Wednesday, July 15, 2009

Are Compact Fluorescent Bulbs Good or Evil?

I know, I know, debating the merits of light bulbs may be a slightly unusual hobby. Bear with me for a bit. It turns out that I heard a rumor a few weeks ago. The rumor was that there was something about the way that the new Compact Florescent (CF) bulbs drew power from the power lines "saved energy" at the expense of the power company. Supposedly the power company was not measuring the true power that was being consumed behind the meter, but was instead using an approximation. The way that the CF bulbs worked was supposed to, intentionally or not, be out of phase and therefore have a larger power usage than the meter would be able to measure and charge for.

I have been a fan of green technologies for quite some time now. I have been paying a premium to have "Pure Green" power piped into my house for the past 9 years and have changed almost all of the bulbs in the house to be CF. Hearing that they might be consuming more power than was apparent was an issue for me.

Digging a little bit more, I still do not have the answer. Or, it might be more accurate to say that I have several answers, they are unfortunately neither definitive nor consistent. Before we get into what I have discovered to date, let's quickly review some terms:
  • Real Power - The power the device actually consumes.
  • Apparent Power - How much power the devices appear to use.
  • Reactive Power - The power that is not in phase and creates magnetic fields.
  • Power Factor - The efficiency of the device. What portion of the power consumed is used for powering the device.
  • Billing Based on - power used, not KWH.
  • KWH consumed - not apparent KWH consumed
Here is some of what I have uncovered:

CF bulbs were designed to have us be overcharged describes the situation as a plot to gain money for the power companies. The power companies supposedly charge for apparent power consumed, instead of actual power consumed. They intentionally lie to us to get us to think they are charging us for kwh when they are not. Devices like CF bulbs, compressors, and AC motors cause us to rack up higher kwh than we should be racking up.

Now, interestingly, I agree with this point, if you measure true kwh of the device, it will be lower (based on the power factor) than what the power company will actually bill you. Where I make a distinction is why this is the case. Based on my discussions with Silicon Valley Power (my local utility), the power factor is basically a measure of efficiency in the device. The closer the power factor is to 1.0 the more efficient the device is at translating power used into work performed. CF bulbs, according to some of the articles, are sitting around a PF of 0.5 which means that they are only successfully transferring about 1/2 of the power that goes into the device into light. Now, where does the rest of that power go? Some goes to heat, most goes to expanding and collapsing a magnetic field of alternating polarity 120 times per second. The power is at 60 cycles per second in the US with one up and one down phase per cycle. We are actually consuming the power that is creating the magnetic field. Since it is reactive power, it does not show up in kwh on simple meters.

It is rather expensive to measure the kwh and reactive power. It requires two highly accurate meters if it is being used for billing purposes. These might be large and would be expensive. What the power company does is accurately measure one quantity, amperage. Measuring the amperage that is flowing into your home and knowing the voltage at the source gives you the true power that is used by the system. While it does not provide you with a breakdown of what is going on inside your home, telling you how much reactive power is used, for example, it can give you a very good metering of how much is actually being consumed by your home. Once they know the amperage, they use the voltage to convert the power to the equivalent kwh of your house. You are then billed.

I understand the value of having a resonant circuit when discussing devices. When circuits operate at their resonant values, you end up with a much more efficient device that uses less power to perform the same operation. I am not sure if modifying the power factor by adding a capacitor (as the Atlantic Free Press article stipulates) would actually decrease the amount of power used by the device. If this is true, then the device manufacturers should be "approached aggressively" about the issue. They are saving pennies and wasting thousands of dollars of electricity. My suspicion is that there is some inefficiency that would be corrected but the primary issue is actually one of measurement and not one of actual loss.

I think I may need to purchase one of the mentioned meters and give a few tests a spin. I happen to have a nice little AC motor here that I can experiment with.

An excellent explanation of CF bulbs is on Wikipedia. A similar article on Power Factor is available.

I have also found an article that goes into some details about how the roll out of CFLs was not done well. Depending on how they are used and their environment they will either perform well or very poorly. I found this out when I installed CFLs in my outdoor motion detector. On cold nights or mornings, it would take minutes to light up, or possibly not light up at all.

Personally, my house is filled with these lights. I have found they do dim a little over use, they do not last as long as they are supposed to last when place in ceiling can lights, and they tend to hum when they get old. I like the quality of the light they provide and appreciate the energy savings. I have a few LED lights and enjoy them, but they are so far too expensive to look into using in the rest of the house. I look forward to the days of cheap organic LED lights that allow for dimming.