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 electricity.


     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