Monday, April 30, 2007

Mercury in compact fluorescents

Ah drat. A slashdot article appeared about some poor lady in Maine broke a compact fluorescent lamp and freaked out about the small amount of mercury in it. A questionable journalist wrote an article about the freakout.

I had a draft article about the issue: Compact fluorescents contain mercury. How does this amount compare to the amount of mercury released by using a standard incandescent lamp? So enjoy my sketchy calculations below.

Lamp Amount (mg.)
Pre 1988 T-12:~45
Post 1988 T-12: ~11.6
Typical T8: ~4 to 5
Low Mercury T8: ~3
CFL: ~4 to 5

Type Mercury content mg/unit*
Fluorescent lamp: 10
Straight fluorescent with diffusion barrier coating: 6
Compact fluorescent lamp: 4 - 23 W: 5
26 - 55 W: 10

26 watt CF: 8 hours a day, per year uses 75.92 kWh. At roughly 10 cents/kwh (new IL prices), $7.59 a year.
100 watt incandescent 8 hours a day, per year: 292 kWh. $29.20.

every 1000kWh produces 619lbs CO2 for ComEd power, which was 27% coal. (12 months prior to march 2004) Excelon environmental release
(Although recently it's been very highly nuclear, up to 92% in fall 2006).
2/3 of mercury in coal escapes to air

0.17ppm average Hg content in US Coal
Indiana coal varied from 0.31ppm to 0.02ppm

# The thermal energy content of coal is 6,150 kWh/ton. Even though coal-fired power generators are very efficient, only about 40% of the thermal energy in coal converts to electricity. So the electricity generated per ton of coal is (0.4 ton)(6,150 kWh) = 2,460 kWh/ton.
(ISA: Maximize energy buck with efficient bang)

For our 100W incandescent, it burns 292kWh per year, of which 27% is coal, which means 64lbs (29kg) of coal is burned in IL. 0.17ppm of that is 4.93mg Hg, which 66% escapes: 3.29mg Hg.

Our compact fluorescent will produce 26% of that much mercury, or 0.86mg Hg. At 8000 hours lifetime, that's roughly just short of three years of 8hrs/day. So we'd release 2.37mg of Hg for the lifetime of the bulb, while the incandescent would release 9mg over that same time period. Add the existing 4 to 5mg per CFL, and the CF still is releasing less mercury into the environment.

This calculation gets worse and worse the more coal your power is made from. Illinois has the highest production of nuclear power of any state, so using compact fluorescents reduce the release of mercury into the environment, if you ignore renewables like hydroelectric. The nation as a whole uses 50% coal as its power source.

Friday, April 27, 2007

Hayabusa data release

The ambitious Japanese asteroid project, Hayabusa, has released its data archive. The asteroid Itokawa was the target; whether they successfully picked up any of it might be known if the spacecraft returns to Earth successfully in 2010.

The imager on the spacecraft was AMICA, and the data archive is available here. A sample image would be this one, showing Itokawa truly is a rubble pile.

I took three filtered images taken during an Earth flyby and made the image above from them. I'll play with some of the Itowaka images as well and see what comes out of them.

Thursday, April 26, 2007

Yerkes Observatory trip

The Ryerson Astronomical Society sponsored a trip up to Yerkes Observatory this weekend. We split the 60-odd visitors into three groups and showed them the observatory through twilight. I got to show them the basement and the 24-inch reflector--fairly mundane things, and there is only so much you can opine about the difference between astronomy and astrophysics three times in a row. So, while talking about the infrared camera called HAWC on the second-generation flying telescope called SOFIA, scheduled for its first test flight today!, I tried my best to talk about light outside of our visible range. And I had to bring up near-infrared radiation and took some examples with each group. The above image is from the next morning. Everyone hopefully had fun looking through all the scopes, including the world's largest refractor, at various targets. Halfway through the observing I moved the 24-inch onto Messier 51, the spectacularly interacting galaxy pair in Canes Venatici, just off the handle of the Big Dipper. I would say some two-thirds or more of the visitors saw the spiral arms. After the big group left, the overnighters returned to the 24-inch at as M51 was transitting, the arms were much more evident.

(An example from Ryerson Observatory of M51).

Tuesday, April 24, 2007

terrestrial exoplanet

The Bad Astronomer is reporting the ESO has discovered a terrestrially-sized exoplanet. It seems the ESO hasn't released the embargo on the info yet.

P.S. Systemic talks about it.

P.P.S. The Press Release.

Biodiesel vs. petroleum: greenhouse gas emissions and N2O

A press release recently reported research that claims biodiesel will cause more greenhouse gas effect than using petroleum oil. The gist is that agriculture with industrial fertilizers release some N2O unintentionally as part of nitrogen fertilization, and that nitrous oxide has a much stronger effect on global warming because it has a long lifetime in the atmosphere. The UN defines a "Global Warming Potential" for each greenhouse gas. Lifetime in the atmosphere is the primary factor (perhaps the only factor?), so nonreactive gases like CFCs, which live nearly forever, have incredible numbers (50000) for their "effect". CO2, though, is just defined as 1, even though it has a variable lifetime in the atmosphere of 5-200 years (page 38). I don't know if the spectral absorption of each gas was taken into effect for these--I see no information that it is. N2O lives for about 120 years in the atmosphere, a fairly nonreactive gas, and it is this multiplication factor, (296x), that drives the conclusion about how biodiesel via rapeseed is worse than petroleum in greenhouse gas emissions.

