[ExI] Forbes posting

Keith Henson hkeithhenson at gmail.com
Sat Dec 1 00:16:09 UTC 2012


I am a bit annoyed that nobody seems to be asking the engineers how to
solve the problem.  It's not like we lack for clean energy; the Earth
intercepts only around 1 part in a billion of the Sun's output.

Take solar power satellites for example.  Been understood for over 40
years, the only reason they have not been built is that the cost to
lift parts to GEO is too high by a factor of about 100.

So if you want to consider them, then the question to ask the
engineers is how to get the cost of lifting millions of tons of parts
to GEO to $100/kg instead of $10,000/kg.

It looks like one way is to bootstrapping by building one power
satellite with conventional rockets and using it to power propulsion
lasers.  Because they give much higher exhaust velocity, rockets or
rocket planes powered this way get at least 5 times as much cargo into
orbit as the best chemical rockets.

At a scale large enough to be useful, 500,000 tons per year, the cost
goes to well under $100/kg, the cost of power plants to $1600/kW and
the cost of power to 2 cents per kWh or less.  Power that inexpensive
can be used to make synthetic carbon neutral fuel in any amounts for
around a dollar a gallon.

If we went this way it would take less than 20 years to end the use of
fossil fuel, not by high taxes or carbon credits, but just by making
synthetic fuel cheaper than fossil fuel.  The oil companies (Exxon for
example) already know how to do this.

But it's more likely the Chinese will do it.  About three years ago a
major meeting in China concluded they didn't know how to lift the
parts to orbit at a price that made any sense.  Three weeks ago they
announced a deal to build power satellites with India.  (Google China
India power satellites.)  What happened and why?  Did they figure out
this obvious approach?  Are they trying to get support from India when
the US freaks out about big lasers in orbit?  (They are also weapons.)

It may be that the entire issue of climate change becomes moot before
the next one of these meeting.

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