Cities install streetlights to improve their residents’ safety. Because the streetlights are usually on from dusk until dawn, they consume a lot of power. According to the energy company Echelon, streetlight power bills may be as much as 40 percent of a city’s total energy costs. Installing smart systems to control the streetlights can save a cash strapped city a lot of money.
The idea behind a smart streetlight system is that an operator can control the intensity of the streetlights. This can be done manually by a city employee, or an automated system that uses sensors can be installed, similar to traffic light sensors. The smart streetlight system can dim lights in areas where there is not much traffic. In many locations, if a city installs streetlights, they stay lit at the same intensity until morning. A road may see large amounts of traffic from employees leaving work in the early evening, but it may be completely deserted at 3 am. Dimming the lights is better than shutting them off completely, because turning on certain types of lights consumes more power than normal operation, and there may be a traveler passing down the road late at night.
Installing a smart streetlight system also makes city residents happier. Because each streetlight can be individually tracked and controlled, it is possible to create a customized configuration for every streetlight. Luther College explains that a homeowner can uniquely identify the streetlight in front of his own house, and tell the city manager when the streetlight should be brightly lit and when it should be dimmer.
Several types of bulbs are found in streetlights. One of the most common bulb types is low pressure sodium, which produces an orange color. Low pressure sodium streetlights are popular because they use less energy than other types of bulbs, such as incandescent or fluorescent bulbs. Metal halide bulbs are very bright but they may take several minutes to charge up if they are turned off, according to Jim Terry. Light emitting diode streetlights are another alternative. LED streetlights are very energy efficient. These lights keep their intensity throughout their lifetime, according to Kansas University. Metal halide bulbs gradually dim as they get older. Older sodium bulbs don’t dim, but they use more electricity as they age, so the city has to choose between higher energy bills or replacement costs.
According to the University of Alaska, Fairbanks, each LED streetlight costs about $2,000 for the streetlight itself, and another $500 to install the streetlight. Because LED streetlights normally last around 10,000 hours, the cost of the streetlights is higher than the energy bill savings at 2011 energy and LED prices.