I would have liked to read the actual paper via my institutional subscription, but it's not available yet online or in paper.

The linked press release is actually from a tropical conservation group, and interestingly they happened to add a graph with yields of biodiesel per acre, showing rapeseed as middle of the pack in terms of yield. What would happen to the analysis with other crops? What if we didn't use so much nitrogen fertilizer or didn't exclusively produce rapeseed? (You can nitrogenate with legumes to avoid using some fertilizer). Was the absorption of CO2 from the atmosphere into the plant matter taken into consideration during the analysis? Questions I have, answers I can't find.

You might know rapeseed by another name: a special variety breed called canola (CANadian Oil Low Acid), which has much lower amounts of a naturally occurring toxic acid in it.

Friday, April 20, 2007

IR-block windows

I cut a window out of a piece of polycarbonate to replace the IR-block filter in the modified Canon S300. It's 1.0mm thick, and the infrared block filter was 2mm, so it didn't solve my focus issues. But it helped. I realized today all I need to do is cut another one out and 1+1=2. Sure it won't be optical cement-glued together, or anti-reflective coated, but who cares. I cut the polycarbonate (which is really the protective cover of a package of CD-Rs) with a dremel and ground the sides to fit.

The windows. The cyan one is the original.

This blurry photo is an example. I include it because of the delightful color variations from the mixed lighting. Fluorescents around the periphery and metal halide in the center. The carpet in the center is nearly black to the eye.

UPDATE: Gah. Adding two windows pushes the CCD back too far, resulting in out of focus images.

Thursday, April 12, 2007

IR filtration

The two-layer color negative film sandwich is too strong of a filter for the IR modified Canon S300. It produces a virtually monochrome image, as seen below.

What I like and want is a duo-tone response, with red coming from a little visible red and the nearest of the near-IR, and blue coming from deeper in the IR--at least 800 to 900nm. Vegetation renders pastel blue and the sky and deep red. Most neutral items are a touch reddish, but not too much. Most black fabrics are pastel blue.

I can get it by removing one layer of the sandwich.

I believe the difference is greater when the sun is out and/or when tungsten illumination is being used.

P.S. For kicks here is the latter image with a boosted green channel, extra saturation and contrast: Cloudy Bartlett Quad, IR

Wednesday, April 11, 2007

A blue hat day

A black felt hat, when seen in the near-infrared, is quite reflective.

This was taken with the Canon S300, with no IR-pass filter. It shows a combination of visible light and near-infrared, since the IR-block in the camera was removed. My lighting source was halogen incandescent, a rich source of near-IR light. The black felt is very light-colored in the near-infrared, as bright as the visible tan sweat band, and we see it is even more reflective the further into the IR we go. The blue channel is a combination of visible blue (on a black hat there is none) and infrared radiation leaking through the blue filters on the CCD. Most bandpass color filters also pass light of wavelength double of their design: so blue filters, with a peak transmission of about 450nm, will transmit at 900nm as well.

Monday, April 09, 2007

Trying something different: IR mod for Canon Powershot S300

I've decided to increase posting frequency at the expense of creating fully developed and finished projects. A number of things I've been working on have been taking longer than expected to finish and they are all cool; but if they don't finish nicely, I haven't been posting them.

I previously wrote up some experimentation with my Canon Powershot A95 in the near-infrared; those were done with a stock camera and two or three layers of fully-exposed and developed color negative film. Exposure times were horrendous, though, as the camera's internal IR-block filter fought against the external IR-pass filter. In broad daylight exposures were often 5-10 seconds long.

Anyways, I removed the IR filter from an old Canon S300 and here is an early image.

The IR filter is 2mm thick and in a converging light path--therefore it needs to be replaced or adjusted for; I didn't do that, and instead stuck a very concave lens (a 2x teleconverter) in front of the camera. It gets the nearsighted camera to focus at infinity, for some of the frame. I found that I could take the lens out of the housing of the teleconverter, and place it closer to the camera lens, which helped. I can zoom in just a bit and the focus is at infinity and a lot of the vignetting is gone.

Monday, April 02, 2007


Take a look at Wikisky, an impressive Web 2.0 project from Canada.

Astronomy is one of those fields that has always been obsessed with catalogues--from Hipparchus to modern-day systems, everything needs to be assigned an identity. Nowadays astronomers often don't know where in the sky their objects are; ask them about it and they know the catalog number, but not the constellation.

With the power of cataloging comes the ability to analyze, map, and link. Wikisky does this nicely with the easy user interface that we all use: Google Maps.

In addition, once you've found an object you're interested in, Wikisky will query the Astrophysics Data System for articles with your object mentioned in the text. This at the moment needs a little work to bring up more relevant articles.

I see Sloan Digital Sky Survey data, and also a lot of amateur CCD images; really good imagers add World Coordinate System headers to their FITS headers, and it seems the system must do something with those to grab the right images that contain your object. You can also ask it to query the Digitized Sky Survey for you and pick up an image.