’s assuming auto-start capability?

  39. ‘Was it Oliver who said: “Kill them all, let God decide!”?’ Nah it was a Roman Catholic churchman during the Albigensian Crusade.

    The internet claims: “Caesarius of Heisterbach writes around 1230 AD about the infamous order Amalric (papal legate and Cistercian abbot Arnaud Amalric) gave when his crusaders breached the gates at Béziers and found not just Cathars, but Catholics too.”

    “The military leader of the army was Simon de Montfort, a French nobleman highly motivated by the Pope’s promise that he could keep the land of any heretics he killed.”

    Rather like a communist army, evidently they had a general being policed by a commissar.

  40. Without electricity the petrol pumps don’t work. So fossil fuels aren’t that much better.

    Only farmers with diesel tanks etc have been OK for transport in the worst NZ areas.

    Fossil fuel powered generators, with fuel also taken in, have been key in the cleanup. But ordinary people have the range in their tank, electric or petrol.

  41. @ dcardno – it’s only going to take a few seconds for a diesel genset to start and reach governed speed. The remaining time would be for this speed to be “tweaked” in order to get it synchronised with the grid. As for “From Cold” – expecting them to take full load when stone cold is asking for trouble, and I think most such gensets will have water and oil heaters running continuously, possibly even a pre-start electrically driven oil pump to avoid damage to bearings which haven’t done any work for (possibly) months…

  42. Some commenters seem to think that the 200MW number should actually be 200MWh. I don’t think so. On Googling a bit it seems that this facility has been bought by an energy investment company, GSF, and the 200MW comes up in their info, which has to be legally accurate if they are trying to attract investors. So the 200MW looks like what’s on the plate stating its power output.

    While they are keeping schtum about the actual energy capacity, I don’t think it can be much more than 200MWh – the 2-4 hour endurance in their FAQ would be unlikely to be at full rated power output. So it’s a grid balancing aid rather than an energy storage facility.

  43. Bloke in North Dorset

    February 17, 2023 at 3:01 pm,

    I’ll defer to your obviously more current knowledge as I’ve been retired nearly 7 years.

    However you’ll have to forgive my scepticism as I was tangentially involved in the Royal Signals investigation in to the memory effect on NiCad batteries when they were introduced. We were told that there was no such thing, but as it affected the new radios in NI we were seeing real world consequences.

    I’ve also seen too many pictures of other batteries bursting in to flames, again something flatly denied.

  44. The cost of Dinorwig was £425m, taking inflation into account, thats about £4bn today, and with a capacity of ~9,100MWh that works out at £440k per MWh inflation adjusted. The costs of producing grid scale batteries should be in the region of £120k per MWh. Add ancillaries, installation, etc. and we should still be comfortably under £250k per MWh, so around half the price.

    Of course Dinorwig has been operating for just shy of 40 years. Obviously it has maintenance costs, stuff will need replacing and so on, but the bulk of the cost was shifting 12 million tonnes of rock to form the cavern and tunnels, and that investment will be good for at least as many decades to come. I would not put too much money on the batteries, which I suspect form the bulk of the cost, lasting more than a single decade…

  45. Gareth, it just occurred to me that 200 MW = 66,666,666 electric ‘Kettlesworth’* of juice. Maybe that’ll do?

    *3KW variety,not the weedy 2, 1.8 or .9 versions the continentals are allowed.

  46. @drcardno

    Diesel gensets: yes, thinking of ones with remote/auto-start. If you need to phone a bloke to go press a button it’s obviously going to take longer. The only ones of any reasonable size that I’ve had anything to do with were in a datacentre. If the power went down, you obviously started worrying, but if the generator wasn’t up in 30s the priority switched from chasing the DNO about when grid power is going to be back to drop-everything-and-get-it-working.

    NiC(a)d cells are famous for the memory effect where they need to be fully discharged before recharging. IIRC it’s something to do with crystallisation of something occurring at the point where you switch from discharge to recharge; this was one main reason for the shift from NiCd to NiMH for portable devices through the ’90s, the other being that Cd is more expensive to handle and dispose of properly.

    Li-NMC cells can catch fire, Li-FePO4 ones less so. Unlike the NiCd issues above which are inherent with the chemistry, Li-NMC fires are primarily caused by mechanical damage to the cell or overheating. Given it is reasonably new technology to deploy these batteries at the scale that they are in vehicles and grid-scale storage, expect there to be teething troubles while the best ways of doing things are worked out.

    Also expect to see disproportionate media coverage about a battery fire because it’s “new”. One of the modules in the Tesla array in South Oz (?) went up a while back. It was contained within the module as designed, replacing the module might be a million quid, nobody was injured and the rest of the system continued operating throughout. That made international news — obviously not the bits about nobody being hurt or the containment system working as designed, just the fact of the fire.

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