So, Tesla….

A wall-mounted battery which would store energy from solar panels and wind turbines as well as taking power from the National Grid during cheap periods, will be available in Britain by the end of the year.

At a launch in California this week, the car manufacturer Tesla claimed the new device could change ‘the entire infrastructure of the world.’ And British environmental groups said it could become as common as central heating.

Tesla Chief Executive Elon Musk said the rechargeable lithium-ion battery could store up to 10kWh of energy, enough to power 100 boils of the kettle, 10 washing machine loads or 20 days of laptop use.

You know, I’m deeply unconvinced that lithium is the correct battery te3chnology for someone to have in their home. It would most certainly (well, I bloody hope it would at least) fail any sort of fire test for an apartment bloc.

Those fire risks seem worthwhile in transportation because of he power to weight ratio. But for a static battery it doesn’t seem worth the risk somehow.

71 thoughts on “So, Tesla….”

  1. In rural areas without mains gas, houses usually have big oil or gas tanks in the garden. They contain far more stored energy than a Tesla, but you don’t hear daily stories about them blowing up.

    Given how (relatively) little energy is in a Tesla battery, and given that size isn’t an issue for domestic use, they could easily build in an automatic fire extinguisher.

  2. bloke in france

    Tesla is supposed to be this wizzo tech company, but when you look under the hood the tech is much less impressive. Lithium ion has been around for yonks.

    Then we have a problem with energy density, at least 20 times less than gasoline. So that dinky wall mounted battery won’t get you far.

    Perhaps he’s forgotten that the UK uses 240V. So that’s either a pile of 75 batteries or a transformer in the garden shed giving off that annoying hum they all do.

  3. @ AndrewM

    Said tanks (particularly gas ones) are always sited in the garden well away from the house, or anything else likely to catch fire.
    That is completely different from having something capable of releasing over 10kwh of heat into my living room in a matter of seconds in the event of it being triggered into thermal runaway.
    I’m not too impressed about the idea of driving round in a car full of the stuff (diesel cars are much less likely to catch fire in accidents than any other sort as diesel isn’t explosive at normal room temperature and pressure), the idea of having a device that could become a huge fireball in my living room impresses me even less, especially when there is no actual need for it.

  4. 10kWh? that’s about £1.30 worth of electricity. In a battery costing $3,500 plus installation and all the other gubbins to get it to work. Plus you have to pay for the electricity (possibly by paying over the odds by using solar panels).

  5. Bloke in North Dorset

    Ian B
    May 2, 2015 at 8:25 am

    And people need inefficient local energy storage why, exactly?

    Cos by the time the assorted feeble minded greenies and lefties have finished dicking around with energy generation and prices it will be the only way you can get your washing done and have a cup of tea in the resulting brown-outs and even black-outs, especially when the sun don’t shine and the wind don’t blow.

  6. IanB: “And people need inefficient local energy storage why, exactly?”

    Piddle power. After you (generic you not you personally–I hope) have been stupid enough to accept a smart meter and they turn the juice down to get their wind-wanked system going, having a battery may be the only way you will be able to use your washing machine when you want. Rather than after midnight on Sunday when they will let you have enough power to do so.

  7. So Much for Subtlety

    Yeah. This is absurd. I think he needs to use some other form of storage. Batteries are just too dangerous.

    I suggest a very large fly wheel spinning in a vacuum. To get decent speeds.

    At least it won’t burn.

  8. kW (kVA) is the unit of energy; kWh is the unit of consumption.

    A consumption rating of 10kWh means consumption of 10kW for one hour, or a consumption of 1kW for ten hours, or anywhere in between.

    For example that means a user could run 5 two-bar electric fires for an hour… but use the battery for nothing else, or could run two two-bar fires for two hours and boil the kettle twice.

    But it will also depend on the kVA. For example a cooker circuit has a 30A fuse so can draw up to about 7kW, whereas a 13A circuit can draw about 3kW, but the mains input has a rating of up to 60A, so up to about 14kW of power can be drawn at any time.

