(Following is a response to a post by John Dodge on his blog “Design Engineering at Large” on March 12)
Your comment reflects the same eco nonsense that has been one of the biggest problems in making real progress. I’ll never forget on the first Earth Day, a science teacher at Pollard Middle School in Needham, MA, said that all plastics should be biodegradable and he halted a groundbreaking polystyrene recycling project at the school. The facts: Plastics should not be biodegradable because waste should not degrade in a landfill. They’re anaerobic: no air and no oxygen – and very little soil for that matter. We don’t want waste degrading and polluting aquifers, or creating gas clouds.
Ditto the Earth People’s drive to stop use of plastic foam cups for coffee. Those extremely useful and environmentally benign foam cups were replaced with double-strength bleached cardboard that don’t provide adequate insulation. And their net environmental impact was significantly worse than the foamed plastics they replaced, which by the way contained no chlorofluorocarbons or other damaging additives.
So you think that “all plastics should be recyclable”. Well in the first place most plastics used in packaging are very recyclable. The ones that aren’t are designed that way for a very good reason: they serve a useful purpose such as multi-barrier food protection that would require a huge output of energy to preserve foods if they were not used. More plastics are not recycled because It makes no economic sense to do so and the amount of energy expended in their processing and logistics more than outweighs any theoretical benefit in their recycling. Plastic recycling makes sense if you have a pretty clean stream of like materials. Like PET or high-density polyethylene bottles. Replace with paper? Paper processing requires trees; it requires those trees to be taken to an energy-intensive processing plant, which uses lots of nasty chemicals like chlorine which have been dumped en masse into the Great Lakes. Those paper products don’t degrade in landfills either. And when they’re burned in incineration plants, the chlorine gives off chemicals similar to those discharged by PVC. When you burn a polyethylene container in a waste-to-energy plant, you get a fuel source better than coal – but without the sulfur.
Are you getting the drift John? This is a complicated issue. I have just touched the surface here. What we don’t need our simplistic pronouncements, like we used to hear all of the time from the Greenpeace types.
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