White LEDs for a Brighter World

deepfry writes "CBC radio today featured an interview with Dr. Dave Irvine-Halliday, an engineering professor at the University of Calgary, who's developed a home lighting system for the developing world using a combination of white LEDs, pedal generators and rechargable batteries. This type of "pico-power" can make a huge difference in the lives of villagers in rural areas where being connected to a power grid is not an option and probably never will be. Read about the Light Up the World project and make a donation."

Comments

Light up?

[Anonymous Coward]

"Read about the Light Up the World project and make a donation."

It ain't no joke, I'd like to buy the world a toke...

too expensive.

[rschwa]

uh, ok. $1 a piece for a .1 watt bulb. sounds great. Exactly how many would I have to gang to be able to read my newspaper?

Re:too expensive.

[TrumpetPower!]

uh, ok. $1 a piece for a .1 watt bulb. sounds great. Exactly how many would I have to gang to be able to read my newspaper?

Because, while that bulb only consumes 0.1 W, it gives off as much light as a much brighter incandescant bulb. I didn't see figures in the article, but one would figure that it's better than what you get with flourescent lights.

I've replaced many of the lights in my apartment with compact flourescents. Typically, a CF bulb that outputs as many lumens as a 100 W incandescant bulb will only require 20 - 30 W. Reading a newspaper with a 20 W incandescant isn't practical, but the 20 W CF is more than bright enough.

b&

Re:too expensive.

[jmv]

uh, ok. $1 a piece for a .1 watt bulb. sounds great. Exactly how many would I have to gang to be able to read my newspaper?

Maybe not that many... Remember that the efficiency of a normal light bulb is very very bad, since most of its energy is dissipated as heat. I wouldn't be suprised if a 100W bulb only produced 1W of visible light.

Re:too expensive.

[suwalski]

What you do not realize, judging by your post, is that the average 20 mA white LED looks brighter than the average 40W 120V bulb. A single one makes an excellent flashlight. A few of them together make an awesome lightsource.

Re:too expensive.

[Fulcrum of Evil]

I wouldn't be suprised if a 100W bulb only produced 1W of visible light.

It's usually around 3W. IIRC, flourescent runs around 25W.

Re:too expensive.

[Mahrin Skel]

That's not so bad. I just bought flourescents to replace some of my incandescents for $10 apiece, and a big part of why wasn't the power savings, it was the reliability. 10 foot ceiling in the kitchen, and outdoor lamps blowing at least once a month, the flourescents went into the same sockets and have a MTBF of 5000 hours. These WLED's are supposed to be good for 20 times that, and would fail "soft" because of the multiple sources in one unit.

$25 to never need to balance on top of that stepladder in the kitchen again? Sounds like a deal to me. I could even see $50. Be even nicer if these don't have the flicker issues of flourescents (which is why I won't use them for reading or near the computer). And it beats the hell out of the RF units, which would kill both my phone and my network.

--Dave Rickey

Re:too expensive.

[jmv]

I realize that, but even supposing your numbers are correct, we're talking 10 of those $2.50 (the $1 is in quantities of 100000!) LEDs to match 1 100W bulb.

Yes... but who said it had to be equivalent to a 100W bulb? The sensitivity of the eye is (IIRC) roughly logarithmic so 10 times less light is still not that dark. I'd bet with a .1W LED you could see everything in one room (which means in the whole house for those people). It won't be very bright, but it'll work.

Re:too expensive.

[GutBomb]

the places these would be installed in do not have existing fixtures, since they are not connected to a power grid.

Re:too expensive.

[Omnifarious]

it gives off as much light as a much brighter incandescant bulb.

Really? How does it do that?

It uses quantum effects to generate the light. It'd take a long time, and a little more knowledge than I have to adequately explain how semiconductors create light. The short explanation, with terms left unexplained, is this:

A solid-state semiconducting diode is one type of semiconductor (N-type) with an excess of free electrons (not a negative charge, precisely) and another type (P-type) with an excess of 'holes', or places where it's favorable for an extra electron to be. You could think N-type as a flat field of golf balls and P-type as a field of little cups.

Now, the field is flat, so there's no reason for the golf balls to go anywhere. There's also a small wall between the golf balls and cups. Applying an electric charge to the system both tilts the field, and adds extra golf balls to the side farthest from the cups. When a golf ball lands in a cup, it moves into a state where it has less potential energy, particularily since it's also just gone over the little hill.

Now, systems of atoms release energy through distributing vibration. So, a real golf ball and cup would heat up a little, and you get some sound (vibrating air). But, electrons absorb and release energy by absorbing and releasing photons, or 'particles' of light. So, when the electron (golf ball) falls into the hole (cup), a photon of a specific frequency (because it's a very precise amount of energy) is released.

No energy is really lost in this whole process. A tiny bit of energy is lost to resistance as the electrons (and holes actually, but that made the analogy trickier) moved over the surface, and some of the photons will be absorbed before they leave the semiconductor, but it's largely very efficient.

Now, that will make an LED of one, specific color, determined by the depth of the holes, and the little ridge (band gap) between the plane of electrons and plane of holes. In order to get white light, you have to have more colors. This is usually done by packing three LEDs together in the same package, along with some system of getting their light to mingle and be reflected in a particular direction. This system too absorbs some of the photons, but it's also pretty efficient.

In contrast, incadescent bulbs work by exciting lots and lots of electrons in a filament into random states of excitation, and when they come back down, they release photons of all kinds of wavelengths, mostly in the deep infrared. Incadescent bulbs therefore waste tons of energy in heat.

Flourescent bulbs are a bit better in the they excite electrons in a gas to a very high energy state using high voltages. These electrons then release mostly UV when they drop back down, but there's a phosphor coating on the inside of the bulb that absorbs UV and re-releases visible light photons. This is lots more efficient than an incandescent bulb, but a lot of energy is still lost.

Re:too expensive.

[jedidiah]

It probably wastes less energy.

Just contemplate incandescent versus flouresent. If you've ever tried to touch the former after it was just turned off, you probably got a nice little burn. Do the same with a flourescent and you don't have the same problem.

THAT represents the energy that an incandescent bulb wastes relative to a flourescent.

LEDs may just take this efficiency a step further by only producing what is useful for illumination rather than generating lots of heat or non-visble light.

