CFL versus LED lights

[Fluorescence]

hello,

I am seeking advice on Compact Fluorescent Lamps.

They are selling them for 8p each in places in UK now...as they say they are answer to energy saving over incandescent.

However, June 08 "Electronics world" says each CFL contains 4g of Mercury.......and in EU alone this equates to 5600Kg of Mercury having to be disposed of per year due to finished bulbs. This Mag also says 1g of Mercury put in a 20 acre lake would make all the fish unfit for human consumption.

Im no health and safey stickler, but my great grandmother was killed by mercury in Hat making , and i know its a real bad chemical.

I am amazed CFL's are being brought in on mass to our lighting problems.

I was told that say an ~11W offline CFL would be more efficient than an equivalent lumen rated offline LED light because the CFL converter is basically a ferrite push-pull transformer putting high frequency, high voltage AC across the CFL....and since the voltage is high, the current is low and its more efficent than an LED light where the converter would have a low voltage DC output, hence higher current, and worse efficiency.....due to I^2R losses

do you believe its true that the CFL really is more efficient than a similar lumen rated offline LED light?

 

[dpc]

All fluorescent bulbs contain small amounts of mercury, I believe.

What do you mean by "offline" as applied to these lights? Must be a usage I'm not familiar with.

I don't think the I^2R losses in LED lighting are going to be too significant.

I would have assumed that LED lights would be more efficient, but you would have to include the rectification losses if they are running from dc, I guess. But I don't really know. The CFL is much cheaper right now than an LED light and has much more flexibility in terms of color spectrum of output.

 

[zappedagain]

In the USA recycling programs are being set up for CFLs to reclaim the Hg; I don't know how many still end up in the trash (mine are collecting in a bag on my workbench at the moment).

Is WEEE covering the CFLs in the UK?

Here is what Consumer Reports says about CFLs:

"It might seem as if the use of CFLs is simply swapping one problem with another. But according to the EPA, replacing incandescents with CFLs actually results in less mercury in the environment. That’s because most of the electricity in the U.S. comes from coal, which emits mercury when burned. Since CFLs require less electricity than incandescents, mercury emissions would actually decline."

http://blogs.consumerreports.org/ho...esultPageIndex=1&resultIndex=5&searchTerm=cfl

So coal and CFLs for today, solar and LEDs for tomorrow!

 

[itsmoked]

dpc; 'off-line' refers to something being powered directly off of 'country mains'.

Fluorescence; It's very hard to compare LEDs to CFL. They are simply different. LEDs are highly directional verse CFL which are entirely non-directional. LEDs last vastly longer than CFLs. And of course CFLs have 10 years on LEDs. The Chinese are pouring out ship loads of crappy one year life CFLs and we haven't reached that state yet with LEDs. Presently, LED lighting costs more than 20x of CFL. That's just not going to cut it in the market.

Right now, CFLs are over all more efficient at converting watts to lumens, but not much more, just slightly more. This is rapidly changing with time and I suspect LED lamps will handily surpass CFLs with time. There are not any large powering-the-light differences between the two. The real difference is watts to light, called efficacy. When LED lamps become far more efficient at this conversion than a mercury arc in a glass envelope than it won't matter if, deriving the correct excitation of the lighting element, is slightly less efficient.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[VEBill]

The mercury in one CFL bulb (5mg tops, some are 1 mg) is about the same as about 30 of those little 170g cans of tuna (at the upper limit for human consumption of 1 ppm).

Those first generation high power LED light bulbs that I've seen are all heatsink. Makes one wonder if there aren't some significant improvements in LED overall efficiency coming soon.

 

[IRstuff]

Many LED designs are grossly overdriven,so the heatsinks are necessary to prevent meltdown.

TTFN

FAQ731-376

 

[dpc]

"offline" - Thanks, Keith. Once again, separated by a "common" language.

 

[IRstuff]

No kidding; that's the exact opposite of what it means in a computer context.

TTFN

FAQ731-376

 

[itsmoked]

dpc; It's used constantly in electronics power supply conversations as a delineation, since in low power stuff battery and low voltage is just as common.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Fluorescence]

thankyou for these responses.

