LED lighting for submersible tubeThe “Photon Injector” is a system where two distinct wavelengths of light energy supplied by LED emitters are mounted at one end of a suitable optical tube which is later submerged into the algae growth medium.

Note the purple color emitted by the Photon Injector.  Blue and Red wavelengths are combined to simultaneously stimulate both photo-reaction centers, in this case, to stimulate the Chlorophyll-a molecules present in the photo reaction centers of the algae.

The Photon Injector shown here uses an acrylic tube sealed at one end.  At the other end (Top End) an array of LED is fabricated to fit with the LEDs facing down into the tube.  At the bottom of the tube a mirror is fixed to back reflect any photons which have not exited the tube.  The LED array at the top of the tube is formed from waterproof electrical and mechanical fittings which assist in keeping moisture out of the inside of the tube.  The tube acts as a conduit for the photons to travel down the tube, and also as a diffusing element which allows photons to exit the tubes at many different angles.  Algae have chloroplasts all over the outside surface of the cells.  These chloroplasts are the optical conduit which begin channeling energy from the absorbed photons by the primary and accessory pigments such as Chlorophyll-a which are present.

LED light sources offer great thermodynamic efficiency which is important for commercial growers.  The important aspect of LED lighting for algal growth is close control over three factors:  wavelengths, intensity, and duration.  Each of these parameters will guide the application of LED lights.  LEDs can be deployed for algal growth by building apparatus which either irradiate your algae from within the growth vessel (photobioreactor), or from an external source, or a combination of both.

Photons entering a water body from the surface (such as with natural systems with the sun’s diurnal pattern of rising and setting, changing in length of day and average intensity with the changing seasons), are either absorbed, or scattered (Diffusion).  Particles within the water column, either natural or man-made, either naturally occurring or synthetic of all sizes will either absorb photons, or diffract them scattering them (called normalizing) through the water.

Algae have photo-reaction centers (chloroplasts) which in the case of green algae are present all over the outer surface of the algal cell.  These photo-reaction centers perform the actions of capturing photonic energy of proper wavelengths from incident light (either natural or artificial in source), and absorb those photons (445 nm and 645 nm peak response in Chlorophyll-a) which “resonate” when stimulated with these specific wavelengths.

A commercial incentive for cultivating Algae as a feedstock recognizes that natural sunlight contains a “spectrum” of biologically useful wavelengths called Photosynthetically Active Radiation (PAR) which ranges from 400 nm to 700 nm.  Interesting, that within the vast and broad spectrum of electromagnetic-radiation, life uses a very available fraction, less than one Octave.  And, of this narrow spectrum of photons which penetrate the atmosphere, only a small fraction is photosynthetically ideal to primary pigments like Chlorophyll-a, which produce the majority of Oxygen and base-nutrition which keeps the entire biosphere, including us, alive.

It’s this small actual fraction of sunlight which is needed for growing plants which draw Algal Farmers to using LED lighting sources.  Thermodynamically, LED’s pack a punch for using only the energy required at high efficiency to stimulate photosynthesis, and therefore, algal growth.

Contact Toby Kinkaid info@solardyne.com


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