A bank of incandescent flood lights can generate as much (waste) heat as one might generate with an electric space heater.

Re:too expensive.

[cowmix]

I just want to know why my two LED flashlight was 35 bucks!

Re:too expensive.

[kcbrown]

The measure of what it "looks" like should be how much light is reflected off an object at a given distance, not how bright the bulb itself looks. The latter is very misleading since the surface area of a typical LED is many times smaller than the surface area of a typical light bulb, so a LED can "look" much brighter compared with a 40W bulb even if the total light output is much less.

Re:too expensive.

[Fulcrum of Evil]

That would imply that your typical fluorescent light bulb is almost 10 times brighter than a 100W incandescent bulb.

This is true for a 100W flourescent and a 100W incandescent. However, flourescent bulbs are bigger, so the lumens aren't quite so concentrated, and most of them are less than 100W - closer to 40.

Re:Quality of Living???

[geekoid]

Ride a bike for 10 minutes, get a couple of hours worth of light so you can read and learn.

Why only the developing world?

[TrumpetPower!]

Why limit something like this to the developing world? If the developed world used low-power, high-efficiency lighting, we'd dramatically reduce the consumption of energy and non-renewable resources. If these lights are cheap enough for the poorest on the planet to consider using them, there's no doubt that they'd save the industrialized nations amazing amounts of money, as well.

Frankly, I suspect we'd do more for the developing world by adopting this sort of thing for ourselves--which is not to say, of course, that we shouldn't encourage them to skip our wasteful ways in favor of the right way to do things.

b&

Re:Why only the developing world?

[Tycho]

The problem with white LED's is that they can be inconsistent in their color. If you will recall they are made by placing a small amount of white phosphorus on the light emitting element of a high powered blue LED. When the phosphorus is bombarded by blue photons it emits photons that make up the rest of the visible light spectrum. The issue with manufacturing white LED's is that it is difficult to make white LED's that are consistent in their color and brightness. Too little phosphorus and the LED's light can look a little blue. Too much phosphorus and the LED is dimmer than a good white LED. If the phosphorus is placed off center the light produced by the LED varies in color and brightness. Of course their are grades of LED's, but the higher quality LED's cost more. Some people in developed nations might find these quality variations unacceptable. Now don't get me wrong there are some places where I could stand the inconsistencies of white LED's, like in a garage, a hallway, or some other room where tasks are done that do not require the color to be consistent. I would find it annoying to have inconsistent light in some place where I would be reading though. For that matter while I cannot be sure as I do not use makeup, applying makeup might be difficult in light that has color and intensity variations.

Re:Why only the developing world?

[MeNeXT]

Yup they would be great as a porch light or outdoor lighting.

Re:Why only the developing world?

[Psiren]

applying makeup might be difficult in light that has color and intensity variations

Oh, I agree. Theres nothing worse than going out wearing blue lipstick when you meant it to be purple. Really makes you look like a prat... ;-)

Re:Why only the developing world?

[stu72]

You forget that the biggest reason people paint or repaint is because they're bored of the colour - the pain my last 200 years, but the fashion for any particular shade will not.

Bringing downt he price...

[chill]

One way to bring down the cost would be to sell them in the developed world. A finished product, that could screw into a standard light socket, but use 1/100th the power to provide the same light would sell well in the U.S.

Especially with all the noise about power shortages and rolling blackouts.

Selling them in the U.S. and the rest of the developed world would go a long way towards creating enough demand for serious mass production.

Re:Bringing downt he price...

[ivan256]

Where do you get your information? Do you make it up? What makes you think that a white LED lamp that produces as much light as a fluorescent lamp would use 1/100th the power?

White LEDs are only about twice as efficient as modern fluorescent bulbs, and less efficient then high pressure sodium lighting. They're also way more expensive to purchase than fluorescent bulbs.

Re:Bringing downt he price...

[oolon]

And of course the big advantage of fluorescent tubes is that they can run of AC, which is already wired into the house, if every LED array required a transformer to fit in standard socket, the efficency of the system would drop fast.

Personally I hate the light from flurorescent tubes, and will stick to my nice halogen lights.

James

Re:Bringing downt he price...

[nolife]

Compact fluorescent bulbs are a very good alternative. They come in many shapes and sizes, last roughly 7000-10000 hours and use about 75% less power then incandescent. I've seen 5 packs of bulbs at warehouse clubs for under $19.
They are getting physically smaller and cheaper all the time.

Re:Bringing downt he price...

[chill]

The number was a rough guess. Assume a 40w lamp uses, I dunno, 40w of electricity. Then assuming that the picture on the page was showing an actual lamp -- with an array of 10 LEDs, each consuming 0.1w of power, that works out to 1w of power.

That right there is a 1/40 ratio. Factor in the *much* longer MTFB, the reduction in heat energy emitted, etc. and it is a damn good ratio.

Yes, I would like to see a lumens output rating on the LEDs for a better comparison. I've seen reports of 120 lumens from a 5W white LED package. A standard 40w is 460 lumens.

So, that is only a 1/2 ratio, which isn't good. However, factor in the much longer life and reduction in heating and it adds up.

For a bit more info:
http://www.eet.com/story/OEG20001212S0034
http:// www.efi.org/articles/bulbs.html
http://www.lumile ds.com/newsandevents/news_index.h tml?page=http://www.lumileds.com/newsandevents/rel eases/press04-14-02.htm

Re:Bringing downt he price...

[AnotherBlackHat]

Last year, the numbers were something like this;

Lumens/Watt;
85-95: 32 watt T8 fluorescent
60-65: standard F40T12 cool white fluorescent
48-60: compact fluorescents
20: T3 tubular halogen
15-19: white LED
17: standard 100 watt incandescent
6: incandescent night light bulb (7w)
6: incandescent flashlight bulbs

The very best white LEDs are still under 35 lumens/watt, or about 1/2 the efficency of a flourencent. They have been steadily improving however, and around 2004 should surpass them.

But not today.

-- this is not a .sig

Re:Bringing downt he price...

[ColaMan]

You're half right - Actually the ballast is also there to limit the current flowing through the tube.

