scholarly journals Academic Research Perspective of LEDs for the Horticulture Industry

HortScience ◽  
2015 ◽  
Vol 50 (9) ◽  
pp. 1293-1296 ◽  
Author(s):  
Cary A. Mitchell
Keyword(s):  
Energy Savings ◽  
Technology Development ◽  
Light Emitting Diode ◽  
Academic Research ◽  
Sole Source ◽  
Systematic Research ◽  
Light Emitting ◽  
Research Perspective ◽  
Specialty Crop ◽  
Research And Education

Following is the invited perspective of an academic researcher and director of a multi-institutional research and education project tasked to test the feasibility of adopting light-emitting diode (LED) technology for application by the commercial horticulture industry. Academics researching basic specialty-crop responses to spectra, intensities, and durations of lighting with LEDs often find technical queries from growers, vendors, and entrepreneurs to go beyond the capabilities and scope of systematic research to answer definitively. Differences between commercial and academic research approaches to LED technology development are noted, including legal obstacles to open collaboration. Early generation commercial LED technology for horticultural applications is based on research begun >20 years ago. The basis for selection of various LED wavebands for inclusion in LED plant growth arrays is presented for both commercial as well as research applications. Advantages of light distribution from LED sources for different crop applications are presented, especially including close-canopy and intracanopy lighting, both of which contribute substantially to energy savings. Challenges to providing accurate LED light prescriptions for different crops are discussed, including those for supplemental lighting as well as for sole-source lighting applications. Anticipated trends are projected for horticultural applications of LED technology, including multispectral, individually adjustable, high-intensity arrays; increasing electrical efficacy of future LEDs; and reduced costs of mass production for particular applications.

scholarly journals Increased Plant Quality, Greenhouse Productivity and Energy Efficiency with Broad-Spectrum LED Systems: A Case Study for Thyme (Thymus vulgaris L.)

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 960
Author(s):  
Jenny Manuela Tabbert ◽  
Hartwig Schulz ◽  
Andrea Krähmer
Keyword(s):  
Broad Spectrum ◽  
Energy Savings ◽  
Light Emitting Diode ◽  
Thymus Vulgaris ◽  
Light Spectrum ◽  
Light Emitting ◽  
Biomass Yields ◽  
Lighting Systems

A light-emitting diode (LED) system covering plant-receptive wavebands from ultraviolet to far-red radiation (360 to 760 nm, “white” light spectrum) was investigated for greenhouse productions of Thymus vulgaris L. Biomass yields and amounts of terpenoids were examined, and the lights’ productivity and electrical efficiency were determined. All results were compared to two conventionally used light fixture types (high-pressure sodium lamps (HPS) and fluorescent lights (FL)) under naturally low irradiation conditions during fall and winter in Berlin, Germany. Under LED, development of Thymus vulgaris L. was highly accelerated resulting in distinct fresh yield increases per square meter by 43% and 82.4% compared to HPS and FL, respectively. Dry yields per square meter also increased by 43.1% and 88.6% under LED compared to the HPS and FL lighting systems. While composition of terpenoids remained unaffected, their quantity per gram of leaf dry matter significantly increased under LED and HPS as compared to FL. Further, the power consumption calculations revealed energy savings of 31.3% and 20.1% for LED and FL, respectively, compared to HPS. In conclusion, the implementation of a broad-spectrum LED system has tremendous potential for increasing quantity and quality of Thymus vulgaris L. during naturally insufficient light conditions while significantly reducing energy consumption.

Current Status of GaN-Based Solid-State Lighting

MRS Bulletin ◽  
2009 ◽  
Vol 34 (2) ◽  
pp. 101-107 ◽  
Author(s):  
Shuji Nakamura
Keyword(s):  
Continuous Improvement ◽  
Charge Separation ◽  
Energy Savings ◽  
Light Emitting Diode ◽  
Current Status ◽  
Light Emitting ◽  
White Leds ◽  
Semipolar Gan ◽  
Near Future ◽  
Nonpolar Gan

AbstractThe continuous improvement in luminous efficacy of “white” light-emitting-diode (LED) sources offers the potential of considerable energy savings in general lighting applications. Recent experiments at UCSB have demonstrated 117 lumens per watt (lm/W) in white LEDs, with further improvements expected in the near future. Considerable progress has also been achieved using nonpolar GaN, such as a-plane {1120} and m-plane {1100} GaN, or semipolar GaN substrates. Such devices avoid the deleterious effects of charge separation due to spontaneous and piezoelectric polarization inherent in most c-axis-oriented devices.

scholarly journals Comparison of Intracanopy Light-emitting Diode Towers and Overhead High-pressure Sodium Lamps for Supplemental Lighting of Greenhouse-grown Tomatoes

2013 ◽  
Vol 23 (1) ◽  
pp. 93-98 ◽  
Author(s):  
Celina Gómez ◽  
Robert C. Morrow ◽  
C. Michael Bourget ◽  
Gioia D. Massa ◽  
Cary A. Mitchell
Keyword(s):  
High Pressure ◽  
Energy Consumption ◽  
Energy Savings ◽  
Light Emitting Diode ◽  
Significant Proportion ◽  
Fruit Production ◽  
Light Sources ◽  
Node Number ◽  
Light Emitting ◽  
Supplemental Lighting

