Newstrack: Shining a brighter light on city streets

Background

Alliant Energy had been studying replacing the high-pressure sodium light bulb casting a yellowish-orange glow on downtowns and residential streets around Iowa with a more efficient, brighter white light.

Alliant had its sights on light-emitting diode, or LED, lights, which shine brighter and farther, last longer and use less energy. They've also traditionally cost more, hampering a change.

By 2013, LED prices had fallen enough, and with a plan to switch lights one at a time as each sodium light fails, the cost-benefit equation finally balanced out to where the long-term cost savings of LED offset the initial investment, said Justin Foss, an Alliant spokesman.

What's happened since

In 2013, Alliant started a pilot project to replace 2,000 light bulbs, and since has ramped up to a full-scale effort.

So far, the energy company has replaced 20,000 lights out of an estimated 100,000 in Alliant's Iowa service area, which stretches across most of the state, Foss said.

'We know we are putting a lot more light on roads and using a lot less energy to do so,” Foss said.

What's been changed and hasn't is pretty obvious, he said. The sodium lights fade by the time they reach the street, whereas the LED beam blankets the road with light with limited fade, he said.

Crews are virtually always out replacing a failed bulb somewhere, he said. The replacements are phased in when the existing sodium bulbs blow out or some component, such as a sensor eye breaks, Foss said.

The goal is to complete the installations in five to eight years, he said.

The upfront cost difference is substantial - $370 per LED unit compared to $20 for a high-pressure sodium light, Foss said. But over the long haul, the LEDs save money, which in turn is passed on to customers, Foss said.

Those savings come in manpower and energy savings.

The high-pressure sodium bulbs have a five- to seven-year life span, while LED bulbs can last 10 to 20 years, Foss said. Meanwhile, many of the LEDs are 80 watt bulbs compared to 100 watts for the old bulbs, he said.

When the project is finished, Alliant estimates a reduction of 1.8 million kilowatt-hours per month. That is the green house gas emissions equivalent of 256 fewer passenger cars on the road per year, Foss said.

The energy cost savings passed on to the communities using Alliant will be $23,000 a month, Foss said.

'When you are talking on a scale of 100,000 lights, we found that the reduction pays off,” Foss said.

Cari Pauli, a traffic engineer for Cedar Rapids, communicates with Alliant, and she also is involved in updating the 1,000 Cedar Rapids operated streetlights, in a similar, one at time fashion. However, they haven't started replacing the decorative lights because they are still too expensive, she said.

The LED conversion is saving the city about $2,500 per month in its Alliant bill, and that's with about 30 percent of the 9,878 Alliant operated streetlights, she said. There's also hope for more savings if new tariff rates are set, she said.

The other benefit is a better quality light, which has been getting positive feedback, she said. The white LED light shows color, and they are more directional rather than spraying outward.

So that means less light pollution in the sky, she said.

"It's a very good thing they are switching these out," she said. "It looks more like a natural light. We see all benefits, and I can't see a downside."