What (roughly) happens is:

You turn the power on.
The starter heats the two filaments, via the ballast, at either end of the tube for a few seconds, and then breaks that circuit. Since there was current flowing through the ballast , and the ballast is inductive (well, the old types)
a high voltage kick is produced, which is placed across the tube, which fires it.
That great.
Except that the problem is that the voltage required to maintain the arc inside the tube is a lot less than the voltage to start the arc, so you need to regulate the current through the tube to stop it from blowing up. The ballast, being inductive, presents a nice resistance at the mains frequency of 50/60Hz, which limits the tube current under normal operating conditions.

Anyways, that's how I remember it.

Those new-fangled solid state ones might as well be magic - they have the same effect, but how is a different matter.

Re:Bringing downt he price...

[glitch!]

You're half right - Actually the ballast is also there to limit the current flowing through the tube.
...
a high voltage kick is produced, which is placed across the tube, which fires it.

Except that the problem is that the voltage required to maintain the arc inside the tube is a lot less than the voltage to start the arc, so you need to regulate the current through the tube to stop it from blowing up.

That sounds about right. I remember doing my own experiments with fluorescent tubes. My own goal was to produce a circuit that had zero flicker and dimming control. These experiments were all with DC, of course. It is possible, but a real pain in the ass to control...

If memory serves, a cold tube will start glowing somewhere over 200 volts, and have a nice medium-low glow around 300 volts or so. I think that the gas started ionizing pretty well before it hit 400 volts. The current seemed to be pretty much a linear function.

Now a hot tube (filaments glowing) is a different matter. Once the gas started ionizing, the current goes WHAM! (96 point bold with a hundred exclamation points) and the voltage for full output is around 60 to 70 volts. I suppose that would be almost an amp at that point, a far cry from the tens or hundreds of milliams with the higher voltage cold cathode...

My experience with White LED's

[Bonker]

About a year ago, I got a kitsch keychain from a vendor who was trying to sell software to my company. We didn't purchase the software, but I have held onto that keychain.

Let me describe it. It's oval in shape, about 3cm long by about 2cm across and 1 cm thick. Inside the body of the keychain, which is clear vinyl, you can see the mechanism that makes it so neat, which is a small watch-type battery, a very small resistor, and one of the newer white LED's. The clear plastic vinyl is red, so when you squeze the thing, it's light is very slightly pink.

Now, here's the thing that makes me keep this around. This little piece of what I would othewise call 'crap' is brighter than my 'keychain-size' Mag Light! I can easily read by or do computer maintenance with this toy. If I had five or six of them, I could reasonably light a room for however long the batteries lasted.

White LED's are the wave of the future, IMHO. They're cheap in terms of production and electricity cost. I also understand that they're significantly easier on the environment than incandescent bulbs or flourescent tubes. Unless you overload it with current, which I understand is very difficult since many come with tiny regulators in the form of attached IC's, they don't burn out, making replacement costs plummet.

Make my next lightbulb a white LED

Re:My experience with White LED's

[dachshund]

You can buy a similar product here. I'm not sure exactly sure if the white bulb is an LED, but it's bright as hell and it's lasted me a couple of years on a single watch battery (with no signs of fading.)

They also make an IR version, for those of you with night vision goggles. And no, I don't work for the company, but I'm really impressed with their product.

Re:My experience with White LED's

[thesolo]

You're describing a Photon Light. You can buy them at ThinkGeek!

I love them. I keep 2 on my keychain at all times. You just never know when you might need one. The last CAT5 drop I was doing, the power went out (I was working in a thunderstorm). Thanks to my Photon Light, I was able to finish the drop with no problem at all. 2 White LEDs and I had more than enough light to keep working for over an hour straight.

Re:My experience with White LED's

[Bonker]

While the same size, the little light I have is probably much simpler than the one advertised at ThinkGeek. I'm guessing that it's total cost of production was around $3.00US

Re:My experience with White LED's

[CaptainCarrot]

They're cheap in terms of production and electricity cost.

Then why the hell are they so expensive? Check out the prices on available white LED replacements for incandescent bulbs, here for example although there are other vendors. The light equivalent of a 40W bulb will run you almost $200! I'm not even certain that's worth it even if it does last 100,000 hours.

Re:My experience with White LED's

[lupine]

This place offers 17 led bulbs(comperable to a 25w bulb) for $39, but they wont sell to developed nations(usa).

This place has 20 led bulbs for $60.

here is a place that has dimmer(?) bulbs for 30-35 bucks.

here are some really cool sunlight powered outdoor led lights for $80.

Finally

[yasth]

Light to starve by

white leds for a thinner world

[reboot_imminent]

i don't know about developing countries, but think about how much good it would do to get the overweight sedentary people here in the US off their asses and on a bike. Aside from energy savings, think of the savings from improving health

Re:Great!

[bwhaley]

Here is a link to some products with white LEDs. Hopefully they can find some better uses =p

white LED != efficient

[Lumpy]

Yes they are bright, but they make horrible area lighting. the most efficient lighting to date is still the compact flouresent and Cold Cathode flouresent lighting. It has the greates lumens per watt output compared to anything. White led's look bright, but are a concentrated beam, that same beam spread out to a 180Deg will be worthless. There used to be "tests" in home-power magazine that claimed white led's were superior.. but forgot to take into effect that the other lamps also lit up the room instead of a white spot on the bench aimed at the sensor.

Re:white LED != efficient

[Lumpy]

Ok then take this for example...

efficient lighting

task lighting is a very new and rare to see concept. 99.997% of all homes still have a single bulb at the ceiling or on a lamp to light the room.

Re:white LED != efficient

[Lumpy]

and therefore you eliminate the efficiency. a single item is efficient putting 500 together to reproduce what 1 inefficient item can do is not.

500 white LED's produce less light than 1 Compact flouresent bulb does for the same 5 watts of power, thereby making them very inefficient... for now. the technology behind the white led can be expanded, and we may see a true semiconductor bulb soon.

Re:Better off?

[Ian Bicking]

You should stop being so paternalistic and conservative. The attitude of your response shows you romanticize poverty, and mistake powerlessness for aestheticism.

Re:Better off?

[bahtama]

Darksky.org is an organization dedicated to fighting light pollution.

This was also featured on Talk of the Nation on NPR last week. It is worth a listen.

Re:Better off?

[RobinH]

Some people might be better off without lights or connection to a power grid.

So I suppose it never occurred to anyone that this might be of use in hospitals or clinics?

