Outdoor Lighting: Tempe vetoes LEDs, chooses induction street lights

Erik Sine · July 20, 2011

20 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.

YYZ · July 21, 2011

Interesting about AZ, but their reservations about heat are not misplaced. It's not that LED systems can't work, but they are far more reliable in more temperate or northern locales than they would be in a desert environment.

Seattle recently announced that the first 6000 street lights are doing very well and they are going to continue until the total number of units is around 41,000.

http://www.ledsmagazine.com/news/8/7/11

Interesting that the Seattle story was posted the day before the Tempe one (the same source as your news release above), but you chose to bypass the positive story for one that is less so. I'm not saying either is right or wrong, just curious about what gets posted and why - they're both on the same topic and equally newsworthy, no?

Erik Sine · July 21, 2011

Following your link it was about a week earlier. That didn't come across the news alert, and when they do I pick and choose based on the headlines, I get way too many every hour. Sorry.

But after looking at the link you posted it never discussed what was initially spent to save $300,000 a year. As you know, I'm not a big fan of Retrofitting unless it makes absolute sense, whether it's T12's to T8's (which makes no sense in interior facility lighting), or Neon/Fluor to LED.

That article seems more of a marketing greeney environmental article than a factual one.

YYZ · July 21, 2011

Using the math n your article, it puts the value of each street light at $333. I'm not sure if this is fixture cost or installed, but let's go with it.

6000 fixtures x $333 = ~$2 million. Saving $300K per year puts the payback at 7 years, which isn't so good.

41,000 fixtures x $333 = ~$13.65 million, to save $2.4 mil per year = about 5.6 years payback on energy alone.

Thing is, the payback number isn't the only value to look at...

What do these cost to maintain over their life, compared to existing or competing products? Union guys in bucket trucks cost $100s per hour, which could adds some sort of saving.

More importantly, if these fixtures are high PF (very likely so), then the utility can save a whole lot on the generation and transmission side - maybe even enough to bring the payback down from 7 years to 4. The city saves money on their bills and the hydro company saves on power generation.

Add in the ability to dim or reduce power during non-peak hours, etc, and there are further savings available.

Any savings in this regard can offset the need for new power generation that would otherwise be needed just based on population growth. 41,000 fixtures saving say 60W ea would be over a million kw/h per year (1 mW) - the size of a small power plant. How much would the new power generation cost if it had to be built? That's a pretty huge savings also.

Lastly is the improved visibility. I know it's not really part of the discussion here - but what price do we put on increased safety?

They have to be efficient, reliable products of course - which not all LEDs are (see Columbus, Ohio in your link), but there's more involved that the simple upfront cost divided by energy use.

Erik Sine · July 21, 2011

I agree with you there. Also, with high cost components, for each failure or breakdown, even breakage before or during installation will push the ROI figure back.

What I'd like to know is also the usable light that it' putting out. Does really make a difference value/cost. Is it enough ambient light as well as surface light?

Unlike the problems that California has with the wacko fringe envronmentalists, not sure how bad it is in WA.

YYZ · July 21, 2011

LEDs are actually more efficient than Sodium (in terms of lum/W), so I have no doubt that the light is more or less equal, but even if actual measured lumens are a little lower, it could be fine since cooler color temps are more more receptive to the human eye. Our visual acuity and peripheral visual are vastly better at cooler color temps than with the yellow-orange of Sodium lamps.

If we were talking end users or business paying, it would be a tougher sell - but these are local governments and utilities putting up the money, so the bigger picture has to be considered in terms of power factor, generation and distribution, long term power planning, etc...

Switching to LEDs may be very costly, but if they can offset population growth in terms of increased power needs, we're talking billions in savings of not having to build new power plants and transmission systems. It would be nice to see those calculations and reports, for sure.