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Advocacy vs. Science

Filed under: — gavin @ 1 April 2009

The advocate will pick up any piece of apparently useful data and without doing any analysis, decide that their pet theory perfectly explains any anomaly without consideration of any alternative explanations. Their conclusion is always that their original theory is correct.

The scientist will look at all possibilities and revise their thinking based on a thorough assessment of all issues – data quality, model quality and appropriateness of the the comparison. Their conclusion follows from the analysis whatever it points to.

Which one is which?


595 Responses to “Advocacy vs. Science”

  1. 551
    Mark says:

    ““Used up” is the wrong word.”

    Then there’s 100% recycling possible, isn’t there.

    Unlike coal, oil or unstable atoms, where they are used up by the extraction of the energy from them, there is nothing used up in a lead-acid battery.

    So the lead-acid battery can be reused perpetually.

    It will take energy to reverse or undo the changes but 100% of the lead is still lead. Acid can be remade or recovered 100%.

    Why then is “lead acid batteries wear out” mean that lead acid batteries can’t be reused?

  2. 552
    Nick Gotts says:

    “religious fanatics who’ve openly stated their intention of committing genocide?” – James

    I’m no fan of the Iranian theocrats, but this claim is just nonsense.

  3. 553
    Brian Dodge says:

    I wasn’t referring to $10k EV batteries backing up the grid. I was pointing out that the existing SLI batteries in the US fleet of passenger autos could supply significant backup power to the nation’s grid. At 10% discharge, they could sustain about 1200 cycles; after they died, they could be replaced for

  4. 554
    Brian Dodge says:

    (wups forgot about less than symbol)

    less than $200 with a larger capacity battery that could handle 5k cycles, deeper discharge, and still provide the electricity for starting, lighting, ignition.

    Yes, the costs if unreimbursed would be a tax to support renewable energy electrical grid, but they wouldn’t be $1k per year. I would prefer a market where the stored power returned to the grid would be metered and I would get paid for it. Since I’m retired and don’t drive much, I might actually make money providing backup power for profligate electricity users (which would incidentally encourage them to use less).

    “Chicago, Ill. (June 20, 2005) — The lead-acid battery industry, with help from consumers and retailers, recycled 99.2 percent of used battery lead (or 11.7 billion pounds of lead) from 1999 to 2003, according to a new report issued today by Battery Council International (BCI) the industry’s trade association.”
    http://www.leadacidbatteryinfo.org/lead-acid-battery-recycling.htm

    recaptcha oracle says “relation develop”. Twixt my Toyota Matrix and Duke Power?

  5. 555
    James says:

    Mark Says (17 April 2009 at 4:37 AM):

    “Why then is “lead acid batteries wear out” mean that lead acid batteries can’t be reused?”

    I think you’re being deliberately obtuse. When did I, or anyone, ever suggest that lead-acid batteries (or any other kind) can’t be recycled? The point is that the recycling costs money, and that cost has to be paid & accounted for somewhere when you’re adding up the total cost of the system.

  6. 556
    James says:

    Nick Gotts Says (17 April 2009 at 7:31 AM):

    “I’m no fan of the Iranian theocrats, but this claim is just nonsense.”

    Oh? Perhaps you should pay more attention to the daily news, or use Google. Took maybe 10 seconds (I’m not a fast typist) to find the first referance (of about 353,000): http://www.washingtonpost.com/wp-dyn/content/article/2006/08/03/AR2006080300629.html

  7. 557
    SecularAnimist says:

    Not sure of the relevance of the discussion of lead-acid batteries.

    James referred to battery issues in the context of “electric car batteries” that would be “put to work in a smart grid” for storage purposes, and experience more discharge/recharge cycles as they both charged from and provided power to the grid.

    But modern hybrid-electric cars use nickel metal hydride (NiMH) batteries, not lead-acid batteries. And the advanced batteries being developed for electric cars are mostly lithium-ion.

    Which is not to say that there are no issues with those types of batteries, but recycling lead isn’t one of them.

    From a hybrid cars FAQ:

    Q: How often do hybrid batteries need replacing? Is replacement expensive and disposal an environmental problem?

    A: The hybrid battery packs are designed to last for the lifetime of the vehicle, somewhere between 150,000 and 200,000 miles, probably a whole lot longer. The warranty covers the batteries for between eight and ten years, depending on the carmaker.

