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The Last American Light Bulb

by Mark W. Hibben
10/4/2010

An Incandescent Past

The incandescent filament lamp was a quintessentially American invention by a quintessentially American inventor, Thomas Edison.  General Electric’s closing of the last light bulb plant in the United States on September 24 seems emblematic of an overall industrial decline in the United States that needs to be addressed by policy shifts both at the corporate and Federal government levels.

GE didn’t just close the plant; it also took the opportunity to shift some incandescent lamp production to its Monterrey, Mexico facility, so the plant closure was as much about off-shoring as it was about obsolescence.  In fact, the incandescent lamp has become obsolete, and its replacement in the consumer market by more energy efficient compact fluorescent lamps (CFLs) and LED lamps is already well underway.  Future lighting technologies such as LED-Quantum Dot hybrids (LED-QD) could provide an opportunity for a resurgence of American manufacturing that would also be “green”.

An Opportunity for Obama Bashing

The GE plant closure has been seized upon by an increasingly strident American Right as an example of “big government killing jobs”.  Such statements simply ignore recent history.  Current Federal regulations do mandate the phasing out of incandescent lamps starting in 2012, but this was put into place by the Energy Independence and Security Act of 2007, which was signed by the Republican President George Bush.  Bush was hardly a champion of big government, but he did understand the need to encourage energy conservation in the US.  The regulations require that lamp efficiency improve by 25% starting in 2012, effectively banning incandescent bulbs.  There are some exceptions such as 3-way bulbs and other decorative bulbs, which GE is now producing in Monterrey.  In looking for ways to reduce energy consumption by consumers, the light bulb was just too easy a target to pass up.  A 40 W incandescent lamp has a luminous efficacy of about 12.5 lumens/watt.  A lumen is a measure of lamp brightness as perceived by the human eye, and the power in watts measured in this case is just the wall plug electrical power consumed by the lamp.  In contrast, a CFL has a luminous efficacy of about 60 lumens/watt.  For most consumers, this has become an easy choice, even if they aren’t particularly environmentally conscious.  GE’s closure of the Winchester, VA lamp plant well ahead of the Federal mandate was a simple acknowledgement of the market realities.  US consumers are switching to CFLs, and no CFLs are made in the US.

Green, Yet Dirty

It may be just as well that CFLs are not made in the US.  These work the same way that fluorescent lamps have always worked, by electrical discharge through mercury vapor. 

The discharge produces mostly UV light, which is converted to visible light by the fluorescence of phosphors coating the inside of the glass tube.  UV “black lights” are simply fluorescent lamps without the phosphor coating.  Mercury vapor is highly toxic, and both the production and disposal of CFLs present environmental and worker safety problems.  Lewis Carroll’s Mad Hatter was a reference to a very real environmental problem that existed in England in Carroll’s time: mercury was used in hat making, and hat makers were succumbing to mercury poisoning, which often manifested as a form of dementia.   Usually, the mercury risk posed by CFLs to the consumer is minor, however.  CFLs are safe as long as they are intact, and even a broken bulb releases only a small amount of mercury vapor. 

That US lighting companies chose to simply re-brand Chinese-made CFLs is an example of the logical consequence of globalization.  In addition to the labor cost advantage that Chinese manufacturers enjoy, they also don’t have to worry about US EPA and work place safety regulations that domestic US manufacturers must contend with.  The manufacture abroad of CFLs is just one example of American manufacturers making a logical economic decision given international trade policies, relatively high domestic labor costs, and increasingly stringent environmental regulations in the US.  Until something changes in this equation, it almost always works out that it’s less expensive to manufacture abroad.  And no, I don’t think the way to restore US manufacturing  is to relax environmental regulations or reduce wages for US workers.

The LED Revolution

US consumers now have the option to buy lamps based on “white light” LEDs, and although they are still very expensive, they last about five times as long as CFLs, and 50 times as long as incandescent lamps.  LED lamps have approximately the same luminous efficacy as CFLs, but have other advantages: they turn on instantly without any warm-up period and they can usually be dimmed with conventional dimmer switches.

Most consumer white light LED lamps work in a way similar to the fluorescent lamp, but without the mercury vapor.  A blue emitting LED illuminates a phosphor coating and the resulting light looks bluish-white.  A typical output spectrum is shown next panel.

