[ExI] Comment for Scientific American

Dan TheBookMan danust2012 at gmail.com
Mon Oct 5 20:47:56 UTC 2015

On Mon, Oct 5, 2015 at 12:57 PM, Keith Henson <hkeithhenson at gmail.com>

> On Mon, Oct 5, 2015 at 5:00 AM,  John Clark <johnkclark at gmail.com> wrote:
> > I don't see solar power satellites providing energy cheaper than fossil
> > fuel anytime in the immediate future, to me even terrestrial solar and
> wind
> > seem too dilute and intermittent to compete with coal economically.
> The dilute factor isn't as much of a problem in space where you don't
> have to support the concentrating surface against gravity and wind.

For sure. It's not the right comparison to make.

> But if power satellites can't proved energy cheaper than any other
> source (except hydro which limited) then they just won't happen.

The big problem with power sats for now is the huge initial investment. I
think if and as launch capabilities expand, prices go down, and extraction
of ET mineral resources occurs, this will change. But it doesn't seem like
that it [power sats] will be a game-changer for more than a decade.

> > The only fuels I can think of that
> > have a chance to beat coal in both the short term and the long are
> Uranium
> > and Thorium. In the case of Thorium by long term I mean billions of
> years,
> I am slightly curious how you computed this.  Even without growth, I
> have never seen estimates for how long thorium will last that exceed a
> few centuries.
> Not that it makes a lot of difference.  Whatever we turn into over the
> next 5-10 decades can solve their own problems.

If that's your horizon, to my non-expert eye, power sats look like a good


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