2007-02-24 15:14:49 UTC
were working on new technology that could eventually make
incandescent lamps as efficient as CFLs. The short term
goal is 30 lm/W. I can't find a copy of that press release
at the moment, but it does raise some interesting questions.
I have not had any connection with GE incandescent lamp
technology since I retired in late 1999. There were two
publicly-known technologies they were working on at the time
that, if improved, could raise the efficacy of incandescent
lamps to the 50 to 60 lm/W range.
The first is IR reflecting films, a technology that is
already in commercial use. Considering that 90% to 95% of
the energy generated by an incandescent filament is radiated
away as IR (depending upon where you define the long
wavelength end of the visible spectrum), using IR films to
raise the efficacy of incandescent lamps by a factor of 3 or
even 4 is possible. Low-voltage IR-halogen filament tubes
may already meet the initial goal of 30 lm/W. (Most
IR-halogen lamps are reflector lamps so I don't have ready
access to data on bare filament tubes, but this is what we
suspect Osram is doing with their e-Pro lamp.)
The second technology area is selective emitters. These can
be tungsten that has light-wavelength-sized patterns that
reduce emission of IR radiation while not reducing visible
emission, or they can be materials that are inherently
selective emitters. The prospect for these lamps was raised
by John Waymouth at LS:5 in York, UK in 1989. Research at
the old Bell Labs and more recently at GE R&D has shown that
it is possible to produce an efficacy gain through use of
patterned tungsten or alternate selective-emitting
materials. However, to the best of my knowledge, no one
has been able to develop a system that maintains this
efficacy gain for more then a few hundred hours at the
temperatures required for efficiency light generation.
This should be an interesting area to follow. Perhaps there
will be more information at Light Fair.
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