I have now found out that "Blue Light Hazard" supposedly afflicts white LEDs (obviously blue LEDs too).

http://texyt.com/bright+blue+leds+annoyance+health+risks

This is becasue a white LED is a blue LED coated in phosphor....the blue light hits the phosphor and comes out of the LED as white light.

...but some blue makes it out too...and since blue light has a wavelength wavelength less than 500nm, it can cause permanent eye damage (so they say) and depletion of melatonin in the body (so they say)

However, even if this were true, fluorescent lights actually emit UV light, (also less than 500nm in wavelength) and this is converted to white light by the coating around the glass...

..so would fluorescents be just as dangeroues in this respect due to "leaked" UV light (in the same way that white LEDs "leak" blue light ?

 

[jraef]

All lights are dangerous in their extremes. Sunlight irradiates you with UV, candles and other ignition light sources cause fires and smoke, incandescent is wasteful and leads to environmental poisoning, fluorescent has Hg, LEDs make you eventually want to commit suicide...

Some are just a little more dangerous than others. If we are to live without danger from our light sources, we must become mole people, sniffing around in the dark.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[IRstuff]

Photons energetic enough to fly through space are potentially dangerous...


TTFN

FAQ731-376

 

[stephenw22]

I'm still a big fan of regular incandescents over either CFL or LED lighting. However, CFL lighting seems to still have a lead over LED lighting for overall efficiency.

That said, I think efficiency is overrated, at least for the northern climate I live in. During the summer, when my house needs cooling, I'm barely using any lighting, as the days are long and there is plenty of natural light. In the fall, winter, and spring, the heat given off by the lighting offsets the amount of forced-air heating required for my house. Electric heat is slightly more expensive than the gas furnace, but not by that much.

 

[whitehendrix]

efficiency is a matter wasted energy converted to heat.

i would DEFINITELY say that LED's are far more efficient at the moment just in general, since they produce VERY little heat at all.. now, granted.. using LED light soures in the household will change your average numbers taking into account voltage trasformation and rectification.. of course every little step thru a regulator or diode or winding will knock down the efficiency.

"technically" a REAL easy simple circuit for an LED driver (for regular 120V household use) could consist of a resistor and a pair or 2 or diodes.. no coils.. no MAJOR losses except voltage stepdown, but what would actually be more effient? going thru a transformer or a resistor?

look at the CFL now.. we need to step up the frequency and voltage going to the bulb.. that kinda throws our numbers up right off the bat!! given time, perhaps both will be phenomenally efficient.. at least i hope so..

 

[MacGyverS2000]

Just came back from a two-week Caribbean cruise, else I would have jumped in on this one sooner...

LEDs have already surpassed CFLs in terms of efficiency. For example, early this year Cree announced a white LED that output 900 lumens at <10W, and it can be picked up by the layman (just the LED, not in socketed form) for $20 in onesies. That will replace a 75W incandescent quite nicely. The issue still remains pricing of a socketed unit.

the cheap CFLs are failing so quickly because they're not being used "as designed". The bulbs were "designed" to be used in tabletop lamps, which places the electronic ballast below the CFL bulb, keeping it relatively cool. Many people, however, are typically using them in ceiling lamps, placing them on their sides or upside down. This means the ballast now has to deal with waste heat from the bulb itself, leading to an early demise from cheap components and construction.

This is becasue a white LED is a blue LED coated in phosphor....the blue light hits the phosphor and comes out of the LED as white light.

Not quite. Blue light leaks out, but that's by design. The phosphors glow yellow when excited with blue light, tricking the eye into believing it is seeing white (since the yellow light excites the green and red cones in the eye).

Dan - Owner

http://www.Hi-TecDesigns.com

 

[marginal]

macgyvers2000:-
thanks for getting back on this...

"the cheap CFLs are failing so quickly"

Do you think these "light-bulb" CFL's are failing because of the electrolytic capacitor in them being the weakest link ?

 

[MacGyverS2000]

I've never taken the time to do a post-mortem on a dead one, but if the cap isn't dried out by the time it dies it most certainly isn't fresh. All it takes is to run those components for a few hours a few degrees above their rated max and lifetime is significantly shortened. I also imagine any driver chip is probably having its limits pushed or exceeded (the really cheap ones probably use transistor loops rather than chips). Not much else in there... some diodes, inductor/transformer

Dan - Owner

http://www.Hi-TecDesigns.com