The pulser pump is the simplest water powered device in the world. It has no moving parts to fail.
And the mechanical mathematician allows poor people with no great mathematical skills to easily make a parabolic solar cooker. (from mud as part of the walls of  their houses, or cardboard or other material.
The only outside input required is tinfoil or other reflective material.
Anybody who is willing the make either and publish their results is greatly appreciated.
Thank You Brian White

Check out this solar cooker link for the basic principles of solar cooker design:

http://www.solarcooking.org/sbcdes.htm ;

 I've never heard of the pulser pump before, but a quick search of the web turned up these two links:

http://www.earthtoys.com/emagazine.php?issue_number=03.10.01&;article=pulser 

http://members.tripod.com/~nxtwave/gaiatech/pulser/index.htm ;