April 22, 2009 By Elaine Rundle
San Jose, Calif., is embarking on its second pilot project of converting streetlights to utilize light-emitting diodes (LEDs), which can be networked and have a longer lifespan than traditional streetlight bulbs. The city will retrofit 125 of its 65,000 streetlights by June.
According to Jim Helmer, director of the city's Department of Transportation, the main drivers behind the project are contributing to the urban forestry program, which means adding more trees to sidewalks while ensuring that light penetrates through the trees down to the street; providing white light versus the yellow light the current streetlights emit; reducing maintenance by having increased bulb life expectancy; and increasing energy savings.
Helmer said the city was looking for new streetlights that had GPS in the heads so that they would know their location. "No matter where that light gets installed, the light would understand where it is, and it would memorize the sunrise and sunset patterns for that area," he said. "It would have that built into its programmable memory."
This allows engineers to program the light to give 50 percent output for the first hour of sunset, then burn at 100 percent when it's pitch dark and at sunrise begin lowering the output. Helmer said traditional streetlights burn full strength as soon as their photo eyes alert them to turn on, which could be as soon as the sun begins to set but too early to require 100 percent output.
The LED streetlights will be connected through the electrical wires that feed electricity to the lights. The power lines will carry the communication signal and allow engineers to control the lights from a remote location. The network also will provide real-time updates on the lights' statuses, which lets maintenance workers know immediately when a light is out.
Vendor BetaLED will provide the streetlights, and Echelon's i.LON SmartServer monitors and controls the streetlights.
Helmer said the pilot program is funded through the U.S. Department of Housing and Urban Development's Community Development Block Grants. The lights will be installed in the Hillview North neighborhood, which qualifies for the funding because it is a low-income area. He said the neighborhood also had poor lighting and was missing many street trees, so it aligned with the city's Green Vision plan goal No. 9, which says by 2022 the city will plant 100,000 new trees and have a zero emissions street lighting system. The neighborhood also is a good location because it's located near the Lick Observatory, an astronomy research center, which will benefit from the lights' ability to be dimmed at night, therefore reducing the light pollution and aiding research.
San Jose's first LED streetlight pilot program converted five lights that communicated wirelessly through radio waves. Helmer estimated that the first set of lights will provide a return on investment after 10 years. However, he said like any new industry the costs will be reduced as the technology improves and the ROI should decrease to two or three years.
Helmer said San Jose will use $2 million of its federal stimulus money from the Energy Efficiency and Conservation Block Grants for the LED initiative. The city also is requesting $20 million from the transportation infrastructure program to continue LED retrofitting. He said the pilot projects will enable the city to be ready to spend the stimulus money quickly, while creating jobs -- such as software, communications and lighting engineers and maintenance workers -- saving energy and making a good investment for the economy.
Helmer compared the move to using LEDs in traffic signals with retrofitting streetlights with the bulbs. "I think LEDs revolutionized the traffic-signal head industry," he said. "Today they burn one-tenth the energy that they did 10 years ago. So we're saving 90 percent of the power that we used to use. It is possible in streetlights to continue to reduce our power consumption and get longer lamp life, if we treat our streetlights more similar to traffic lights."
When all of the city's 65,000 streetlights are converted to LEDs, San Jose expects to reduce its energy use by almost 40 percent.