ASSOCIATED PRESS
The nation’s roads are a major source of greenhouse gases, but it’s not just from the cars and trucks traveling on them. Streetlights also consume their share of energy.
By switching to a more efficient lighting system for roads, the D.C. region and the country’s nine other largest metropolitan areas could reduce annual carbon dioxide emissions by 1.2 million metric tons — the equivalent of taking 212,000 vehicles off the road. Such an effort also could save $90 million a year, according to a study released in March.
“Even if there wasn’t the thought of global warming, this would make sense because it saves electricity, it saves taxpayer dollars,” said Robert Grow, the study’s author and government relations director of the Greater Washington Board of Trade.
Mr. Grow wrote the report as part of a fellowship on sustainable growth, funded by the Ford Foundation through the American Chamber of Commerce Executives. He focused on two strategies. One was switching to lamps with electricity-sipping, light-emitting diodes, called LEDs. The other was to create a centrally controlled streetlight network that allows managers to adjust brightness based on environmental conditions and to quickly pinpoint malfunctioning lights — including those that stay on in broad daylight.
Mr. Grow said he was surprised that the country hasn’t taken more action to improve streetlight efficiency.
Perhaps the biggest effort is in Ann Arbor, Mich. The city announced in October the conversion of roughly 1,400 downtown streetlights to LED lights, an effort estimated to cut electricity use in half. The lights are manufactured by Durham, N.C.-based Cree Inc. Other manufacturers promise similar savings.
LED traffic lights have become common in much of the country, but LEDs that produce white light, instead of red or green, use newer technology.
Ram Sarma, an Arlington County official, said LED streetlights have been available long enough to provide sufficient information about costs and potential savings.
Arlington, which has committed to reducing greenhouse gases produced by the county government by 10 percent from 2000 to 2012, is installing five LED streetlights. The county wants to gather feedback from drivers on the quality of the light before embarking on a wholesale replacement project.
The high-pressure, sodium lamps that Arlington now uses are about a decade old. They are about 25 percent to 30 percent more efficient than the mercury vapor lamps that they replaced, Mr. Sarma said.
Mr. Grow also looked at the centrally managed streetlight network implemented in Oslo. The Norwegian system feeds data into a control center that keeps track of lights that need to be fixed and automatically dims streetlights based on the season, local weather and traffic density. Streetlights at dawn, for example, don’t have to be at full power, said Julia O’Shaughnessy, a spokeswoman for San Jose, Calif.-based Echelon Corp., which owns the technology used in Oslo.
Mr. Sarma knows about the technology but said the capital costs were too high and potential savings not great enough for Arlington.
Mr. Grow said it would take nearly $70 million to install such a system throughout the D.C. area and about seven years to recoup the costs in energy and maintenance savings.
Based on Oslo’s experience and the estimates of LED streetlight manufacturers, Mr. Grow’s analysis assumed a 50 percent reduction in electricity usage for any kind of streetlight improvement. He said the D.C. area alone could save $6 million a year on electricity and reduce carbon-dioxide emissions by nearly 78,000 metric tons.
Mr. Grow then extrapolated his basic assumptions to the other metropolitan areas.
Maryland State Highway Administrator Neil J. Pedersen said the agency was reviewing Mr. Grow’s report and would consider efficiency improvements to the lights on the roads it operates.
“There are capital costs associated with it that we need to understand,” he said. “There’s still questions about what the longevity is of some of these lights.”
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