City swaps out streetlights, gains energy savings

CARLSBAD — The Carlsbad City Council accepted a $938,900 grant from the U.S. Department of Energy, almost one-third of the total cost to replace more than 7,000 high-pressure sodium streetlights throughout Carlsbad with high-efficiency induction lights. The project will reportedly save nearly $400,000 a year in energy and maintenance costs while reducing the city’s greenhouse gas emissions.
According to city sources, the switch to the new lights will reduce the city’s energy consumption for street lighting from 5.1 million kilowatts a year, to just more than 2 million kilowatts. The vast majority of the new lights will use fixtures approved by the International Dark Sky Association. The fixtures direct light downward. The new lights also have half the wattage of existing lights and produce less reflective glare.
Once the new lights are in place — a process that will take 14 to 16 months — the city expects to see a reduction of 1,240 tons year of greenhouse gas emissions, the equivalent of taking 170 cars off the road for a year, or planting 124,046 trees.
The changeover to induction lights is estimated to cost just more than $3 million. About half of the money comes from a combination of federal grants and incentives from San Diego Gas & Electric. The city will also receive a low-interest loan from the California Energy Commission to pay for the rest of the project, and the loan will be repaid through savings in annual maintenance and electricity costs. The California Energy Commission recently reduced the interest rate for the loan from 3 percent to 1 percent, which will result in an additional $30,000 of savings to the city.
City staff has estimated that once the high-pressure sodium lights are replaced with energy efficient induction lights, the city’s annual $600,000 bill for street lighting will be reduced by $290,000. The city expects to save an additional $100,000 per year in maintenance costs, because the new lights have longer warranties.
In addition, induction lamps have an expected life span of 100,000 hours, 24 years, versus a 25,000-hour lifespan, six years, for the current high-pressure sodium lamps.
The last major change to the city’s streetlights occurred 30 years ago, when the city changed from mercury vapor lights to the present high-pressure sodium lights.
Along with a reduction in greenhouse gas emissions, the new induction lights are made with less mercury than the current lights. Less mercury in the lights is expected to save money on hazardous waste disposal and reduce impacts on the environment.
The new induction lights contain one-tenth of the mercury as the current high-pressure sodium lights, and the mercury is in a solid form, rather than liquid or gas, which makes it easier to recover and recycle than the material used in the current lamps.
The new lamps also offer a public safety benefit. Their illumination appears white rather than the yellow light of the high-pressure sodium lamps. Witnesses and crime victims will be able to more accurately describe colors, facial features and other visual details to law enforcement.
The city has installed several induction lights in the downtown village area to test the lights’ effectiveness. During its research, city staff also tested LED lights, but determined induction lights have a more established track record, a longer warranty and are less expensive.

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