    The outout rating of the battery… the fuse protecting it… will determine what appliances and how many at a given time can be run. If it is less than normal domestic rating, it will give less than normal performance.

    New domestic UK properties have a 20kW supply, older ones 14kW, and thus have a consumption rating or 480kWh, 336kWh.

    For a battery to replace grid supply in the home, it would have to be huge, and would require significant input to keep it charged which would require an very large solar array bigger than most roofs unless you have a large mansion.

    Renewables and solar and wind power all sound fine if you ignore physics…. and of course the weather.

    Is it not ironic that some think the solution to climate change is to switch to energy sources heavily reliant on and affected by changes in climate? (Wind speeds/direction, cloud cover, hours of sunshine, precipitation… that sort of thing.)

  9. bloke (not) in spain

    Two things on energy storeage & energy densities.
    1) The actual densities have been mentioned, by others. That’s going to be a mighty strong wall to hang those batteries on.
    2) Batteries aren’t, yet, anywhere near capable of providing the energy densities of hydrocarbons. But fuels have another advantage. It’s hard to get the energy out of them. They need to combine with oxygen to release it. Deny the oxygen & they’re as safe as water. Even if you get a fuel excursion & it ignites, it still needs a supply of oxygen to burn. Which is limited by the surface area of the fire. So you can contain & extinguish the unintended release of fuel energy. Except in some cases. Explosives generate energy in the same way fuels do. Except the “fuel” in the explosive is provided with its own oxidant. The energy available in a kilo of explosive can be a fraction the energy in a kilo of central heating oil. But you get it all at once. ANFO.
    Likewise, the energy in a battery is available without adding anything. Once it starts to break down, out it comes. And it depends how quickly it comes out. Higher the density, the quicker. Fuel fire, you might get 2000C. Batteries can give you serious temperatures. Try welding with them. Up in the hundreds of thousands degrees. if you could dump all the energy in a laptop battery in one go you’d have an explosion rival a hand grenade.

  10. “if you could dump all the energy in a laptop battery in one go you’d have an explosion rival a hand grenade.”

    How would you do that? Just out of curiosity.

  11. bloke (not) in spain

    SMfS, the technologist, strikes.
    “I suggest a very large fly wheel spinning in a vacuum. To get decent speeds.”
    The “decent” speed you’d need to make it worth putting an energy storing flywheel in a vacuum would put the pseudo-mass of the outer portions of the flywheel in the hundreds of tons. Remember, surface area rises by the square, mass by the cube. What are you holding it together with? If it doesn’t hold together – bingo – instant energy release. Very instant. Very impressive.

  12. Those fire risks seem worthwhile in transportation because of he power to weight ratio. But for a static battery it doesn’t seem worth the risk somehow.

    In addition – these batteries are an inferior solution, compared to lead-acid, where there are no space constraints.

    Such as a small home. Lead-acid would have 3-4 times the volume at a lower price compared to what Musk is offering. So unless you’re trying to store enough power to run your home for weeks or live in an incredible tiny house, lead-acid is a better solution.

  13. Consider me underwhelmed. I was expecting something a little more than a small battery for your house. From the sounds of it they are creating a supply chain to consume old Tesla car batteries.

    What I was expecting was something with enough capacity at home to charge your electric car quickly – at a similar speed to a Tesla super charger – as well as doing this solar/grid balancing nonsense. But that would be exceedingly expensive.

    Alternatives to a battery are flywheels or compressed air batteries.

    ZT said:

    @Alex: Actually, the price of Musk’s battery, before subsidies, is ~$18k.

    I’m guessing that is for the battery in the cars, which can be up to 85kwh capacity.

  14. Mr Ecks
    May 2, 2015 at 12:41 pm

    “if you could dump all the energy in a laptop battery in one go you’d have an explosion rival a hand grenade.”

