Energy, budget concerns prompt review of street-lighting

Friday, July 10, 2009 | 12:01 a.m. CDT
GRAPHIC | Columbia Water and Light has proposed replacing a large number of mercury vapor lamps with high-pressure sodium bulbs because they have been shown to be more efficient.

COLUMBIA — When the city decided to install streetlights on unlit stretches of Forum Boulevard in 2007, some residents along the thoroughfare pushed back with worries about too much light in their homes.

The Water and Light Department looked into installing more aesthetically pleasing fixtures that better directed the light downward.

Street lamp technology 101

Columbia’s streetlights are installed and maintained by Water and Light, and all of them are high-intensity discharge lamps, which are similar in design to fluorescent light bulbs. They work by having an electric current pass through the sodium or mercury gas inside the glass bulb, which eventually causes the gases to release energy in the form of light. High-intensity discharge lamps also require a device called a ballast to regulate the current and provide the high start-up voltage needed to operate the lamp.

Unlike incandescent light bulbs, which are widely used in homes, there is no filament that is heated to cause a release of light energy. Incandescent bulbs, therefore, do not require the use of a ballast and have the capability of being turned on immediately. In contrast, because high-intensity discharge lamps take a while to light to full capacity, they are used widely in street lighting, where they can stay on for hours. They cannot be practically used with motion sensors.

Columbia uses two types of high-intensity discharge lamps for streetlights: high-pressure sodium and mercury vapor. Sodium lamps emit a yellowish light; mercury lamps appear greenish.

Although there are several criteria by which light bulbs are evaluated for their efficiency, one of the main principles engineers and city officials have looked at is how much light is produced per unit of energy consumed, or lumens per watt.

Mercury vapor lamps are considered old street-lighting technology and are significantly more inefficient, yielding 25 to 60 lumens per watt. Newer sodium lights are among the most efficient lights available on the market and give off anywhere from 50 to 140 lumens per watt, according to U.S. Department of Energy. In comparison, the standard filament bulb in the home gives off 10 to 17 lumens per watt.


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The push and pull over streetlights along Forum was triggered by a citywide review, initiated by former Water and Light Director Dan Dasho, to catalog streets that weren't well lit.

Connie Kacprowicz of the Water and Light Department said the Forum Boulevard episode prompted the City Council in November 2007 to begin reviewing the city’s overall policy on streetlights. Nearly two years later, the issue of streetlights has taken on a new urgency as the city looks for ways to trim costs from a strained budget.

Jim Windsor, manager of rates and fiscal planning for Water and Light, said a portion of the city’s annual budget from the general fund — about $1.4 million — pays for street lighting.

In response to a council request to save on the cost of lighting streets, Water and Light in May proposed upgrading or removing 2,585 of the city's 8,950 streetlights, with the majority being replaced with more efficient bulbs.

As conversations arose about the possible darkening of some city streetlights, council members and city officials were quick to clarify that nothing of that sort would happen anytime soon. First Ward Councilman Paul Sturtz said the report was framed in a way that made it “alarmist.”

Kacprowicz said streetlights have been a point of contention for quite some time, and there are lots of opinions.

“Some people want fewer streetlights, and then there are others who want more streetlights,” Kacprowicz said. “And it’s gone back and forth like that, depending on who’s on the City Council.”

Some council members have been quite vocal about the need for alternate ways of lighting streets, including Sturtz and Karl Skala of the Third Ward. Their concerns about street-lighting covers several fronts, including the need to decrease costs, reduce carbon emissions, reduce light that is wasted in illuminating the skies rather than the streets and maintain public safety.

Most parties agree that the city can reduce costs without resorting to drastic changes by simply replacing older bulbs with more efficient ones.

Although light bulbs are evaluated for their efficiency based on several principles, one of the main criteria is to look at a bulb’s efficacy, or how much light is produced per watt.

Columbia uses two kinds of streetlights: mercury vapor and high-pressure sodium.  Based on data from the U.S. Department of Energy, sodium lamps are 200 percent to 300 percent more efficient than mercury vapor lamps.

