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Secondary Off-grid User-supplied 12VDC Bus In The Home

Keep your existing mains wiring, but add a second set for 12VDC, that doesn’t show up on the electricity bill, and boast about it.
  (+13, -2)(+13, -2)
(+13, -2)
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There are ideas even here in the halfbakery, in this department, detailing the pros and cons of, for example, a 12V house. Bear in mind that technology has subtly crawled into a slightly different market state by now, in late 2010, allowing feasibility of some things but not necessarily others yet.

I propose an idea that isn’t really much of an idea of and in itself, but the emphasis behind it is perhaps the novel thing.

Have a 12VDC bus around the house. This can power a lot of things these days, such as high efficiency ridiculously bright 12V LED clusters, LED strip lighting etc. It can power radios, perhaps LCD screened televisions, perhaps audio systems, probably printers, almost certainly netbooks (but laptops will prefer 18V-24V, best wait till they phase out), phones, smartphones, external hard drives, NAS boxes, scanners etc. Many things in the home currently plug in via a power adaptor anyway, and a new power adaptor arrangement to feed from 12VDC is in most cases a trivial rearrangement to achieve.

This 12V bus would be powered entirely from sustainable energy of your own sourcing. Solar (monocrystalline and polycrystalline) cells would “top up” the supply batteries. The supply batteries at this stage would likely be a fairly substantial battery of LiPo cells, with an appropriate charging arrangement for that type of technology. Wind turbines would also add to the top up. If you live near an estuary, an arrangement involving a plank of wood that has a float on the end and a geared pivot on the other, might tap the lunar energy as the river level goes up and down twice a day every day for free. Things like that.

So, 12V in the house isn’t a novel idea. Solar charging and wind charging a LiPo bank isn’t, either. And using devices in the home that get their energy from lower voltages instead of mains isn’t a novel idea really, either.

The idea here is that the user of such a system can overtly make purchasing choices, that gradually populate the house with devices and systems that make a decreasing impact on the electricity bill and more to the point, a requirement for an external electricity supply into the home at all. At the moment, a typical home is full of devices, and they all depend wholly on the fact that you’re connected to the grid. Increasingly you’d move away from the grid, and become more dependant upon your own low-volt bus. It might become a matter of pride, and conscience, that each new device you might install, each new lighting system, etc, is entirely off-grid. That’s the idea. A gateway to gradually affordability of increasingly higher off-grid status. Your off-grid ratio, small though it may be, might be something that you could take online into public knowledge — encouraging a competitive element.

Of course, there’ll be things you can’t go entirely off- grid for, without a lot of hassle, such as everyday cooking, hot water and heating, big heavy duty stuff like that. But those aren’t necessarily used constantly or for long periods (well, heating obviously is). The small devices, and lighting, is often utilised in combination for most of an evening each day, etc. The off-grid quotient is not really going to outbalance the on-grid requirement by a long chalk, but if it is measurable, quantifiable, it is also boastable and competitiveable, and the more of it that happens, the better for all of us really.

And of course, if the sun hasn’t been out for weeks and there’s no wind and you’re not near a river, you could always top up from the mains. But imagine the pain of defeat in having to admit that you’ve resorted to that.

Ian Tindale, Sep 14 2010

Twelve Volt House 12_20volt_20house
Isn't this the same? [nineteenthly, Sep 14 2010]

Just a FYI http://en.wikipedia...iki/War_of_Currents
Edison supported DC, Tesla supported AC [Jinbish, Sep 16 2010]

I'm just contrary High-tension_20mains
Copper is just too expensive [coprocephalous, Feb 01 2011]

David Mackay: "Sustainable Energy - without the hot air" http://www.withouthotair.com/
[hippo, Feb 01 2011]

David Mackay: "Sustainable Energy - without the hot air" - extract http://www.inferenc...r/c11/page_68.shtml
"All the energy saved in switching off your charger for one day is used up in one second of car-driving" [hippo, Feb 01 2011]

[link]






       Similar to the linked idea but more detailed so [+]. The standing charge for the main supply would still be levied.
nineteenthly, Sep 14 2010
  

       I've read 78% of this idea.   