Electric supplemental lighting can account for a significant proportion of total greenhouse energy costs. Thus, the objectives of this study were to compare high-wire tomato (Solanum lycopersicum) production with and without supplemental lighting and to evaluate two different lighting positions + light sources [traditional high-pressure sodium (HPS) overhead lighting (OHL) lamps vs. light-emitting diode (LED) intracanopy lighting (ICL) towers] on several production and energy-consumption parameters for two commercial tomato cultivars. Results indicated that regardless of the lighting position + source, supplemental lighting induced early fruit production and increased node number, fruit number (FN), and total fruit fresh weight (FW) for both cultivars compared with unsupplemented controls for a winter-to-summer production period. Furthermore, no productivity differences were measured between the two supplemental lighting treatments. The energy-consumption metrics indicated that the electrical conversion efficiency for light-emitting intracanopy lighting (LED-ICL) into fruit biomass was 75% higher than that for HPS-OHL. Thus, the lighting cost per average fruit grown under the HPS-OHL lamps was 403% more than that of using LED-ICL towers. Although no increase in yield was measured using LED-ICL, significant energy savings for lighting occurred without compromising fruit yield.

scholarly journals Using Movable Light-emitting Diodes for Electricity Savings in a Plant Factory Growing Lettuce

2014 ◽  
Vol 24 (5) ◽  
pp. 546-553 ◽  
Author(s):  
Kun Li ◽  
Qi-Chang Yang ◽  
Yu-Xin Tong ◽  
Ruifeng Cheng
Keyword(s):  
Energy Savings ◽  
Light Emitting Diode ◽  
Electricity Consumption ◽  
Light Emitting ◽  
Light Utilization ◽  
Lettuce Growth ◽  
Left And Right ◽  
Plant Yields ◽  
Butterhead Lettuce ◽  
Main Factor

In this study, the effects of light-emitting diode (LED) panels with different illumination schedules and mounted above butterhead lettuce (Lactuca sativa var. capitata) seedlings on lettuce growth and photosynthesis were examined, and the performance of the vertical and horizontal movable system on energy savings was evaluated. The illumination schedules used were fixed LED [F-LED (four LED panels illuminated the area below)] and movable LED [M-LED (two LED panels moved left and right once per day to illuminate the same area as F-LED)] at distances of 10 and 30 cm above the seedlings. The plant yields were uniform in all LED treatments. The highest light utilization efficiencies and lowest electricity consumption were found for the treatments with irradiation from a shorter distance above the seedlings. The true leaf numbers and ascorbic acid concentrations were the highest in the M-LED and F-LED treatments at a distance above the seedlings of 10 cm, while the leaf lengths and sucrose concentrations in these groups were significantly lower than those in the 30-cm treatment. These results indicate that illumination with M-LED can halve the initial light source input while maintaining yield and that sustained illumination from a shorter distance above the seedlings is the main factor in electricity savings.

LED life prediction based on lumen depreciation and colour shift

2016 ◽  
Vol 49 (1) ◽  
pp. 84-99 ◽  
Author(s):  
AN Padmasali ◽  
SG Kini
Keyword(s):  
Life Prediction ◽  
Energy Savings ◽  
Light Emitting Diode ◽  
Light Output ◽  
Light Sources ◽  
Colour Stability ◽  
Light Emitting ◽  
Colour Temperature ◽  
Life Estimation ◽  
Chromaticity Coordinates

Light emitting diodes, with advantages in energy savings, luminous efficacy and greater reliability, are becoming preferred over conventional white light sources. Currently, only light output depreciation is considered for life estimation of light emitting diode luminaires but it is recommended to include colour shift variations for applications demanding colour stability. In this paper, an extended Kalman filter is employed to determine L70 life and colour temperature degradation over life of a light emitting diode luminaire. The colour shift in terms of Duv is determined by statistical polynomial cure fitting. The variation in chromaticity coordinates over life is determined and life based on colour shift is determined by acceptable Duv limits. The results are compared to life determined by the IES-TM-21 method and the correlated colour temperature limits taken from the luminaire data sheet.

scholarly journals Competing in the Global LED Industry: The Case of Taiwan

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Yu-Shan Su
Keyword(s):  
Value Chain ◽  
Economies Of Scale ◽  
Energy Savings ◽  
Light Emitting Diode ◽  
Economies Of Scope ◽  
Value Chains ◽  
Light Emitting ◽  
International Firms ◽  
Industrial Value Chain ◽  
Optimal Efficiency

Light-emitting diode (LED) is a very essential application for energy-savings nowadays. The revenue of the Taiwan LED components industry is ranked top one in the world, followed by that of Japan and South Korea. Based on the advantage of their electronics industry, Taiwanese LED companies create a unique model to compete with the international firms. Large international LED companies achieve economies of scale by vertically integrating their operations. Taiwanese LED companies specialize and achieve an optimal efficiency by vertically disintegrating across the upstream, midstream, and downstream sectors in the value chains. Taiwanese LED companies create economies of scale and economies of scope through a complete industrial value chain.