    How would you do that? Just out of curiosity.

    You wouldn’t. Its an interesting mental image but its like saying that if you converted the mass of a paperclip to energy you’d have an explosion the size of ‘Fat Man’ (21 kt).

  15. bloke (not) in spain

    @Agammamon

    I’ve done this stuff. Even lead acid are inferior. if you discharge L/A batteries completely, the technical term for them is f***ed. There ‘s a graph, depth of drain/available recharge cycles shows the best duty cycles for L/A are around 40-50% discharge. So twice as much battery capacity as you thought you’d need.

  16. OK, sure – but how much lead-acid sotrage could you get for $3000?

    I’ve probably screwed up the calcs but using *commercial car* batteries it seems you can get 10Kw/hr for $2000.

    Course, it’ll take 120 batteries to do so . . .

  17. bloke (not) in spain

    @ Agammamon

    It’s not like total conversion of energy. Matter/anti-matter or something. The energy is accessible. Use it to charge a large capacitor & you can have it all in one go. Great fun! Do it with a dud capacitor, might even get your grenade. Why they’re tested…carefully.

  18. bloke (not) in spain

    Decent 100 A/hour 12V batteries are around £150. Maybe a thousand cycles if you treat them gently. But the capacity drops with cycles & depth of drain. Digging deep if there’s a power famine could cost you hundreds of pounds in lost battery life.

  19. bloke (not) in spain
    May 2, 2015 at 1:17 pm

    @ Agammamon

    It’s not like total conversion of energy. Matter/anti-matter or something. The energy is accessible. Use it to charge a large capacitor & you can have it all in one go. Great fun! Do it with a dud capacitor, might even get your grenade. Why they’re tested…carefully.

    But, in either case, you’re not going to get all the energy out from the *battery* at once – which is by I said it was for mental comparison, like showing how much energy is tied up in mass by showing how big a boom you could make with a single gram.

    You can certainly put all the energy into a capacitor and then release it from the capacitor all at once – I’ve done that a few times (sometimes even on purpose – with tiny ones) – and you can get it out of the battery dangerously quickly.

    You just can’t get it out fast enough to turn the battery into a hand-grenade.

    So Mr. Ecks plan to gift ‘specially-prepared’ iPads to his local pols needs to be rethought.

  20. bloke (not) in spain

    By the way. Car batteries are NOT deep drain. They’re high output/ shallow drain. They’re totally unsuitable for power storage. F**ks ’em

  21. bloke (not) in spain
    May 2, 2015 at 1:23 pm

    Decent 100 A/hour 12V batteries are around £150. Maybe a thousand cycles if you treat them gently. But the capacity drops with cycles & depth of drain. Digging deep if there’s a power famine could cost you hundreds of pounds in lost battery life.

    How does that compare to Musk’s batteries under the same condition?

    Marketing aside, I don’t think he really expects people to be daily using 5kw/hrs out of his battery pack to run things after the sun goes down and their solar panels don’t work anymore.

  22. bloke (not) in spain

    “I don’t think he really expects people to be daily using 5kw/hrs out of his battery pack to run things after the sun goes down”
    What does he expect, then?
    After the sun goes down is the period of highest energy use. Winter? Colder? People stay in more? Shorter days?
    Anyone can do solar energy solutions for the equator.

  23. I would image that he actually expects it to be used as a short-term emergency power supply during an unscheduled outage.

    Meaning long periods of non-use with short periods of light use to keeps some lights and a tv running until mains power is restored.

    Unless he’s expecting a sudden huge upsurge in people installing solar panels, that is.

  24. bloke (not) in spain

    “So Mr. Ecks plan to gift ‘specially-prepared’ iPads to his local pols needs to be rethought.”

    Oh, easy. Little transformer. Fill the iPad case with high voltage capacitor. Push the on button, Plod’s toast.

    Wonder someone hasn’t already done it. That’d teach ’em being nosy..

