Article

2006-02-17 Iraq

LEDs for white light now at 57 lumens per watt

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Posted by mhw 2006-02-17 14:57|| || Front Page|| [11130 views since 2007-05-07] Top

#1 Price per watt? I doubt most homeowners will be able to afford to replace regular bulbs with LEDs one for one, at least for awhile.

Posted by Jonathan">Jonathan 2006-02-17 15:11|| 2006-02-17 15:11|| Front Page Top

#2 CREE sells to distributors who then price them as they see fit.

We are still a few years away from the great price/efficiency breakthrough

Posted by mhw 2006-02-17 15:25|| 2006-02-17 15:25|| Front Page Top

#3 I'm not sure there's oodles in lighting. The big electric hogs are your refridgerators, freezers, ovens and air conditioners.

Posted by Chuck Simmins">Chuck Simmins 2006-02-17 15:47|| http://blog.simmins.org]">[http://blog.simmins.org] 2006-02-17 15:47|| Front Page Top

#4 Fred would be justified by adding an energy section because it is a legitimate theater in the GWOT.

Posted by Penguin 2006-02-17 15:56|| 2006-02-17 15:56|| Front Page Top

#5 Just the other day I was talking with Mike Holt, CEO of Lumiled - maker of the world's brightest commercially produced LEDs. His company's target is to make the first solid state automobile headlight.

I can actually remember when HP (which Lumiled spun off of) came out with the first discreet package red LED. At their original list price of $5.00 each, your average automotive CHMSL (Center High Mount Stop Light - pronounced "chimsel"), would cost a mere $1,000. Gotta love the steep decline in COG that all semiconductor devices experience.

III-IVs compounds (used for LEDs) have proven the most intractable of the various semiconductor types. Only with the advent of successful Czochralski (CZ) counter-rotating boule and seed crystal pullers has there been the sort of large diameter substrates required for bulk device production.

III-IV based microprocessors (with almost limitless top-end speeds) were supposed to be the end-all and be-all for computing until they discovered just how finnickey and contamination sensitive these odd materials are (not to mention power hungry). As an example, gallium arsenide (GaAs) is a compound made of the elements gallium and arsenic. The eutectic characteristics of gallium are quite strange, in that when a piece of room temperature gallium is placed in your hand, it will begin to melt. Yet, by adding just a small proportion of arsenic to it, suddenly its melt point rockets to over 1,000°C! One can easily imagine the complications of keeping impurities out of the crystallization process when even minute traces dramatically alter the critical parameters of lattice formation. For another example, whereas nonconductive silicon is doped into conductivity with elements like boron, phosphorus, antimony and arsenic, gallium arsenide is actually doped with silicon.

As to the white LEDs, these devices, like all LEDs, actually emit only one frequency of light. The trick to getting spectral emission is by making the LED emit ultra violet light and then coating the interior of the emitter's package lens cavity with phosphors (just like your television screen) that finally emit light in a variety frequencies. Quite an elegant solution, but one that sucks down power efficiency in the seconday emission process. This is why Cree's high-efficiency LEDs are such news.

Posted by Zenster 2006-02-17 16:18|| 2006-02-17 16:18|| Front Page Top

#6 We've replaced a number of incandescent lights in our home with fluorescent ones. The incandescent lights lasted about three months. The flourescent bulbs use 1/5 the energy and last up to three years. Technology will be the key to reducing our total energy requirements. It's just going to take time. I'm waiting for someone to invent an electric motor that runs off the Earth's magnetic field.

Posted by Old Patriot">Old Patriot 2006-02-17 16:22|| http://oldpatriot.blogspot.com/]">[http://oldpatriot.blogspot.com/] 2006-02-17 16:22|| Front Page Top

#7 Nikola Tesla powered a lot of stuff off the Earth's magnetic field about 80-100 years ago.

Posted by Mullah Richard 2006-02-17 16:45|| 2006-02-17 16:45|| Front Page Top

#8 I'm waiting for someone to invent an electric motor that runs off the Earth's magnetic field.

Paging Nikola Tesla!

Posted by Zenster 2006-02-17 16:45|| 2006-02-17 16:45|| Front Page Top

#9 Zenster put me in touch with Mike Holt, I have a very profitable market he's not touching.

Posted by 3dc 2006-02-17 18:10|| 2006-02-17 18:10|| Front Page Top

#10 There are lots of energy "tricks" that will be used in the future.

For example, though solar cells won't be powerful enough to run your a/c, they might be used to lower the temperature of your crawlspace by 50 degrees, from very hot (140 degrees) to just warm (90 degrees), which in turn would make your a/c much cheaper to run.

