From Flickr Creative Commons - emilymcmc

I’ve briefly mentioned the Great Pacific Garbage Patch here before. It consists of a vast quantity of particulate plastic, floating in the middle of the Pacific Ocean (there’s similar ones in other oceans too).

There’s a lot of people out there who have come up with ideas for cleaning it up, including several with ideas to build floating islands out of recycled plastic.

I just came across something that might be easier and cheaper to implement.

There’s a substance called pykrete which is ice mixed with sawdust (or some other kind of fibre). You may have seen the episode of Mythbusters where they fired bullets at it (they bounced off) and then built a boat of the stuff.

Materials like pykrete can be made out of a wide variety of substances (in this case small bits of plastic) suspended in water and then frozen; the results can be stronger than concrete, and (obviously) lighter than water. The only problem is keeping it cold.

My idea is as follows:

• Build a mold in the shape of a pipe. Use plastic particles dredged out of the ocean and filtered pure water to make a pykrete pipe from the mold. The result will look like a PVC pipe (except colder).
• Freeze the pipe into the middle of a larger cube of pykrete.
• Join frozen blocks together so that the pipes connect.
• Attach a pumping station and refrigeration unit, and run low temperature brine through the pipes to keep the whole thing cold.
• The pumps can possibly be run by solar panels sitting on top.
• Once the platform is large enough (and thick enough), put on an insulating layer and top it off with a few meters of topsoil. Then build on it. Or plant crops.

I haven’t looked at this in detail, but I think it can be made into a self-sustaining system fairly easily, once the platform is large enough to support a water recycling system, a refrigeration unit, a pump, and something to power it all. I don’t think it would be particularly expensive to bootstrap a project like this either.

For reference: there’s estimated to be around 5kg of particulate plastic per square kilometer of water in the Gyre. A boat with a large dredge and a small water filtration system could make a few big blocks of pykrete per day. Within a few weeks, it might be possible to build a big enough platform to move all of the equipment over, and to continue operations from it instead.

UPDATE: This summer (2012) I’d like to try building a small scale model to see if this is feasible. Location would be a lake somewhere in Southern Ontario (if someone has a cottage that could work, please let me know). I’d be interested in hearing from anybody who wants to help out – particularly if they have access to a refrigerated shipping container.