Does anyone realize how important low cost oil lamps were to families back during the industrial revolution. In those times, a worker would generally work all day until dark, and then after work, spend an hour or two of quality time with his/her family. How much quality would your time have if it was dark and you had no light source?

We all need to step back from our CRTs/LCDs for a second and realize that many places haven't even reached where the western world was 100 years ago!

Neato Stuff

[mikers]

I didn't take any courses from this prof, but some of my friends in school did.

What he is doing is kindof neat... He wants to equip poor villages (in places like Nepal) with electric lighting that better utilizes the minimal generating capacity they have.

I know you can get white LEDs as replacements for flashlights that will increase the battery life approximately 20x. For those Petzl headlamps a standard Duracell battery will give you about 6H of light with a standard bulb, but is rated at 100H with a superbright LED. And as far as I know the superbright gives you equivalent illumination - just at higher efficiency.

When I was in Nepal a few years ago, most rural villages would have power (all from hydroelectric) but it was unpredictable and unreliable. Also the generators were small and there were limits on how many bulbs each place could have. Replacing regular bulbs with white leds would save power - and make battery backups realistic.

Thats one way out of the dark.

m

No, it's not too expensive

[north.coaster]

Here's a quote from the Web Site:

I should point out that a single WLED provides sufficient light to easily read a book or to study with. My wife, who wholeheartedly assisted me in Nepal in 1999, has amassed ample field evidence to support this last statement. It is very significant to the developing world that these wee marvels of technology can effectively light an entire kitchen table area using less than one watt of electrical power and there are none of the attendant dreadful pollution and fire dangers associated with the use of kerosene lamps.

Please read more of the web site before commenting. /Don

Re:Quality of Living???

[rainwalker]

Have you ever used any of the "traditional" light sources he is trying to eliminate in the article? And, have you ever visited any of the communities this is targeted towards? In the US, there is absolutely no reason to use this kind of system, but the rest of the world does not always have the same standards of living that the US does.

I spent some time working in rural villages in the Dominican Republic, and I can guarantee that you have no idea what real poverty is until you have been to some such place. These people had no electricity (the nearest town with power was 40 miles away), no potable water or sewage, nor any other form of technology more advanced that several hundred years ago. Their lives are regulated by the day/night cycle; you get up at dawn, work hard, and go to bed at dusk because kerosene is too expensive, as are candles. I really hope you weren't suggesting using electric lanterns, as that would just have been silly. THAT is the target market for these kind of devices. He is talking about producing these for about $50/household, maybe less. This probabally won't be paid for by the people themselves, but more likely by first-world charity organizations, or subsidies from the parent government.

Please, please read and comprehend the article before you reply.

Which is the in shape uneducated one

[bluGill]

I can see it now: Some third world family of 12. Dad says to the 3rd kid "Okay, your the dumb one so the rest of us can learn. You get to spend the rest of your likfe riding the exercise bike while the rest of us learn to read."

Don't feel bad for the "dumb kid" though, he will go on to win international biking compititions, while the rest of the family trys to compete in the rat race with millions of other people.

Re:Better off?

[pokeyburro]

Our village elders agree with you. I'd say more, but we're on a hunt for witches and evil spirits right now, and the others tend to get suspicious if I don't join in...

power generation and use in developing countries

[happyclam]

Many developing countries are in very sunny locations. Solar panels are really getting cheaper. For example, plastic solar cells that can be "painted" onto clothing are strong enough to power portable radios. I bet they'd be powerful enough to charge up that battery that runs the LEDs.

A very interesting read about solar is From Space to Earth, which discusses the use of and need for solar power in developing countries.

One thing that is clear is that power in rural areas is greatly needed for things like well pumps; powering reading lights is great, but it would be better used for true necessities. (though light becomes necessary when you need to fix that broken well pump...)

Re:brightness is as brightness does

[tps12]

Not to mention, I need a nice Gandalf wallpaper (well, okay, maybe not "need"...). I want a close-up where he looks pretty stoned, like in most of the movie. I would prefer his pipe to be featured, if at all possible, and no writing (titles, copyright notices, etc). 1024 or larger, please. I know someone reading this has the perfect image for me!

I think it speaks for itself.

Hmm

[Have Blue]

Who's seen Soylent Green? :P

Re:Better off?

[jafac]

what most people don't realize when they look up at the night sky, is that even under ideal circumstances, with the naked eye, you're really only seeing a minute fraction of what's out there. There are only two galaxies visible to the naked eye, and one of them, we're in. (the milky way). The other one is only barely visible to the naked eye. Consider the billions upon billions of galaxies out there that are too far away to be seen by the naked eye.

Looking at the sky with the naked eye in no way gives a true impression of how vast the universe is. It doesn't even scratch the surface.

Re:Great!

[Deagol]

I don't think this would work, and here's why.

I have a chain of 3 lights in a long wooden case at home that my wife uses to sprout and start her garden plants. We used to use 100W incandescent bulbs. Worked fine.

We went on an efficiency kick and replaced every bulb in our house with those 20W curly CF lights (sold at Costco @ $20 per 5). We did this with the sprouter. Didn't work so good.

If I remember my solar energy figures, one gets a nominal 1000W per square meter of direct sunlight. I'm sure I could duplicate the luminosity (correct term?) with maybe 100-200W worth of florescents, but there will not be 1000W of radiant EM energy hitting that same area (how can you, if you put &lt 1000W in you can't very well get 1000W out!).

I think LEDs would be even worse for plants, as they're pretty close to monochromatic light, and I think plants need a fuller spectrum anyway.

Re:Light the World?

[leshert]

The light pollution you see in those images is from misused wide area lighting.

I doubt that all the WLEDs ever created, used in task lighting the way this article mentions, would show up on one of those pictures.

Read the article, and think about it...

Great. Let's Really Annoy The Third World

[istartedi]

How many of you have ever seen a white LED light, much less read by one? I saw one in one of those Sharper Image type stores a while back. It was a flashlight that had a light that reminded me of a cross between flourescent and those annoying blue headlights.

I realize they are efficient, but they are just not very pleasant. They might be useful as porchlights, but I wouldn't want to sit in a room with one and read for any length of time. Also, LEDs are probably not made in those countries. Simply giving them things is not going to encourage development (assuming that you think development is a good thing). I think we are better off educating the 3rd world then just giving them things. Educate them in math and language, and then they can solve their own problems, and in a way that will be suited to their culture, without contributing to the growing disatisfaction with the "imperialist" West. If you have to give them lights to educate them, give 'em good old incandescent/battery lamps. Kids won't be encouraged to learn under those annoying white lights.