The peak at about 460 nm is the blue output of the LED itself, which is based on a gallium nitride (GaN) or indium gallium nitride (InGaN) semiconductor.  The output from 500 nm (green) to 800 nm (near infra-red) is the output of the phosphor used for this particular white LED, cerium doped yttrium aluminum garnet (Ce:YAG). 

White LEDs can have a rather cold bluish cast as a result of the leakage of the blue “pump” beam, but this can be ameliorated by providing a thicker more absorbing phosphor layer.  The cost of this is a somewhat reduced luminous efficacy, since the phosphor generates some heat when it “down converts” the shorter wavelength blue light to longer wavelength green-to-red light.

Quantum Dot Serendipity

A discovery by a graduate student at Vanderbilt University may help make LED lamps more attractive to consumers by endowing the lamps with a more natural light output akin to the old fashioned incandescent lamp while preserving the luminous efficacy of the bluish white LED.  Michael Bowers was working on the chemical synthesis of “quantum dots”, in this case, very small particles of crystalline cadmium selenide that contain only 33-34 pairs of atoms.  This particular size of quantum dot has been dubbed the “magical size” because the synthesis process employed naturally prefers this size.  When Bowers explored the optical properties of these “magical size” dots he made an interesting discovery: when illuminated with a blue LED, an emulsion of the dots glowed with a yellowish white light.  The broad band character of the light output had been unexpected, and appears to be a direct consequence of the small size of the dots.  Because the “magical size” dots form preferentially, they can be manufactured economically and incorporated into organic paints and films and applied as thin coatings to optical windows.

A Massachusetts startup, QD Vision, now produces a quantum dot based “filter” for LED lamps that are being made by another company, Array Lighting.  The lamps are not easy to find, but can be purchased on-line from Green Lighting Supply. The advantage of the LED-QD lamps is that the spectrum of the light output is more biased towards the yellow, as shown next panel.

The light output of the lamp appears warmer and more like the traditional incandescent lamp.  This property is quantified in the Color Rendering Index (CRI) which rates lamps according to their ability to accurately render colored materials reflecting the lamp illumination.  Incandescent lamps have a CRI of 100 by definition.  CFLs typically have a CRI in the 80s, whereas the quantum dot/LED hybrid has a CRI of 90.

American Innovation: Alive and Well

The LED-Quantum Dot hybrid lamp is another quintessentially American invention that should provide reassurance that technological innovation is alive and well in the United States.  It’s not absolutely clear that this technology will prevail in the market place: CFLs will probably always be less expensive, and there may be other technologies as yet undeveloped that may come to dominate the lighting market.  Whether innovations such as the LED-QD lamp can be translated into meaningful job growth in the US is a matter for US economic and trade policy, which in my view should be kept largely separate from environmental policy.  Under no circumstances should a sane environmental policy have to take a back seat to job growth.

The economic imperatives that have been driving American manufacturing out of the US have grown concomitantly with globalization and “free trade”.  While international trade has certainly increased the overall prosperity of the global human community, I doubt that it follows that prosperity must increase in all places equally.  Has the growth of prosperity in the developing world come at the expense of the developed world? 

In terms of GDP growth, this had certainly not been the case, at least up until the latest recession.  Certainly, there’s no reason to think that global prosperity growth is a zero-sum game.  But manufacturing jobs growth in the third world has very demonstrably come at the expense of manufacturing jobs in the US and other developed countries.  The shrinkage of the manufacturing work force was for a long time compensated in the US by the growth of service sector jobs.  However, in the Great Recession (which is supposedly over) many of those services became “non-essential” as businesses and consumers cut back expenses.  The net effect is that the economy has become brittle and less resilient under economic stress, and jobs recovery a painfully slow process. 

I wouldn’t claim to know what the solution is to the problem of jobs recovery in the US, except that I have a sense, as do most Americans, that the current Administration isn’t doing enough.   So far, the Administration has advocated investment in forward-looking “green” technologies, which is all well and good.  The problem is that there’s nothing preventing these jobs from being off-shored once these “green” industries reach a sufficient level of maturity.  Until this problem is addressed at a Federal policy level, the US economy will continue to bleed jobs overseas.  This may require Federal policy makers to come to grips with a reality at odds with the dogma of free trade:  adherence to free trade principles may not always be in the best interests of the United States.

  • 1.
    Plant Closure
  • 2.
    Obama Bashing
  • 3.
    LED Lamps
  • 4.
    Spectral Shift
  • 5.
    Quantum Dots
  • 6.
    Alive and Well
  • 7.
    Jobs Recovery
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