Effective use of natural sunlight in a habitat.

On Jul 26, 2007, at 01:24 UTC, Dave Handwerk wrote:

> For electricity we will need first to generate it,
> then to transmit it (through wires) into our habitat,
> then finally to change it back into light. Admittedly
> it will be cheaper than on earth, probably about half
> as expensive, say $0.12/KW-hr. This should include
> the transmission wire. Next you have the light bulbs,
> and consider their initial costs, lifetime, and
> efficiency (relative to heat generated).

Just to be clear, you wouldn't be using actual light bulbs for this.
More likely you'd be using OLED panels, which last much longer, can be
tuned to emit just the frequencies needed, and generate almost no waste
heat.

> Now consider sun light: here we need to collect and
> concentrate it (probably with a mirror), then transmit
> it (either through a window and possibly several
> mirrors, or through fiber optical cables), (we may
> filter out certain parts, just as we can control the
> colors of the light bulbs). Finally we need to
> disperse it where needed, with a mirror or lens.

And you've left out the most expensive part: we need to then reject
(radiate) all the waste heat. Sunlight causes quite a lot of that;
plants (for example) can use only a small part of the spectrum, and the
rest gets converted to heat. Filtering isn't an answer, because most
filters work by absorbing the unwanted frequencies, converting them to
heat as well. Dichroic mirrors (which selectively reflect certain
frequencies) are possible but quite expensive.

Well, actually that's probably the second-most expensive part. A much
worse (but harder to quantify) cost is all the design compromises you
have to make in order to reflect or pipe light into a rotating habitat.
(Though granted, if you don't restrict yourself to *imaging* optics,
then this part gets quite a bit easier.)

Best,
- Joe

Joe Strout -- joe@...
Strout Custom Solutions, LLC