Pedal power is green - soylent green that is....

[jerryasher]

Home pedal power via bicycle generators was written of in Harry Harrison's Make Room, Make Room (aka Soylent Green). Edward G. Robinson pedaled away throughout the movie" to generate the home power.

Great idea but....

[zandermander]

Having lived in a developing country for several years, I can appreciate this groups efforts and the technological advances made here but...

Where I lived (a rural part of Thailand) very few if anyone would have used the generator. Why? Because they can rent car batteries from a business down the road for all their electrical needs (which are very few - a few flourescent lightbulbs and occasionally TV).

In my case, the business was hooked up to the power grid for recharging batteries but I also saw even more remote places where they had a generator (gas? Diesel? Never checked) for the same purpose.

Having participated in harvesting rice, I really doubt any farmer would want to hop on their pedal-powered generator at the end of a day of back-breaking field work to charge up their batteries for a night of bad soap operas.

Build your own..

[nolife]

I've bought and used these LED's before. You can find them cheap here.
I've built a few things with these and they are impressive. A solar cell, two AA rechargable batteries and one of these lights can be put to use just about anywhere.

Kenya does it better

[Astrorunner]

In Kenya, there are several private companies that are selling solar panels to do the same sort of thing, except without all that nasty stationary bike stuff. Just pop the solar cell on the roof of your hut and you're in business. Turns out its not that terribly expensive, even by African standards. Currently you have some options if you're in a rural area in Kenya, and by some, I mean two, that being, taking your car battery to a charging station, or making payments on a solar panel. Its not a tough choice.

Still a ways to go

[horati0]

I work in the lighting industry with conventional means of producing light (florescent, incandescent, etc) and have done some testing on LEDs. The most important thing to realize is that the light being produced is not a pure "white" light.

Typically the manufacturer will use a blue LED and coat the outside of the lens with a yellow broadband phosphor, which when the blue light is filtered through it, appears white. True white is extremely difficult (and expensive) to produce; it's still years away and it has to do with the ability of the diodes to produce certain wavelengths of light.

As far as efficiency, yes, LEDs are quite effecient at producing light at a given (low) wattage but they are still not as bright as conventional light sources. The rating of an LEDs efficiency is measured in lumens per watt; a bulb with a higher lumen per watt rating is more efficient than that of a lower one. At this point, red LEDs are the most efficient, which is why many applications that use LEDs (exit signs, car turn signals, etc) are red.

Manufacurers claim a 100,000 hour life span of LEDs. What most of them fail to mention is that to acheive this, the power supply that the LEDs are attached to has to be set at a low current. Low current means decreased brightness. If the current is increased past the manufacurers recommended setting, you will get higher brightess but the lifespan will be cut short severely. Not to mention the fact that many LED applications where companies are touting 100,000 hour lifetimes (approximately 10 years) haven't been around that long to confirm or deny it.

LEDs are not going away, however. It's not a question of if they go mainstream, it's when. And I have no problem with that, it's just that from what I have observed, the manufacurers are dispensing half-truths and outright lies about this stuff. People take it for gospel because big companies are developing the technology (GE and HP-funded Agilent come to mind) so they figure it must be true.

Whatever. It's reall not going to make that much difference in the long run. Just want people to know there's more behind it.

Re:Still a ways to go

[jaoswald]

The other contributing factor for red LEDs replacing red lamps is that "red" incandescent lamps are white incandescent bulbs with red filters in front. The filtering substantially lowers the emitted light per unit input power, increasing the advantage of red LEDs.

Swimming Pools

[Apreche]

they've had LED lighting systems for homes and swimming pools for years now. The pedal generators and rechargable batteries are a new idea. But LED lighting systems have been around. However they are quite expensive.

You get a bed of white LEDs in your basement, and you use fiber optics to bring the ligh to different places in your home. Works really well for swimming pools, and is most often used there, because it doesn't bring electricity near the water.

Absurd!

[SPYvSPY]

a) Apparently you don't have access to common sense either. Criminals prefer dark alleys to well-lit streets. The "data" that you fail to cite is probably inconclusive, since there are a billion variables involved with comparing the crime trends in location A to the crime trends in location B.

b) Where are you getting this stuff? If we didn't have well-lit urban culture, we'd still think that the Earth is a flat disc a few miles in diameter, with a large mechanical sphere surrounding it. That's not exactly what I'd consider an appreciation for the vastness of the Universe.

c) People watching television probably learn more about the vastness of the Universe than you will staring at the night sky.

Stop puking up luddite FUD, please. You're making a mess.

Re:Absurd!

[ShavenYak]

Point a) I agree with.
Point b) - We discovered that the world was round and orbited the sun before we had electric light.
Point c) - Not if they're watching Survivor and Fear Factor. ;)

How about this?

[wizarddc]

Found this on google, of course

http://www.ccrane.com/120_volt_white_led_bulb.asp

An led array that screws into regular fixtures. A little pricey at US$59.95, but it it never burns out, the your total cost would be 59.95/infinity, or is my math wrong? ;)

Dimmers?

[3ryon]

My question about LED's is this: Can I use a dimmer? It seems like an LED would have to be either On or Off. Is that the case?

If so, perhaps someone will invent a lightbulb where when only a small amount of current is applied that one or two LEDs come on. As more current is supplied more come on. Possible?

Re:Better off?

[2names]

Seconded by a non-nazi, non-AC.

On the other hand...

[MadFarmAnimalz]

It occurs to me that this extreme level of efficiency just begs to be hooked up to an array of solar cells, not an exercise cycle.

Solar cells have been underutilised as a source of energy due to the low yield.

This seems like a nice and symbiotic combination of different technologies... "Hey, the solar cells don't give me much electricity, but the white LEDs illuminating the office building don't need all that much anyhow. W00t!"

Liights & Geeks

[JohnHegarty]

And for all the geeks who like lights.. or something : http://www.thinkgeek.com/stuff/gadgets/lights.shtm l

Go buy some now.