    Battery toxicity is a concern, although today’s hybrids use NiMH batteries, not the environmentally problematic rechargeable nickel cadmium. “Nickel metal hydride batteries are benign. They can be fully recycled,” says Ron Cogan, editor of the Green Car Journal. Toyota and Honda say that they will recycle dead batteries and that disposal will pose no toxic hazards. Toyota puts a phone number on each battery, and they pay a $200 “bounty” for each battery to help ensure that it will be properly recycled.

    There’s no definitive word on replacement costs because they are almost never replaced. According to Toyota, since the Prius first went on sale in 2000, they have not replaced a single battery for wear and tear.

  8. 558
    Doug says:

    I don’t have enough insight into the many facets of the system analysis to comment on the meat of this discussion, but I will say that I found the following comment (by Gavin? not sure) in the link above somewhat confusing, if not troubling.

    “I’ve said quite a bit about feedbacks lately and it’s a little old now, but many WUWT commenters still seem confused about how postive feedbacks relate to an unstable system. Lindzen has recently been using the “gas pedal” analogy (not only in Watts’ post, but at the skeptic conference) in which positive feedbacks are supposed to be analogous to someone changing the gas and brake pads in your car. If you want to slow down, you actually speed up. Apparently it follows that climate does not act this way. Actually feedbacks don’t really act this way either. If we let the moving car roll on a flat, frictionless surface (with no influence from the tires or air resistance) in the absence of any net force change, it will roll forever by Newton’s laws. Think of this as some equilibrium condition, with the climate analog being radiative balance. Pushing your gas or brake is more like the “radiative forcing” on the car which essentially puts it off of its current course. Positive feedbacks simply let the planet equilibriate at a higher temperature than the sensitivity from CO2 alone, but the same principle that balance is acheived still applies. Feedbacks go up like a converging power series and therefore never get strong enough to override the fourth power dependence of thermal radiation and trigger a “runaway.” In short, positive feedbacks can be stable and don’t require any runaway scenarios.”

    Your analogy seems irrelevant to a discussion of feedback (at least in the sense of classic control system theory) in that it assumes no external stimulus. Feedback, positive or negative, is a response to perturbation of the system. Your supposition of a frictionless environment with no net force change means there is no perturbation, and hence, no reason to ever push the gas pedal.

    Am I missing something?

    I’m also somewhat confused about the idea of positive feedback not necessarily causing runaway conditions. If one feedback out of many is positive, I agree that the system can be stable. However, if the summation of all feedbacks is positive, it seems to me that it is indeed unstable by defintion.

    Have I got that right?

  9. 559
    James says:

    SecularAnimist Says (17 April 2009 at 2:29 PM):

    “Not sure of the relevance of the discussion of lead-acid batteries.”

    I think it’s because post #541 calculates the number of lead-acid batteries needed to store a specified amount of power.

    However, the principle applies to all (AFAIK) battery chemistries. They do eventually “wear out”, and will no longer hold a full charge. This is true of NiMH batteries as used in current hybrids. I know, as I had to rebuild the battery pack in my Insight last year, after about 8 years/125K miles. I do have one of the more stressful driving regimes for a hybrid, so most would probably last longer. However, my driving (fully discharging up a mountain, then recharging on the downhill side) is probably typical of what batteries in a load-balancing situation would see.

  10. 560
    JamesC says:

    This is a first time post and I’m not sure if this is slightly off-topic, but I’m wondering if there is any interest here in producing a chapter by chapter peer review/rebuttal of Ian Plimers’ latest tome? I have a tedious relative who I fear is going ambush me with factoids from this book every time we meet for the next few years. I realise this might be a large task considering the length of the book – perhaps it could be done in the form of a moderated Wiki or something similar (I see that some media commentators have already fallen for the old proof by verbosity ploy).

  11. 561
    Mark says:

    “However, the principle applies to all (AFAIK) battery chemistries. They do eventually “wear out”, and will no longer hold a full charge.”

    But they don’t “wear out” like coal does.

    So you can take the battery, retrieve ALL the material that is required to make a new battery, and make a new battery.

    Which will then wear out after a lot of use. Which you then take and retrieve ALL the material that is required to make a new battery, and make a new battery.

    Which will then wear out after a lot of use…

    It’s called “recycling”.

    Try that with coal.

  12. 562
    Mark says:

    “I think you’re being deliberately obtuse. When did I, or anyone, ever suggest that lead-acid batteries (or any other kind) can’t be recycled?”

