LED Street Lights Testing in California

The LED Street Lights Testing was hold in California. As we all know that high-efficiency white LED street lights will cut energy use by 30 percent to 60 percent every year.

Garden Grove is testing four 250-watt LED street lights on Civic Center Drive at Acacia Parkway, said Senior Analyst Chau Vu. Whether the city will switch over to LED will depend on how this testing goes, she said.

“In the next six months to one year, we’ll look at how much wattage these lights use up,” she said. “If it does what they say it can do, then it’s definitely worth it for the city. These lights can save a lot in terms of energy and money.”

LED lights are also easy to maintain because they last longer, Vu said. The downside is that they cost significantly more. While a regular street light costs $300 a fixture, LED lights cost about $2,000 a fixture.

LED lights are constructed with 100 percent recycled aluminum, contain no mercury or lead and do not require hazardous waste disposal handling. The city of Los Angeles is testing 100-watt LED lights.

Garden Grove was one of the first cities in the state to install LED lights on traffic signals. These test lights are manufactured by a company called Leotek and were donated to the city by South Coast Lighting.

So, if the tests prove successful, the city should do their best to change all street lights to LED.

Salmon DNA LED Bulbs

It is reported that the latest LED breakthrough comes from the University of Connecticut, and it uses salmon DNA to create very long-lasting white LEDs (though they can be tuned to other colors). By now a lot of cool LED technology still needs to make its way from the lab to the store, it’s exciting to see that engineers are still finding new ways to squeeze more performance out of those semiconductor diodes.

Fluorescent dyes (two different ones, spaced between 2 and 10 nanometers from each other) are added to the DNA molecules, which are then spun into nanofibers. These are very durable because DNA is a particularly strong polymer (it has to be!) (they should last 50 times longer than acrylic, for example).

A LED emitting ultra-violet light is then coated with the DNA nanofibers: “When UV light is shined on the material, one dye absorbs the energy and produces blue light. If the other dye molecule is at the right distance, it will absorb part of that blue-light energy and emit orange light.” Using DNA has the benefit of orienting the dyes “in an optimum way for efficient [fluorescence energy transfer] to occur,” according to David Walt, a chemistry professor at Tufts University.

To tune the light quality, all you need to do is vary the ratios of dye. The light can be tuned from cool white to warm white, for example.

Unfortunately, numbers on how many lumens per watt these LEDs produce haven’t been released yet (though that might just be because they’re still improving them), so it’s not clear if the main benefit from these will be the longer life, or if the extra fine tuning will also mean better light quality than other white LED (like those that use quantum dots, for example), or if energy efficiency will also be superior. But it’s a new trick that will no doubt be useful. Maybe someday we’ll have a bit of DNA in our lights.

The LED Streetlights Could Drive You Crazy and Make You Fat?

This is a test on LED streetlight. During the day, the block of bungalows and houses at 22nd Avenue East and East Mercer Street looks like most of Capitol Hill. But at night, it looks crazy. This is one of seven test areas in the neighborhood where Seattle City Light swapped the high-pressure sodium streetlights, which emit a warm orange hue, with glaring LEDs. City officials want to replace all 40,000 residential streetlamps in Seattle with the new light-emitting diodes by next year to save energy and money. But the lights cast a sickening hue. “It is a very cold color—zombie blue,” says Dan Travers, who lives on the block. “My first thought was that people are going to look scary under these lights.”

“It looks like you are in a supermarket aisle,” says Andie deRoux, who lives in an apartment building seven blocks west of Travers. Abby Katzman, who has lived on the eastern slope of Capitol Hill for 20 years, says, “I like the energy it saves, but it does seem very cool and wintery.”

On the shortest night of the year, just after dark at 11:00 p.m., I walked to each of Seattle City Light’s test areas to see what’s sparking revulsion from Travers and others who live under the lights. The beams from the high-intensity, light-emitting diodes are striking. The rays turned my skin the color of white taffy and cast crisp shadows on the pavement. “Zombie blue” is exactly right: Like a day-for-night special effect in a vampire movie, the test streetlights create the sort of atmosphere where you almost expect the undead to emerge from the flower beds and begin eating your face. Everyone I spoke to enthusiastically supported the idea of the LEDs—which require 50 to 60 percent less electricity for the same lumens—but most resented the quality of the light itself.

The problem with the new lights isn’t just aesthetic. According to Dr. David Avery—a professor of behavioral sciences and light therapy at the University of Washington and the region’s leading researcher on the impact of light on human chemistry—the LED lights could interfere with human biorhythms. Certain photoreceptors in the eye’s retina react to cooler colors of the light spectrum, sending a signal to the brain that the sun is up. When humans see the blue light, our bodies think it’s daytime. “The sensitivity to these cells for the blue and greenish color makes perfect sense, because the sky is blue. So for millions of years, life has evolved with this 24-hour rhythm of blue light being very prominent for part of the day and then darkness,” he says. “This is kind of a conductor of a circadian symphony in the brain and body.”

