Ben Bova's SPS cost claim (was An Energy Fix Written in the Stars)

> Ben Bova, to the Washington Post, writes:
>
> > a single SPS could deliver five to 10 gigawatts of energy
> > to the ground continually. Consider that the total
> > electrical-generation capacity of the entire state of
> > California is 4.4 gigawatts.
>
> That (4.4 gigawatts) would be merely the nuclear portion (two reactor
> units at Diablo Canyon, and two reactor units at San Onofre (SONGS)).
> California's total electrical generating capacity is 53 gigawatts.
> http://www.world-nuclear.org/info/inf65.html

One should always be suspicious of quotations taken out of context. Though
he does seem to have dropped the ball on the 4.4GW thing. The full article:
http://www.washingtonpost.com/wp-dyn/content/article/2008/10/10/AR2008101002
450.html

> > I admit, solar power satellites won't be cheap. Constructing
> > one would cost about as much as building a nuclear power
> > plant: on the order of $1 billion.
>
> $1/watt? Is that right? Did the ISS array also cost $1/watt?

But ignorant strawman questions add nothing to the debate. Note for example
that Mr Bova does not specify the power output of his proposed SPS. Nor does
he state what assumptions he is making as to production run length and
non-recurring costs. It's also possible Mr Bova was purely refering purely
to assembally costs, and ignoring launch and material costs, which would
have been a little naught of him.

Mentioning the ISS was (in my opinion) another mistake Mr Bova made, as it
draws attention to NASA's political, managerial, engineering, and financial
incompetence. For example NASA is also famous for spending a hundred
thousand dollars on a hammer. That doesn't prove it's impossible to buy a
hammer at a lower price. Yet the majority of people, dispite all common
sense to the contrary, will assume that it *does* mean precisely that.

My past calculations lead me to believe that a 10GW SPS would cost $70B;
ignoring non-recurring costs. The average nuke produces 1GW of power, so
let's say $10B. Some things will not scale down. That assumes that
everything is launched from earth at a reasonable estimated (and industry
supported) RLV cost of $500/kg, and NASA's baseline 10,000tons per GW
estimate from two decades ago. If we instead assume that the material comes
from the moon, we can probably cut that estimate in half, down to $3B.
Again, some parts will have to be made on Earth. If we assume a modest x10
solar concentration design, with simple heat pipe cooling, we can efectively
eleminate 80% of the weight, and cost, and it comes down to (oh look) less
than $1B.