Artificial lighting, huh?

WHOEVER IS SENDING US MESSAGES PLEASE STOP

Joe Strout wrote: On Feb 11, 2008, at 2:20 PM, Combs, Mike wrote:

> I wouldn't worry about the labor so much as the expense. As soon as
> these 600x600dpi displays become as cheap as aluminized Mylar and
> glass
> on a square meter basis, I'll take this idea as seriously as the
> original proposal. Even a modest cost difference on a square meter
> basis would add up to an enormous cost difference when talking about a
> square kilometer of surface area.
>
Right. Of course in the case of natural lighting, it's not just the
cost of the Mylar and glass that matters; it's also all the costs
that result from adopting this (rather severe) design constraint on
the geometry of your habitat. Those are harder to compare directly,
but no less real.
> The other main issue is, even if we assume 40% or 50% efficiency solar
> cells, what is the efficiency of these LEDs? If we start out with
> light
> and want to end up with light, not having to go through intermediate
> conversion steps is the same as 100% efficiency.
>
Well, you have a good point, and LEDs are not currently the most
efficient form of lighting (the best is sulfur discharge lamps, at
55%, or at least was when I last looked into this a couple years
ago). However, mirrors and windows aren't 100% efficient either;
some light is absorbed or scattered in useless directions. Fiber
optics would be even worse. The efficiency is still probably much
higher than a solar-electric light system, of course.

Best,
- Joe