Neil's News

Entropy

31 December 2006

A couple of weeks ago I poked fun at Americans. Now let's poke fun at Canadians.

The main hall of Ottawa's airport (YOW) is lit by powerful spotlights located at ground level and aimed at the ceiling. Indirect illumination is a good way to light a large area since one doesn't have blinding points of light and hard shadows. Bouncing the beams off the ceiling also provides twice the diffusion distance, plus whatever diffusion properties the ceiling surface itself has.

Now for the perplexing bit. Mounted on the ceiling at the hot-spots of each of the spotlights are clusters of nine photovoltaic panels. This means we have incandescent lights converting 10% of their power to light, hitting photocells which convert 10% of the light to electricity. Yes, it's a perpetual motion machine with a 99% loss per cycle.

Ok, there must be a rational explanation for this. But it's been eluding me since I first saw this Rube Goldberg contraption five years ago. Any ideas?

Quadir suggests that this setup forms a wireless power transmission system, thus allowing one to get power to some mystery object on the other side of the roof without ruining the building's aesthetics by running wires. Though the photograph shows that ceiling is already infested with what appear to be pipes for the fire suppression system. A wire running next to these pipes would be invisible.

Max hits upon a very plausible idea: "They're reflectors, not PV panels. Note that they're considerably more shiny than the white sheet-metal ceiling, and set at a variety of angles. Solar collectors (whether PV or thermal), on the other hand, are invariably designed to reflect as *little* light as possible."

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Neil Fraser: News: Entropy