    When you said they “wear out”.

    That is no problem when you can recycle completely the materials used in the battery to make a new one.

    If you accept that, then why is saying “Lead-acid batteries wear out” a problem? You recycle it.

    Unlike coal.

    You seem to be acting obtuse in insisting that “they wear out” is a problem.

    I’m being obtuse to make you say that you CAN recycle them.

    And now you have, why is it a problem that you have to recycle them? Why is “they wear out” a problem? There isn’t and it’s not. Stop being willfully ignorant and drop a made-up problem.

  13. 563
    James says:

    Mark Says (18 April 2009 at 5:58 AM):

    “I’m being obtuse to make you say that you CAN recycle them.

    And now you have, why is it a problem that you have to recycle them?”

    You know, you really need to work on your reading comprehension :-) When have I ever said that batteries can’t be recycled? What I’ve said from the beginning, and repeated until my fingers have gotten tired of typing, is that recycling batteries costs money, and that cost has to be added to the cost of any electric power system that makes use of batteries.

    Why do you find this idea of cost so hard to understand? Your conception of battery use seems to invoke a recycling fairy, who’ll just wave her magic wand and (perhaps with a twanging sound & twinkling stars – can’t forget the special effects) bring those old batteries back from the dead, at no cost. Sorry, but I suggest not looking to Disney for your power system engineering :-)

  14. 564
    Mark says:

    You need to work out what you’re trying to say.

    You never mentioned the cost, you just said “batteries wear out”.

    They don’t.

    They change chemically in a reversible process that results in lower charge retention.

    Now, why is that a problem? When you use oil, it’s gone. It doesn’t come back. There’s no reversible process to recreate it.

    So you have the ENTIRE ORIGINAL COST to go through again.

    Batteries? Minimal cost, since all the raw materials are there in pure and processed form. No need to remelt the ore bearing rocks. All that original expense avoided.

    So, why didn’t you just say “There’s a cost to recycling batteries that will change the operating cost of renewables”? Only NOW are you doing so.

    And it took my mimicking of your obtuseness before you did so.

    So, now we have “recycling batteries add to the cost”.

    That’s not a big impediment really, is it. It’s not as if lead and acid will run out because we have to recycle them, is it.

    Not a problem.

    Took you a long time to get there.

  15. 565
    David B. Benson says:

    Doug (5558) — No, I fear you haven’t. From
    http://en.wikipedia.org/wiki/Positive_feedback
    “As long as the loop gain, i.e. the forward gain multiplied with the feedback gain, is lower than 1 the result is a stable (convergent) output.”
    where the feedback in question is the sum of all the effects, both positive and negative.

  16. 566
    dhogaza says:

    And it took my mimicking of your obtuseness before you did so.

    Actually James did so back up in post #555, at the latest.

    And he’s correct when he says the battery “wears out”, even though the lead (in the case of lead-acid batteries) or other materials can be recovered through recycling.

    That still leaves the cost of recycling and the cost of buying a replacement battery – in his case, the context was having to replace the battery of his Insight after eight years.

    Or are you telling us you recycle the lead from your own car’s lead-acid battery and rebuild it yourself, using that lead, using a zero-cost process of your own invention?

    That would be quite the trick, Mark.

  17. 567
    Mark says:

    “Or are you telling us you recycle the lead from your own car’s lead-acid battery and rebuild it yourself, using that lead, using a zero-cost process of your own invention?”

    Nope.

    Please tell me where I said it didn’t cost.

    So it seems YOU are saying that it is a zero cost process. Care to tell us?

  18. 568
    James says:

    Mark Says (18 April 2009 at 5:53 PM)

    “Please tell me where I said it didn’t cost.”

    Humm… Post #564? Where you write

    “You never mentioned the cost, you just said “batteries wear out”.

    They don’t.”

    If, as you claimed, they didn’t wear out, there’d be no cost for recycling. Of course you go on to contradict yourself, as you write “Batteries? Minimal cost, since all the raw materials are there in pure and processed form.”

    In fact that cost, for the lead-acid batteries you were discussing, is not minimal. Most of the lead in “new” batteries is currently from recycled sources. (60-80 percent, according to this site: http://www.batterycouncil.org/LeadAcidBatteries/BatteryRecycling/tabid/71/Default.aspx ) That makes it pretty simple to get a rough estimate of the cost of recycling a battery: just go down to your local auto parts place, and look at the prices. (IIRC, around $50-60 for a small 12-volt auto battery, last time I bought one.)

