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n:vision 23W (100W equivalent) compact fluorescent
New bill would mandate that light bulbs produce 120 lumens per watt by 2020

It looks as though energy efficiency is still a big priority for municipalities and countries across the globe. We've already detailed energy-efficient LED lighting efforts put forth by Raleigh, NC. We've also discussed how Australia and the European Union (EU) plan to get rid of incandescent light bulbs by 2009. The United States is also moving towards ushering out inefficient lighting with H.R. 1547, which was published on March 15, 2007.

The bill (PDF), which was submitted by California representative Jane Harman, indicates that light bulbs which have an overall luminous efficacy of 60 lumens per watt (lm/W) will be prohibited by January 1, 2012. The energy requirements get progressively steeper every four years. On January 1, 2016, the requirement will grow to 90 lm/W and will reach 120 lm/W by 2020.

A traditional 100W tungsten incandescent light has an overall luminous efficacy of 17.5 lm/W. A 23W compact fluorescent (100W equivalent) has an overall luminous efficacy of 60 lm/W.

Exemptions could be made by the Secretary of Energy for certain applications where it wouldn't be feasible to use energy-efficient lighting. These include applications related to military, medical or matters of public safety.

If an exception is made by the Secretary of Energy, that still doesn't give entitle the recipient to a free pass to continue using outdated technology. The exemption will only be in effect for two years after which the current enacted requirement will have to be adhered to.

The bill also notes that consumers and businesses will be given incentives to encourage the use of energy efficient light bulbs.



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By BigT383 on 3/22/2007 1:18:01 PM , Rating: 4
Though, you could start seeing lighting transformers being built into, say, the house- right next to the breaker box in the basement or something.


By borismkv on 3/22/2007 1:44:01 PM , Rating: 2
That would result in even lower efficiency, since the power cables running from the transformer to the light sockets would work as a giant resistor. The longer the cables, the more power you lose. That's the main reason AC is more efficient over long distances, it doesn't lose nearly as much power from cable resistance. Ultimately, you'd need to include the transformers in the light sockets themselves, which would cost a lot more money than just having one transformer.


By repatch on 3/22/2007 2:34:36 PM , Rating: 2
Sorry but you are completely wrong there. Whether AC or DC, the power loss due to the "resistance" of the line is identical (for relatively low power levels).

In fact, if you want to get really technical, the effective resistance of a line is HIGHER for AC then for DC due to the skin effect, however at the power levels we are talking about (wires in a home) the skin effect can be ignored.

The ONLY benefit AC has over DC is you can use a transformer. This allows the power companies to step up and down the voltage very simply and efficiently, reducing the current flowing through the transmission lines.

Since power loss in a wire is I2R you can save alot of power and use much thinner cable by sending a high voltage.

The problems with AC are the skin effect (which, described in a simplistic way, results in AC current only flowing through the outer portion of the wire, giving an effective higher resistance, and higher power loss) and impedance coupling to ground. For VERY long high power lines DC is actually used, an example is the James Bay project transmission line in Quebec Canada.


By borismkv on 3/22/2007 3:17:40 PM , Rating: 2
Thanks for the correction. Now I get to add another thing to the list of reasons I'm glad that particular electronics professor retired :D


By Howard on 3/22/2007 4:01:46 PM , Rating: 2
Skin effect is negligible at 120Hz.


By Howard on 3/22/2007 4:05:54 PM , Rating: 2
Oops, meant to say 60Hz. Specifically, the skin depth at 60Hz is about 8.5 (IIRC) mm, meaning that skin effect only kicks in at a diameter of about 17mm. If 17mm wasn't enough for the current, it would probably be at a high voltage anyway.


By Hawkido on 3/22/2007 4:40:59 PM , Rating: 2
quote:
The ONLY benefit AC has over DC is you can use a transformer. This allows the power companies to step up and down the voltage very simply and efficiently, reducing the current flowing through the transmission lines.


I can think of another benefit or two:
1. You can easily convert AC to DC, the reverse is incredibly wasteful and complex.

2. When DC shorts out the whole line lightes up like a lightbulb filiment. Causing fires in houses along the entire trail all the way back to the power source. Ever seen a car's DC wiring fry? You gotta replace the entire wiring harness or else use a butt load of electrical tape. When AC shorts out heat is only generated at the short.

3. If you are planning on running DC to everyone's house, I suggest you pay their life/fire insurance for them as well.

Read Tesla's work, he wanted the Hz in the 200 range for Flourescent bulbs. The light emitted is far more solid and brighter and bulbs longer lasting at that Freq.

Also look up the number of technologies that require AC vs. DC. Generators generate AC electricity, you will loose half the generated amount of electricity when you convert it to DC. (Sine wave grounded at <0 vs. current flowing in the reverse direction <0)


By saratoga on 3/22/2007 7:17:10 PM , Rating: 2
quote:
When DC shorts out the whole line lightes up like a lightbulb filiment. Causing fires in houses along the entire trail all the way back to the power source. Ever seen a car's DC wiring fry? You gotta replace the entire wiring harness or else use a butt load of electrical tape. When AC shorts out heat is only generated at the short.


AC and DC both do this if theres enough current in the short. Its not like AC doesn't heat the lines too.

quote:

Generators generate AC electricity, you will loose half the generated amount of electricity when you convert it to DC. (Sine wave grounded at <0 vs. current flowing in the reverse direction <0)


Rectifiers like you're describing exist in textbooks only. Modern DC supplies are typically 65-90% efficient for consumer level applications.


By knowyourenemy on 3/23/2007 1:50:29 PM , Rating: 2
Thanks for clarifying. My grandfather was one of those electro engineer guys from ages past, and he has always told me those massive power lines that go cross-country are DC... I knew some information presented here wasn't straight when someone argued AC is better than DC for long distances.


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