scholarly journals Findings from a Pilot Light-Emitting Diode (LED) Bulb Exchange Program at a Neighborhood Scale

2019 ◽  
Vol 11 (14) ◽  
pp. 3965 ◽  
Author(s):  
Sadie M. Witt ◽  
Shelby Stults ◽  
Emma Rieves ◽  
Kevin Emerson ◽  
Daniel L. Mendoza
Keyword(s):  
Energy Efficiency ◽  
Low Income ◽  
Power Plants ◽  
Energy Savings ◽  
Salt Lake ◽  
Light Emitting Diode ◽  
Pilot Project ◽  
The United States ◽  
Light Emitting ◽  
Neighborhood Scale

In the United States, 44% of low-income households struggle to pay their utility bills, affecting their ability to afford necessities such as food and health expenses. There is a high demand for, but low availability of, energy efficiency services in underserved neighborhoods, creating an opportunity for community-based programs to fill this inherent gap. This pilot project aims to bring energy savings and education to a uniquely targeted portion of Salt Lake City, UT, through the exchange of light-emitting diode bulbs and examines its feasibility in addressing energy insecurity at larger scales. Through the 8-month project duration, 1432 bulbs were exchanged at 23 events reaching 181 households in low-income areas that, through a year of use, were estimated to save residents approximately $18,219 in electricity bills, reducing CO2 emissions from power plants by 122 metric tons. Since this pilot reached less than 1% of households, we extrapolated a reach of 2%, 5%, and 7.5%, and found substantial potential decreases in power plant emissions and financial savings. Ongoing expansion efforts include more direct engagement with trusted members of the targeted communities and stronger attempts to engage participants in energy efficiency education as our project encountered some difficulties in reaching the intended population.

scholarly journals Who will win the future of display technologies?

2018 ◽  
Vol 5 (3) ◽  
pp. 427-431 ◽  
Author(s):  
Hepeng Jia
Keyword(s):  
Technology Development ◽  
Liquid Crystal Display ◽  
Light Emitting Diode ◽  
Associate Editor ◽  
Production Costs ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Technology Leader ◽  
Display Technology ◽  
Lower Production

Abstract In recent years, China and other countries have invested heavily in the research and manufacturing capacity of display technology. Meanwhile, different display technology scenarios, ranging from traditional LCD (liquid crystal display) to rapidly expanding OLED (organic light-emitting diode) and emerging QLED (quantum-dot light-emitting diode), are competing for market dominance. Amidst the trivium strife, OLED, backed by technology leader Apple's decision to use OLED for its iPhone X, seems to have a better position, yet QLED, despite still having technological obstacles to overcome, has displayed potential advantage in color quality, lower production costs and longer life. Which technology will win the heated competition? How have Chinese manufacturers and research institutes been prepared for display technology development? What policies should be enacted to encourage China's innovation and promote its international competitiveness? At an online forum organized by National Science Review, its associate editor-in-chief, Dongyuan Zhao, asked four leading experts and scientists in China.

scholarly journals Light emitting diode (LED) use in artificial lighting for broiler chicken production

2014 ◽  
Vol 34 (3) ◽  
pp. 422-427 ◽  
Author(s):  
Mayara R. de Santana ◽  
Rodrigo G. Garcia ◽  
Irenilza de A. Naas ◽  
Ibiara C. de L. A. Paz ◽  
Fabiana R. Caldara ◽  
...  
Keyword(s):  
Weight Gain ◽  
Feed Intake ◽  
Broiler Chickens ◽  
Energy Savings ◽  
Light Emitting Diode ◽  
Carcass Weight ◽  
Feed Conversion ◽  
Carcass Yield ◽  
Light Emitting ◽  
Artificial Lighting

Light emitting diode (LED) has been used in commercial poultry industry by presenting superior energy savings and providing feasibility on production process. The objective of this research was to evaluate performance and carcass yield of broiler chickens exposed to different LED colors compared with fluorescent lamps. For that, two experiments (E1 and E2) were performed and 2,646 Cobb® chickens were used. In experiment E1, male birds were exposed to 20 lux artificial lighting with red, yellow, blue, and white LED bulbs; and fluorescent bulb. In experiment E2, male and female birds were exposed to 15 lux artificial lighting with red and blue LED bulbs; and fluorescent bulb. Cumulative weight gain (kg), feed intake (kg), feed conversion, hot carcass weight (kg), carcass yield (%), and breast and thigh + drumstick yield (%) were used as response variables. Results showed no difference (p > 0.05) among treatments for performance, carcass yield, and cut yield in experiment E1. In experiment E2 there was only difference between genders (p < 0.05) and males showed higher total weight gain, feed intake, hot carcass weight and thigh + drumstick yield. Different LED color use had same effect as fluorescent lights on broiler performance and carcass yield.

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