What if it was made of adamantium?

  By Shamus   Jan 3, 2006   7 comments

Brian Tiemann poses a question about using flywheels to store produced energy, and Steven Den Beste runs the numbers.

A couple of years back SDB moved from writing about politics to writing about anime. This didn’t bother me much, since I love both subjects, and thinking about anime is arguably better for my blood pressure. However, the one thing I missed was these posts about why magical solutions to our power needs were preposterous.

Real engineers like SDB – as opposed to software engineers like myself – have the ability to translate the world into numbers and play with it in a way I can only envy. A real engineer can tell you why you can’t generate power using 600 million tons of turkey guts or billions of tons of corn stalks . He can tell you that to provide power for vehicles in Southern California you would need 231 square kilometers of solar panels that we can’t build. (And even that’s assuming you allow for some 2nd law of thermodynamics violations).

In a lot of ways this stuff is similar to the old, “how much would a million pennies weigh” sort of things we’d read as kids. They are fun problems that tell us more about the average person’s slippery grip on large numbers than they do about actual science.

Take a look at SDB’s answer to the great big flywheel proposal. There are a lot of serious engineering problems with it, and he outlines them in cruel, pipe-dream-killing detail. Looking at the list, most of the challenges would be mitigated by moving to many smaller flywheels. This moves the challenges from the areas of physics (how do you dissipate all that heat / maintain a huge vaccuum / keep it structurally sound / balance it / etc) to logistics (how much will all the flywheels cost, how much space will they need, and where the hell would you put them?).

If I had any grasp of it, I would work out just how many you would need and how much space they would take up. But I can’t. However, if you think about it, you can intuit that the flywheel array would need to be many, many times larger than then dam / wind turbine / solar collector / turkey gut liquifier / etc, and (unless you want to deal with a whole new set of problems) it would have to be part of or next to the existing power source.

I find this stuff to be fun to read and think about. I only wish people who advocate these pie-in-the-sky proposals felt the same way.

7A few comments. Call it seven-ish.


  1. ME AGAIN says:

    i started to read this article but then i got bored so i stoped
    now its your turn to stop…….BEING SO BORING

  2. Nice piece. However, the blog entry you linked to regarding carbon sequestration shows a rather fundamental error in thinking. It basically claims that there’s no difference between:

    X – Y + Y

    and

    X + Y

    Where X is the amount of carbon currently in the atmosphere and Y is the amount of carbon which is both sequestered out of the atmosphere by growing corn and the amount of carbon put back into the atmosphere when you burn (or let decay) the ethanol and other byproducts from that corn; OR the amount of carbon you put into the atmosphere when you burn an amount of oil equal to the ethanol you would otherwise be burning.

    Basically, with ethanol, you have a system in equilibrium: You pull Y amount of carbon out of the atmosphere and then put Y amount of carbon back into the atmosphere.

    When you burn oil, OTOH, you’re moving the system out of equilibrium. (At least in any timescale meaningful to us: If you give it a few million years, natural processes will pull that carbon back out of the air and resequester it in oil.)

    Similarly, as he notes, existing forests only sequester a small amount of carbon (because only a tiny fraction of the forest’s biomass becomes buried in such a way that it doesn’t release the carbon back into the atmosphere). However, when you plant new forests, his point falls apart: Sure, if you look at any given tree, it pulls in X amount of carbon and releases an essentially identical amount back into the atmosphere when it dies. But if you increase the number of trees, the amount of carbon sequestered in the total population of trees at any given time will also increase.

  3. Alkaru says:

    There is no difference between X – Y + Y and X + Y – that’s part of boolean algebra. Don’t know that fits in with the example but the maths is sound…

  4. I’ll openly admit that I have no deep knowledge of boolean algebra. That being said, using boolean algebra (which is designed to assess logic operations and is, therefore, useful for design electrical circuits) is completely inappropriate for the situation being discussed.

    As for whether X + Y = X – Y = Y, let’s take a simple scenario: X = 2, Y = 10.

    X + Y = 2 + 10 = 12

    X – Y + Y = 2 + 10 – 10 = 2

    The functions are CLEARLY not equivalent.

    X, in this case, is equal to the current level of carbon in the atmosphere.

    Y, in this case, is equal to the carbon being burned in our automobiles.

    In the case of burning oil, you have X + Y. Carbon which has long been sequestered in oil is being released into the atmosphere as you burn that oil. The total amount of carbon in the atmosphere is increased by Y.

    In the case of burning ethanol, you have X – Y + Y. As you grow the corn from which ethanol is made, the corn pulls Y amount of carbon out of the atmosphere. As you burn the ethanol, Y amount of carbon is released back into the atmosphere. But since you already pulled that carbon out of the atmosphere, the total amount of carbon in the atmosphere does not increase.

    This is, of course, simplified beyond belief. (Not all of the carbon pulled out of the atmosphere by the corn is released by burning the ethanol. Growing corn requires energy which may or may not release fossil fuel carbon into the atmosphere. And so forth.) But it demonstrates the fundamental error in logic in the article Shamus linked to.

    To put it simply: The guy says “none of these things works, because the amount of carbon on the planet basically stays the same!”. But he’s ignoring the fact that we don’t actually care about the total amount of carbon on the planet: We’re only concerned by the amount of that carbon that’s currently in the atmosphere. That’s what causes global warming.

  5. Shamus says:

    Sigh.

    You guys are right. We can replace our energy usage with corn stalks and flywheels.

    Now go build one and prove SDB wrong. You’ll get the last laugh. (And get rich!)

    Good luck.

  6. roothorick says:

    That corn carbon article is just plain wrong. I’m not a farmer, but if I were, it would make perfect sense to me to mash up those corn stalks and dump them into the fertilizer bin. It would make my fertilizer go a lot farther, though since I’m taking something away from the soil — you know, the corn itself? — I’ll still need some.

    What so many people fail to realize is that there is, in fact, a closed system operating in a vacuum — the planet Earth itself. Its only interaction with the outside universe is absorption of radiation from the sun, and re-radiation of that energy into the cosmos. Matter, generally, never enters or leaves the planet. Where’s the carbon in those corn stalks coming from? The very atmosphere it’s vented to when you burn the corn stalks, of course!

    The “problem” of leftover corn stalks has been solved. Frankly, the guy comes off as just plain stupid — what, do you really think the first tribesmen to maintain patches of corn outside their mud huts didn’t at some point decide they have to deal with the stench of rotting corn stalks?

    As for the turkey guts, well, I’d have to see the article. A “honey-colored fluid” certainly isn’t oil, but it might still be useful if it can be refined into an engine-usable fuel, or even a lubricant. That said, I’m not gonna defend it. Yet.

    And I’m certainly not gonna defend flywheels. The only way it would work is to operate the flywheels in a vacuum, and building a vacuum vessel large enough to house a flywheel that can store a significant amount of energy without breaking apart, would cost way too much, and you would be able to see the vessel from space. Not to mention the astronomical energy cost of evacuating such a vessel. Could you make it work if you threw enough money at it? Oh, of course. Is it actually anywhere near practical? Of course not.

  7. roothorick says:

    And I know someone is gonna call me out on matter never entering or leaving the planet. Yes, I know, meteoroids occasionally hit the earth. But the number of things that actually make it through, without bouncing off, isn’t significant, and even then, it’s certainly not carbon. While that piece is flawed, the argument holds regardless.

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