Really, the answer is: We can't. There are no oil deposits to use in plastic creation. We can recycle plastics we bring to Mars with us, but with no major local sources, plastic making via petroleum will be prohibitively expensive. And, since we use plastics in pretty much everything, this is a pretty big deal. So, we need a functional replacement.
There are several potential replacements being developed by people who figure that Earth is going to run out of oil pretty soon, and be in a similar situation (which is true, and will make plastic alternatives, especially biodegradable ones, a pretty decent investment direction starting around 2020 or so, when rising oil prices make them the cheap alternative.) Let's look at these one at a time, and see if we can choose the best option.
One option is using mycelium. In this TED talk, Eben Bayer outlines a way to create new plastic-like materials. His company has developed a way to grow mycelium, which is basically mushroom roots, into a replacement for styrofoam, moldable into any shape, growable, and 100% compostable. It uses farm wastes like rice hulls and mulched corn husks for food, and the mycelium as a glue and polymer to provide shock or acoustical absorbency. It is fire resistant, light weight, and uses all materials with no waste, since it incorporates any un-eaten corn husks or whatnot into the structure of the end product. It makes great insulation, and they are even researching how to use this mycelium glue to replace things like particleboard and fiberboard, which are wood byproducts and thus won't be available on Mars for a long time after colonization. Really, one of the coolest companies I found, so check them out here!
It's cool, but not a complete solution. Styrofoam is only one style of polymer based material, and the process takes a bit more time and storage space than normal plastic manufacturing, since each product in a run requires a separate mold, and takes about five days to grow. That decreases turnover time, limiting capacity somewhat with regard to Earth bound use. But, on Mars, quantity won't be too important for the next hundred years or so, and mycelium has the added benefit of improving soil quality, meaning that littering with this stuff would actually help the colony out, rather than polluting. A further advantage is the fact that since this process involves growing fungus to fit a mold, the factory equipment involved is pretty simple (mulcher, cleaner, pasteurizer, and some way to mix in the fungus), and would not take up too much space on the colony ship.
So, these shrooms should definitely make the trip, but more is needed for the more diverse, high-tensile uses of plastics. You can't use Styrofoam to replace a heart valve, or as a microwaveable dish, or as the external shell of your laptop. So we look at other alternatives. One promising alternative is starch plastics, which are biodegradable, and can be worked into a wide variety of strengths and flexibilities, allowing them to substitute for most other types of plastic easily. The main drawback here is that they usually use high soil depletion food crops, such as corn, as the source of the starch. This is a double whammy on the new colony, because not only will using these crops to make plastic reduce the available food supply, growing this kind of crop in the first place will deplete nutrients from soil which is already in desperate need of enriching. Corn requires constant application of fertilizer or it will deplete soil in only a few harvests, and constant fertilizer is something that should not be counted on, on Mars. Other crops with lower soil impact will be preferable for the first few years.
The last option I want to explore is algae. Several US companies are already starting to create plastics out of algae, and although some of them use petroleum based additives the technology for pure algae plastic is not at all distant. Algae is cheap and easy to grow, hydroponic, which means it doesn't deplete soil nutrients at all, and inedible, so it doesn't have a tendency to drive up food costs on Earth, or make colonists on Mars choose between getting food or the container to put it in. It can be used almost exactly like starch to make plastics, with only slightly more processing, and can create the same wide variety of products. The one problem is that in its current incarnations, algae based plastics are not biodegradable; in other words, they are just like normal plastics. If we go to Mars, it would seem intelligent to live green from the very start, and thus never need to deal with the problems we made for ourselves on Earth. Of course, biodegradable algae plastics are not out of the question, and in fact are under development currently (see here to read more).
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| This is algae! It's your friend! |
Really, some combination of the three is likely to be the answer to the question of Mars plastics. Algae and mycelium will be needed just to fill out the biosphere, whether we make plastics out of them or not, and corn is a food crop that we should certainly bring along, even if we don't grow it for a few years while we build up soil quality (which is a whole issue in itself, to which I will probably devote an entry at some point). Mycelium manufacturing takes the least equipment, making it most economical, but the low variety of present uses is limiting, and I wouldn't really want to drink from a styrofoam cup made of fungus, even though it would probably be very safe.
Oh, yeah, and the algae factories apparently smell like a fish market. Ah well, that's the price you pay, I suppose.
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