       I don't see why this is such a good idea. I'm going to pay £N00 to have the wiring installed. Then I'm going to hook it up to my solar panels. Then I'm going to buy special 12V equipment, or adaptors to run existing appliances from 12V. If I buy a special 12V TV, do I still keep the 240V one for use at night?   

       Would I not be less silly to feed my solar panels into my regular house wiring through an invertory thing? Then they will provide as much of my 240V consumption as they can, without any new wiring or dedicated devices. If I want boastability, I can buy one of those panels I've seen which displays how much electricity is being used, and how much of it is coming from the solar cells.   

       I don't see what you're trying to achieve here.
MaxwellBuchanan, Sep 14 2010
  

       //Mr Tindale's point is, that if you just run it all into the mains, then you don't get such an obvious reminder//   

       So, I'm going to pay for extra wiring and extra appliances for a reminder? What's wrong with a 6ft-tall digital display saying "I'm making 28% of my own electricity right now!!" ?   

       Also, the first thing any sane person would do would be to buy their elves a big 12V transformer to supplement the power input from the solars, so that they can still watch their 12V TV when the sun's not out, instead of having to put it away and bring out the old 240V TV every evening. So, you'll still have no idea how much of your power is coming from solar.   

       I think this is dumbington dumb with a side order of dumbth.
MaxwellBuchanan, Sep 14 2010
  

       I sorta like it, but isn't there a (good) reason we don't use 12VDC ?
FlyingToaster, Sep 14 2010
  

       Both higher voltages and AC transmit better, not generally a problem in household lengths, but noticeable over longer transmission lines.   

       If you start with 12 or 24V DC, then you already have several devices in your house that run on that, and you presently have to use a voltage converter to step down to it. Computers are a major one (the power supply does the conversion). Changing out for a 24V power supply is not difficult, and will definitely waste less energy than converting up from solar panels and back down for the computer.   

       Likewise, most cell-phone and other portable electronics devices run on low voltage DC (5, 9, 12). It is considerably more effecient to charge these directly from a low voltage source, even one that needs to be stepped down, than from an AC source.   

       The conversion or purchase of other devices to use low voltage really only makes sense if you have a consistent supply of solar power (with batteries). Otherwise, an inverter probably does make sense.
MechE, Sep 14 2010
  

       I meant not a problem for loss, not power load. My last house had a 220 circuit for an airconditioner, and they're common for electric stoves as well. (Note, I'm US, so 110 normal). It's not unusual for houses to already have a separate circuit for high power appliances, this setup would just require a re-definition of high power.
MechE, Sep 14 2010
  

       //re-definition of high power// anything that's gonna set the house on fire, I imagine... say >120-240W (based on 12V) to allow for a 10-20A load on a line... but that's 10-20A total, not just for one device.
FlyingToaster, Sep 14 2010
  

       I'm reserving a bun for this idea to be handed over at such time as a minimum of 50% of "common" devices adopt a standard supply requirement voltage. If there were a 'standard' of 12v (or 9v or 5v or 6.345v) I'd be happy to install a suitable DC bus alongside my 240v AC mains. I'd happily forego all that tosh about bragging rights and holier-than-thou stuff though. I don't care what you think of my consumption. I'd like a convenient way to connect the plethora of low volt devices to their corresponding power feeds without the ugliness of all the different transformers taking up wall sockets.
Tulaine, Sep 14 2010
  

       It would be much more fun (if you insist on having independent circuits) to step up the solar and have a 10kV circuit in your house.   

       The wires would be much thinner (albeit with thick insulation), and you could have great fun making sparks. It could also be wired directly to your electric fence.   

