Notes from Windward: #69
Solar Parabolic Trough
building the second half
The solar parabolic trough is crucial to the energy system being built
at Windward. The trough will concentrate sunlight (of which we have
plenty from spring to fall) on the boiler tube. The boiler tube will
have either water or heat transfer oil within, allowing for the heat
to be pumped away and used. Since I am also building the axial-flux
alternator, I know that part of this heat will convert water to steam
to run the steam engine which drives the alternator to make
We began setting up the solar boiler last fall. We put up the support
posts. The shipping container and posts are set up so that the boiler
runs east-west. This allows sunshine to fall from morning to evening
onto the reflecting parabola without having to adjust the angle of the
parabola during the day. The trough will need to be tilted as the
seasons progress, however. This could be accomplished using the
Butterfly control computer whose programming is still in the works.
Last year we built one half of the parabolic trough. We
call this skeleton the T-Rex, since it sort of looks like the ribs of
a giant dinosaur. Last December we were able to get another satellite
dish from our Goldendale connections (thanks, Pete!), so once the snow melted and it
got warm enough to work with metal, it was time to disassemble it in
preparation for making the second set of T-Rex ribs.
I started with half of the dish.
First I took it apart into quarters, and removed the metal screens.
Then I used a metal saw and a grinder to break apart the pieces to get
the metal curves I need to make the T-rex ribs.
Notes From Windward - Index - Vol. 69