[ExI] Wash post comment

Keith Henson hkeithhenson at gmail.com
Tue May 8 04:38:52 UTC 2012

It's a shame the climate debate became so polarized.  No matter if
carbon contributes to some kind of climate change or not, energy *is*
getting more expensive.  Anyone who fills up at the pump should be
able to agree that we really need to bring energy cost down.

That really can't be done with fossil fuels.  What's left is under
deep water or otherwise expensive to get out.

Of all the possible sources of energy, solar is the best, but it's
awful dilute, intermittent and costs a lot to collect it.

That's not the case out in space.  The sun shines almost all the time
on geosynchronous orbit.  We could put very light power satellites out
there where they could collect a hundred times as much energy as the
same mass on Earth.  The problem is that even with lightweight
collectors it's too expensive to haul millions of tons to orbit.

There are two ways around this problem, get the materials from space,
or cut the cost of lifting parts from Earth.  In the end, we will use
parts made out of asteroids, but for the present, reducing the cost to
orbit looks like the shorter-term approach.

There does seem to be a way to do it, beamed energy propulsion.  That
uses lasers from high orbit heating hydrogen in teakettle rockets.
Because of the excellent performance of hot hydrogen as a reaction
mass, rockets using it can get 25% of their starting mass into orbit.
That's at least 5 times more than conventional rockets.

The result is electric power for half the cost of power from coal and
carbon neutral synthetic fuels for a dollar a gallon.  Google dollar a
gallon gasoline if you want the math details

The problem is getting the first propulsion lasers into space.  Even
though it will be very expensive and may require hundreds of
conventional rocket launches, the payback is so high that the entire
cost can be paid back from profits in three years.

My background is engineering, I can work out how it might be done and
how much it would cost, but raising the tens of billions needed for
the first propulsion laser is beyond me.

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