A quick glance at a satellite image of the lit-up earth outlining the continents of the world easily show the energy demand civilization imposes on the night. Streetlights and other other lighting across the globe consume up to 20% of total electrical energy produced. In the United States 22% of electricity consumed is used for lighting.

James Sun, founder of Dew & Ken Technologies of Madison, Wisconsin notes that “In U.S. cities, streetlights consume tremendous amounts of energy each night”.

Sun’s company is one of several innovators in LED technology looking to lessen the load from streetlights and other outdoor municipal lighting applications.

Most streetlights today consist of High Pressure Sodium (HPS) lamps consisting of pressurized sodium gas that produce that familiar pinkish glow. HPS lighting has been in wide use for about a decade and is considered much more efficient than the older fluorescent, incandescent, and mercury vapor lighting fixtures.

The next step in street and outdoor lighting is the LED (light emitting diode), which really isn’t a lightbulb at all per se, but a semiconductor that glows when tickled with electricity.

The Great Streetlight “Controversy”
Street lights have a proud history in the United States and around the world – people are passionate about their streetlights. That’s one thing I’ve discovered while researching this post. From blogs devoted to the nostalgia and “style” of streetlights to sometimes rancorous debate over the relative efficiency of LED’s vs. HPS – people have surprisingly closely held ideas about the best way to light our streets and other public spaces.

Despite the ongoing debate in some circles, it’s pretty clear that LED lighting is the most efficient means in terms of energy use, longevity, maintenance, and usable light output. According to the Department of Energy, adoption of LED lighting in the United States can:

• Reduce electricity consumption by 62%
• Reduce carbon emissions by 258 million metric tons
• Eliminate the need for building 133 new power plants
• Lead to a financial savings in excess of $115 billion

Still, many municipalities are wary of moving into LED technology due to the large capital expense of LED’s combined with what some see as an unproven technology.

But that is changing.

LED City
In December of 2006 a parking garage in Raleigh, North Carolina was lit using LED’s, thus launching LEDCity, a program designed to promote deployment of LED lighting in cities across the globe. The program began with initial support from Cree, Lighting Science Group, AmTech Lighting Services, and Progress Energy, with a growing list of sponsors and supporters as the program gains traction.

Municipalities involved in the program include Toronto, Raleigh, Ann Arbor, and Austin. Ann Arbor’s ambitious goal to convert to 100% LED lighting will be completed within the next two years. The city anticipates a cut in energy consumption and maintenance costs by at least half with a reduction in carbon emissions by 2,425 tons annually. The initial investment should be paid for in less than five years. Winner of the ICEI Local Governments for Sustainability inaugural Climate Innovation Invitational, the program Ann Arbor is implementing is a model for public LED lighting.

More LED Innovations and Innovators
The potential of LED lighting for high-power lighting applications is bringing many innovators to the fore. James Sun’s Dew & Kemp (whose website, linked above, is in need of some professional copywriting help) was a finalist in the Wisconsin Governor’s Business Plan Contest. Currently employing 20 employees worldwide, Dew & Kemp’s current market focus is in Sun’s native China, with 260 LED streetlights installed there and orders for 2,800 more. Dew & Kemp’s innovation with LED’s centers around heat dissipation (a problem for large LED arrays) and computerized control. Says Sun:

“We can reduce the current a lot after midnight, for instance, and turn it down to save on energy”

Networked monitoring and control of streetlights isn’t restricted just to LED’s. Streetlight Intelligence, a publicly-held company traded on the Canadian TSX Venture Exchange (SLQ), offers the Lumen Streetlight Intelligent Management system (SIM) for computerized and networked control of HPS streetlights. According to Streetlight Intelligence the system delivers up to 50% energy savings, reduces maintenance costs by 25 to 40%, and eliminates up to 50% of greenhouse gas emissions.

 The bottom line is that LED lighting is no longer used for indicator lights on electronic gadgets. LED’s have moved out of the electric device and geeky flashlight, into the ceiling lighting fixture, and now outside into commercial, large-scale, high-power lighting situations. Even critical applications like theatrical lighting, where directivity and color temperature are key, LED technology is starting to make inroads.

And so it goes for the blogger as well. My desk is lit with a 36–LED-array desk lamp. Just as with the large municipalities, my up-front capital expense may have been higher when purchasing the lamp as compared with the more conventional variety, but I’ve reduced my energy consumption and don’t plan on the lamp requiring any maintenance (other than a light dusting) anytime soon.

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