According to Avery, “Theoretically, if someone has one of these LEDs or a blue light outside their window, it could fool the eyes and the brain into thinking that the sun is still up, so the melatonin hormone might not rise normally and sleep might be disrupted.” Incandescent lights, the standard bulb in homes, are on the red end of the spectrum. (You may think of them as being white, but they’re not.) Shifting the city’s primary outdoor lighting to blue-hued LEDS, Avery adds, “would be a major change in terms of our environment.” Studies suggest that people exposed to daylight at the wrong hours, like those who work night shift, have more health problems such as high blood pressure and obesity, Avery says.

Mayor Greg Nickels wants most Seattle residents to be living under new streetlights by 2015. Seattle City Light intends to install the lights specifically in residential areas—not commercial arterials or industrial zones, which require more illumination than LEDs can affordably provide.

“They would save about nine million kilowatt hours and about $408,000 a year,” says Seattle City Light spokesman Scott Thomsen. An LED lamp uses only 50 watts, while traditional high-pressure sodium bulbs require 130 watts and waste electricity on heat. The conserved power roughly equates to the energy used by 750 single-family houses a year, Thomsen says. Moreover, the LED lamps last three to four times longer—up to 18 years—which drastically reduces maintenance costs to the city. (The city currently pays about $100 in labor costs to replace each dead bulb.)

But LED fixtures cost much more. Whereas the bulbs in the existing fixtures (awesomely dubbed “cobra heads”) cost about $15, the LED lamps are part and parcel with their fixtures and each costs $300 to replace, says Edward Smalley, Seattle City Light’s streetlight engineering manager. “The real payout for the city, to the customer, is not having to go out to change the light.” Funding to kick-start the program comes from a $6.1 million federal stimulus grant to reduce energy use. Of that, $1 million will go toward installing the first 2,500 streetlamps next year, assuming the Department of Energy approves the expenditure this summer. If the city council expands the program, new streetlamps citywide will cost about $20 million.

City officials acknowledge the test lights aren’t great. (A different brand of LED is being tested at each site, or in some cases the same brand at different levels of brightness.) Although some people like the lights, other people in the test areas have been complaining—in one area, the reaction from residents has been so intense that Seattle City Light is canceling that test site. And it is continuing to look for better technologies. There’s a relationship between a light’s warmth and how much energy it saves. High-pressure sodium lights, which give off that night orange glow, emit light at about 2200 degrees Kelvin. But the pilot LEDs are between 5000 and 6000 Kelvin. While Smalley acknowledges the new lights are “a lot bluer, for sure, than what we have now,” LEDs as warm as the old lights aren’t energy efficient enough to be practical. Seattle City Light will begin testing slightly warmer-hued streetlamps in Seattle’s South Park neighborhood in late July. “We are looking at 4000 degrees Kelvin and above, so that way we can provide the best comfort for the city and the energy savings that we are looking for.”

Anchorage has begun installing 16,000 LEDs streetlamps, San Francisco has announced it will convert 30,000 streetlamps, and Los Angeles has announced plans to convert 140,000 lamps. Smalley says that technology to produce energy-efficient LEDs with a more palatable hue is evolving, with new generations of lights emerging as quickly as every six months.

Considering the bulbs live longer than most pets, the city should take as much time as necessary to pick a light we can live with for a while. Smalley said that those folks who dislike the lights, stay tuned and look to our next test sites like South Park. No one has locked into what you see out on the street now.

The First Purely White LED Produced in Korea

It is claimed from Korea Researchers that the world’s first purely white LED (light-emitting diode) has been produced in Korea.

Soo-Young Park, a professor of organic materials for photonics at the Department of Materials Science and Engineering at Seoul National University in Korea, led the group, which includes researchers from the University of Valencia in Spain.

LEDs are much more energy-efficient than incandescent or compact fluorescent lightng (CFL), but the quality of light they can give a room is up for debate.

Because LEDs do not naturally produce white light, getting them to look like they do adds to their production cost, making them much more expensive than your average incandescent or CFL. Many companies have been trying to come up with different LED recipes and components to produce a nice white light, while keeping the consumer cost down.

Park and his group claim to have engineered a molecule with one orange and one blue light-emitting material that produces a white light in the visible light spectrum when put together.

In other words, they say they’ve invented a white-light-emitting diode.

Repeated laboratory tests apparently showed that the new form of LED molecule is efficient, color stable, and able to be reproduced again and again, making it a legitimate candidate for use in LED lighting.

A detailed explanation of the group’s molecular work can be found in the current issue of Journal of the American Chemical Society.

