Michael Ash <mike@[EMAIL PROTECTED]
> wrote:
>I mentioned a roof because it should scale horizontally to a basically
>infinite degree, and as a roof it doesn't have to be particularly tall.
>You'll need sup****ts at frequent intervals, of course, but that's
entirely
>doable. You may be able to piggyback on buildings and utility poles to
>some extent if you want to make it cheaper, but with enough money,
roofing
>a city with glass ought to be entirely feasible with current technology.
"Enough money", but what *would* the cost be? As an advocate of roofed
cities, I need to learn this.
Going with the heater approach: I see estimates of $10-20/foot2 for
heated driveways -- *not* including the cost of tearing up the ground
and putting it back. Also, I hate these units.
One square kilometer, 1e6 m2. 5000-25,000 people in urban environments.
Energy budget of 50 to 250 megawatts, though most of that is thermal.
Annual income of $150 to $750 million. (I picked $30,000/capita.)
Maybe 1-5% available for wacky projects, over 30 years, which washes
out.
Heated driveway installation: call it $200/m2, $200 million. OTOH those
are made to sup****t high energy rates; rather than building everywhere
and running at low power, we might build many fewer, and run those at
high power. Cost of $20-40 million, giving 50-100 Watts/m2.
Lightbulbs (or simple resistors) everywhere: Maybe $10/lamp, 1 lamp/m2,
$10 million?
Space heater: I see a $60 one claiming 1500 Watts. One of those per 15
m2, $4/m2, $4 million.
Operation: 100 W/m2, 100 megawatts. Kind of high, especially if
electric. Overkill? 8.8e8 kilowatt-hours, $88 million/year if
electric. I don't how much good 10 W/m2 would do.
Roofing: I see greenhouse cost estimates of $7.50/foot2, which I'll
consider a lower bound -- much lower, given the height needed for an
urban roof, though they may include equipment we don't need. 1/8 inch
plexiglass, Lexan, or glass seem to be about $4/foot2 -- don't know if 1/8
inch is thick enough! We need weather resistance. Anyway, we're
probably talking at least $100 million construction, but hopefully much
lower operation cost -- we're not aiming for some precise temperature,
just "warmer". Of course there's maintenance, and dealing with summer.
Conclusion: something's doable, with high densities or cheap energy.
-xx- Damien X-)
|
