Archive for the ‘military’ Category

Space-based Solar Power or Dyson Specks
2009.09.23

There has been a bit of buzz around space-based solar power (SBSP) and when a friend chatted me up about it today, I decided to organize my opinions about the technology and share them here.  SBSP is not a new idea.  They amount to the smallest useful Dyson Sphere.  SBSP is ugly so I’ll rename them Dyson Specks for the remainder of this essay.

The idea, as you can read in more detail from the links, is that a geostationary satellite captures some energy from the sun and beams it down to earth where collectors gather it and convert it to electricity.  Sustainable, carbon neutral, green energy.  A veritable panacea and a damn sexy concept for anyone who’s ever turned their eyes skyward in wonder.

As a bit of an aside, the media coverage mentions “beam” and “microwave” when it concerns getting the energy to the ground.  I will call this “beam” what it is by referring to it as a “laser” from here forward.

Other articles discuss the engineering difficulties so I’ll ignore them here.  Let’s take a flight of fancy and say we can wave a magic wand and construct our Dyson Speck out of thin air.  What do we now have?  We have a pretty stellar (sorry) source of energy.  But there are side effects I haven’t heard mentioned yet.  I’ve heard that the laser could be some 10 km in diameter when it gets to the surface of the ground.  So we have a 10+ km diameter section of the earth permanently dedicated to receiving this energy safely.  This is not an insignificant alteration of the biosphere.

We also have a column of air 10 km in diameter and 120 km high that will be continuously heated by this microwave laser.  That’s a lot of air.  We may not be producing greenhouse gases anymore but now we’re heating the atmosphere directly with bonus solar radiation that would have otherwise sped out to the cosmos.  We’ve effectively increased the surface area of the earth.  This sounds like a great recipe for global warming to me.  If this technology becomes popular and we someday have 1000 of these satellites powering population centers all around the globe, how many watts of power will we be feeding directly into the atmosphere and what effect will that have on surface and ocean temperatures?  What about the impact on weather patterns?  One small benefit, I suppose would be the surreal and beautiful photos of the way these lasers would perforate clouds and otherwise manipulate atmospheric moisture.  But at what cost?

In order to keep the solar panels pointed at the sun, the satellite will have to expend a fair amount of energy to remain in position.  It will have to have fairly powerful propulsion to achieve this.  This subtle artifact leads me to my biggest concern about Dyson Specks.  The powerful propulsion mechanism required to keep the laser focused on the right spot while keeping the arrays pointed at the sun will make retargeting the laser swift and accurate.  What if the laser were fitted with a lens or mirror that it could use to focus its laser to, say 10 meters wide.  Now we have a weapon of mass destruction that can quickly target any point on half the globe with a push of a button.

The military says they are interested in this technology for providing power to tactical field operations, and I’m sure that is part of their motivation, but I think this is Strategic Defense Initiative (aka Star Wars) Redux.  What better way is there to furtively reinstate a controversial program than to greenwash it?

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