According to the U.S. Department of Energy, mercury vapor lamps yield only 25 to 60 lumens per watt. Sodium lamps, among the most efficient lights available on the market, emit anywhere from 50 to 140 lumens per watt. By comparison, a standard filament bulb at home may only give off 10 to 17 lumens per watt.

Skala said that the energy utilized in lighting streets in areas with no population could be used to fund the city’s electric needs during peak air conditioning periods during the summer.

“It’s like burning money,” Skala said. “It’s got to stop someplace, and we have to get it under control. The easiest thing to do, the low-hanging fruit, is to get rid of the mercury vapor lamps.”

Of the 8,950 streetlights maintained by the city, 1,561 of the older mercury vapor streetlights remain in service. Water and Light has proposed replacing all of them with more efficient sodium bulbs, partly also because stricter federal regulation passed this year intends to phase out mercury vapor lamps. Kacprowicz said some of those lights have worked for more than 30 years.

Identifying burned-out streetlights and replacing them is one of the responsibilities of Water and Light night crews. 

“If nobody needs transformers fixed, or if there’s no lights to be turned on or off, a night truck will go around looking for streetlights to repair,” said Dan Stokes, electric distribution manager. Unless street light outages are reported, many of the repairs are not planned but are made on the spot.

On average, 12 lights are repaired per week during both day and night shifts, Stokes said.

Because street lights are not metered, accounting for the cost of electricity to keep them operating is based on estimates.    

According to the proposal reviewed by the council on May 13, replacing a combined total of 1,173 of both types of streetlights with more efficient bulbs would cost Water and Light $279,792 in material and labor costs alone.

In addition to the mercury vapor lamps' upgrade to high-pressure sodium bulbs, additional savings would come from replacing a large number of the 250-watt high-pressure sodium bulbs with a lower-wattage 100-watt bulb of the same type.

The switch to a 100-watt bulb is estimated to reduce the cost of operating each bulb by $9.82 per month. Similar alterations across the city, where higher wattage bulbs are replaced with more energy-saving ones, would yield an estimated $51,743 in total annual savings after factoring in replacement costs, according to the Water and Light report to the council, simply because of the lower wattage.

Many 250-watt sodium lamps burn in residential areas, making them good candidates for the lower-wattage bulbs. Water and Light line superintendent Anthony Caskey said the difference in lumination is noticeable — he likened it to someone downgrading their incandescent light bulb at home from 120 to 60 watts.   

This difference in lumination is what has prompted some city utility customers to complain when mercury vapor lamps are replaced with high-pressure sodium bulbs.

Kevin Thornton, a supervisor and line worker for Water and Light, said that though the city aims to eliminate the mercury vapor bulbs, customers have complained about how the sodium lamps “do not emit as warm of a light.”

As early as a year ago, mercury vapor lamps have been taken from one location and shifted to another to appease customers’ demands, Thornton said.

“We replace mercury vapors with high-pressure sodiums, but in the past, we’ve had to find another mercury vapor to replace a burnt-out bulb after a customer complained," Thornton said. “If the City Council decides to go with the proposal, then they have to stand behind it and not bow down to those few customers that will complain about the lack of lighting.”

The report sent to the council suggests taking 812 streetlights out of service, including removing the poles and fixtures. The one-time cost would save an estimated $72,779 a year. Like the bulbs slated for replacement, the streetlights proposed for removal are scattered around the city.

The proposal requires a large initial investment from the electric utility, Windsor said.

“We are assuming by doing this work, the streetlights will be in place for at least 20 years, and we will be able to recover the cost over a 20-year period,” Windsor said.

Windsor doesn’t predict that users will pay higher utility bills to help pay for the project. He also says the electric use isn't the major cost involved for street-lighting. Since lights are ideally only on for half the time of the year, it's the capital cost of infrastructure and maintenance that is the larger cost.

“We analyze cost of service for separate classes of customers, and street-lighting is in its own class,” Windsor said.  

