They look white but shine "green." And they could save lots of dough.

Energy-efficient LED and induction lamps have been installed in streetlights across Salt Lake City as an experiment to see if the environmentally friendly bulbs could save the city meaningful money.

The test is part of Mayor Ralph Becker's ongoing energy assessment, done in conjunction with energy-services company Seimens AG. The mercury-free lighting, with reduced light pollution, would slim the capital's annual streetlight energy use by up to 50 percent.

"Our commitment to livability through sustainable and environmentally sound practices," Becker said, "is hitting the streets with this initiative."

If the test satisfies the city, most of its 15,000 streetlamps could get the upgrade.

"People are really looking at energy consumption on these lights that burn through the night," explained Mike Barry, a city transportation engineer. "It's a huge chunk of change."

But so too is the upfront cost to install the newer technology. Right now, the brown street poles have either yellowish high-pressure sodium or metal halide lamps. Both are from the 1970s era. Induction or LED lights would cost $200 to $300 more per fixture, but would save money in the long run because no maintenance is required.

"You just put them up and you don't have to mess with them," Barry said. "The fact that you don't have to be out changing bulbs all the time is environmentally friendly."

The old "high-intensity discharge" lights have a life span of about two years, while the new ones last 10 to 15. "That savings," Barry added, "will pay for the product in 12 years."

Based on the test at eight locations, transportation officials will make a recommendation to the City Council, likely next month.

"It has possibilities," Councilman Carlton Christensen said. "We want to make sure the technology is sound before there is widespread implementation."

Christensen says the city also is looking into a comprehensive upgrade for all street lighting. "Maybe something like this is a nice segue."

Last year, the city burned nearly 14 million kilowatt hours of electricity to power streetlights, officials say, releasing almost 6,500 tons of carbon dioxide into the atmosphere.

djensen@sltrib.com