       (I am curious as to whether the mixing of Solar and Industrial electricity in the same circuit is covered by a mitzvah....)
MaxwellBuchanan, Sep 14 2010
  

       What are you people doing using such vast current draws? Most stuff is quite low power. Even my computer (the one that isn’t a laptop or netbook — my EPIA ME6000) runs off a small laptop PSU (into a DC-DC converter that plugs into the ATX power socket). The monitor runs off another, but I’m fairly sure both would suffice on one PSU. LED lighting doesn’t need such huge currents at 12V. What are you doing on 12V that needs a 1KW load? Cooking on it?
Ian Tindale, Sep 14 2010
  

       Don't forget that if you have a DC source, you're going from DC to AC to DC, so that's the loss you're saving. I also prefer 24V to 12V, but that's mostly because I play with lots of industrial control systems, which typically are 24.
MechE, Sep 15 2010
  

       Another minor factor (and yes it is minor, but still) if you're looking at ceiling mounted lights, and roof mounted panels, you can potentially have very short (1-2m) runs between source and sink.
MechE, Sep 15 2010
  

       //Modern wal-warts only drop a couple of percent in converting from mains to e.g. 12VDC.//   

       My gut feeling** is that if there is merit in having a 12V supply (eliminating individual transformers/rectifiers for small devices) it could be done at socket level. Each wall socket could have a standard plug-point and a "mains-lite" DC supply (tapped of the mains via transformer in the socket).   

       This obviously doesn't involve using the renewables aspect of the main idea, but it also means that you don't need a second ring of copper around the house.   

       {I keep thinking that if I have a renewable source, why not just plug it into the grid?}   

       **Using my gut because I haven't the back-of-envelope to hand to do [bigsleep] style calculations.
Jinbish, Sep 15 2010
  

       // Likewise, most cell-phone and other portable electronics devices run on low voltage DC (5, 9, 12). It is considerably more effecient to charge these directly from a low voltage source, even one that needs to be stepped down, than from an AC source.// Actually probably not. Most 12V devices are made for cars so not optimized for efficiency but just low cost. To get 9VDC in your house the mains power in run thru a transformer which steps it down to an about 9VAC which is then retified to 9VDC. To drop 12VDC to 9VDC you stick it thru a Zener diode and loose a bunch in heat.   

       If you really want to save power you should frequency multiply the mains, the way computer power supplies do. It will freak out any series AC motors you have, but all your transformers will LOVE you.
MisterQED, Sep 15 2010
  

       // Likewise, most cell-phone and other portable electronics devices run on low voltage DC (5, 9, 12). It is considerably more effecient to charge these directly from a low voltage source, even one that needs to be stepped down, than from an AC source.// Actually probably not. Most 12V devices are made for cars so not optimized for efficiency but just low cost. To get 9VDC in your house the mains power in run thru a transformer which steps it down to an about 9VAC which is then retified to 9VDC. To drop 12VDC to 9VDC you stick it thru a Zener diode and loose a bunch in heat.   

       If you really want to save power you should frequency multiply the mains, the way computer power supplies do. It will freak out any series AC motors you have, but all your transformers will LOVE you.
MisterQED, Sep 15 2010
  

       [MisterQED] Again, this idea assumes a 12V supply separate from the mains, so charging from those is more efficient. If you are stepping down from mains, then not so much.
MechE, Sep 15 2010
  

       I can't even pretend to understand all this, though i will. I like this for several reasons. One is that you could just install it yourself and run it off some kind of home made way of generating electricity without it having to have the oompf behind it that the mains seems to have right now. The other is that when i run through the things which i imagine draw a lot of power here, i come up with fridge, washing machine, cooker, hoover, kettle, juicer and food processor, and i think that's it. Other things have been replaced, and the interesting thing about that list is that only the juicer and the food processor are really not doable in other ways.
nineteenthly, Sep 15 2010
  

       The other thing to consider is that there’s pretty much nothing in a modern telly, even the bigger ones, that requires higher voltages than about 12V. They can be supplied with quite a low amount of power internally. This wasn’t the case when the referred idea “12 Volt House” was written. Everybody had inefficient and bulky CRT tellies then.
Ian Tindale, Sep 15 2010
  

       sp: inefficient and bulky CRTs with great picture quality
Jinbish, Sep 15 2010
  

       // To drop 12VDC to 9VDC you stick it thru a Zener diode and loose a bunch in heat.//   

       Actually, I think most DC:DC convertors don't do that any more. They work by chopping the incoming DC at high frequency.   