Another "trick" is a simple passive water tank that acts as a pre-heater for your water heater. Used only in summer, the tank sits on your roof exposed to the sun. City water pressure is enough to fill the tank. By heating the water another 20 degrees, before it goes to your water heater, gives you hot water much faster and cheaper. In winter, you just drain the tank and bypass it.

The use of ethanol fuel cells will also be a big plus. At the peak of the year when temperatures are at extremes and energy prices are highest, you disconnect your power from the grid and use your own fuel cell to run your home power. Or you use your fuel cell for just your most consumptive energy uses, like a/c or heaters.

Though something like LEDs for light may be very conservative of power, like phosphorescent, their light may not be terribly pleasant. So why not mix and match? Use LEDs or phosphorescent for extended use, lights that burn all night, for example. Incandescents and LEDs for typical daily use and special lights like plant lights for plants, or sunlight-bandwidth or Ott lights for the winter months.

The bottom lines are expense, ease of use, efficiency, durability, and location. Different strokes for different folks.

Posted by Anonymoose 2006-02-17 18:34|| 2006-02-17 18:34|| Front Page Top

#11 lighting represents 10% of the US total energy use... so yeah that's oodles in my book. The other question on these LEDs is how long they last? Also the big problem with florescents as far as I'm concerned is you can't put them on dimmers... that's a non-starter for my home... LEDs you can.

Posted by Damn_Proud_American 2006-02-17 18:49|| 2006-02-17 18:49|| Front Page Top

#12 Another "trick" is a simple passive water tank that acts as a pre-heater for your water heater. Used only in summer, the tank sits on your roof exposed to the sun.

Passive solar hot water is widely used here in Oz. In Perth you get sufficient hot water for about 8 months of the year from solar alone.

I had the idea of using a water filled layer in your roof space as combined insulation and a heat sink. One of the problems here is we have a large diurnal temperature range, and for a lot of the year, even though it is warm to hot during the day, it's cool at night. The heat sink would even out the temperatures in the house over the day/night.

Posted by phil_b">phil_b 2006-02-17 18:52|| http://autonomousoperation.blogspot.com/]">[http://autonomousoperation.blogspot.com/] 2006-02-17 18:52|| Front Page Top

#13 The other question on these LEDs is how long they last?

Nominal lifetime for an LED device is a mere 100,000 hours. White LEDs are somewheat lower at a paltry 30,000 - 50,000 hours. The LEDs used in undersea fiber optic cable relay boosters must meet an average lifetime of 30 years.

For some real fun, check out this future application for ultra-high-power LEDs in laser driven fusion reactors:

http://www.llnl.gov/str/Payne.html

Figure #3 shows a bank of high-power micro-collimated laser diodes. Wowsa!

CAUTION: Do not stare into laser with remaining eye!

3dc, take a number! My reason for meeting Mike Holt was rather specific. I've got a presentation worked up regarding an untapped billion dollar market for LEDs. My home computer is out of commission for a while. When it is back up, I'll find a way to send you a note and we'll see what we can do to get you hooked up ... all for just 1%, kid.

Posted by Shaviting Slomp2149 2006-02-17 19:32|| 2006-02-17 19:32|| Front Page Top

#14 What the?!? The above was Zenster, of course.

Posted by Zenster 2006-02-17 19:34|| 2006-02-17 19:34|| Front Page Top

#15 For a truly inspiring story of invention and subsequently dogged persistence, read the tale of Shuji Nakamura and his creation of the vital blue laser diode.

http://www.sciencewatch.com/jan-feb2000/sw_jan-feb2000_page3.htm

Determined to avoid the short lifetime of zinc selenide based devices, he pioneered innovative techniques of MOCVD (Metal Oxide Chemical Vapor Deposition) reactor processing to utilize the less apt (at the time) gallium nitride compound. His secret was a dual gas flow regimen, one parallel stream of reactive gas to enhance deposition and another perpendicular jet to compensate for the substrate's thermal loss.

Nakamura perfected the processing of this critical component, without which the CD-DVD format would not exist. He spared no personal expense and, in the face of withering criticism, brought this useful device to market.

His work was then appropriated by the Nichia company, where he began his efforts, and after a protracted court battle Nakamura won one of the largest inventor vs. corporation lawsuits in Japanese history. Some ¥20,000,000,000 or ~$170 million USD was awarded. His article is well worth reading.

Posted by Zenster 2006-02-17 20:33|| 2006-02-17 20:33|| Front Page Top

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