The
common incandescent light bulb found in any home has also been a handy source
of heating for the past century. Hatcheries use light bulbs as a heat source
to warm baby chicks. People use them to germinate seeds indoors in the winter
and restaurants use them to keep food warm on the serving counter.
Unfortunately,
this convenience also points out the major flaw in the remarkable invention
that brought light to every home: Incandescent light bulbs are primarily producers of heat, not light.
If
what you’re after is bright, clear, balanced illumination, a conventional light
bulb is a very poor choice. In fact, it wastes 90 percent of the electrical
energy it uses. Meanwhile, it requires burning a lot of coal to create the
needed electricity.
Until
fairly recently, no one really cared. Coal was cheap, and so, therefore, was
electricity. Only when the energy crisis of 1973 hit did people begin to think
differently about wasting fuel.
At
that time, Edward Hammer, an engineer at General Electric, invented a compact
fluorescent light (CFL) that could replace incandescent lamps and use 75
percent less energy, even while it lasted 10 times as long as an ordinary light
bulb.
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Like
conventional fluorescent tubes, the CFL works by exciting mercury vapor with
electric current. The mercury vapor then emits ultraviolet light, which can’t
be seen. But, the UV light hits a special coating on the inside of the glass,
and that coating, called a phosphor, gives off light in the visible range.
The
CFL took a while to find its market. For one thing, the energy crisis ended
and people went back to their old ways, taking energy for granted. For
another, when GE realized that it would cost $25 million to build factories to
produce the new bulbs, it shelved the idea.
But
in the 1980s, Philips and a German company called Osram — a division of Siemens
— began turning out usable CFLs, and during the 1990s and into the 21st Century, they have gradually become
widely accepted.
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However,
even as CFLs were penetrating the marketplace, scientists kept working on an
even better...