  25. You don’t get 100% from matter/anti-matter since much of the energy ends up as neutrinos, just to be picky.

  26. bloke (not) in spain

    “Meaning long periods of non-use with short periods of light use to keeps some lights and a tv running until mains power is restored”
    Wouldn’t a box of candles & a battery TV be cheaper? Both on Ebay.

  27. bloke in france

    What would be the cost and space requirement for getting some 3.2V dc Li-ion batteries to supply 240V ac? Anyone on here got the tech / time to calculate?

  28. Cheifo is not impressed with the Tesla hype either and prefers his Honda generator.

    As one of the commentators put it: “Another sell the sizzle and collect the subsidies.” Something Musk has developed to a fine art.

  29. Kevin B. He’s not wrong. I got a small ! Kw (pure sine wave) petrol 4 stroke suitcase genny from China a couple of years ago. Enough to power the router, TV’s laptop etc. Cost was under £115.00 on ebay, and it will charge 12v DC lead acid if needed.

  30. 1. Cuz I’m lazy: Why does energy cost so much more in Europe than US? (Gasoline anyway).

    2. For the $’s involved, in the US I can have a big gas powered whole house generator running my 2 big HVAC systems and the rest. I don’t like all the pain & suffering the greenies want to impose when it seems to be all pain for no, or at most very little, gain.

  31. bloke (not) in spain

    Thought you might have, Ian. Good name for a spaceship too.
    Almost Iain Banks.

    On hanging Tesla batteries on your garage wall:

    Just checked the Tesla ad.

    “Operating Temperature – -4F to 110F / -20C to 43C”

    Garage. Single story building. large roof area/volume. Even in UK it’s common to have garages heating up to over 43C on strong summer sunshine.. They are, after all, not designed as habitable rooms. Poor ventilation, flat roofs, no separated roof space. And the high temperatures will be coming at the same time the battery will be producing heat. As a by-product of the charging process.
    So not on the garage wall. Not unless you completely redesign garage. Or fit aircon. uses electricity to…oh.


  32. How would you do that? Just out of curiosity.

    Short circuit it. You really don’t want to drop a bare piece of metal across a rechargeable battery, which is why they are designed with the contacts countersunk and camera batteries (which are likely to spend a lot of time outside the camera as spares, knocking around in a case) come with covers.

    Also, try dropping a screwdriver across both terminals of a car battery. Or rather, don’t.

  33. “Musk could sell condoms to eunuchs”

    And get a Dem administration to give him “loan guarantees” (i.e. subsidies) to do it.

  34. John B:

    No. kW is a unit of power, kWh is a unit of energy. Power is the rate of using energy. A 10kWh battery in theory will supply a 1kW fire for 10 hours, but in practice the capacity will only be close to 10kWh if the consumption rate is *really* small – a couple of hundred watts perhaps.

  35. Don’t see the point of a battery at home, particularly lithium. Doesn’t store enough to be useful. Dangerous if neglect accidentally becomes abuse. Needs a controlled environment.

    Lead acid is no better than lithium if you’re actually going to be charging and discharging them. Worse, maybe. They don’t last long if you use them.

    I’d have thought if space and weight is no object, nickel iron would be the way to go. Very long life, don’t mind deep discharge. Used to be used on locomotives, maybe still are. I think all you have to do is keep the electrolyte level up (it can boil off) and avoid getting lots of CO2 from the air into them as it forms carbonates at the top of the electrodes. They’re not common, though, so really expensive last time I looked.

    But still, nobody’s given a reason for doing it that makes any sense.

    Oh, and flywheels? They *really* scare me. What d’you do when you realise a bearing’s running hot? Run away and wait a week or two for your house to autodemolish I guess.

    Compressed air: hugely inefficient. Takes a vast amount of energy to compress, which you dissipate as heat. Then when you use the air everything freezes up. Compressed air trams had big bottles of hot water under pressure to warm the air a bit. Every few yards they needed recharging with a steam hose.

