Re: StratoSolar

Keith Henson wrote:
> StratoSolar
> 
> This is off NDA so I can go into detail.
...
 > Ed's
> approach, which he named StratoSolar, was to reduce the mass from
> hundreds of kg per kW to a few tens of kg by moving the solar
> concentrator into the stratosphere as a large, lightweight, buoyant
> structure.
...
> The concentrated sunlight gets to the ground via a hollow light pipe
> lined with highly reflective prismatic plastic.  Preliminary
> optimization for kg/kW leads to a 30-meter diameter light pipe with
> less than 10% loss.  A larger pipe has lower losses but uses more
> total material per kW.

Keith--

Hi.  StratoSolar is interesting.  I looked at the website
when you mentioned it a month ago.  At the time, this
was my main objection:

> I see bigger problems with losses in the light pipe.
> The plan seems to be to have a flexible tube lined
> with reflective material to guide the solar radiation
> down to steam turbines or whatever on the ground.
> Most of the light would have to reflect off the sides
> many times, losing at least a few percent of its
> intensity at each reflection.  So nothing makes it
> to the ground, and the light pipe melts.  There may
> be solutions to this too, but they're going to be
> tricky. 

How many reflections are you assuming light will make
as it goes down the pipe, and how glancing are they?

				---David