Carbon Sequestering Sculptures

I recently realized that I wasn’t taking full advantage of how the Maker community has expanded over the past few years and the fact that there are tons of DIY contests running all the time.  After browsing around a bit, I decided that I wanted to try to enter the Instructables 3D Printing Contest.

I wanted to create an entry that was simple, didn’t require any custom parts/electronics aside from the 3D printed pieces, and was a little outside my current knowledge base.  With those criteria in mind I decided try to combine my interests in 3D printing, environmentalism, and carbon sequestration technologies.  Since ugliness is an argument often used against wind turbines and other green tech, I wanted to try and create something both pleasant to look at and beneficial to the environment.  I ended up trying to design a sculpture that also sequestered atmospheric carbon (CO2) using cyanobacteria.

Since I already had some transparent PLA filament lying around, I designed a simple, hollow sculpture with thin walls (~.5mm) to maintain a high transparency in order to let the rich green color of the algae show through and provide the algae with enough sunlight to live off of.

twist
An OpenSCAD rendering of a simple hollow sculpture.

Since the algae feed off CO2 from the air, the container couldn’t be too deep or too narrow, otherwise the algae at the bottom wouldn’t receive enough air and would die off.  This could be solved by buying an aquarium air bubbler, but I wanted to keep the project as simple as possible.

2015-07-06 21.11.12

For the algae, I decided to use Spirulina because I found a handy growing kit for it.  The kit arrived in the mail, I followed the instructions, and soon I had my very own algae cluster growing!

Printed simple sculpture
Printed simple sculpture

With the algae ready for transplantation I printed out my sculpture/container design.  Once the sculpture was printed, however, I started running into problems.  It seems that when the walls of the container are thin enough to remain mostly transparent, they’re also too thin to be waterproof!  After filling up the container (luckily I tested it with tap water first), little droplets immediately started seeping through the gaps between the print layers.

2015-07-06 21.02.21

In an attempt to compensate for this, I tried using a transparent coating to seal up the holes but maintain transparency, but as is visible in the above photo, with the 3-5 coats necessary to prevent leaking, the sculpture was more opaque than I would have liked.

So while the project ultimately didn’t pan out, I learned some useful things about 3D printing:

  • PLA is difficult, if not impossible, to waterproof
  • Transparent filament isn’t actually that transparent using FDM printers, though it would be good for light diffusion

And I got to go a little more outside my comfort zone and learn some things about algae and biological processes.

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2 thoughts on “Carbon Sequestering Sculptures

  1. My experience of growing algae (to feed Daphnia to feed fish) is that if you bubble them with a stone, there is soon sufficient protein or other surfactant in the water to make a foam. I eventually worked out how to make a large single bubble every minute or so which was sufficient to keep the algae from settling out. I used a large demi-john of the sort that is sold for wine making.
    Also many algae will stick to surfaces so after time you would likely have film on the inner surfaces of tubing or sculpture.

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