    Me, I’ve got a couple of petrol generators.

  36. kWh is a weird unit. 10 kWh is about 36MJ. About a litre of petrol, to the nearest thumb.

  37. Surreptitious Evil

    If I wasn’t in the intermission at a concert, I’d monologue about the issues with submarine batteries. Lead / acid, in my day, and running at about 740V across the end terminals. Scary fuckers.

    Wouldn’t quite vaporise you if you fell across them but you’d certainly be deader than a Lib-Dem MP on Friday.

  38. Ian B
    May 2, 2015 at 1:43 pm

    You don’t get 100% from matter/anti-matter since much of the energy ends up as neutrinos, just to be picky.

    I wasn’t talking about M/AM annihilation but simply mass to energy conversion – without specifying any particular mechanism and any inefficiencies it might have.

  39. bloke (not) in spain
    May 2, 2015 at 1:45 pm

    “Meaning long periods of non-use with short periods of light use to keeps some lights and a tv running until mains power is restored”
    Wouldn’t a box of candles & a battery TV be cheaper? Both on Ebay.

    Absolutely – and the real world costs mean its going to be cheaper to fly or drive from LA to SF rather than take his ‘hyperloop’.

    Real world costs mean that its cheaper to buy and run an SUV and a motorcycle than to buy a Tesla.

    There’re very few miracles Musk can’t pull off as long as he gets enough public money to hide the true costs.

  40. Bloke in Costa Rica

    Flywheels aren’t completely impossible. Some quick tinkering in Mathematica gives a hollow stainless steel cylinder 1m long, 40cm outside diameter, 25 cm inside diameter at about 3500 rpm to store 10 kWh. If it’s buried in a vault in the garden it’s probably pretty safe. The JET project at Culham uses a huge flywheel (9m dia) because it can’t draw enough instantaneous power from the grid to do a shot. I seem to recall there were some French telephone exchanges using flywheels as a UPS.

  41. @Gareth: The battery for a Tesla car costs $40k. If it discharges completely (say, you left the car parked at the airport for a week or two) it is defunct. (Not covered by the warranty, either).

  42. So Much for Subtlety

    Bloke in Costa Rica – “Flywheels aren’t completely impossible. Some quick tinkering in Mathematica gives a hollow stainless steel cylinder 1m long, 40cm outside diameter, 25 cm inside diameter at about 3500 rpm to store 10 kWh. If it’s buried in a vault in the garden it’s probably pretty safe.”

    I was not, of course, being serious. But as storage goes, fly wheels have been near contenders since the 1970s at least. There are plenty of discussions about using them.

    The problem being that you need the concrete vault in the garden. The idea of what a fly wheel would do, given its outer tip is probably spinning close to the speed of sound, if it came apart always amused me. There is a reason that jet airplanes moved their engines to pods outside rather than bury them in the wing.

    Still, if we are going for concrete vaults in the garden, and we are ruling out a wormhole to Barsoom, then I would go the whole Hog and get some high level nuclear waste, just the daughter products by preference, in glass or Synrock. A reasonably small block would provide all your heating needs.

    Planning permission may be a little tough.

  43. Bloke in Costa Rica

    I meant to say 40cm/25cm outer/inner radii. That gives you 36 MJ rotational KE at 366 radians per second angular velocity. Of course you’d need a sight more than that as drawing power from it would slow it down and alternators only work in a range of frequencies. The high frequency AC out of the alternator would be regenerated to give stable 50/60Hz which you can do these days at very high efficiency.

    The rotational KE of a cylinder goes like the fourth power of the radius and the square of the angular velocity (in fact for a cylinder height h, inner radius a, outer radius b, density ρ, angular velocity ω the KE is h π ρ ω^2 (b^4 – a^4)/2) but linear velocity at the outer edge is linear in r and ω. Gas turbines tend to fail rather more frequently than one would like because they’re engineered to have a low moment of inertia and are hence a bit flimsy. A honking great lump of stainless steel would be unlikely to fracture. I would imagine a domestic flywheel storage unit would come ready-encapsulated in its concrete armour so all it would need would be a gang of navvies to dig a bloody great ‘ole and then you could crane it in.

