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SSL (solid state lighting) is
youngest lighting technology and by now is believed to be more efficient than incandescence and fluorescence due to fact that SSLs produce light at or near visible part of spectrum and as a result emitted light can be used straight or with minor conversion. One of most important advantages is that SSL technology has eliminated damaging components from light sources (remember: light emitting diodes contain no ultraviolet unless they are produced as UV LEDs).
NASA is already using SSL in its space farming systems. The reasons are quite simple: incandescent or fluorescent lamps are not efficient enough for such purposes, because they consume a lot of electrical power, generate heat and contain electrodes that burn out (maintenance costs are high). This is why NASA’s plant physiologists started to work with light emitting diodes (blue and red) to grow salad plants such as lettuce and radishes. The researchers found our that blue and red light is essential for plant growth and, in general, a percentage of 8% blue LEDs and 92% red LEDs, both with same frequency and relative intensity per LED, are enough for a harmonious evolution. Blue has a smaller influence than red; however a percentage between 1% and 20% of blue light can be selected, depending on plants and their growth requirements. The NASA scientists have tried to create most cost and energy efficient light sources possible, and this is why they have eliminated from fixtures other colours normally found in white light. "What we've found basically is that we are able to limit amount of colour we give to plants and still have them grow as well as with white light." said research scientist Greg Goins of Dynamac Corp. LEDs are not only ones efficient for growing plants: sulphur microwave lamps are most efficient light sources known to man, that can generate as much light as noonday sun, perfect for illuminating large-scale systems such as greenhouses. For smaller applications, such as indoor gardens, LEDs seem to be right choice.
Pros and Contras LED Grow Light Systems
There are some pro and contras when it comes to LED grow light systems. When planning such farming alternatives, one has to carefully consider that plants do use light at all wavelengths from UV to IR, as explained above, needed to convert water and carbon dioxide into sugars. Some plants use more red and blue, less green and yellow, while others use green as much as they use red and blue, as well as light in between. If LEDs are chosen for brightness, there is one aspect to be underlined: they just look bright because their light is unidirectional and their size is small. To get enough light there are many LEDs needed, that’s why cost of LED arrays or LED modules is so high. LEDs can be calibrated to emit only light most efficient for plants, but not all light plants need. This is why such light sources are recommended only in places where direct light from sun is not enough or inexistent – space farming for example. Also in places where light from sun is too strong and can harm plants with high emission of UV, LEDs are a good choice, because UV filters are stopping some of useful wavelengths too. In wintertime weather conditions restrain crop production; this is why greenhouses need a substitute for natural light. It makes sense to deliver plants minimum lighting conditions for a corresponding evolution.
There are some significant factors to take into account when choosing light sources for such applications and these are low costs, energy efficiency, long life, and ability to withstand voltage fluctuations, modularity in order to grant users possibility to assemble arrays that gives as much light as needed, where needed. LEDs are pretty efficient in conversion of electric power to light, in any case more than traditional fluorescent and incandescent lamps. Due to fact that light emitting diodes can be manufactured to emit a specific wavelength and are expected to have a long life span (from 50000 hours up), many plant physiologists are considering using them in large applications. Compared to LEDs most of other traditional lamps have to be replaced every two-three years. Other features such as choice of viewing angles, control options, instant turn on times, cold start and much more, recommend semiconductor devices. At present this is still an expensive technology, but in time LEDs efficiency will be maximized while prices reduced and these details are a good base for future planning.
My-tronic GmbH to Produce LED Grow Light Systems on Request
It is so far clear that in order to produce efficient LED grow light systems a lot of investigation is necessary. It is not enough to mount some blue and red LEDs on a PCB and say: “that’s it; we’ve got plant growing LED system”. NASA created only a mechanism that delivers minimum amount of light needed for some plants. For greenhouses on Earth other questions need to be answered: how much blue, how much red? What about other colours, what about UV and IR? Should light pulse? Should it be dimmed in morning and evening to imitate natural conditions (sunrise and sunset?). Do plants need light at night? And list remains opened.
At my-tronic GmbH there are no plant physiologists, but only engineers ready to bring their technical expertise to scientists in order to build best light sources for LED plant growth systems. The domain is still new and can be considered a challenge for any researcher. Still my-tronic’s engineers know exactly which are LEDs’ limitations, what can be done with such devices and what not. And company’s motto: “bringing light in your lives” is also a statement of commitment to life and development.
Mihaela Lica started her career as a reporter for the National Romanian Radio Station, worked as a PR Referent in a bank, later used to work as a military journalist for the Romanian MoD and now she is the PR and Media Manager for the German company my-tronic GmbH.
