Solar Power isn't Feasible!

Solar Power isn't Feasible!
This cartoon was on the cover of the book "SolarGas" by David Hoye. It echoes the Sharp Solar slogan "Last time I checked nobody owned the sun!"

Saturday, June 5, 2010

You can try this at home: Working toward the elimination of our plastic waste stream

Tonight I took some of our plastic grocery bag and plastic wrapper waste and put it in a small coffee can (with a stone for weight) and immersed it in the basket of my new stainless steel electric deep fryer (the kind with a thermostat for making french fries) set to 360 F. 45 minutes later, with no smoke or fumes or smell, all was melted down into a manageable recyclable product.

 The can in the fryer has holes punched in the bottom so that oil fills it; this keeps it stable on the bottom of the fryer and lubricates the melting plastic so that it doesn't stick to the can.

The end product is a hard block of plastic that can be cut, shaped, drilled and recycled. I make mine by scooping the plastic goop with two metal forks  from the can in the fryer into the cut end of a  discarded plastic bottle and letting it cool down. Because the plastic was melted in vegetable oil it does not stick to the container it is put in.  After it cools you pop it out.  The compressed blocks of recycled plastic bags float in water, but even if they found there way into the ocean (unlikely because they no longer get lifted out of garbage pits and landfills and streets and sewers by the wind) they would be unlikely to be eaten by wildlife as they no longer resemble jellyfish and they cannot entangle wildlife either. They would be much easier to remove from the environment too. But they could also be used as building blocks for all sorts of products, from bowls and plates to benches and manhole covers. One could conceivably create pressure molds for all sorts of products; a pressure mold would make a more uniform product.

It is "no duh" obvious, but until you try it yourself at home you don't really feel the impact in your bones where your whole mind-body complex says, "boy, this is such an easy way to eliminate plastic bag waste -- the scourge of cities like Cairo where plastic shopping bags have too low a resale value to be gathered for recycling and so end up floating around the city where they are sardonically called "Egypt's National Bird". But with the "deep fryer approach the volume can be safely and easily reduced and turned into a higher density product that can be accumulated and transported easily for resale, or can be put into molds to make bowls and other value added objects.

The trick now is to find a way to do the melting on a larger scale and to keep the oil at 360 F without consuming too much energy. One thought is to have submersible metal containers that you pack with plastic and place as inert "bricks" at the bottom of deep fryers that are being used to cook falafel or fried foods. One would, in effect, be "renting space" in the fryer, and the containers, while melting the plastic, might also help to keep the temperatures constant in the fryer (phase changes discourage temperature changes until the phase change is complete; does this apply to plastic too?)

Since the plastic would never touch the cooking oil, as it would be sealed in a metal container, there would be no worry about contaminating the cooking oil. We could also heat the oil with biogas, but having a thermostat that keeps the temp constant, so the plastic doesn't burn, would be trickier than with an electric deep fryer. My one worry about submersible containers is that as the plastic melts there would be expansion of gases so it would need a thin metal tube (which could be made into a handle) that let overpressure escape.

The beauty of this is simply proving to myself (and my family, who were skeptical, and made me do it on the porch) that melting down our plastic waste would produce no fumes or smells or dangers, would not catch fire, would not spatter, and theoretically could reduce our waste stream on a daily level. My next step will be to get a much larger deep fryer and go for larger quantities of plastic waste.
For more detailed instructions on "plastic smithing" using plastic bags, see this instructables:


Marcel said...

Nice one. Really liking this.

There's a big difference from doing this over an open fire as we've seen before. The challenge now, aside from upscaling as you say, is to find ways of moulding and up-cycling the resultant mass.

Well done. Thanks for sharing.

Colombo said...

Yeah! This is real cool. I did the same thing except I cooked it directly in the oil. I love the double boiler idea. I cut them into kids' building blocks and it was featured on Make: Magazine. Check out my original post here: