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Laser Blast Makes Regular Light Bulbs Super-Efficient
guruevi writes with news that a process using an ultra-powerful laser can crank up the efficiency of everyday incandescent light bulbs. Using the same laser process covered several years ago, the tungsten filament has an array of nano- and micro-scale structures formed on the surface making the resulting light as bright as a 100-watt bulb while consuming less electricity than a 60-watt bulb and remaining much cheaper to produce. "The key to creating the super-filament is an ultra-brief, ultra-intense beam of light called a femtosecond laser pulse. The laser burst lasts only a few quadrillionths of a second. To get a grasp of that kind of speed, consider that a femtosecond is to a second what a second is to about 32 million years. During its brief burst, Guo's laser unleashes as much power as the entire grid of North America onto a spot the size of a needle point. That intense blast forces the surface of the metal to form nanostructures and microstructures that dramatically alter how efficiently light can radiate from the filament."
But it doesn't matter (at least to those of us in the USA), because in 2014 incandescent bulbs will be banned.
End of lesson. You may press the button.
This is the might Slash. We can understand proper units.
Femto = 10^-15
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Perhaps it operates more efficiently, but it doesn't sound like it is so efficient to produce. Unless I'm misunderstanding or misrepresenting the verbiage from the summary.
You forgot that femtosecond part. The usage of the whole USA grid is for an incredibly tiny fraction of a second, 10^15 of a second. The USA grid is 4x10^15 watts. So really, if you want to translate it into a more sane energy understanding, its about four watts per bulb to do this.
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Yeah, and they contain enough mercury to poison 4000 gallons of drinking water! Yay!
You screwed up your units, there. (watts)x(seconds) = joules.
You also forgot the negative on the exponent, but I'll forgive you for that...
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... Guo's laser unleashes as much power as the entire grid of North America onto a spot the size of a needle point.
What?
For one femtosecond (10^-15 seconds). Rough figure from the world factbook shows the U.S. + Canada averaging 497 GW. So, if the laser fired one thousand pulses per second, it would only draw 5 W from the wall (assuming 100% efficiency). It's another case of really big numbers combining with really small numbers to yield nothing spectacular.
Approx. energy used by NA grid in one year, 4x10^12 kWh Approx. mean power to achieve this, 4.5x10^11 W Approx. energy used in one femtosecond pulse 4.5x10^-4 Ws = 1.26x10^-10 kWh So quite a high repetition rate is allowed before the energy usage is noticeable.
Energy and Power are not the same. Specifically, Power is Energy divided by Time. W = E/t
Based on just the US, which for the sake of half-arsed napkin engineering on /. I will double to get total energy usage for North America in 2005, we're talking about 58000 TWh / 8760 h = 6.621 TW average power output.
Thus the laser pulse itself uses 6.621E12 W * 1E-12 J = 6.621 J.
The "efficient" lightbulb saves 40W. 6.621 J / 40 W = 0.165 s.
So it takes less than a second to recover the energy used by the laser. I'm sure the laser system itself uses more power than what is just in the beam, but the point is, ridiculous amounts of power in ridiculously short amounts of time results in quite rational and manageable power levels.
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Compact florescents emit audible noise. Incandescents only emit noise if you but a cheap dimmer switch on them that chops up the sine wave. LEDs, as far I can tell, are silent. LEDs have good enough light now, they just need to be cheaper.
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A lot of mercury is released into the atmosphere from burning coal for electricity. According to the Australian version of the EPA, powering a traditional incandescent light bulb will release of about 13.4mg of mercury over its lifetime versus 2.7mg for a CF bulb. CF bulbs contain 5mg of mercury or less so if you didn't recycle any you'd still release less mercury than would have been released by an incandescent bulb.
Home Depot recycles them for free now and infrastructure to recycle them is spreading all of the time.
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FYI the best Flourcent bulb is 100 lm/Watt (CFL is 60-72) while the best white LED is 131 lm/Watt (over 150 lm/Watt for some other colors.) http://en.wikipedia.org/wiki/Compact_fluorescent_lamp#Energy_efficiency
so while currently most CFL beat most LED in efficiency, inherently it looks like LED has a better future. Especially with LED lights having a longer (best case) lifetime, and being instant on to full power, and no high voltages present.
