[tt] Fwd: [Solar Power Satellite Place] 'Drilling Up' into Space for Energy

[Eugen Leitl]

On Tue, Dec 25, 2007 at 10:27:50AM -0600, Bryan Bishop wrote:

> : While great nations fretted over coal, oil and global warming,
> : one of the smallest at the U.N. climate conference was looking
> : toward the heavens for its energy. 

Rather insane, for a small nation.
 
> : Unlike other ideas, however, one this year had an influential
> : backer, the Pentagon, which is investigating whether
> : space-based solar power — beaming energy down from satellites
> : — will provide "affordable, clean, safe, reliable, sustainable
> : and expandable energy for mankind."

Of course, the real motivation is to beam power down upon battlefield,
whenever it might be. Wonder how they want to restrict usage just
to the friendlies, though.
 
> : It could be done with today's technology, experts say. But
> : the prohibitive cost of lifting thousands of tons of equipment
> : into space makes it uneconomical.

Meanwhile, Nanosolar currently claims 0.30 US$/Watt of panel in production.
 
> : That's where Palau, a scattering of islands and
> : 20,000 islanders, comes in.

Even more nuts, they're pretty close to the equator. Insolation should
not be a problem, and they certainly don't need a lot of energy, and
most of it during daytime anyway.
 
> : In September, American entrepreneur Kevin Reed proposed at the
> : 58th International Astronautical Congress in Hyderabad, India,
> : that Palau's uninhabited Helen Island would be an ideal spot
> : for a small demonstration project, a 260-foot-diameter
> : "rectifying antenna," or rectenna, to take in 1 megawatt of

Measly one MW at that. Pathetic.

> : power transmitted earthward by a satellite orbiting 300 miles
> : above Earth.
> 
> : Low-orbiting satellites, as proposed for Palau, would pass over
> : once every 90 minutes or so, transmitting power to a rectenna for
> : perhaps five minutes, requiring long-term battery storage or

Yes, you need quite a lot of them birds. But they would provide global
coverage then. Rectennas are pretty cheap in comparison. But, solar
cells are their own receptacle, and in theory rectenna approach would
work for the solar spectrum too, at quantitative efficiencies.

> : immediate use — for example, in recharging electric automobiles via
> : built-in rectennas.

Wow, the first plan involving a LEO bird constellation. Maybe these 
people are not complete idiots.
 
> : Most studies have focused instead on geostationary satellites,
> : those whose orbit 22,300 miles above the Earth keeps them over a
> : single location, to which they would transmit a continuous flow of
> : power.
> 
> : "You just have to find a way to make it cost-effective." 

Captain Obvious strikes again! It's completely trivial, just reduce
the cost of putting mass into LEO by 1-2 orders of magnitude. A child
of five could do it. It's, like, nobody's been trying for the last
half century.
 
> : The panel's 2007 reports didn't address space power's potential,
> : Schock explained, because his team's time horizon didn't extend
> : beyond 2030. But, he said, "I wouldn't be surprised at the
> : beginning of the next century to see significant power utilized on
> : Earth from space — and maybe sooner."

If power is sufficiently cheap, then costs and overall cycle efficiencies
to cover nocturnal usage lose their sting. Fuel cells for hydrogen are
now almost platinum metal group free (nickel is almost enough).

-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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