[km790816]

Go buy some now: theLEDLight.com

My biggest problem with these bulbs is finding ones that have a nice, soft light. I don't want my bed room looking like an office. I spend enough time there as it is. Does anyone have experience with how 'pretty' the light from these is?

Re:Go buy some now.

[dolanh]

Oh well, no modding power for me this time :)

I partially solve this issue with the compact flourescents in my house by choosing lampshades with a warm characteristic like Japanese paper lanterns.

As most photographers follow, the "temperature" of the light is really what determines how "pretty" you consider it. Incandescent is way down the spectrum from flourescent. I don't really know where LED is, but I imagine it's closer to the latter than the former.

Nothing innovative about this

[mrroot]

using a combination of white LEDs, pedal generators and rechargable batteries.

Nothing innovative about this, the Professor was using pedal generators to power ALL KINDS OF THINGS while shipwrecked on Gilligan's Island back in the late 60s / early 70s.

I saw the presentation a few months ago..

[reverse flow reactor]

I saw this guy present this project a few months ago (as a presentation for Engineers Without Borders) and it is really important work.

One of the biggest problems in third world countries is that taking care of food and water is an all day task. There is no time for learning to read and write during the daylight hours. These lights allow people the opportunity to learn to read and write after the sun has set.

This is a very important task if we hope to help the people in remote areas. The target areas tend to be areas with no electricity, no running water, and very few fascilities at all.

And I have seen the LEDs that he uses light light up a mid-to-large size lecture theatre to the point that I could read a paper in fornt of me, 5 rows away from the source!

-----

Re:Oh! And encourage exercise!

[MSBob]

...And would keep many Americans in (better) shape, which means fewer pounds commuting daily, which means less gas burned by American SUVs, which means less pollution! You're right, the benefits just keep on piling up.

Buy them here, Re:Why only the developing world?

[bourne]

Frankly, I suspect we'd do more for the developing world by adopting this sort of thing for ourselves

A quick Google search turns up The LED Light, and they have a collection of "bulbs" that fit into 120 Volt AC sockets (That would be them things in yer house, at least in the US)

Very expensive though - "36 LED bulb...comparable to a 30 watt incandescent bulb" costs $190.

Another site I've run into in the past is LEDTronics which looks more in line with the geek need for way too much information, and component-level purchasing. I can just see the mod case now...

Currency conversion fees US-Canada?

[Fencepost]

If folks in the US want to send them a donation, what's the minimum practical amount given conversion fees?

I know that for many European countries check cashing/currency conversion fees can easily be more than the actual value of a check, and while I'm sure it's much simpler (and cheaper) between the US and Canada I'm also sure that there will be some charges.

So, what's a practical level?

Benchmark needed

[MadFarmAnimalz]

I for one would be interested in seeing a benchmark between this and the white LED's we're talking about here.

Like LEDs? Go here . . .

[slurry47]

http://ledmuseum.home.att.net/ledleft.htm Seriously cool site.

LED light previously featured

[Sarin]

on slashdot a year ago orso,
I remember there was a big light, that consisted of multiple leds (thought about 100-300) that you could program with your pc. It could change color to all the colors you wanted. I believe the casing was black and it costed about $600.
I was searching for this item last week, because I wanted it for my new house, but I couldn't really find it, perhaps someone bookmarked it, or knows a simular light?

Thanks in advance.

Re:Great. Let's Really Annoy The Third World

[Jumperalex]

White LED's have come a LONG way. They now actually sell several different WLED's that have varying tempreture ratings to them. From soft white to the very blueish light you mention.

As for the WLED's not being produced in that country ... so what. Eventually someone WILL build a plant there when they realize the tremendous demand that has been created. Then as people aren't running around collecting fire wood, or sitting around in the dark they can actually then BE educated by reading etc.

"Kids won't be encourged to learn under those annoying white light" Um how do you know. Maybe it is only annoying to "us" because we are used to using innefficient incandescent bulbs. And you would rather us give them those rather than LED's? So instead of giving them one of our imperialist invenetions that is usable with their meager power production capacity you would rather us give them one that sucks every available bit of juice they have. Riiiiight that is good thinking.

Re:Better off?

[jedidiah]

The nature of cultures 10 mellenia ago really have no bearing on this discussion. Your post isn't a troll; it's a red herring. Unless you would like to propose some viable method through which much of the third world can revert to Bushmen practices, bringing them up is largely irrlevant. We have to deal with the here and now. We have to deal with where people are NOW, not with some ideal that this planet won't even support.

There's simply not enough planet for the 6 Billion of us to revert to roaming around in Chimp troops.

The least you could do is relate the situation to the aboriginal conditions of the areas in question.

Bingo

[SeanAhern]

You're right on.

With as long as we've had "100 watt" and "60 watt" lightbulbs, people have gotten it into their heads that the wattage rating is a measure of the light output.

I would have to work out the physics to see if it's possible, but I don't immediately see any barrier to a .1 watt bulb of some new technology giving the same light output as a 100 watt incandescent tungsten filament bulb.

Re:Great. Let's Really Annoy The Third World

[Old Wolf]

If you had read the article, you would know that the main thrust of this initiative is to allow people in developing to study for more hours in the day -- precisely what is needed for the education you suggest.

For spot lighting, a white LED is 100 times as efficient as an incandescent light. Have you ever used a mechanically-powered torch? Quite a bit of effort is required to produce a useful beam (which is even then hard to keep constant).

I would suggest that LEDs are not "annoying" to children who may never have seen a lightbulb in their life, or not spent significant time under one.

Children in developing countries are quite enthusiastic about the learning thing, unlike many Western societies where school is something dreaded, and they wouldn't dare touch an encyclopaedia (or even a book!) at home.

2001

[pmz]

Wouldn't it be really neat to have computer room floor tiles each with a tight grid of white LEDs under a clear plastic covering? Imagine a computer room with these floor tiles and a single IBM server standing in the middle...

Re:Better off?

[ColaMan]

Some people do not want or have a need for the modern medicine that a hospital or clinic would provide.


I think that the "some people" that you refer to are in the minority.

I understand that 'some people' may not want modern medicine due to various reasons. Of course, 'some people' would prefer to die in agony from a burst appendix than get medical help. 'Some people' get a nice case of lockjaw from the tetanus infection they got from a cut. 'Some people' walk with a limp from that leg that they broke when they were six. 'Some people' just plain lose all their teeth by the time they are 35, presuming that they live that long.