    I like doing these sort of back-of-the-envelope things.

  44. bloke (not) in spain

    Thanks for the impressive math, BiCR. Unless I’ve got my math wrong ( most likely in the order of mag dept 😉 ), 10kW/H is equivalent to about 1 25 Kg of TNT’s worth of energy. Even with a concrete vaulting, hunk of mass with that energy’d take lot of containing. Even if didn’t penetrate the vault, the spalling off the outside would be lethal to anyone nearby.
    So it’s concrete enclosure & burial.

  45. So apparently I get the choice of a battery that will burst into flames and pull my wall down, a flywheel that might spontaneously fragment with catastrophic results, a cube of nuclear waste or a litre of petrol.

    I’m voting “litre of petrol” at this election.

  46. So Much for Subtlety

    Ian B – “So apparently I get the choice of a battery that will burst into flames and pull my wall down, a flywheel that might spontaneously fragment with catastrophic results, a cube of nuclear waste or a litre of petrol.”

    Yeah but amusing catastrophic effects. And before you make up your mind, remember it is a pretty small cube of nuclear waste. A tonne of spent fuel gives off about 10 kWs of heat after a year in the cooling pool. Most of that is made up of the fission products doing their thing. But they are only 3% of the waste. So most of that heat comes from just 30 kilograms of waste.

    Unfortunately the heat decays fairly rapidly over time. By the tenth year that tonne would be down to 1 kW. I suppose you could have 10 three kilogram blocks and replace one every year. But as the loss of heat does not continue down in a linear fashion, you might just block up a ton of it and be done. You would have too much heat early on, but 100 years later, your home would still be warm.

    Or alternatively you could be sensible. No one in their right mind would use a battery designed for light weight and compactness for household storage. What is the point? Space is not at a premium. You may as well use a sensible battery technology. Something that relies on fluids you can store in large amounts for instance. TW might like this one if he is in the metal waste business:

    http://en.wikipedia.org/wiki/Vanadium_redox_battery

    But this one is probably more sensible:

    http://en.wikipedia.org/wiki/Polysulfide_bromide_battery

    Not the nicest chemicals in the world mind you.

  47. So apparently I get the choice of a battery that will burst into flames and pull my wall down, a flywheel that might spontaneously fragment with catastrophic results, a cube of nuclear waste or a litre of petrol.

    I’m voting “litre of petrol” at this election.

    Sorry, but that’s a big fat fail. It’s not – y’know – “green”… Hence, you will not be allowed to choose.

  48. Bloke in Costa Rica

    bnis: it’s kWh not kW/h. Watts is power (energy per unit time) so multiplying it by time gives you back energy. One kiloton TNT equivalent is defined as one teracalorie which is 4.184 MJ/kg. So 10 kWh = 36 MJ is about 8.6 kg TNT equivalent. Flywheels would need to be buried deep, in thick containment vessels.

    My personal favourite is microscale municipal nuclear plants. A plant about the size of an office block would generate 100MW, cost about $100 million and provide power to between 75000 and 200000 homes, depending on which country we’re talking about. It would be buried, safe against accident or attack and above all local which alleviates a lot of the single point of failure problems you get with the One Big Plant model.

  49. So Much for Subtlety

    Bloke in Costa Rica – “My personal favourite is microscale municipal nuclear plants. …. It would be buried, safe against accident or attack and above all local which alleviates a lot of the single point of failure problems you get with the One Big Plant model.”

    Edward Teller and Hans Bethe always said that reactors ought to be buried. The other advantage of this is presumably it could be used for district heating. Reactors, like most generators, waste a lot of heat. If you had small scale locally sited reactors, you could pipe the waste water into people’s homes.

