Wednesday, August 08, 2007

Bad science - Google Blackie

Mark Ontkush has caused something of a stir with his assertion that Black Pixels are the New Green Pixels. The idea is that a monitor takes more power to show a white pixel than a black one. So change the color of the Google home page from white to black and you stop global warming.

Only problem here is that Ontkush had not actually measured the amount of power typical monitors consume when displaying a black or a white pixel. And people who have report the opposite of what he claims when an LCD is involved. Ontkush has since expanded on his original post, but still not enough measurement.

What we need here is some science, as in actual measurement. Where is power consumed in the modern home? Is it in heating, lighting, electronic gadgets? Does a 42" LCD consume more energy than a traditional CRT telly? Are we targeting resources at the right culprits?

Another caveat that has to be applied here is the cost of air conditioning. If you live in a cold climate waste heat is a benefit, if yuou are paying to cool the building you pay for waste heat twice - once to create it, then to dispose of it.

Without measurement we have no way to tell.

For example, I strongly suspect that a drip filter coffee maker with a stainless steel carafe saves a considerable amount of energy with respect to a traditional glass pot standing on a warming plate. The stainless steel carafe keeps warm of its own accord, the warming plate version stays on for as much as two hours before turning itself off.

I can come to a pretty accurate evaluation of the costs/benefits of switching to a stainless steel carafe as an individual consumer. If the hotplate is consuming a hundred watts that makes 0.2 units per time coffee is made, at 5 cents a unit that is a cent per pot. Making two pots a day I save $7 a year. So it will be 3 years before I recover the $20 extra cost of the higher priced model.

On pure economics the stainless steel carafe does not pay back in terms of energy savings even on a pretty optimistic set of assumptions. In practice the payback is much faster because the glass carafes only last a couple of years before being dropped and cost $15 to replace, if this is actually possible.

If we are going beyond the individual consumer we have to consider a much wider range of issues, in particular how much energy does it take to make the glass carafe versus the stainless steel one? Manufacture of both materials is highly energy intensive.

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