Saturday, February 18, 2012

The electric slide

I occasionally borrow a hand-cranked generator from the physics folks a floor below. It's a very simple device, exquisitely crafted by someone likely dead now. It should work well for another hundred years.

It's simple, and makes the concept of "generating" electricity accessible. If you spin a coil of copper inside a magnet, you push electrons. (You do not, of course, create these electrons anymore than you create the magnets or the wire.)



If you put some resistance in the path of these electrons, say, a light bulb, you need to crank much harder to spin the coil. Again, you can feel this. You are converting mechanical energy into something that "pushes" back.

It takes a fair amount of force to brighten up a reasonably sized bulb.

If a child learns nothing more than this, that to "create" electricity requires a push, that it's not magic, that you don't get electricity for nothing, she's a step ahead of most adults.
***

When I crank on the generator, I breathe a little harder as my muscle cells are called on to work. My cells burn up organic molecules, breaking down into carbon dioxide, using oxygen to catch the remnants of these molecules, spent electrons, in the depths of my mitochondria.

When I crank on the generator, the concentration of carbon dioxide in my room rises a tiny bit--the same carbon dioxide implicated in global warming.

When I crank on the generator, my muscles warm up a little bit--when I convert chemical energy into mechanical, I am less than 100% efficient. The heat I lose no longer serves me.

When I crank on the generator, I make energy increasingly less useful, energy captured as bonds by plants, now released as mechanical energy by me, so I can see photons emitted from the lamp. It took a bucketload of sunlight to produce a thimble's worth of incandescence.

A young child does not need to know any of this to know that generating electricity requires a push, and that the more electricity you need, the more push you must provide.
***

I remember learning about electric generators--it was a classic mid-20th century 16 mm film, moving images of the Hoover Dam with a sonorous male (always male) voice extolling our  country's technological virtues.My brain whirs with the clickety-ckickety of a 1963 projector when I think of dams. Children are that impressionable....

A huge dam with huge turbines generated huge amounts of electricity. Somehow that juice got to the wall. It cost nothing because rivers were meant to be damned.

In junior high, my class visited the Oyster Creek nuclear plant, and again we learned about huge turbines generating huge amounts of electricity, clean energy, so safe school children wander within yards of a nuclear reactor.
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Turns out most electricity generated in the States comes from burning coal, a process remarkably similar to the way I extracted energy from last night's clams. Oxygen strips off electrons from unstable organic molecules, coal and clams to carbon dioxide and water. I do it in a lot more steps, or else I'd spontaneously combust, but the end result is the same. The universe has smaller, more stable molecules, and useful work can be done.

Either way, something had to put the unstable molecules together in the first place. Both coal and clams rely on the nuclear furnace just under 100 million miles away, both coal and clams rely on plants to do this. You don't get something for nothing in the natural world.
***

This is a Chevy Volt. It is an electric car.


You can plug it into your wall and pretend it's green. Or you can start thinking about where things come from, where things go.

If giant hands holding up the Earth assuage whatever feelings you might have as we plunder the planet, then we get the planet we deserve. Nothing comes from nothing.


 GM is depending on your ignorance (and your guilt) to shell out over $30,000 for a car.Before you do, come on by B362, and I'll let you crank on our class generator for a bit.


You're an adult now--time to give up magical thinking.






We can argue about the efficiency of coal-generated generating plants vs. gasoline engines, about the relative costs of charging a car during peak or off hours, about the carbon cost of making huge batteries, about the break point (likely around 80k miles) where a Volt may be greener than your Daddy's Oldsmobile, about the risks and benefits of dams, of nuclear rods, of dams, of wind, of solar, of tidal generators.

And these could be interesting discussions....

If you don't believe in magic




First photo from Old Pinawa self-guided tour online brochiue here


8 comments:

Sue said...

Two thumbs up! Can I borrow this to share with my physics class?

I also wanted to send my condolences on the ginko tree. There was a beautiful ginko tree where I went to college. I remember holding my breath as I walked past but also the beautiful yellow leaves in the fall.

John T. Spencer said...

I always wonder about another side effect of embracing the green machine: if something feels "green" then it seems one is more likely to use it as if it truly is sustainable. Drive a gas guzzler and you think about fuel effeciency. You don't go overboard on how often you drive - both due to the social and economic forces behind this. Yet, drive a Volt or a Leaf or whichever monosyllabic trendy green car you choose and it seems like there would be less of a sense of conservation in daily habits.

For what it's worth, I went back to riding my bike for awhile - until someone broken into our garage and stole my bike. I'm not sure if my calories are energy-effecient, but I'm pretty sure that when I ride a bike I have a better sense of what's pushing it forward beyond magic.

John T. Spencer said...

Oh, and I feel like I should add the words "boogie woogie woogie."

Anonymous said...

We don't reduce pollution, we merely change where the pollution is generated. Asking questions such as "where does the hydrogen come from? Where does the electricity come from?" has me labeled as a cranky naysayer. As long as "someone else" has to deal with the pollution and byproducts, the vast majority of the population does not seem to care. They have not yet integrated into the global spaceship.
And as a further crank, I include: what happens when we take energy out of the wind, the waves, the tide,and convert it into energy (and heat)? What happens when we capture sunlight that used to reflect back from the surface and instead turn it into energy (and heat)? There is no free lunch.

doyle said...

Dear Sue,

Of course--all CC, all the time.


Dear John,

Boogie woogie woogie indeed. Bicycles may be the greatest machine ever invented.

As always, thanks for your thoughts.


Dear Anonymous,

The Law of Conservation of Mass/energy is no joke. Thanks for dropping by, whoever you may be....

Jeffrey Michals-Brown said...

Love your generator and lightbulb for getting kids an intuitive "feel" for energy. The electric car thing is interesting. I understand that it puts out less CO2 per mile than most cars, even if charged entirely by coal-fired plants--though it's a close race. But putting a lot of them on the road will require a big increase in generating capacity. And charging the things at night when rates are lower paradoxically means burning more coal for the purpose than if doing it during peak hours, since the clean but expensive gas-fired plants only come on line when demand is higher. One further thought: getting all the SUV drivers into ordinary compact cars would make a much bigger difference to CO2 emissions than getting the compact car drivers into hybrids--that's the bigger difference in fuel economy. Anyway, since my little Corolla (I love my manual transmission) gets almost the same mileage on my highway commute as a Prius, I'm not giving it up just yet.

Dani said...

Thank you! I keep trying to explain this "simple" fact to those ignorant adults around me that insist it is a "green" way to go!
So glad I am not alone in my thoughts.

doyle said...

Dear Jeffrey,

The CO2 generated breakpoint is fun (in a geeky way) to try to calculate, but I agree that it will be slim, and that reducing the mass we're accelerating will ultimately prove far more beneficial than sliding over to a hidden source of energy.

Cars should be reserved for hauling things more than half your body weight, or for distances more than two miles. (Heh, how's that for arbitrary!)

Thanks for your words.


Dear Dani,

It's frustrating, no? Even those of us on the side of the angels need to think....