But I'm sure 'most people' would rather have a hospital or clinic nearby. And, when it comes down to it, most people are pretty flexible about issues such as their personal beliefs conflicting with urgent medical treatment.

The fact of the matter is that it's our duty to provide opportunities for those who are less fortunate than us to improve themselves. That hosptial or clinic full of modern medicine has to be there on the off-chance that it might save a few lives and improve their quality of living. If pedal-powered LED lights gets it there, well I'm all for it.

If you can get a population that is healthy , they can get on with improving their situation. If they're so busy fighting to keep alive, well improvement takes a back seat.

This has turned into a bit of a rant. But having visited places where "upper class" living means having a toilet (which may be flushed with a bucket), it kinda stirs me up a bit.

Yet another slashdot topic ruined

[lsd4all]

I don't post often but when I read the headline of this topic, I wanted to add my two cents. After reading the article and everyone's posts (most posts being irreverent or poop-joke related) I have finished another chapter on my book of human ignorance.

As U.S. citizens, we live in a wasteful society of throw-away everything and unlimited (we think) natural resources. When you go home tonight, make a note of how many lights you have on in your house. If you live alone, this will be a good test to see how much energy you use, if you have family members, roommates, etc you can also monitor the total energy consumption in your house. OK, so you got five lights on and you are the only one home. Now add the energy used to power your fridge, microwave, water heater, stereo, dishwasher, TV, computer(s), aquarium, Nintendo, space heater, furnace, the list goes on. Are all these items 100% necessary? of course, this America and we demand convenience 24/7.

I am no better than you, I waste energy and it bugs me to go outside and watch the power meter spinning like a twirling dervish when I got the guys over for band practice. But I am aware of what I use and I do my best to conserve energy. I live in the NW US and we have lots of hydro-electric power plants on the Columbia, I am not a save-the-salmon radical but I don't want to see all the changes we make on the environment in the name of power generation to go waste on every single light in my house. If there is a new technology to limit energy use, I am all for it. In fact I have a few solar panels and few devices (lights & a TV) that I can use with my "free" power. In our lifetime, home-based power plants (natural gas-hydrogen based fuel cells, PV, wind power, etc) will become popular and necessary in many highly populated areas. Third world countries need this technology now since its price is low and their living conditions are so medieval compared to ours that any change for them is better than nothing. Our turn is coming soon.

My fifteen minutes are up. Here are some other links on energy-related websites/products.

Home Power Magazine

Jade Mountain Alternative Energy Devices

White LED made from Blue? why not just add R+G ?

[Ark42]

My PC has plenty of red and green LEDs, so why both with this phosphorus addition to try to make it white? Doesn't blue+red+green = white?
Just stick 50 of each together in interleaved and let them blend to white..
What I dont really get either is why these lights for sale at theledlight.com cost so much? Is the cost for brightness or what? It seems that standard LEDs used in PC cases and other blinky status lights on almost anything electronical cost a lot less.

The biggest problem?

[DrCode]

Seems like the biggest problem is that a bulb that provides light equivalent to a 30 watt incandescent is $190!! Thats a little steep when you can get compact flourescents for around $8.

Re:Generators at 1000 RPM?

[ColaMan]

Ever heard of pulleys or gears?

Re:Better off?

[benedict]

Would *you* like to live in primitive conditions?

Already used widely by hikers

[guanxi]

I can't be the only one who has one, since everybody else I meet on the trail raves about them:

The Petzl Tikka -- $40 'white' LED headlamp; the best innovation in outdoors equipment in decades:
http://www.petzl.com/petzl/publicFamille ?id=LAMP&r ub=sport

Using WLEDs for auto reading lamp - excellent!

[Goldenhawk]

After hunting around for a reasonably-priced reading spotlight to mount in the minivan for my kids to read after dark, I couldn't find anything that was (1) bright and clear at low wattage (2) priced under $100US (3) small enough to hide in the trimwork. Then putzing around Radio Shack one day, I saw the rack of white LEDs, and decided to give them a whirl.

I bought 6 WLEDs for about $30, a couple 100-ohm resistors and 1K trimmer pots for current limiting and dimming, and went home. Half an hour and a few solder joints later, I had mounted the 6 LEDs shining thru holes in my overhead panel, pointed at my steering wheel area (hey, first I helped MYSELF, not the kids). I found that I could run three LEDs, with a voltage drop of about 3.5V each, in series with the fixed 100 ohm resistor and a trimmer pot. So two sets in parallel worked well. I couldn't wait until nighttime.

After dark, out to the van I went. Switch on - WOW.

First impression - the color was all wrong. Until I realized that I'm so used to yellow light that pure white was almost distracting. But the light was BRIGHT and very crisp. From about 18 inches from LEDs to reading material, with only 6 LEDs, I had more light than with the original dome light 20 inches away, and the color was perfect - I could enjoy reading material with photos, without straining to see the colors. The pool of light was about 15 inches across. The LEDs I used are rated at 30deg beam spread (to the point of half brightness) so that seemed about right for six lights pointed a bit apart from each other. Best of all, unlike a dome lamp, there was NO spillover light to the rest of the interior - with the light on I could still easily see out the front to drive. Don't try that for long with a glaring dome lamp.

One other thing was worth noting - there were faint yellow/blue bands in the pool of light, noticable only when looking at a large mostly blank page. This is probably due to the blue LED/yellow phosphor combination used to make white light.

The biggest problem was cost. At Radio Shack prices of $4.99 each, I couldn't affort enough LEDs to do the other five seating locations. But it was still far cheaper than a quality aircraft-style reading lamp, and just as bright. If I wanted more brightness, I can easily add more LEDs.

Check out this link - http://www.theledlight.com - for some really cool ideas, parts, kits, assembled lamps, all based on LED technology. Really cool, and a LOT cheaper for the bare LEDs than Radio Shack. About $2.50 or less each.

Soon I'm going to order some bulk WLEDs from them - and light up the rest of the vehicle interior.

NO!!!!!!!

[fmaxwell]

A variable resistor is all you'd need to make a dimmer switch.

When a resistor drops the voltage, it does so by using turning current into heat. The entire purpose of using LEDs in this project is to make high-efficiency lighting to run off of batteries charged by people-powered generators. Using series resistance to reduce brightness is no better than putting a smoked lens in front of the LED array.

