Forum, I read with great fascination recently, Robert Zubrin’s book The Case for Mars. I was particularly interested in the idea put forward in the book, where ethylene could be synthesised from the Martian atmosphere. Ethylene is a starting material for the manufacture of petrochemicals. It seems to be entirely feasible, that plastics could be produced on a substantive scale from the CO2 rich Martian atmosphere, if sufficient energy were available, in the form of a nuclear reactor.

Could this idea be used on earth I wonder, to produce plastics and fuels from the trace carbon dioxide in our atmosphere? In the current carbon critical climate, such a process would be highly desirable, but it would require vast amounts of energy. The raw material, carbon dioxide, is available everywhere on the globe. I suggest, that all we would need is a sufficiently powerful energy source with low impact both environmentally and economically to take advantage of this ubiquitous resource. Say, such a system was set up, utilising the geothermal energy that is available in volcanically active areas of the earth. Would this be an economically feasible way of producing fuels and plastics? And to what extent, could such a system contribute to offsetting the global warming crisis?

Photosynthesizing organisms already take atmospheric carbon dioxide and build bigger carbon molecules from it all the time, powered by solar power.

Of course, they tend to do silly wasteful things with it like grow and reproduce, but sufficient genetic engineering could produce photosynthesizing organisms that sacrifice growth and/or reproductive rates to divert as much carbon as possible into production of "excess" carbon compounds...

I would say it is possible, but very far from economically viable. You would need a lot of energy; you are basically taking the reaction of burning ethylene and oxygen, to produce water and CO2, and running it backwards. At the point that our power is that cheap to make the viable, we won't be burning fossil fuels for power anyway, so you could just use crude oil to make your ethylene.

Delvo is right, and this is basically the idea behind using plant matter (corn, for example) to make alcohols and other renewables. The advantage is your power is free (sunlight), but your efficiencies are low, and depending on whose numbers you believe, may be too low as a fuel source. But there is research going on about using plant matter to make plastics, for example.

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Martian windfarms?