[ExI] ?Existential hysteria (John Clark)

Keith Henson hkeithhenson at gmail.com
Thu Jul 31 17:35:30 UTC 2014

On Thu, Jul 31, 2014 at 5:00 AM,  John Clark <johnkclark at gmail.com> wrote:


> Myhrvold wasn't suggesting anything as ambitious as a space elevator, just
> a light hose about 2 inches in diameter going up about 18 miles. In one
> design he burns sulfur to make sulfur dioxide, he then liquefies it and
> injects it into the stratosphere with a hose supported every 500 to 1000
> feet with helium balloons.

I sat through a detailed presentation by Greg Benford on the
engineering details in 2009, same meeting where I gave my first talk
on power satellites as a solution to carbon, climate, etc.

Liquid SO2 is 1.437 times as dense as water.  18 miles would be about
the same as a 26 mile deep ocean.  That's around 3.8 times the depth
of the deepest place in the ocean.  The SO2 has to be pumped up in
stages, a lot of them.  The design of the hose, the pumps, the
supporting balloons and powering the pumps is not a trivial task.  I
worked on a much less daunting 20 km StratoSolar design, this is
almost 29 km.

> Myhrvold thinks this design would cost about 150
> million dollars to build and about 100 million a year to operate. In
> another design that would probably be even cheaper he just slips a sleeve
> over the smokestack of any existing small to midsize coal power plant in
> the higher latitudes and uses the hot exhaust to fill hot air balloons to
> support the hose.

Hot air for this use is not reasonable engineering.  How do you keep
them hot?  Benford didn't mention it.  I have a hard time imagining
that Myhravold would propose something with that big a hole in it.  Do
you have a pointer to his proposal?


> As I said the facts are that China isn't going to be any more receptive to
> the idea of abandoning coal than we in the west would have been a few
> decades ago UNLESS there is a energy source that is cheaper than coal. I
> think Thorium may be that source, I am certain that solar is not.

I agree with you on the need for cheaper, and thorium might do the
job.  The most optimistic number I have seen for ground or even
StratoSolar in future decades is about 8 cents per kWh, more than
twice as much as coal.  On the other hand, have you not paid any
attention to my talking about space based solar for the last several
years?  If it is worth doing at all, the eventual cost needs to get
down around 2-3 cents per kWh.  That takes cheap transport to GEO.

The artwork on Google drive shows a Skylon cargo container being added
to a second stage.  The second slide shows the cargo under way using
VASIMR engines making the purple glow.  The engines are powered by
microwave from the ground.



The method looks like it will get solar power from space down well
under the cost of power from coal.


More information about the extropy-chat mailing list