       Nevertheless, I suspect we are quibbling over a few pounds-worth of electricity, in comparison to hundreds of pounds worth of new wiring and general grief. (My grief, as it happens, is particularly expensive.)   

       Would the inestimable and generally wise Mr. Tindale actually in reality do this in his own home?
MaxwellBuchanan, Sep 15 2010
  

       Yes. Probably.
Jinbish, Sep 15 2010
  

       (That was actually a question for the inestimable and generally wise Mr. Tindale.)
MaxwellBuchanan, Sep 15 2010
  

       Ah. Right. I see - the clue was in the question, wasn't it? Sorry.
<shuts gob>
{Just saying that I bet he would...}
Jinbish, Sep 15 2010
  

       If you're going to go off-grid with it without replacing the things which need big mains power, a few hundred quid's a pretty good investment. You can heat the house, cook and have hot water without electricity, you can sweep the floor rather than hoovering, you can hand wash your laundry. Fridges are a luxury and there are other approaches to food preservation. Nothing to lose really. Well, i do value the food processor and i've used a manual one and it was rubbish, and the juicing's good too.
nineteenthly, Sep 15 2010
  

       And you can wash with rusty nails and phone people using the sun and three toothpicks.   

       The motivation behind this idea seems to be a combination of:   

       (a) keep your solar and mains electricity completely separate so that you can show [off] exactly how much of your power is solar and/or   

       (b) save energy by using low-voltage DC to drive some devices directly, instead of via an invertor and then a transformer.   

       Both reasons seem pretty pointless to me.   

       Ian, Ian, Ian - inventor of the famous two cups of coffee... Can you, hand on heart, say that this is something you would do, given the choice? And, of course, you do have the choice: solar cells exist, as do numerous 12V appliances.
MaxwellBuchanan, Sep 15 2010
  

       Not that I'm recommending it, but someone out there makes a bike mounted blender.
MechE, Sep 15 2010
  

       I’d definitely do it given the money but at the moment I’m skint and workless, so spending anything on anything right now is out. In a way, I’m more motivated by the idea of leaving a wind turbine out (there’s one out right now, and it was quite windy today) and bringing it in and using it until it’s flat, then popping it back out again, and so on. Same with solar chargers.   

       Last year, to circumvent the impossibly high electricity bills, we obtained a liquid fuel heater (Corona RX23) which worked out fantastically effective, and independently of the grid (ie, if there were a power cut).
Ian Tindale, Sep 15 2010
  

       I think this is worthwhile because of the existence of the standing charge. The cost of my electricity consumption has in the past been way below that and it presents a barrier to getting it cheaper. A card meter is too expensive per unit. Does the standing charge still exist though?   

       [Ian], i achieve that by burning wood because i'm lucky enough to have fireplaces.   

       [MechE], yes, but is it precise enough? I ended up with massive chunks of chickpea, carrot or whatever because the gears didn't fit together well.
nineteenthly, Sep 16 2010
  

       My twopenneth - I see the greatest benefits here being the ease with which you can hook-up alternate energy generation systems without having to step-up to a heart-stoppingly scary 240V - let's face it the design requirements that informed taking the decision to go for 240V domestic are largely all legacy today - no great problem with that - but that status quo does make amateur power generation and subsequent engridderisation a bit of a task.   

