LED Street-Lights are Greenest Choice, Life-Cycle Study Shows

LED street light photo

Image: Knossos
Induction Lights Are Close, But No Cigar
Most people who have been following lighting tech seem to be convinced that light-emitting diode (LED) lights are the future, but it's always good to see new research being done on them. The more sure we are that they're the way to go, the better. It always sucks to invest a lot of time and money into something only to later realize that it's not nearly as good as we were first led to believe (*cough* corn ethanol *cough*). Researchers at the University of Pittsburgh have conducted the first cradle-to-grave assessment of LED streetlights, and the results are interesting.
street light comparison chart LED image

Image: University of Pittsburgh
Engineers in the Mascaro Center for Sustainable Innovation based in Pitt's Swanson School of Engineering compared LED streetlights to the country's two most common lamps-the high-pressure sodium (HPS) lamps found in most cities and metal halide lamps akin to those in stadiums-and the gas-based induction bulb, another emerging technology billed as bright and energy efficient. The team reported that LEDs may carry a formidable price tag, but in comparison to HPS and metal halide lamps consume half the electricity, last up to five times longer, and produce more light. Induction lights proved slightly more affordable and energy efficient than LEDs, but may also have a greater environmental impact when in use. The authors also noted that LED technology exhibits more potential for improvement and may surpass induction lamps in the future.

That last line is important. LEDs are still improving, and further advances in color quality, efficiency and manufacturing (to reduce cost) should make the choice even more clear-cut.

The environmental impacts of making the bulbs and disposing of them also favors LEDs: "producing LED housings-composed largely of plastic and wire-consumes far less energy than manufacturing aluminum-heavy HPS casings. LED bulbs also contain no mercury and fewer toxins, such as iodine and lead-HPS and metal halide bulbs packed an average 15 milligrams of mercury each, with induction bulbs averaging 6 milligrams."

But this should be kept in context. Pollution coming from power plants produce "up to 100 times the environmental impact of manufacturing", so energy efficiency really is key for a light to be green.

street light photo

An endangered species? Photo: Flickr, CC

On cost:

"The City of Pittsburgh estimated that, per year, replacing HPS lamps with LED streetlights would save Pittsburgh $1 million in energy costs and $700,000 in maintenance, while reducing carbon dioxide emissions by 6,818 metric tons. [...] As an example, 40,000 LED lamps could initially cost the City of Pittsburgh as much as $21 million versus approximately $9 million for metal halide streetlights. Yet replacing metal halides could cost as much as $44 million before the LED lamps needed a first replacement."

See also: Illumitex Wants to Make Your Lightbulbs Square (and More Efficient)

Via University of Pittsburgh
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