[ExI] Millions of tons to space

[Keith Henson]

On Tue, Mar 29, 2011 at 5:00 AM,  Stefano Vaj <stefano.vaj at gmail.com> wrote:
>
> On 27 March 2011 21:18, Keith Henson <hkeithhenson at gmail.com> wrote:

snip

>> A power satellite project of significant size (enough to make a
>> difference in world energy) requires at least a million tons per year
>> lifted to GEO.
>
> My (unrhetorical) question is: once you have bootstrapped space-based
> solar power can you make use of its proceeds to maintain it?

The single biggest cost item is the lasers, for a million tons per
year it takes 6 GW at $10 per watt or $60 B.  The peak investment
might be around $100 B.  If you start with something like a Skylon, as
you add laser power the payload fraction goes up and the cost per kg
goes down.  I have not put this into a detailed business model yet.
The initial target would be a production rate of 200 GW per year,
worth at least $320 B per year.

At $100 per kg, the cost to run the transport system is $100 B per
year.  This produces 40 5 GW power sats at $1.6 B per GW.  Paying they
off over 10 years gives you a cost of 2 cents per kWh.  At this price
the demand for power is so high (much of it would be used to make
synthetic gasoline) that the production at this or a higher rated goes
on for several decades.

> And if yes, would a series of Project Orion launches (the
> effectiveness of which I understand actually to increase with the
> scale of the launch...) enough to bootstrap it?

Sorry, no.  You need a continuous flow of materials, not a one shot or
a small number of launches.  We are talking about at least 4 flights
per hour for decades.

Keith