       If we already had a common system of 12DC, it would be trivial to knock-up whatever power-generation systems you liked - encouraging open-source development and stimulating a market for components - a much easier market to serve than one that supplies fully fledged assembled products (higher capital requirements). It's about choosing a standard that facilitates that kind of amateur tinkering from which interesting, powerful and collectively arrived ideas emerge - benefitting all. Like the internet, only with more electricity.   

       In a world where people are expressing concern about power generation, is it better to leave development in the hands of a small number of centralised, high-capital organisations, or to lower the costs of development* to a point where anyone can do it and new ideas can emerge from the masses - this is not about AC vs DC, this is democracy in action!   

       *Yes, we all have to pay to get this stuff installed, but that's what they said about double glazing, loft insulation and certified gas fitters - and most of those things have probably been for the best in the long run.
zen_tom, Sep 16 2010
  

       Hmm, I admit I did skip the calculations - but, having given them a cursory glance - note that the comparative wall-wart figures aren't there - accepting the consequence that copper demand goes up, how is that offset by the wallwartium demmand going down? (Or am I missing something?)   

       And, here's a question - assuming a wall-wart converts from 240V to 12V in one direction - is it possible for it to work the other way around? Could I plug my bank of choppy-generated power-smoothing 12V car batteries into a series of recycled wallwarts and have them pump 240V back into my ringmain?
zen_tom, Sep 16 2010
  

       I don't think it would influence the cost of copper much because it would probably be a hobbyist-style project. Also, could you not use aluminium? If this is for microgeneration it doesn't seem that wasted electricity would matter so much. I imagine stapling stuff to the walls rather than getting a qualified electrician to do any of it.   

       For that matter, why just stick to one power source? Could you not deal with the loss by having a series of circuits, each powered in a local way, supplying a few appliances?
nineteenthly, Sep 16 2010
  

       // setting fires in walls //   

       Not if the cables are stapled to the room side of the walls. You can smell them catching fire and deal with it when it happens.   

       I'm not really talking about this in the abstract. I'm considering how to cope without ordinary mains electricity because it's a drain on financial resources, and we have a cabin in the woods without any electricity because the truck batteries used to supply it were allowed to deteriorate. My solution there is probably going to be solar-powered light bulbs hung up outside the building under glass during the day to be used at night.
nineteenthly, Sep 16 2010
  

       I think an important component of this idea (which as I say isn’t much of an idea, more of an arrangement of thinking about existing ideas) is that there’s perhaps a generational time lag in terms of consumption. I know that when I was young I would think nothing of leaving lights on all the time, but as I now (struggle to) pay the bill, I see that I not only turn stuff off, but actively seek to replace functionality with far lower consumption items than before.   

       I mean, a 500W pc and monitor was mentioned here. That’s just bloody insane. That’s, well, I don’t know how many 60W light bulbs left on for hours at a time, but it’s quite a lot, especially as all of those 60W lightbulbs now only use 11W each. Most of the music in the house is from radios that have rechargeables in, other than a small efficient pair of Bose active speakers I got about 15 years ago (I have no separate huge amp at all). I don’t think I’ve ever had a computer that uses as much as a toaster or half a kettle or a halogen flood light capable of lighting a huge area, but my computer power consumption has naturally decreased with increased laptoppery and netbookery.   

       Everything is becoming lower power drain apart from cooking and heating. I suspect that my idea won’t make as much sense to this generation as it does to a few generations into the future, where much lower power per functionality is markedly different to what it is now.   

       I have a large quantity of devices either charging or powering from plug packs (as have most of the population of the world, no doubt) and the low- voltage side of those has never burned the wall (nor the floor, which they trail all over). In fact, I notice an increase in the devices that charge from USB sockets, and therefore their plug pack is nothing but a SMPSU with a USB socket on it. But we’re not talking about a significant load. Most of those power supplies are in the quite low milliwatts capacity and the actual consumption is quite a lot lower.
Ian Tindale, Sep 17 2010
  

       <irrelevant aside> Is it just me, or did the UK used to be a proud 240V AC, instead of this namby-pamby 230V? When did we lower ourselves to the standards of our neighbours in Europe?
MaxwellBuchanan, Sep 17 2010
  

       //Modern wal-warts only drop a couple of percent in converting from mains to e.g. 12VDC.//   

       Hmm, these days 80% efficiency for things like phone and laptop chargers while pc's are ~85% at best. The remaining energy losrt here is burned off in the device.   