    That battery might store about 1 KWh. Since US energy consumption runs about 10 billion KWh a day (per http://www.eia.doe.gov/neic/brochure/electricity/electricity.html ), simple arithmetic gives a ballpark figure of 10 billion auto batteries needed to provide back up for one day’s consumption, at a cost of about $500 billion – plus of course the expense of connectors, charge controllers, and the like. Given a 5 year service life (roughly my experience of automotive batteries), that’s an ongoing $100 billion per year. Figure maybe $350 per person? Now consider that my electric bill runs about $600/year, so just adding this battery storage increased it over 50%.

    Of course there are some technical details that complicate this simple picture, one being that automotive batteries are designed to produce large bursts of current (“cranking amps”) for starting rather than steady power. For that you need deep cycle batteries, which tend to be more expensive (though that may just reflect the smaller market). Here’s a link if you want more info on batteries used for power backup: http://www.windsun.com/Batteries/Battery_FAQ.htm

    Disclaimer: as usual, the numbers are just “back of the envelope” figuring, using what info I could quickly find by web searches. I could easily have made mistakes, so corrections are welcome, as long as they don’t involve waving of hands or magic wands :-)

  19. 569
    Mark says:

    “Humm… Post #564? Where you write

    “You never mentioned the cost, you just said “batteries wear out”.

    They don’t.”

    If, as you claimed, they didn’t wear out, there’d be no cost for recycling”

    Nope, that’s “batteries don’t wear out”. That isn’t “Batteries don’t need recycling”.

    Glass bottles don’t wear out. They can and are recycled. But the bottle remains a bottle in any way you wish to consider it without wearing out, except by damage to the item. And in that case, you still have almost all the glass (all the glass if it’s merely cracked) to make 1 bottle.

    “Batteries don’t wear out” is not “Batteries don’t have to be recycled”. What it means is that saying “batteries wear out” is only a resource problem when you mean it no longer exists or has lost its ability to be reused.

    Because, you know that batteries here are being considered for use to store energy. But guess what? The energy needed to restore operational capacity to the battery can be done WHEN THE SUN IS SHINING, or when the wind is blowing. At that point, you don’t have an energy problem, do you.

    [Response: This topic has clearly moved from minor interest to tedium. No more please. - gavin]

  20. 570
  21. 571
    Rod B says:

    SecularAnimist (557) and a bit from James (559): that runs counter to common knowledge. Maybe we (I??) have been too sheltered. The incorrect perception is a major “negative” toward hybrids. Good stuff to know about hybrid batteries. Are they still highly expensive to replace as common knowledge also says?

  22. 572
    MikeN says:

    Doug, consider if the feedback is .5
    Then you start with an increase of ten, then with feedback, you get 5 more, then 2.5 more then 1.25 more. Keep doing that and you see the total is 20.

  23. 573
    dhogaza says:

    Good stuff to know about hybrid batteries. Are they still highly expensive to replace as common knowledge also says?

    Hard to say, when the Prius hit its ten year anniversary Toyota pointed out it never had to replace a battery due to age.

    What data do you have to support “common knowledge”?

  24. 574
    James says:

    Rod B Says (20 April 2009 at 10:54 AM):

    “Good stuff to know about hybrid batteries. Are they still highly expensive to replace as common knowledge also says?”

    (Hope this doesn’t contribute to Gavin’s tedium…)

    I honestly don’t know how much it would cost to replace a hybrid battery that’s not under warranty with a new-from-factory one, because that’s not what I did. I got a used battery pack from a wrecking yard ($250 plus shipping), and rebuilt a good pack from the two.

    Internally, the Insight pack is composed of 20 “strings” of 6 high-current D cells welded together. Generally a “bad” pack only involves the failure of one string (and probably only one cell of the string). So I disassembled the packs, tested the strings, reassembled a pack using the best 20, and popped it back in the car. Now I’ve got a good battery again, and a bunch of spare cells for playing around with.

