[ExI] 10 mega construction projects that could save the environment and the economy

[Keith Henson]

On Sat, Dec 3, 2011 at 5:00 AM,  Anders Sandberg <anders at aleph.se> wrote:

snip
>
> Space elevator: This is what we ought to start working on the minute we
> have figured out fullerene cabling. But it is one of those high
> threshold projects with pretty annoying failure modes.

At least we know that single walled nanotubes won't do it.  At at
tension short of what is needed, they become unstable with 6 member
rings becoming 5 and 7 member rings and the nanotube parts like a
stocking with a run in it.  Sorry.

Space elevators are still useful in setting the minimum energy standard to GEO.

A 60 ton per hour transport rate need about a GW to power a loop
cable.  Using climbers powered with a laser, the input would be at
least 10 times that high what with conversions and the need to lift
dead weight (PV cells and motors).  Using the same lasers and reaction
engines using hydrogen will probably lift the same mass without the
failure modes.

> Lunar ring: Let's do this once we have the space elevator in place. And
> a treaty that ensures that nobody uses the moon as a phased array maser.

Lunar ring is a variation on space based solar power, usually based in
GEO.  I see it as a factor of ten more expensive per kW, but have
never actually done the numbers and have never seen anywhere where
they have been done.

Keith