       On top of this, the power factor can be very low. Starting around 0.4 for small items and heading up to 0.8 for things PSUs with active power factor correction. This isn't very good as it causes the current to be out of phase with the voltage. This is another form if inefficiency, but here the reactive power lost is burned up in the distribution network rather than your home. You do poy for it though as your meeter sees all the current sloshing about whether it's i phase with the voltage or not - as it pays no attention to voltage... (energy lost here is a further 20 to 60% - more or less).   

       So, if you had a 12V system, no power factor correction would be needed, an instant win sving up to half the energy for small devices. Couple that with small DC-DC converters being aboe to convert at 95% efficiency and more would be saved.   

       Other items with really lousy power factor include CFL bulbs (energy saving type), LED's and motors. This is because they are have very non linear voltage-current charictoristics, or in the case of the motor, a huge reactive impedance.   

       Anyway, the 12V bus would save all this added loss - which is greatest in low power items and lighting systems. However, if I was to do it, then I'd run a highly efficient power factor currected 240VAC (UK) to 12VDC converter and not bother with the batteries and solar (6th floor appartment with no room for such).   

       Lazyness dictates that I'll not do this, and insted will continue to leave lights on in rooms that I've left.
saedi, Sep 19 2010
  

       Energy is energy. Producing electricity using solar panels may be a little less destructive than using coal or nuclear, but the //powered entirely from sustainable energy// thing is just nonsense, and one of the dangerous myths of our time.   

       In addition, storing electricity in batteries before using it, regardless of the energy source, is much more destructive (and expensive, which is almost the same thing) than using mains electricity.
spidermother, Feb 01 2011
  

       Dunno, [spidermother], I really have to disagree with pretty well everything you just said.   

       "Sustainable" energy in the form of well... burning crops and forests basically... is preferable to oil because there's at least *some* responsibility tied to it. One would hope that you'd start off with grassland and not old-growth trees.   

       Likewise a wind/solar to battery, while only say 50% efficient is, in fact, free energy... at least until the point where you're screwing over ecosystems to get it. Again one would hope that you're putting panels/mills on the roof or on bare rock.   

       I've been toying with a "12V" house in the form of using battery power everywhere; not lines, just batteries that get dragged around from room to room: it'd save poking holes in the walls and dealing with mouse damage.   

       Regarding heating, there's direct solar or, barring that, mechanical conversion; disregarding conduction losses it's going to take 1kWh to raise the temperature of a cubic metre of water by 1C, may as well skip the lossy "electricity" step if possible. Not something you can do to run the TV though, or stay up past sunset.
FlyingToaster, Feb 01 2011
  

       My point is more subtle than that, which is why the myth is so insidious. Note that I did not say that producing energy sustainably is less bad than producing it unsustainably.   

       The problem with "powered by sustainable energy" is that it is just an accounting fudge.   

       1) Make 1 unit of electricity by burning coal.   

       2) Make 1 unit of electricity using solar panels.   

       3) Use 1 unit of electricity to run my computer.   

       They are different, though related, things. I can't just declare that 2) and 3) are directly linked, therefore 3) has no impact on the environment. That's cheating. If a business tried the equivalent with their accounts, they would go bankrupt.   

       The problem I have with batteries is simpler. Batteries require resources,including energy, in their construction. They have a finite number of charge cycles. If you calculate the total cost per joule of electricity stored over the lifetime of the battery, purely in terms of depreciation to zero of the battery, you will find that it is rather expensive electricity, even disregarding the cost of generating the electricity. That money was spent on mining, manufacturing, etc, which begs the question, is $100 worth of battery really better, in any way, than $20 worth of electricity? I don't know for sure, but my instinct screams no.
spidermother, Feb 01 2011
  

       Not so much if the chemicals in the batteries are recycleable into new batteries for less money/energy than it would cost to drag the stuff out of the ground again.   