Re:NO!!!!!!!

[BlaisePascal]

A resistor converts a voltage drop into current, and in a very prescribed, predictable amount.

LED's work longest when the current through them is low, and they have a constant voltage drop across them. To change the brightness of an LED, you change the current going through it, but the voltage drop remains the same. So to get a dimmer, you need a constant voltage, variable current power supply. A battery and a resistor does that.

Some math: Let's say you have an LED rated at 3.5V drop, 20mA max current, and a wattage of 0.07W (by my calculation. You have 3 Alkaline cells in series (1.5V/cell, 4.5V total) powering it. You must drop the voltage by 1V, and limit the current to 20mA total. That calls for a 50Ohm resistor, and a total power usage by the resistor of 20mW. Add a potentiometer in series (0-200Ohm), and you have a dimmer that takes your LED from using 90mw to using 18mW. Not exactly a power-hog.

Re:NO!!!!!!!

[fmaxwell]

I'm assuming that your math is correct as you clearly know what you're talking about and I'll agree that the voltage drop and current limiting is necessary when your battery voltage does not match your LED's rated drop.

But the more efficient approach is to choose your voltage carefully and to string LEDs in series to get the desired voltage. If you are going to convert the energy into something, light is a far better choice than heat.

Alternatively, one could use 555 timer chips to create pulse-width-modulation to control the brightness. Also much more efficient than resistors.

Woohoo! Found them!

[ArcticChicken]

This proved to be one of the more painful web searches I've done in a while!

Here they are:
Color Kinetics

It looks like they've further developed their spotlight products since that original Slashdot article.

Re:Light the World?

[Sabalon]

Well, as one of those astronomer fucks...

It's not that you want lights on - they are a good thing. It's that the ground is where needs to be lit, but the lights we complain about are the ones that light the ground, but 60% of the light goes elsewhere - mostly up.

Drive past a shopping center on a cloudy night and look how well lit the clouds are. Just what good is that doing?

And even before I was an astronomer fuck I wanted night time to be dark, not this pale it has become.

For a really good quality LED keychain light..

[Belly]

Check out http://www.arcflashlight.com

The Arc AAA is a great little light that is very rugged, waterproof, runs off a single AAA battery with good longevity (using a step-up voltage regulator) and *very* bright. I have a couple of these - been carrying one on my keyring for about 6 months and its never failed me. White LEDs are great..

we'll never see the stars now...

[acomj]

Great. More light polution. The developing world will get lights and the developed world will get brighter..

What stars???

usa at night

There are already groups for keeping the night dark.

Pico-Power!

[sharkey]

Ha!! Up yours, vi! Eat me, emacs! I've got PICO-POWER!

Re:Oh! And encourage exercise!

[Waffle Iron]

...And would keep many Americans in (better) shape, which means fewer pounds commuting daily, which means less gas burned by American SUVs, which means less pollution!

The energy saved moving around fewer actual fat pounds is only a secondary effect. The main effect is this: If you don't have an enormous fat ass, you're less likely to feel that you need a 5774 pound vehicle to accomodate your girth.

Re:Use as PDA backlight?

[ScottBob]

They're used quite extensively as backlights for industrial equipment, I know some of the newer Fluke multimeters use white LEDs to backlight the display for nighttime use. Also, Gameboy Advance has outboard white LEDs that you can plug in the link cable slot, and I'm pretty sure some geek case modder types have installed white LEDs in their GBA's.

Re:Better off?

[ahfoo]

Bzzt!
Nah, sorry man. That's a common misperception. Soap is much older than civilization. People used to think it was a Roman invention, but then evidence of it turned up in Egypt and now it's safe to assume it was probably one of man's favorites since before agriculture and probably not much more recent than fire and the concept of cooking. Think about it, a chunk of fat simply has to fall into the ashes of a fire to form a layer of soap. Combining fat and ashes makes soap and that's all there is to it. If you're the chief soap renderer for your tribe, it does help to heat the two ingredients in a clay jar --keep that in mind in case you ever fall into a time machine heading backwards. Never know.
Seriously, soap is not some high-tech ultra modern invention. It's cool, sure but it's not a modern invention.
Indeed, the bubbles that soap makes are very similar in structure and composition to the foam on the oceans and there is reason to believe that such omnipresent spherical lipid structures in conjunction with the action of the ocean's tides may be the true origins of the first cellular membranes. So, you could say that soap preceeds life altogether and may be the basis of life. So, there goes the idea that soap is a recent invention.
This is off-topic though, so I'll AC it in.
Your helpful tutor AhFoo

Re:Buy them here, Re:Why only the developing world

[geoswan]

Very expensive though - "36 LED bulb...comparable to a 30 watt incandescent bulb" costs $190.

They claim the light lasts for 100,000 hours. And an ordinary bulb lasts, what, 600 hours? Do you think the price is so high because they are supposed to be comparable in price to a regular bulb?

experience as hiking/caving flashlight substitute

[peter303]

On the positive side these lights burn 5-10 times longer on the same amount of batteries and the bulbs last forever. On the negative side, these systems are three times more expensive than their incandescent batteries, but pay for themselves in battery savings in couple weeks of constant use. Also in the minus column is the beam quality of the light- not as focused as incandescent. I'd be hesitant to use it as a night bike light source or in a snowstorm for that reason.
Conclusion: an execellent backup source (you should have three light systems for climbing), but not quite ready to replace incandescent fully.

Re:Better off?

[ShavenYak]

There are only two galaxies visible to the naked eye, and one of them, we're in. (the milky way).

The other one you refer to is obviously the Andromeda galaxy, or M31. However, M33 is visible to the naked eye under good conditions, and there are reports that M81 is also.

Re:Big Blue (and I'm not talking about IBM)

[matrix29]

I'm not so sure that blue LED lighting "can make a huge difference in the lives of villagers in rural areas where being connected to a power grid is not an option and probably never will be."

Uh, there is a windup flashlight that is powered by a spring and that runs a regular flashlight bulb. A quick GOOGLE for "windup flashlight" gives me a LED flashlight called the FREEPLAY. The other flashlights on that site cost $27 for a radio/flashlight +rechargeable battery +spring power. The solar-powered +rechargeable batteries bicycle light is $20.

http://windupradio.com/