LED’s have been shown to be effective for all types of controlled environment agriculture, whether you run a greenhouse or indoor farm, grow annuals or hydroponic lettuce. The use of LED’s as supplemental greenhouse lighting and sole source lighting for indoor operations has received a great deal of press in recent years. They are efficient users of electricity. They don’t heat the surrounding air and growers can choose the color spectrum emitted.
The downside is that converting to LED’s can be expensive. What each grower needs to decide is if the upfront cost of conversion is worth future savings on the electricity bill, longer bulb life and potentially greater control over plant development. Results from three different studies on the performance of LED’s as grow lights are highlighted below. Links to case studies of grower trials is also shared as well as links to a number of lighting manufacturers who work with the greenhouse industry. Hopefully, the information provided will help you decide for yourself if converting in whole or part to LED lights is right for your operation.
According to a research report, LEDs for Energy Efficient Greenhouse Lighting, LEDs can provide many benefits to the greenhouse industry:
- Reduction in energy consumption up to 70% compared to traditional light sources.
- Fast switching and steady state operation.
- Simple electronic dimming function.
- Reduction of cable gauge (and hence cost and weight).
- High Relative Quantum Efficiency (RQE): Red light has the highest RQE, meaning it is the most efficient at photosynthesis. Blue light is about 70 to 75% as efficient as red light.
- Stable temperature inside the growth chamber and greenhouse.
- Ability to control spectral composition of blue, green, red, and far-red wavelengths.
- Reduction of heat stress on plants.
- Reduction in watering and ventilation maintenance.
- Lifetime, reliability, and compact size as the major technical advantages over traditional light sources.
Researchers from Purdue University tested LED’s as sole source lighting in a vertical growth room and as supplemental lighting in a greenhouse. They determined that the “… results of this study indicate that plugs grown under LEDs in a greenhouse are of similar or better quality than those produced under HPS or PL lamps. Additionally, our study demonstrates that bedding plant plugs can be effectively grown under sole-source LEDs in multi-layer, vertical growth rooms without negatively impacting the finished quality of the five species we tested.”
A third study, Economic Analysis of Greenhouse Lighting: Light Emitting Diodes vs. High Intensity Discharge Fixtures, concludes that “the most efficient HPS (High Pressure Sodium) and LED fixtures have equal efficiencies, but the initial capital cost per photon delivered from LED fixtures is five to ten times higher than HPS fixtures. The high capital cost means that the five-year cost of LED fixtures is more than double that of HPS fixtures. If widely spaced benches are a necessary part of a production system, LED fixtures can provide precision delivery of photons and our data indicate that they can be a more cost effective option for supplemental greenhouse lighting.”
LED use in greenhouses and indoor farms is still in its early days and maximizing the effects of artificial light is still not an exact science. As Rebecca Knight from Illumitex wrote in a recent blog posting “What this means is that although we can calculate the cost, efficiencies, and mechanical aspects of lighting; it’s modeling the effects of light on the end product (which is living) that is much more challenging.”
Case StudiesHort America’s, a certified partner of Phillip’s Lighting, have posted many case studies of both flower and vegetable growers who trialed LED’s in their growing operation. Find out what their experience has been. An article in Greenhouse Grower references a number of grower experiences with LED’s. Or watch this video of Tangletown Gardens’ yearlong trial comparing LED’s to High Pressure Sodium lights.
If you are thinking of trying out LED lights in your growing facility, consider looking into federal and state grant programs to help finance the conversion. The USDA manages the Rural Energy for America Program which provides grants and loans to “agricultural producers and rural small businesses to purchase or install renewable energy systems or make energy efficiency improvements.” Be warned. The application process is extensive and will require a tremendous investment of time. Illumitex, the LED lighting manufacturer, will provide customers with assistance on the application.
To find out what programs are available in your state, visit the Database of State Incentives For Renewables and Incentives®. The state of Massachusetts, for example, offers a number of programs to help farmers become more energy efficient. The U.S. Small Business Administration also provides a state by state list of state and local energy efficiency programs.
These manufacturer’s of LED’s are marketing specifically to greenhouse and indoor growers.
Choosing which lighting system to use in your growing operation requires consideration of a number of factors. Cost is just one of them. At this point, many growers have trialed LED’s so take comfort in knowing others are blazing a trail. Take the time to do some research, talk with more than one lighting manufacturer, talk with other growers. Trial LED’s in your own operation before making the leap to a complete conversion. Then blaze your own trail!