scholarly journals Modelled impacts of a potential light emitting diode lighting system conversion and the influence of an extremely polluted atmosphere in Mexico City

2021 ◽  
pp. 239980832110127
Author(s):  
H Lamphar ◽  
S Wallner ◽  
M Kocifaj
Keyword(s):  
Mexico City ◽  
Urban Areas ◽  
Energy Savings ◽  
Light Emitting Diode ◽  
Visible Spectrum ◽  
Special Focus ◽  
Light Emitting ◽  
Environment And Health ◽  
Polluted Atmosphere ◽  
Night Sky

Currently, many cities worldwide are changing current existing and mostly outdated lighting situation systems from inefficient lamps to light emitting diodes (LEDs). Providing the opportunity of energy savings, they can help in preventing influences to the night sky and furthermore issues for human health, wildlife and environment. This work simulates a potential LED conversion for the megacity of Mexico City and investigates impacts to conservation areas. Modelled for the whole visible spectrum, the analysis places special focus on the effects of applying various colour temperatures. Additionally, a highly polluted atmosphere was included as theoretical model, something applying to megacities in particular, to see impacts on skyglow of such an environmental contingency. In general, results show that the night sky brightness increases significantly with increasing colour temperature of LEDs if the lumen output is kept constant. It is shown that a potential conversion requires a thorough adjustment, otherwise negative impacts on environment and health might rise. Furthermore, an increased aerosol optical thickness ends in producing more diffuse light, identifying a major concern for the environment. The results obtained in this paper may be a strong motivation to ascertain measurements conducted in other large urban areas correlated to the computational results presented here.

Using the private finance initiative for energy efficiency projects at the urban scale

2016 ◽  
Vol 10 (1) ◽  
pp. 99-117 ◽  
Author(s):  
Alberto De Marco ◽  
Giulio Mangano ◽  
Fania Valeria Michelucci ◽  
Giovanni Zenezini
Keyword(s):  
Energy Efficiency ◽  
Urban Areas ◽  
Light Emitting Diode ◽  
Project Finance ◽  
Private Finance Initiative ◽  
Content Type ◽  
Light Emitting ◽  
Alternate Forms ◽  
Private Investors

Purpose – The purpose of this paper is to suggest the usage of the project finance (PF) scheme as a suitable mechanism to fund energy efficiency projects at the urban scale and present its advantages and adoption barriers. Design/methodology/approach – A case study is developed to renew the traffic lighting system of an Italian town via replacement of the old lamps with new light-emitting diode (LED) technology. Several partners are involved in the case project to construct a viable PF arrangement. Findings – The case study presents the viability of the proposed PF scheme that provides for acceptable financial returns and bankability. However, it also shows that the need for short concession periods may call for a public contribution to the initial funding to make the project more attractive to private investors. Practical implications – This case study is a useful guideline for governments and promoters to using the PF arrangement to fund energy efficiency investments in urban settings. It helps designing an appropriate PF scheme and understanding the advantages of PF to reduce risk and, consequently, increase the debt leverage and profitability of energy efficiency projects. Originality/value – This paper contributes to bridging the gap about the lack of works addressing the implementation of the PF mechanism in the energy efficiency sector in urban areas. The importance of this paper is also associated with the shortage of traditional public finance faced by many cities that forces to seek for alternate forms of financing.

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.

scholarly journals Controllable Synthesis of All Inorganic Lead Halide Perovskite Nanocrystals with Various Appearances in Multiligand Reaction System

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1751 ◽  
Author(s):  
Chen Chen ◽  
Louwen Zhang ◽  
Tielin Shi ◽  
Guanglan Liao ◽  
Zirong Tang
Keyword(s):  
Light Emitting Diode ◽  
Dominant Role ◽  
Photophysical Properties ◽  
Reaction System ◽  
Visible Spectrum ◽  
Peanut Oil ◽  
Light Emitting ◽  
Perovskite Nanocrystals ◽  
Halide Perovskite ◽  
Lead Halide

All inorganic cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals (PNCs) exhibit promising applications in light-emitting devices due to their excellent photophysical properties. Herein, we developed a low-cost and convenient method for the preparation of CsPbX3 PNCs in a multiligand-assisted reaction system where peanut oil is applied as a ligand source. The mixed-halide PNCs with tunable optical-band gap were prepared by mixing the single-halide perovskite solutions at room temperature. The resulting PNCs had good monodispersity, with dimensions of 8–10 nm, high photoluminescence quantum yield (96.9%), narrow emission widths (15–34 nm), and tunable emission wavelength (408–694 nm), covering the entire visible spectrum. Additionally, various morphologies of PNCs, such as nanospheres, nanocubes, and nanowires, were obtained by controlling reaction temperature and time, and the amount of oleamine with multiple ligands in peanut oil potentially playing a dominant role in the nucleation/growth processes of our PNCs. Finally, the resulting CsPbBr3 PNCs were employed to develop a white light-emitting diode (WLED), demonstrating the potential lighting applications for our method.