The LED at home being a new trend, with in-efficient transformers, and cheap production units likely causing damage to their reputation. Much like Fluorescent is still trying to get over the poor initial products reputation (with odd colors, poor life, and several minutes of power up, with constantly buzzing transformers, and odd harmonics with monitors, video cameras, and TV's.)
Dunno if this is gonna happen yet, or not, but I've seen articles about the use of oLed sheets as light sources - instead of being a 'bulb' in the usual sense, think more like those ceiling mounted fluorescent light fixtures with diffusers so common in schools, office buildings, and retail. Or, think of a computer monitor that is all white (although, the light need not be pure white - could be offwhite colors - could even change the color when you want, maybe), but brighter. They also say that OLEDs will become thin and flexible, so you could take your OLED 'film' and wrap it around a curved surface or something.
So, you could have lighting that looks like a sort of 'standard' table-lamp with a lampshade - except the 'lampshade' is actually the OLED 'film', giving off light directly into the room, with no bulb inside the lampshade.
That's still a number of years into the future, if it ever happens. OLEDs have to become many times cheaper than they are now before that'll happen.
Never. Incandescent light bulbs are banned from Europe in a coupe of months.
Watts is a measurement of joules per second, so if you multiple power by time (as in applying 4x10^15 Watts for 10^-15 seconds) you get 4 joules.
Fewer, not less.
HTH. HAND.
a longer description of Power Factor:
http://www.ee.bgu.ac.il/~instlab/Experiments/05_FlurLamp/PowerFactor1.pdf
Cause (huge power x femtosecond) << (small power x months). It's right in the summary. Femtoseconds are bloody short.
:x
Incandescent lamps fail because the hot filament sputters off metal, gradually thinning the filament until it breaks.
You can slow this down a little by using gases like halogens or krypton, which reverse the sputter or slow the sputter, but the benefit is not dramatic.
To dramatically increase lifetime, you run the filament less hot. But while the lifetime goes up as the square of the voltage going down, the efficiency goes down as the cube (I think it's the cube might be more). So for the sake of efficiency, you want the hottest filament you can have.
This is the tradeoff with double-life incandescent light bulbs. The money they save you in lamps is more than offset by the cost of electric. The filament is a colder blackbody source, it lasts longer, it's more yellow, and less efficient. Don't use them unless they're for a bulb that's hard to change, like something you have to climb a ladder to get to.
In the opposite way, running a 75-cent lightbulb above the rated 2700k temperature, you'll get it more efficient and get whiter light. The bulb won't last as long you'll have to change it frequently. Maybe that makes sense for you, maybe not.
You don't seem to appreciate just how short a femtosecond is. As it is only 1e-15sec (1 millionth of a nanosecond), that means a pulse of 1e15W (1 million terawatts) would use only about 1 joule of energy.
So let's say for the sake of argument that the power and pulse length are both an order of magnitude larger. Then say it's only 10% efficient, so that the process actually takes 1kJ. This energy corresponds to all of 25 seconds at 40W. In other words, the break even lifetime is under one minute.
1. Only if you use non-dimmer compatible CFLs. These are findable at the local walmart (at least my local one, YMMV) and are easily identified by "DIMMER COMPATIBLE!!!!" on the packaging.
2. No, they do not use that power, by definition. The power is sent through the lines and sent back. There is still transmission loss on that power and it increases plant load, but still less than an equivalent incandescent. a 100W equivalent CFL draws 23W, so 46VA (which gives us 40VAR) using his PF=0.5 figure. Let's be generous and say the grid loss is 50%. That brings the real power use to 23+(40*50%)=43W in actual power used and power company having to push out 46VA.
Compared to a normal 100W incandescent, you're still drawing less than half.
Compared to this new trick, we're drawing about 3/4s the power.
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Actually, most loads in normal households are inductive, and the CFL are capacitive, so the low power factor increases the overall power factor of a home (some of the unbalanced power from your fridge now only have to travel to the nearest CFL, and not to the local transformer station).
But don't expect things like facts to convince the people who irrationally hate CFLs, you cannot reason people out of a position they have not reasoned themselves into.