Archives for Science

Incandescent Lights: What EISA Really Means

Categories: Dear God, Make It Stop!, Eco-nerd, Politics and Local Topics, and Science.

There’s been a lot of press coverage recently of the incandescent lighting provisions of the Energy Independence and Security Act of 2007, and it’s largely been of the form “The US Government is banning incandescent light bulbs.”

While this makes for good prime-time newsvertainment, it’s not really true.

The tungsten light bulb was invented in 1905 as a fairly radical improvement on the earlier carbon filament bulbs, which would generally last less than a week before burning out. The humble incandescent light bulb was pretty constantly improved — both in terms of lifetime and efficiency — until about 1964. At that point in time, a bulb that used 100 watts could put out between 1,300 and 1,700 lumens. And that’s where we are now. The most commonly used incandescent bulbs have seen no real improvements in the past 45 years.

Now, let’s look at what EISA actually says about incandescent bulbs. A careful reading shows that it doesn’t eliminate incandescent bulbs. Far from it. All it does is set minimum efficiency standards for them. The relevant information comes from Pub.L. 110-140, Subtitle B, Section 321 (a)(3)(A)(ii)(I)(cc); the important columns from the table are:

Lumens Maximum
Wattage
Effective
1490 – 2600
72
2012
1050 – 1489
53
2013
750 – 1049
43
2014
310 – 749
29
2014

The four lines in the table correspond roughly to modern 100, 75, 60, and 40 watt bulbs respectively. So, those are certainly aggressive compared to the ’60’s technology that we’re using today. But it’s not a “ban on incandescent bulbs” any more than recent automobile efficiency regulations are a “ban on internal combustion engines.”

In fact, you can already buy, right now in 2009, a number of bulbs that meet these standards. Sure, they’re a bit pricey right now, but so were 13 SEER air conditioners five years ago. When regulations force minimum efficiency standards, economies of scale almost always kick in and drop the prices to be very close to those of the older, less efficient technologies.

On top of this, we’ve seen some extremely promising advances in incandescent technologies, including laser treatment of filaments and coatings that turn waste heat into visible light. Either of these alone would completely blow the EISA standards out of the water, beating them by a margin of more than 30%. And there’s no reason to believe that they can’t be combined with each other for additional efficiencies.

So, before you start writing your eulogies for the humble incandescent bulb, I’d give the industry some time to show us what they can do when given a challenge.

Edit: there are additional EISA provisions that kick in January 1st, 2020; these require an efficiency of 45 lumens per watt or better. This will be more difficult, but the kinds of advances I talk about above are already close to this standard — the laser technique gets you to 35 lumens per watt — so even that isn’t likely to be incandescent’s death knell.

Texas “Body Farm” on Hold

Categories: Food, Politics and Local Topics, Science, and United States of America.

Sometimes the news is breath-takingly weird.

It seems that Texas State University in San Marcos, TX, had to put their “body farm” project on hold. What’s a body farm, you ask? It’s a location to study the decomposition of, well, bodies. Human ones. For forensic research purposes. There are a couple of these in the USA already, but Texas has a different enough climate to warrant one of its own.

But that’s not the really weird part. The reason this is being put on hold is not the obvious “not in my backyard” argument. Rather, it is the concern that the resulting buzzard density might endanger traffic at a nearby community airport.

Chocolate as an Antitussive

Categories: Food, Health, and Science.

According to a 2004 article in New Scientist, theobromine maybe a stronger cough suppressant than codeine.

Theobromine is an alkaloid primarily found in dark chocolate.

Edit: The article did not actually say it was better than Codeine. I read that somewhere else–I forget where.

Edit 2: Anyone in the Estacado Systems office this week would tell you I was in need of such. I tried some–and it worked for a while, anyway. (Thanks, Brian!)

Hypercolor Monitors in the Works?

Categories: Science and Toys.

In an earlier post, I discussed the difference between purple and violet, and explored some of the color limitations of electronic display technology. Phil recently pointed out an article in Wired that discusses the use of adjustable diffraction gratings to produce arbitrary colors. (In practice, the gratings don’t produce the colors; they diffract a white light in such a way that the desired color can be made to pass through a pinhole). In theory, an array of these can be constructed to produce vivid-color televisions and monitors.

There’s something I find a bit suspect about the article, though. I mean, yeah, it’s full of the traditional Wired-style junk science (e.g., using relative voltage to compare power efficiency without taking current into account — plus, it includes a diagram of all the colors monitors can’t display [pause two beats here to let that sink in]), but in terms of color rendering, it says one thing that stands out as really bizarre.

The researchers are quoted as saying they intend to use white LEDs as the light source for this technology.

What?

LEDs are diodes made with materials specifically chosen so that electrons crossing the p-n junction cause a photon to be released. The wavelength of these photons (color of the produced light) depends on the exact materials being used. Note I said “wavelength,” not “wavelengths” — LEDs produce a single color out of the spectrum at a time. (Strictly speaking, they produce a very narrow range of wavelengths, typically about 20 to 30 nm wide, with very steep drop-offs — but this is as close to a pure color as to make no difference for this conversation).

White LEDs can be produced by mixing together two or more carefully chosen single-color LEDs, but this is rarely done. Almost all white LEDs produced today use a blue LED as their base (gallium-nitride based, with a wavelength of ~460 nm); on top of this LED, they layer a phosphorescent substance (cerium-doped yttrium aluminum garnet) which absorbs part of the blue light and emits a yellow light centered around 580 nm.

If you take the light from one of these LEDs and pass it through a prism, you’ll get a very thin, bright line of blue, and a slightly wider beam of orange/yellow/green.

By now, you should see where I’m going with this. If you use a white LED as your color source for a monitor that uses a diffraction grating, the results will be no better than today’s color display technologies, and arguably worse. Not only will you lack the ability to display colors below 460 nm (keeping in mind that s-cones peak at 420 nm: no violet for you!), but you’ll have gaps in the lower green and upper red spectrum as well.

Nonetheless, the adjustable diffraction technology is fascinating, and I hope something like this eventually gets to see the light of day — hopefully using something more wide spectrum than what the article implies for a light source.

Now all we need is a CCD that can record a full-spectrum scene, and we’re good to go.