Campisi, D., Gitto, S., & Morea, D. (2017). Economic feasibility of energy efficiency improvements in street lighting systems in Rome. International Journal of Energy Economics and Policy, 7(1), 190–198.
Abstract: This study evaluates an investment project concerning the redevelopment of the public lighting of the Municipality of Rome. In particular, we consider the replacing of the traditional lamps of the system with LED lamps. We consider the factors that affect this kind of project: the cost of energy, the manteinance cost, the investment cost and the Weighted Average Cost of Capital (WACC). Our results underline the reduction of energy consumption and of the maintenance costs, lower emissions of CO2 into the atmosphere, the reduction of light pollution, the positive effects on road safety and the indipendence by incentives.
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Farahat, A., Florea, A., Martinez Lastra, J. L., & Branas, C. (2015). Energy Efficiency Considerations for LED-based Lighting of Multipurpose Outdoor Environments. IEEE J. Emerging and Sel. Topics in Power Elec., PP(99), 1.
Abstract: Nowadays street lighting accounts for 53% of outdoor lighting use and the market is continuously increasing. In the context of rising energy prices and growing environmental awareness, energy efficiency is becoming one of the most important criteria for street lighting systems design. LED-based lights have become the primary option for replacing conventional light bulbs, being digitally controllable, small, highly efficient, and cheap to manufacture. Advanced control strategies adapted to ambient conditions are needed to combine low energy consumption and high quality light ambience according to changing specifications. This paper describes an outdoor lighting solution aimed at energy efficient performance in the context of multipurpose outdoor environments, where control is crucial in achieving efficiency improvements. The work addresses efficiency at the component level, by optimizing the performance of LED drivers, and at system level, defining the control strategy and associated hardware infrastructure. The approach designed was tested in a real environment. The performance of the lighting installation was assessed using the web-based monitoring application, providing real-time consumption information and aggregated historical data.
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Femia, N., Fortunato, M., & Vitelli, M. (2013). Light-to-Light: PV-Fed LED Lighting Systems. IEEE Trans. Power Electron., 28(8), 4063–4073.
Abstract: This paper discusses the principle of operation, dynamic modeling, and control design for light-to-light (LtL) systems, whose aim is to directly convert the sun irradiation into artificial light. The system discussed in this paper is composed by a photovoltaic (PV) panel, an LED array, a dc-dc converter dedicated to the maximum power point tracking of the PV panel and a dc-dc converter dedicated to drive the LEDs array. A system controller is also included, whose goal is to ensure the matching between the maximum available PV power and the LED power by means of a low-frequency LEDs dimming. An experimental design example is discussed to illustrate the functionalities of the LtL system.
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Gómez, C., & Mitchell, C. A. (2016). Physiological and Productivity Responses of High-wire Tomato as Affected by Supplemental Light Source and Distribution within the Canopy. J. Amer. Soc. Hort. Sci., 141(2), 196–208.
Abstract: The relative coolness-to-touch of light-emitting diodes (LEDs) has enabled commercial implementation of intracanopy lighting (ICL) in the greenhouse. Intracanopy lighting, which refers to the strategy of lighting along the side or from within the foliar canopy, can increase canopy photosynthetic activity, but physiological and productivity responses of high-wire greenhouse tomato (Solanum lycopersicum) to intracanopy supplemental lighting (SL) still are not yet fully understood. Two consecutive production experiments were conducted across seasons in a glass-glazed greenhouse located in a midnorthern, continental climate [lat. 40°N (West Lafayette, IN)]. Plants were grown from winter-to-summer [increasing solar daily light integral (DLI)] and from summer-to-winter (decreasing solar DLI) to compare three SL strategies for high-wire tomato production across changing solar DLIs: top lighting with high-pressure sodium lamps (HPS) vs. intracanopy LED vertical towers vs. hybrid SL (HPS + horizontal ICL-LEDs). A control treatment also was included for which no SL was provided. Supplemental DLI for each experimental period was adjusted monthly, to complement seasonal changes in sunlight, aiming to approach a target total DLI of 25 mol·m‒2·d‒1 during fruit set. Harvest parameters (total fruit fresh weight, number of fruit harvested, and average cluster fresh weight), tissue temperature, chlorophyll fluorescence, and stomatal conductance (gS) were unaffected by SL treatment in both experiments. Among the physiological parameters evaluated, CO2 assimilation measured under light-saturating conditions, light-limited quantum-use efficiency, and maximum gross CO2 assimilation (Amax) proved to be good indicators of how ICL reduces the top-to-bottom decline in leaf photosynthetic activity otherwise measured with top lighting only (HPS-SL or solar). Although SL generally increased fruit yield relative to control, lack of SL treatment differences among harvest parameters indicates that higher crop photosynthetic activity did not increase fruit yield. Compared with control, intracanopy SL increased yield to the same extent as top SL, but the remaining photoassimilate from ICL most likely was partitioned to maintain nonharvested, vegetative plant parts as well.
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Gil-de-Castro, A., Moreno-Munoz, A., Larsson, A., de la Rosa, J., & Bollen, M. (2013). LED street lighting: A power quality comparison among street light technologies. Lighting Research and Technology, 45(6), 710–728.
Abstract: High-pressure sodium lamps are currently the main lamps used in public lighting. However, the possibility of using high-power light emitting diode (LEDs) for street lighting is growing continuously due to their greater energy efficiency, robustness, long life and light control. The aim of this paper is to study the power quality of high-power lighting networks based on LED and high-pressure sodium lamps. Both electromagnetic and dimmable electronic ballasts, which can dim the lamp output smoothly and uniformly, have been used connected to high-pressure sodium lamps. High-pressure sodium lamps connected to electronic equipment have been tested with different arc power levels using dimming on a 230 V power supply. The study presented in this paper is completely based on measurements, including harmonic currents in the frequency range up to 150 kHz for all the technologies. The main results show a broadband spectrum in LED lamps which confirms other research in fluorescent lamps powered by high-frequency ballasts. Results also indicate a decrease in the harmonic value with increasing harmonic order, and a decrease in the harmonic value at half load (60%) compared with full load (100%). Although total harmonic distortion of the current is lower with high-pressure sodium lamps connected to electronic rather than electromagnetic ballasts, LED lamps achieved the lowest total harmonic distortion of current.
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