    The only obvious problem is refueling. Which would have to be done locally. I don’t think the world would be a safer place with lots of trucks driving through suburbia with high level nuclear waste. Perhaps if you had some sort of breeder like the proposed thorium reactors that burned up their transuranic wastes so that only the fission products had to be removed. Preferably after being in-cased in glass or Synroc.

    Although I suppose you could just bury it in people’s backyards.

  50. bloke (not) in spain

    @BiCR
    Contrite on the kWh faux pas 😉

    I got 2.8 MJ/kg for TNT (http://en.wikipedia.org/wiki/Trinitrotoluene#Explosive_character
    That’s apparently based on the explosive power in the absence of atmospheric oxygen to complete the oxidation. Which would be the situation in a flywheel vault up until the vault was breached. And thus the force available to breach it.

    From the same source, I got the energy density of petrol (gasoline for the Yanks amongst us) at 47.2 MJ*/kg. Puts whole new meaning to the words “Goes like bomb, me car, dun’ she?” & energy densities in some perspective.

    * Is it MJ. Or mJ? How should I know? I’m a part time plumber & full time bar fly. Not a f****g physicist.

  51. bloke (not) in spain

    “What if we make a flywheel out of nuclear waste, then hang it on a garage wall?”
    Is that rhetorical, Ian?
    I’d suspected it might be the power plant for the S/S Jesus H.

  52. Bloke in Costa Rica

    bins: I was using TNT equivalent. It’s a rule of thumb, nothing more.

    SMFS: the most promising reactor designs get very high burn-up which reduces the refuelling intervals, and most of them are predicated on the use of on-site encapsulation of waste for removal and transport to a handling facility on a thirty year schedule. There will be several (dozens?) of such reactors in use in the next thirty years although the likelihood of any of them being in the the US or Europe is probably slim, thanks to idiot Greens and their willing dupes in the general populace.

  53. bloke (not) in spain

    “bins: I was using TNT equivalent. It’s a rule of thumb, nothing more.”
    Like I said, I’m a part time plumber, not a scientist. My thumbs are marked in millimeters/10ths. What happens in the application rather than what’s on the data sheet.

  54. Wouldn’t a box of candles & a battery TV be cheaper? Both on Ebay.

    Not when it’s forty below zero and the electricity goes out, and the furnace won’t run because the controller and fan have no power. I seriously thought about wiring in a backup battery when that happened a few years ago, but it’s rare enough that we can just cross our fingers and hope the power comes back on before we freeze.

  55. I would happily take a lead-wrapped brick of nuclear waste to put under my water heater. It’d save quite a bit in gas.

  56. The Williams F1 team developed flywheel energy storage. The idea was to collect energy while braking into a corner, and then use it after the corner to accelerate.

    The F1 rules changed and they couldn’t use it, but they did transfer the technology to Audi, who used it to win Le Mans.

    The most lucrative thing, though, turned out to be to use the technology for buses, which are very suitable because of their frequent stopping and starting.

    http://en.wikipedia.org/wiki/Williams_Grand_Prix_Engineering#Williams_Hybrid_Power
    http://www.gpupdate.net/en/f1-news/308617/williams-cashes-in-with-hybrid-power-sale/

  57. Edward Grant:

    Guess why I bought a diesel genny many moons ago when the kids were little. Really flakey overhead supply in E Anglia then. Fortunately it’s got much better since and I haven’t used the generator in anger for decades.

    IanB has the right idea ATM – “a litre of petrol gets my vote”. Perhaps in future times the economics may favour other small scale energy sources, but it’ll be a while IMHO.

    I did wonder about these batteries as a short term UPS or a peak-lopper but the economics don’t work. A commenter on El Reg did quite a good analysis in a UK context and his payback periods were silly unless he combined it with solar power and the Govt’s feed-in tariff.

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