Behavioral response of adult caddisflies (Trichoptera) to blue and green light-emitting diode lamps

Zoosymposia ◽  
2019 ◽  
Vol 14 (1) ◽  
pp. 59-62
Author(s):  
GORO KIMURA ◽  
GORO TAJIKA ◽  
TOSHIHIRO KUSAMA ◽  
TSUTOMU TANIKAWA
Keyword(s):  
Uv Light ◽  
Diversity Index ◽  
Light Emitting Diode ◽  
Broad Band ◽  
Green Light ◽  
Visible Spectrum ◽  
Ultraviolet Spectrum ◽  
White Led ◽  
Light Emitting ◽  
Wiener Diversity Index

To clarify the effect of the visible spectrum, we collected Trichoptera adults using blue, green, and white light-emitting diode (LED) lamps and black light (BL) lamps. Except for white LED lamps, all lamps emitted broad-band wavelengths in the ultraviolet spectrum. A total of 212 adult Trichoptera were trapped. The most individuals were attracted by BL (96), followed blue (74), green (32), and white (10). Hydroptilidae spp. was the most abundant taxa among the lamps (183 individuals, 86.3%), followed by Cheumatopsyche brevilineata (23 individuals, 10.8%). Only Hydroptilidae spp. was common to all lamps. The Shannon–Wiener diversity index (H’) was highest at 0.96 for BL, followed by green (0.53), and blue (0.28). Trichoptera were attracted to both UV light and visible light. These results suggest that BL is the most useful for faunistic investigations of Trichoptera.

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.

A Study on Energy Saving and Light Pollution of LED Advertising Signs

2011 ◽  
Vol 121-126 ◽  
pp. 2979-2984 ◽  
Author(s):  
Chen Ying Ho ◽  
Hsien Te Lin ◽  
Kuang Yu Huang
Keyword(s):  
Energy Consumption ◽  
Urban Areas ◽  
Light Emitting Diode ◽  
Outdoor Environment ◽  
Light Pollution ◽  
Light Emitting ◽  
Full Color ◽  
Average Luminance ◽  
Color Screens ◽  
Color Screen

Lighting advertising signs not only play an important role in outdoor lighting environment in Taiwan, but also become the main factor of energy consumption in urban areas at night. Light-emitting diode (LED) has been gradually used in advertising signs due to its advantages. However, in order to be conspicuous and legible in the daytime, signs that are excessively bright may result in considerable light pollution and energy waste at nighttime. Therefore, this research aims to measure the luminance of LED signs and traditional internally lighted signs, and analyze the light trespass from each signage. Based on the research results, the energy consumption from a LED full color screen is 12 times more than a traditional internally lighted sign per day. Statistically, all kinds of LED signs are much higher than traditional internally lighted signs in the percentage of excessive brightness and average luminance value. As for the light trespass, since the vertical illuminance on facade facing the signs increases with the increase of the sign area or the decrease of the distance between the sign and the facade, the vertical illuminance on facade facing the signs would exceed the limit of CIE even if the luminance of the signs achieves the standard of CIE in terms of the general conditions in Taiwan. This happens to LED full color screens in particular and thus results in considerable obtrusive light. To sum up, in order to reduce unnecessary energy consumption and improve the nighttime lighting quality for outdoor environment, this research recommends the luminance limitation for light dimming of LED advertising signs should refer to the zoning, time period, and sign area.

scholarly journals Towards rare-earth-free white light-emitting diode devices based on the combination of dicyanomethylene and pyranine as organic dyes supported on zinc single-layered hydroxide

2019 ◽  
Vol 10 ◽  
pp. 760-770 ◽  
Author(s):  
Jeff L Nyalosaso ◽  
Rachod Boonsin ◽  
Pierre Vialat ◽  
Damien Boyer ◽  
Geneviève Chadeyron ◽  
...  
Keyword(s):  
White Light ◽  
Fluorescent Dyes ◽  
Light Emission ◽  
Organic Dyes ◽  
Light Emitting Diode ◽  
Composite Films ◽  
Visible Spectrum ◽  
Light Emitting ◽  
Blue Led ◽  
Display Devices

A new luminescent composite film resulting from the dispersion of luminescent organic dyes in a single-layered hydroxide (SLH)-type inorganic matrix has been developed. Two fluorescent organic dyes emitting visible light upon blue LED excitation were investigated in this study: dicyanomethylene (DCM) and pyranine (HPTS). These dyes exhibit broad emission bands that cover a large part of the visible spectrum. The concept developed in our work consisted in keeping SLH in its wet form to ensure a good dispersion of the fluorescent dyes prior to immobilizing the hybrid materials in a silicone polymer to achieve luminescent composite films. We demonstrate that these coatings stacked upon each other and placed above a blue LED lead to white-light emission with suitable photometric parameters for applications in lighting or display devices: colour temperature of 5409 K and colour rendering index (CRI) of 81.

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