A campaign to conserve energy by switching from incandescent to fluorescent lights has been in full swing for some time, launched by energy genius Amory Lovins, and enthusiastically embraced by the Green politicians and their fellow travelers, in particular, the utility wimps. If the change were carried out everywhere, we are told, it would conserve enough to get rid of most nuclear plants
¾ that is, prevent lowering the death toll and disease incidence from fossil-fired plants. From that noble goal you can once again see that St. Amory is not an energy conserver, but a social engineer.Nevertheless, unlike ozone depletion, global warming and can-cer scares, the idea is not totally preposterous; it has a sound ker-nel surrounded by a voluminous package of bunk, and it is therefore well worth looking at more closely.
An incandescent light, i.e., an ordinary light bulb, emits light from a glowing filament inside a bulb filled with an inert gas. 95% of the electric input energy is wasted as heat, and only 5% is con-verted to light, so that its efficiency is a lamentable 5%.
A fluorescent light works on a different principle, to be ex-plained in a moment. It has a nominal efficiency of 40%, and the eightfold higher efficiency is the healthy kernel inside the bunk, though as we shall see, this does not necessarily translate into cut-ting the overall electricity wasted as heat from 95% to 40%, i.e. to less than half.
Another advantage claimed for fluorescent lights is that their spectrum, or composition of colors summed to yield the bluish-white light, is closer to natural daylight than that of the usual light bulb. However, though it is closer, it is not close, and some people find the light "cold" and irritating. On a more objective level, the cones of the eye's retina have a sensitivity spectrum, too. It will adapt to match natural daylight in all of its forms
¾bright sunlight, overcast, in a forest, etc. But it cannot be stretched as far as the spectrum of a fluorescent light, which is why the dislike of fluores-cent lights by some people may not be pure hysteria.Also, due to the thermal inertia of the filament, an ordinary bulb will give a fairly steady light level, whereas a fluorescent light is switched on and off 120 times a second. This may illuminate some moving objects (such as the spread fingers of one's hand) in jerky, discontinuous positions and give rise to a strobe effect similar to the one that made the spoked wheels in very old movies seem to turn backward.
[DRAWING of fluorescent light circuit: electrodes, starter, choke]
The tube of a fluorescent light is filled with a gas at low pressure such as argon, which is needed only during the starting process, and a small amount of mercury which is the essential light producer.
The light works in three stages. The first is to put a high voltage on the two electrodes at each end of the tube. Their electric field will shock-ionize the gas, which will conduct an arc (an electric dis-charge between the electrodes) that vaporizes the mercury. I will have more to say about this starting stage in a moment.
Stage two: when electrons in the arc strike mercury atoms, the latter will emit ultraviolet light. But that will not give anybody skin cancer, because it cannot get through the glass wall of the tube. (You cannot get a tan by sitting in the sun behind a window.)
Stage three: the coating on the glass is made of a fluorescent material; when it absorbs ultraviolet light it emits visible light, the end product of the fluorescent light.
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Vol. 19, No. 1
Newsletter: Access to Energy Newsletter Archive Volume: Volume 19 Issue/No.: Vol. 19, No. 1 Date: September 01, 1991 08:48 AM Title: Delicate and Fragile
Copyright © 2004 - Access to Energy Newsletter Archive
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