|Outdoor Lighting: Tempe vetoes LEDs, chooses induction street lights|
|21 Jul 2011|
|US Lighting Tech announced that it will supply the city of Tempe, Arizona with 1000 induction street lights after the city decided LEDs weren’t a good match for the desert temperature extremes.|
Tempe, Arizona is embarking on phase one of a street-light-retrofit project and has chosen induction lights rather than LED-based solid-state lighting (SSL) to replace high-pressure-sodium (HPS) and metal-halide (MH) sources. US Lighting Tech (USLT) announced that it will supply 1000 induction lights to the city saving as much as 40% of the energy required to power the lights.
Apparently, the city decided that LEDs aren’t a good match for the temperature extremes of the desert southwest climate. Alexander Ham, Vice President of Operations for USLT said, “After evaluating the two leading street lighting platforms of induction and light emitting diode, or LED, Tempe ruled out LED for its high equipment cost and performance volatility in the temperature extremes of the southern Arizona environment.”
Certainly other municipalities and utilities have made a case for induction lights over SSL – mainly due to lower upfront costs. It remains to be seen if the temperature issue will be a real roadblock for LEDs. It’s well known that luminaire designs must efficiently conduct heat away from LEDs for reliable operation. But LEDs are certainly performing reliably in higher-ambient-temperature environments than the southwest desert night.
Still induction lighting does offer energy savings over legacy technologies. USLT will supply 70W Cobra 100 Series lights to Tempe, in general replacing 125W HPS or MH lights. Induction lights do not offer the fine-grain dimming capability that LEDs can achieve to enhance savings through adaptive controls.
Columbus, Ohio reports bad LED experience
Generally LED street lights are getting rave reviews for everything except upfront costs, but the city of Columbus, Ohio also reported issues with a test of LED street lights according to The Columbus Dispatch. The newspaper reported that some of the energy-efficient lights tested failed within two months of installation.
In actuality, the public utilities spokesperson didn’t specifically detail the problems in a test that included LED and induction lights. Certainly most other municipalities and utilities have had quite a different experience. The utility also said that the lights afforded only 20% in energy savings, so the city will stick with legacy lights for now.
Nearby Dublin, Ohio meanwhile, has banked $500,000 to begin a retrofit of 1500 street lights with LED technology. That city’s testing has shown the LED lights to use 40 to 50% less energy.
Iowa and Mississippi update
The move to LED street and area lights continues to happen in many parts of the US. The Des Moines Register reports that the Iowa city is installing LED-based area lighting in a local Valley Junction park. The city will install the lights this fall looking for 50% energy savings. Moreover, the city will use the project as a pilot that could lead to a retrofit of all of the period lighting in Valley Junction.
In Rankin County, Mississippi the city of Flowood has installed solar-powered LED street lights according to The Clarion Ledger. Also on the solar LED front, the Consortium for Solar Lighting published its first recommended practices document.
|About the Author |
|Maury Wright is a Senior Technical Editor with LEDs Magazine.|
|Name: bob hale Posted: Wed, 20 Jul 2011 23:07|
|Regarding LED operation at elevated temperatures, recall that the Tempe, AZ, area has recently had two daytime dust storms (called "haboobs", from Arabic - "blowing furiously"). During such events, street lighting would be helpful, and arguably even essential along some roadways. While such events don't occur daily, the corresponding daytime ambient temperatures could be 120 degrees F or higher; this is a substantially higher temperature than the relatively cooler typical nighttime desert temperatures, which were mentioned in the article (maybe as examples of inappropriately conservative design temperature targets?).
For metal halide or high pressure sodium lighting systems, such elevated temperatures do not pose a problem, at least for the light source itself.
Keep cool! Best, AZ Bob.
|Name: john bert Posted: Thu, 21 Jul 2011 18:07|
|High ambient temperatures affect traditional light sources just as much as LEDs. If you operate any traditional HPS source in a 120°F ambient the seal at the base of the lamp will overheat, causing short lamp life and the ballast life will be shortened due to the increased temperatures. Ask any induction/HPS fixture manufacture for temperature test data at 120°F ambient and see if everything is operating under temperature. 99% of them will not be able to produce the data. Traditional lighting fixtures are tested at 75°F. Quality LED fixture manufactures are incorporating temperature limiters and other forms of temperature feedback to shut off or dim LEDs when they overheat. If you give the job to the lowest bidder, you are not going to get that manufacturing quality. You get what Columbus Ohio received, fixtures that failed in two months. You get what you pay for.|
|Name: soraawins Posted: Thu, 21 Jul 2011 18:07|
|PSE&G invested in USLT for NJ as well - $50M was available for green lighting and they chose induction over LED, 85CRI, 85lm/Watt, 100k hours, 40% lower up front cost when compared to LED. The main problem is that Cr** XM* still costs $3 each for 10klumns delivered at 100 lm/Watt, 1.7A drive current, 18 LED's that's $54 for just the LED light source. The price for the light source needs to come down to $1/klumen/100lm/w at 85C. Cr** will likely just move up the value chain and compete with their own component buyers as they have with everything else.|
|Name: relumination Posted: Thu, 21 Jul 2011 20:07|
|Those dust storms are rare and the street lights do nothing to help people see. I have been in a few of them and you cannot see 15 feet in front of you let alone 30 feet up to a street lamp.
I think Tempe chose on initial price. No doubt the manufacturer gave them a great price. It is too bad, however, because Tempe is home to Miller Induction which has a great product line and supports local jobs.
The debate will rage on but temperature, in a well designed fixture, is simply not a problem for street lights. Even if the fixture was over 120 degrees for some period each year it most certainly isn't at night. The heat you feel on the street is much more than at lamp height. Furthermore the faxture isn't trapped and any breeze at all will keep the fixture operating just fine.
This piece looks more like a "we won one" announcement by the induction manufacturer. I wish they would be more forthright and say that they bought the project to get the press.
|Name: cedup Posted: Fri, 20 Apr 2012 00:04|
|The green induction fixtures PSE&G put in Jersey are crapping out like crazy, junk components? In my town alone there has to be over 100 failed fixtures, being replaced every time one is reported dead with HPS! They should have done HPS all the time, if they weren't going with LED from legit mfgs, like Philips or GW. The induction fixtures are really bad. Horrible side light through, the glaring cool white light is horrible for driving in wet road weather. HPS, RELIABLE, better light, better optics, cheaper! Where did they find these goofy induction fixtures, in Jersey, horrible stuff.|