    I really think anyone facing a failing battery in an out-of-warranty hybrid should first take a look at salvage parts, for instance here: http://car-part.com/

    I should also mention that my hybrid use probably represents a pretty good stress test. I bought my Insight as salvage & rebuilt it (I enjoy that sort of thing), so it wasn’t eligible for a free replacement under warranty. My driving typically involves roads like these: http://en.wikipedia.org/wiki/Nevada_State_Route_431 http://en.wikipedia.org/wiki/California_State_Route_88 http://en.wikipedia.org/wiki/Nevada_State_Route_722 and I have a neat little box of electronic tricks (MIMA) that lets me override a lot of the build-in hybrid system controls.

  25. 575
    Rod B says:

    I take it then that for the average Joe Driver a battery pack replacement is likely a very major expense but happens very seldom.

  26. 576
    James says:

    Yes, I’d say it’s roughly on the order of a blown engine: expensive, but not something you really expect to see as a normal service item.

  27. 577
    Mark says:

    http://www.wasteonline.org.uk/resources/InformationSheets/Batteries.htm

    And from another site, it shows companies are buying lead-acid batteries for $150 per 100, or 15c per lb.

    Blown engine seems to go for $500 to fix.

  28. 578
    James says:

    And $500 is a good price for a salvage Prius battery pack.

    It’s really not that much different: you could buy a factory new replacement engine or battery pack for your 10-year old beater, but would you? Which is why the oft-cited “$X thousand to replace the battery” is misleading.

  29. 579
    Mark says:

    James, do you have a price for that?

    Because if it’s more than ~$10 to recycle a battery, then those companies are making out like bandits.

    Unlikely, since any other company could sell cheaper and there’s not much of a barrier to entry, not if it’s $1.50 per battery for the battery itself.

    So, do you have anything that says to recycle a prius battery costs $500? Or just thinking it should?

  30. 580
    James says:

    Mark, look at my post #574 above, and follow the link to CarPart.com. Under year & model, select say 2006 Toyota Prius; under part select battery. This will give you a price on used (from wrecks) batteries (or any other part you need) from auto salvage dealers – that is, junkyards – all over the country. You’ll find a good number at $500 or less.

    Note that this is an entirely different matter than what’s usually thought of as recycling a battery. It’s using a still-servicable part (as junkyards have been doing almost since there were cars, and maybe with carriage & wagon parts before that), not breaking down the battery into its component materials and making new ones. I don’t have any info on the costs of that for NiMH batteries, though I’ve read that no one’s actually doing that kind of recycling yet, because so far not enough have failed or worn out to make it worthwhile.

  31. 581
    Mark says:

    James, yes it isn’t the cost of recycling.

    Can you go find a link for the cost of recycling.

  32. 582
    Chris S says:

    A heads-up:

    http://masterresource.org/?p=1966

    I’m sure there’s plenty wrong with Dr. Goklany’s calculations but I lack the economic savvy to see it. I find this quite a depressing article by an apparent ‘global warming expert’ (according to Heartland http://www.globalwarmingheartland.com/expert.cfm?expertId=144 )

    Capthca: and brokers…hmmmm

  33. 583
    beyaz says:

    That still leaves the cost of recycling and the cost of buying a replacement battery – in his case, the context was having to replace the battery of his Insight after eight years.

  34. 584
    Mark says:

    “That still leaves the cost of recycling and the cost of buying a replacement battery”

    Uh, you buy the recycled battery.

    That’s my point.

    It isn’t common enough to be worth making it a new market, so it’s buy a new one or a retread from a car wreck.

    But when there’s enough density of demand, you’ll be buying from one of several competing local suppliers who will buy “dead” batteries for 15c, recycle them for $X and sell them to you refurbished for 1.1 x $X.15c.

  35. 585
    dhogaza says:

    Uh, you buy the recycled battery.

    No, the recycled material goes into the manufacture of a new battery.

    For a lead-acid battery, the relevant question is “how much does recycled lead cost compared to freshly mined lead”.

    I think we all know we can buy 20 lbs or so of raw lead for much less than the cost of a manufactured lead-acid battery.

  36. 586
  37. 587
    dhogaza says:

    But when there’s enough density of demand, you’ll be buying from one of several competing local suppliers who will buy “dead” batteries for 15c, recycle them for $X and sell them to you refurbished for 1.1 x $X.15c.

    Regarding my post above, of course if the battery container, interconnections, etc can all be reused then that, as well as the lead or other material used to chemically store the energy, can be reused.

    But then the “dead” battery won’t sell for $0.15, either.

    And in this case the cost comparison for the lead itself still boils down to “how much to replace the contaminated lead in an old battery with recycled vs freshly-mined lead”.