By using lower wattage or more efficient bulbs, the savings to the city’s general fund occurs not only because of reduced energy costs but also because the cost of maintenance and capital costs will decrease as well.

“It’s the combination of things that allow the reduction of cost to the general fund,” Windsor said.

Newer street-lighting technologies such as light-emitting diodes, or LEDs, have sparked the interest of both council members and Water and Light officials.  Sturtz, who sees Columbia falling behind in terms of progressive answers to energy savings, has championed the idea to devote more attention to LED technology for lighting streets.

Instead of running a current through gas, as with mercury and sodium lamps, LEDs release light energy the way regular light bulbs do. They are a great deal smaller, however, and they don’t have filaments, allowing them to rarely burn out or become too hot. That means more of the energy put into lighting an LED bulb will be transferred into making light rather than heat.

“Certainly converting all the mercury vapors to sodium lamps is a decent start,” Sturtz said. He cited communities that have been experimenting with LEDs, such as Ann Arbor, Mich., that have been getting good results with cost savings.

“My feeling was, these were the trailblazers like Ann Arbor who’ve already done it, and we wouldn’t be going out on a big limb to go on an experiment with LEDs,” Sturtz said.

Kacprowicz said LED companies contact Water and Light on a regular basis, and the city has talked to at least six LED manufacturers that could help install the new streetlights. Most talks broke off, however, over the issue of pricing. LEDs, a relatively new technology for streetlights, are expensive compared with the two types of bulbs the city uses.

“The hope is that LED lights will get brighter and continue to get cheaper,” Kacprowicz said.

Still, Sturtz doesn’t understand why the cost of LED technology is holding the city back. He said that, like many other cities around the country, Columbia could obtain federal stimulus funds to assist in such projects.

“How much money are we willing to spend to save a lot more money down the road?” Sturtz asked. “Are we willing to spend a few millions now to save multimillions down the road? Isn’t that a good investment?”

Skala agreed with Sturtz that Columbia spends a decent amount of money on energy efficiency but nowhere enough to be on the forefront.

Aside from the aesthetic value of decreasing ambient lighting in order to reduce light pollution, a crucial aspect of the street-lighting issue is public safety.

“What we’re doing with more and brighter light is decreasing safety,” Skala said. “On a moonlit night, it seems there is plenty of light on the ground. When you stand under a street light, and then walk into the dark, you can’t see anything.”

Skala has an extensive history with the street-lighting issue from his efforts in wanting to create an outdoor lighting ordinance in 1999 as a member of the Environment and Energy Commission. The city eventually passed an outdoor lighting ordinance in 2006, but street lighting was excluded.

“You can’t always believe what the prevailing wisdom is,” Skala said. “‘Brighter is better,’ I just don’t buy that.”

Officer Tim Thomason of the Columbia Police Department’s Community Service Unit was quoted in a Columbia Daily Tribune article as being hesitant about the idea of reducing streetlights. In the article, Thomason also said that strategically planning the removal and placement of street lights can benefit public safety.

The Police Department, along with Water and Light, now waits for the council to take up the proposal to replace and remove lights citywide. 

Thomason did not respond to several requests for comment, but the Police Department’s public information officer, Jesse Haden, said that while appropriate lighting of city streets is an important part of public safety, it’s just one of a number of issues that include appropriate lighting of buildings and structures.

If residents have concerns about the current street-lighting in their neighborhood or work area, Haden said, they should contact the department and an officer will come by and see it.

“We’re not looking at street-lighting right now,” Haden said. “We’re standing by to see what action to take. We want to educate citizens, regardless of neighborhood, if they have any concerns about lighting.”

While city officials and the public weigh in on lighting streets, the Water and Light line crews will continue replacing and maintaining the thousands of street lights across the city.

“I totally agree that there is a need to reduce wasted lighting, but the City Council has to stand behind those decisions,” Thornton said. “Because there will be people complaining about the lights, and then there will be an additional cost to have to go back and put up the original streetlights.”

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