Why aren't we turning our plastic trash into energy?

In 2008, 85.8% of all of the plastic used in the United States ended up in a landfill. It wasn't reused or recycled, and it wasn't turned into energy. A new study from Columbia University says that turning landfill-bound plastics into energy instead would not only produce energy, but save money and the environment all at the same time.

Most plastics are petroleum products, which means that they're made from the same oil that we refine to turn into things like gasoline. There's a lot of energy locked up in there, and every time we throw away something made of plastic, we're losing out on a potential source of power.

Columbia University has put together a comprehensive report on just exactly how much plastic we waste, and it's staggering: the amount of non-recyclable plastics that ended up in landfills in the United States in 2008 is estimated to be on the order of 28.8 million tons. If all of this plastic could be converted back into oil, it would be the equivalent of 3.6 billion gallons, which is enough to fuel six million cars for an entire year.

While it's easy to talk about turning plastic back into oil in the abstract, is it possible to actually do it on a level that could make these gigantic numbers meaningful? The answer is a resounding "sort of."

There is a process called pyrolysis that can turn plastic into a liquid diesel-like fuel at an equivalent cost of about $45 per barrel, but it's still a relatively new technology that hasn't see widespread adoption. A more realistic way to go (in the short term) might be to just incinerate plastic waste in a powerplant, which could produce as much as 162 million MWh of electricity, enough to power 16.2 million households for one year.

Sounds great, but do we really want to be burning millions of tons of plastic? Isn't that a lousy thing to do to the environment? Again, the answer is "sort of." The idea is that burning plastics would take the place of burning coal, and if we turned 100% of our non-recyclable plastics into energy in this manner, we could avoid mining 27 million tons of coal and ten times that amount of other stuff that we'd have to mine just to get to the coal. And the other part of the equation is that plastic breaks down naturally in landfills, releasing greenhouse gasses anyway, and if we burned it instead, it would actually reduce greenhouse emissions by the equivalent of anywhere from 35 to 70 million tons annually.

So why aren't we doing all of these smart and efficient and eco-friendly things with plastic? One reason: laziness. In order for us to recycle plastics at this level, we first have to separate said plastics from all of our other trash and recyclables, and people just don't do it. Obviously, it's time to bring in the robots.

Study (*.pdf), via CNET

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