According to Mr.Park and his group in their paper, an ideal material for a white-light source should be cost-effective, stable, robust, emit over the whole visible spectrum, not suffer from self-absorption, and its pure color should be easily reproducible. With this goal in mind, we have successfully synthesized and characterized, for the first time, a white-light-emitting single molecule dyad, consisting of two noninteracting chromophores showing excited-state intramolecular proton transfer.

A New LED Light Bulb with 7 Shades of White

“Any color you like, as long as it’s white!” No, it’s not a bizarro version of Henry Ford, just Sharp’s new LED light bulb. Using the included remote control one can dial through 7 different shades of white light – without any white heat.

Ambiance at your fingertips has arrived, thanks to Japan’s Sharp Electronics Corporation. According to Sharp, the new DL-L60AV LED Lamp allows users to adjust the color function of the light bulb through a range of 7 different shades “ranging from a pleasing warm white to a cooler daylight white to match the weather, the season, time of day, purpose, or other preferences.” The adjustment is done via a hand-held remote control that also allows users to tune the brightness of the bulb to suit their preference. Forget Henry Ford, what would Thomas Edison think?

The thought of a single light bulb needing a remote control may seem somewhat extravagant but Sharp intends for the bulbs to act as stand-alone lamps; one per room is enough. The DL-L60AV LED Lamp is rated at 560 lumens – tops in the industry – yet cost a mere penny to run continuously for 11 hours. One especially “bright” feature of the DL-L60AV LED Lamp is its base; exactly the same as standard incandescent light bulbs so it can be used in existing lamps and light fixtures.

I’m not done yet: this bulb is cool – literally. LED’s don’t create heat like incandescent bulbs do, which means they don’t waste energy on creating such heat.

They also differ from incandescent light sources in that they emit very little light in the 350-nm waveband, the part of the light spectrum that lies in the ultraviolet range and attract insects. This makes the DL-L60AV LED Lamp ideal for outdoor use, especially near entry/exit doors.

The DL-L60AV LED Lamp is one of nine new high-efficiency, mercury-free LED light bulbs to be introduced to the Japanese home market this July 15. All have the convenient screw-type base that negates the need for expensive retrofitting. Very cool indeed!

Why the White LED Shows White

The ‘white’ of white LEDs comes from the narrow-band blue naturally emitted by GaN LEDs, plus a broad spectrum yellow generated by a phosphor coating on the die which absorbs a proportion of the blue and converts it to yellow.

‘GaN’ die are actually InGaN heterostructures, which can produce operational wavelengths from green to ultra-violet by varying the relative amounts of indium and gallium during production.

Although this blue die + yellow phosphor approach yields light which appears white, it has little green and almost no red content leading to inferior colour rendering compared with incandescent bulbs and even ‘tri-phosphor’ florescent tubes. ‘Warm white’ LEDs, which include a red-producing phosphor, are an attempt to improve this situation as well as make LEDs illumination more acceptable in living spaces.

LEDtronics has the largest variety of White LEDs and LED lamps on the market from White SMT LEDs, 3mm, 5mm White LEDs, to Direct Incandescent Replacement White Based LED lamps in standard electrical bases and voltages from 6 Volts to 270 Volts. Base styles such as T1-3/4 (5mm) Midget-Flanged White based LED lamps, Telephone-Slide based White LED Lamps, T3-3/4 (9mm) Miniature based White LED lamps, 15mm DC Bayonet based White LED lamps, 15mm SC Bayonet based White LED lamps, A19, R20, PAR20, R30, S11, S14L, G30, Candelabra Screw based, Panel-Mount and MR16-style based White LED lamps. And durable White LED Torches and Flashlights.

White LED

LED technology is driving the future of lighting with the developments made in the efficacy of white LEDs in the past few years,

As white light is the main driver for general illumination, there is a particularly strong focus on improving the efficiency of white LEDs, which currently outperform tungsten halogen lamps with efficacies from 45-55lm.

Manufacturing methods have allowed for significant progress to be made in increasing the efficiency of LEDs. Previously, the only way to produce white LED light was by the additive colour mixing of the three basic colours using so-called “multi-LED”, ie, three semiconductor chips (red, green and blue LEDs) had to be combined.

Today it is possible to produce white LED light with a single chip.

In luminescence conversion, only a blue LED is used, whose light stimulates a luminescent substance that emits yellow light. With interaction, the system produces the colour white.

White light is generated on the basis of a principle similar to that used in luminescent substance lighting. Depending on the composition of the luminescent substance, various white tones can be realised.

White LED versions of traditional luminaires are already available from several manufacturers, particularly in the MR11 spotlight  style.

LED headlights for cars are in the pipeline is producing a range of multi-die packages that are close to producing enough light for road illumination. LED bicycle headlights are already available.