  38. 588
    James says:

    Mark Says (22 April 2009 at 2:48 AM):

    “James, yes it isn’t the cost of recycling.

    Can you go find a link for the cost of recycling.”

    No, I can’t. As I may have mentioned, Google is not my friend – I have trouble constructing queries that return reasonable answers to any but the simplest questions.

    Beyond that, I’m not sure that you could even get reasonable answers for NiMH recycling cost at this point, because the volume’s so small. On the other hand, with lead-acid most of the battery material is recycled, so the cost of a new battery is a reasonable approximation for the recycling cost.

  39. 589
    Mark says:

    But most of that lead-acid is recycled and made into new batteries to be sold to big suppliers of new cars. The competition there is “brand spanking new” where you have the cost of the raw materials to add in.

    As you’ve said now, the current situation is likely an over-estimate of the cost of recycling batteries when using them to retain baseload power from renewables. And it’s likely to go down a lot.

    It won’t be more expensive than it currently is, will it.

  40. 590
    Mark says:

    “For a lead-acid battery, the relevant question is “how much does recycled lead cost compared to freshly mined lead”.”

    At the moment, yes. Because the rate of recycling doesn’t lend itself profitably to industrial scale works in any other fashion.

    But when you have 1,000,00 batteries at a power station nexus to smooth out transient power availability, it will probably be worth actually recycling the battery as in “make it hold all the previous capacity” rather than “dump it and make a new one with the materials”.

    The bloke getting together the idea of a refilling station replacing batteries thinks he can do so cheap enough to be profitable and cheaper than if he’d been running a petrol station.

    I’m sure that he’s been doing the sums.

    We haven’t.

  41. 591
    Mark says:

    And according to taxi drivers, hybrids have lasted 300,000 miles without failing yet:

    http://jcwinnie.biz/wordpress/?p=3579

    Cars in the US didn’t used to last that long themselves not so long ago…

  42. 592
    dhogaza says:

    #591: the battery issue for hybrids has been a bit of a strawman for the “anti” side (not you), as I mentioned above Toyota had said a the 10 year anniversary of the Prius that they hadn’t had to replace a battery due to wear (as opposed to accidents) yet. And at that point in time there were people with hybrids with more than 200,000 miles on them. 300,000 miles is pretty amazing but lower maintenance is a recognized advantage of hybrids. State of Oregon motor pool says that over 100,000 miles operating costs (fuel, maintenance, etc) has been something like 40% less than for conventional sedans of similar size, much more than making up for the premium price they paid for early Prius’s.

    But when you have 1,000,00 batteries at a power station nexus to smooth out transient power availability, it will probably be worth actually recycling the battery as in “make it hold all the previous capacity” rather than “dump it and make a new one with the materials”.

    You also design the batteries different, I’m sure. Can you get the lead out of a modern sealed lead acid auto battery without trashing the case? Don’t know. But I know you could get the cells out of diesel electric submarines during overhaul, they were designed with this in mind.

    Captcha says: “labia $350,000″ … not sure I want to go there! :)

  43. 593
    Mark says:

    “But I know you could get the cells out of diesel electric submarines during overhaul, they were designed with this in mind.”

    Yup. The point being that lead-acid is simple and recycling is easy. Current needs have been predicated over use of this sort of thing merely to START your car. And when batteries are needed for evening out power levels, that will not necessarily be true any more.

    “Captcha says: “labia $350,000″ … not sure I want to go there! :)”

    I dunno, if I had 1/3mil, it’d be tempting to see whether it’s worth it!

  44. 594
  45. 595
    James says:

    Mark Says (22 April 2009 at 2:01 PM):

    “Current needs have been predicated over use of this sort of thing merely to START your car. And when batteries are needed for evening out power levels, that will not necessarily be true any more.”

    Not entirely. Automotive batteries are the largest part of the market, but there are lead-acid batteries built for power applications such as off-the-grid houses and UPS systems. If you poke around here http://www.windsun.com/Batteries/Battery_FAQ.htm you can find some info on the design differences, and current prices.

    My opinion, for what it’s worth, is that batteries wouldn’t be the best option for system storage. High-speed flywheels would work much better: no toxic materials, very little wear or energy loss if they use magnetic bearings in a vacuum, high efficiency conversion that’s not rate-limited in the way batteries are… But they still cost money, and that’s what the renewable-only advocates seem to forget.


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