Wednesday, May 18, 2011

Save the Planet - Kill a Tree

Fermi Problem Friday Wednesday


Capturing carbon dioxide from the air would be a terrific way to reduce the causes of climate change, if we ever find a way to do it effectively. Then you could waste all the gas you wanted, leave the air conditioner on 24 hours a day, eat meat imported from halfway around the globe, and still sleep peacefully in your drafty house with single-pane glass and uninsulated attic. Sure you'd be throwing away lots of money, but that's your right, as long as you don't ruin the rest of the planet while you're at it.

Unfortunately, according to a study by the American Physical Society (note: Physics Central and Physics Buzz are produced by the APS), all the carbon capture technologies we know of are way too expensive to be useful today. Best estimates are that it would cost about $600 per ton to collect carbon dioxide from the air. Considering that the average US household produces 7.5 tons of carbon dioxide a year, that's $4500 every family would have to shell out every year just to cover their own emissions.

On the bright side (I think), it occurred to me that there are already plenty of living things that capture carbon dioxide, including all plants and trees. Trees in particular are mostly carbon, and often weigh a few tons at full size. All I'd have to do to be carbon neutral is chop down enough trees to equal my carbon load each year, then encase them in concrete and drop them in the ocean, or perhaps toss them into a defunct salt mine. As long as they don't rot and no one burns them, they will take a lot of carbon out of the air. I figure it could probably do that for a lot less than $600 per ton.

So, here's the gist of today's problem: is it feasible to grow, harvest, and permanently dispose of trees to pull carbon out of the air? For simplicity, I'm only going to worry about the average US household carbon load. I'll post my solution to the problem tomorrow. Stay tuned to find out if I've saved the planet!!

2 comments:

  1. Great cost benefit analysis of how expensive most carbon capture technologies available in the market. Creative thought on growing tree and sending it to the bottom of the ocean to store away the carbon. Why not make a house with the tree and use the stored carbon? What about the ecological impact of such practices?

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  2. Good point. There's no reason to bury the trees at sea, provided you make sure to use them in ways that ensure their carbon is not released. Maybe we could go back to the pre-plastic and aluminum days. Hula-hoops and frisbees made out of wood perhaps, city buildings built with timber instead of glass and concrete. Those all sound cool to me.

    But to make the Fermi problem simpler, I'm going to start by assuming the wood never gets used. If the numbers work out, then we can talk about useful ways it could be exploited, rather than wasted.

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