LEDs Lighting Up the African Darkness

Peace Corps Online writes "In a non-electrified society, life is defined by the sun and little is accomplished once it sets around 6 pm. Only 19 percent of rural areas in Ghana have electricity. The rest use foul-smelling kerosene lamps to light their huts, which pollute, provide little light and are major fire hazards. But now Philips has partnered with KITE, a not-for-profit Ghanaian organization, to bring artificial light to villages that have no electricity. The new Philips products include a portable lantern which provides bright white light where it is needed, the Dynamo Multi LED self-powered (wind-up) flashlight that provides 17 minutes of light from two minutes hand winding, and the 'My Reading Light,' which is a solar-powered reading light with built-in rechargeable battery. 'People can now do things in the evening,' says Harriette Amissah-Arthur, KITE's director. 'If you could only see the joy these products bring the villagers. You look at their faces; you have to see it to believe it.'"

Comments

Re:Gunfire

[Shag]

A small price to pay for not being eaten by a Grue.

Biased article... phillips

[gravos]

This article is biased towards Phillips' contribution... Shouldn't there at least have been a mention of the "Light Up the World Foundation" and Dave Irvine-Halliday (U of Calgary)?

http://www.ucalgary.ca/oncampus/weekly/nov4-05/schulich-lutw.html

http://www.google.com/search?q=philips+lutw

Re:At the same time, European Union bans incandesc

[berend botje]

It is as if the frequencies in its spectrum just miss the the ones my photoreceptors are tuned into...

Well, that's because the LEDs actually are missing (large) components of the spectrum! :-)

Even when your eyes are tricked into believing the light is white (by equally stimuling the three kinds of color-sensitive cells), the light reflected off of objects isn't "correct".

Imagine two green objects. One has true green pigment, the other has a mixture of yellow and blue pigment. Both look the same under incandescent light, because the light from a glowing filament emits a full spectrum .

When an LED doesn't emit a full spectrum the two objects don't like alike. The "true" green objects only reflects "true" green, not yellow + blue. The "yellow + blue" object doesn't reflect "true" green.

That's why it's hard to see in such light.

Your eyes (or brain) can adapt very well to changes in color temperature (yellowy incandescent light, or the blueish halogen light), but it can't cope with holes in the spectrum.

This goes for compact fluorescent lights as well, even as they keep getting better. The cheap ones are really crappy in this respect.

For fluorescent tubes there is a rating for color temperate and color rendition. It isn't used (as far as I know) for compact fluorescents as they score way to low on this scale. That would make the public relations department of the manufacturers unhappy.

Not so long ago.

[Dan East]

"The rest use foul-smelling kerosene lamps to light their huts, which pollute, provide little light and are major fire hazards."

In other words, the exact same type of lighting my grandfather's household relied on when he was a child. It's easy to forget that there are many people alive today that only had access to very primitive technology when they were young. And it wasn't because they couldn't afford it, but because it didn't exist anywhere on earth.

While I am sympathetic to the plight of countries that cannot afford modern technology for their entire population, and the massive infrastructure required to support it, I do keep in mind that we are talking about a gap of only a few generations - not centuries or millenia.

I have tried it - use the meter correctly

[Kupfernigk]

You are totally wrong. You have to use an incident light meter, it's no good pointing a camera type light meter at the bulb because incandescents all have a bright spot while fluorescents spread the emission over a bigger area.

My own experiments, years ago, showed that in real world use CFLs are equivalent to about four times the wattage of standard 1000 hour incandescents, whereas full size fluorescents produce maybe 5 times the output of the same wattage incandescent. Linear 8W CFLs as used on boats and caravans give about the same actual illumination as a 20W tungsten-halogen bulb, because their light output is much less directional, but then they are much better at illuminating dark corners.

Case in point: when we moved to our present house, the kitchen used 3 100W bulbs. These have been satisfactorily replaced with 3 20W CFLs for the last 20 years. As different types of CFL have evolved, there has been no deterioration in light output, though it is important to buy good quality - GE or Philips - bulbs.

I note that the cost of LEDS is now becoming comparable in lifetime cost with CFLs. The main issue is that LED drivers are relatively inefficient because most of them waste a lot of power in series resistors. What is needed is a really efficient current driver IC for LEDs. This would drive up the efficiency of conversion and make them even more useful in the Third World.