The environmental pony

The Reality-Based Community: Biodegradability: Bug or Feature?

The second part has to do with what happens to the materials after use. For a piece of organic material (plastic, wood, fabric, etc.):, five futures are of interest:
-1.nothing (sitting forever in that landfill);
-2a. burning for usable energy (you can put lots of plastic into a boiler with other fuels directly, or process them into liquid fuel);
-2b. recycling (for example, turning old soft drink bottles into polyester fabric);
-3a.aerobic decay to CO2 and water, which is what happens to that potato-starch bag in the compost; and
-3b.decomposition and decay in anaerobic conditions, which generates methane, an especially nasty greenhouse gas (if you catch the methane and burn it for fuel, this is about equal to 2a). This is what happens in a landfill that’s airtight but isn’t kept dry inside.

Which is most green? If you care about carbon in the atmosphere, 1 is the winner, 2a and 2b are next, though if doing 1 instead of 2a just means more coal goes in the boiler, there’s no real gain, and if 2b requires a lot of fossil energy it may be even worse than 3a. So at least to a first approximation, simply “saving” organic materials indefinitely, which may be a very long time, perhaps until global temperatures are stabilized, is the best option, and this is best done by putting them into a dry, well-constructed, landfill.

Notice (my main point) that this ranking does not depend on how the object in question was made. Though biomaterial may be more green in creation than petromaterial, it doesn’t have any special claim to fate 3a. Biodegradability is better than having plastic junk floating around the ocean or sitting in the woods forever, but it’s a litter and wildlife and aesthetic strategy, and inferior to good housekeeping and landfilling.

Of course any strategy that releases carbon back into the atmosphere is inferior to strategies that sequester it. But given humanity’s past record in this regime, it’s important to consider what happens if we’re stupid as well as what happens if we’re smart. And for that, it seems that making stuff that biodegrades reasonably benignly if you treat it carelessly — and can still be sequestered if you want — is a good idea. (We also have to remember, of course, that collecting stuff and putting it in a purpose-built well-maintained landfill results in a fiar bit of emission as well, so that side of the process starts with a deficit that has to be overcome before you reach neutrality and net sequestration.)

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