GF-DEKA’s Transparent PVC Tubes for Growing Micro-algae
Industry is searching for efficient ways to absorb carbon dioxide (CO2) regarded as one of the major causes of global-warming. Carbon capture and storage is one way. Another is to use the power of the sun and some living organisms like micro-algae to create photo-bio-reactors that can lower the concentration of this particular greenhouse gas.
A few years ago the industry developed a system where specific algae are grown in transparent tubes. These algae are fed with the flue gas of, for example, a fossil-fueled power plant producing large amounts of CO2.
These organisms use sunlight for photosynthesis, just as leaves do, and "eat" the CO2 fed to produce biomass. The algae grown can then be transformed into bio-fuel or nutrient aids or other useful materials.
But how to make it all more efficient? GF-DEKA developed a more affordable and reliable process presented publicly this year.
The algae need the right quantity of light (the tube has to be very transparent) and the right wavelength of light (the right colour: not too much UV, these could kill the algae, nor too much IR radiations, these would bring too much heat).
These optimal growing conditions could be realised by incorporating the right pigments to the PVC tube material to make sure the pipe wall will transmit the right colour.
‘’PVC is the transparent polymer with by far the best cost-performance ratio,’’ says inventor Stefan Schuessler.
Stefan likes to play electrical guitar and compares the selection of the right wavelengths of light with mixing the sound from his guitar.
‘’With my guitar, I reduce or increase some ranges of wavelengths to get the right quality of sound,’’ says Schuessler. ‘’With the tubing, you don't optimise the sound but the colour, using pigments.’’
Inside the tubular reactor the nutrients and the CO2 need to be correctly mixed and fed to the microorganisms. The solution: triangle-like tubing with a different orientation as you move along the pipe, giving the so-called "static mixer" behaviour. This particular shape is given by the extrusion process of the PVC tube with a special technology.
Finally, as the total length of tubes of a photo-bio-reactor can reach several kilometres, the tubing system should also be economical and lightweight and this is also made possible by the fact that these particular PVC pipes have very thin walls. They can be installed flat on the floor or vertically, for instance on the north wall of a greenhouse.
The produced biomass can afterwards be converted into several high value products such as food additives, animal feed, pharmaceuticals, cosmetics, specialty chemicals (e.g. beta carotene or omega-3 or omega-6 essential oils) and many others.
The technology described here should make the installation and maintenance of such photo-bio-reactors much less expensive than the conventional systems. Easier on the budget, better for the planet!
