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Continuous System For Converting Waste Plastics Into Crude Oil
rtoz writes: A MIT spinout company aims to end the landfilling of plastic with a cost-effective system that breaks down nonrecycled plastics into oil, while reusing some of the gas it produces to operate. To convert the plastics into oil, this new system first shreds them. The shreds are then entered into a reactor — which runs at about 400 degrees Celsius — where a catalyst helps degrade the plastics' long carbon chains. This produces a vapor that runs through a condenser, where it's made into oil. Much of the system's innovation is in its continuous operation (video). This company aims to produce more refined fuel that recyclers can immediately pump back into their recycling trucks, without the need for oil refineries. Currently, 2 trillion tons of plastic waste is sitting in U.S. landfills, so there is a huge demand for this technology.
Why even bother with the landfills? There are massive garbage patches floating around in the oceans, the vast majority of which are plastics. If you can get a big enough tanker and implement this system on it, you could probably cut the amount of fuel needed even further - the tanker goes into a garbage patch, melts all the plastic down, keeps the oil, and uses some of it to get back to land. It would probably be more effective than loading fleets of trucks.
I don't know how they define "cost effective", but since the plastic mostly came from oil in the first place, any energy expenditure to recover it is a net minus overall.
For an individual organization that can get a hold of a lot of landfill plastic cheap, this may be a win, but overall it is a fuel source with an energy return on investment (EROI) less than 1.
We're in trouble if we have to start resorting to this as an energy source. Deep trouble.
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The statement that there is 2 trillion tons of plastic in land fills got me wondering how much oil actually goes into producing something. From what I can gather a barrel of oil weighs about 300 pounds so if there aren't any other external inputs into making plastics that would mean that about 13 trillion barrels of oil have been turned into plastic. This doesn't seem the least bit right given that under 2 trillion barrels of oil have been extracted and not all of that went into making plastic. So how much oil actually goes into making plastic and how much is other stuff is use?
This leads me to my next question which is how much of the weight of the plastic is turned into oil? If it is over 1/6 of it then we have the equivalent of more than all presently extracted oil in our land fills already.
Time to offend someone
Pyrolysis for "recycling" plastic waste into oil (or tire waste into oil) has been around since at least the 1990s. The main problems are 2: A) As Irate Engineer states, a polymer is an "added value" and deconstructing polymers back to oil always fails economically when actual recycling to like-polymers is available, and B) as Itzy says, the comparative value of returning it to fuel, vs. leaving it in an Municipal Solid Waste to energy facility and burning it, is small.
I read TFA and cannot figure out what differentiates this from the pyrolysis "waste investments" of the 1990s, none of which really sailed.
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