       But instincts are learned ;) Your $20 electricity might be at the future $100 expense to unscrew the environment.
FlyingToaster, Feb 01 2011
  

       My city has built a desalination plant recently. If the government announced "We are building a desalination plant. It will consume X megawatts. We think it's still a good idea because xyz.", and in a totally unrelated announcement, "We are building wind turbines capable of harvesting Y megawatts of wind energy. We think it's a good idea because abc.", then those ideas could be considered on their merits.   

       Instead, they announced "We are building a desalination plant. It will be powered by 100% renewable energy." Now, that's just bullshit, and it makes me very angry, because most people will fall for it, and they know it. That's the kind of woolly thinking I was trying to show up in my previous comments.   

       Regarding batteries, if you live somewhere with no grid connection, and use very little electricity, you can probably come out ahead, ecologically and financially. The small amount of batteries and panels needed may have less impact than a grid connection would have.   

       //instincts are learned//. Some years ago lead-acid batteries were being sent to Indonesia from Australia for recycling. As a result of the third-world working conditions, many people received severe lead poisoning, and local waterways and soil were contaminated, effectively permanently. That may have helped shape my instinct that batteries could be worse long-term problems than mains electricity generation. Also, nickel cadmium batteries have been sold here for decades. Virtually no one knows where to take them for safe disposal, and many just get thrown out. Do you know what _cadmium_ does to you? That's a whole lot of unscrewing needed.
spidermother, Feb 01 2011
  

       I can recommend the analysis of comparative energy consumption in David Mackay's book "Sustainable Energy - without the hot air". He looks at all the different kinds of energy we use - solar, wind tidal, fossil fuels, etc. and various ways of saving energy (unplugging mobile phone chargers, turning your TV off, insulating your house, etc.) and reduces everything to kWh sums. It's brilliant - I bought the paper copy of the book so I could read it in bed but also the whole book is available online (link) - (I don't think he needs the money - he's a prof of Physics at Cambridge and chief scientific adviser to DECC). My only reservation is that some of the case studies are very UK-centric and not so relevant to US readers.
hippo, Feb 01 2011
  

       No, I’ve no idea whatsoever what cadmium does to me.
Ian Tindale, Feb 01 2011
  

       Cadmium weakens bones until the spinal column starts collapsing under the body's weight, crushing nerves and causing a slow agonising death. Among other things.   

       Yes, more recent battery technologies have fewer heavy metals, but they still aren't environmentally benign, or cost effective. If they were, power companies would use them to cope with demand fluctuations.   

       I'm not entirely against the idea of running some things directly from 12 volts generated from local energy sources, or of having a 12V bus; I hope you don't take my rant as a rejection of your idea in toto. I just don't think moving from grid to batteries like this is really all that green. Its main advantage might be a feeling of self-reliance.
spidermother, Feb 01 2011
  

       To me, the main advantage of going 'off-grid', is that you gain a certain degree of independence from central control (whether that be the power company or the government) and ditto for other utilities (water especially). I think that that would make a huge difference socially regardless of the arguments about sustainability of resources.
DrBob, Feb 01 2011
  

       Yes, that's pretty much what I meant.
spidermother, Feb 01 2011
  

       spidermother, - I didn’t realise that you were ever actually referring to my idea at any time. My idea is about being able to boast about how much of one’s gadgets and devices are powered without reliance from anyone or any system outside of one’s home. It’s a boasting thing for people who are competitive. A pissing contest, basically.
Ian Tindale, Feb 01 2011
  

       Sorry, [Ian]. I thought that was what you meant. I just picked on a couple of points and used them as an excuse to say some controversial stuff I'd been thinking about.
spidermother, Feb 01 2011
  
      
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