Parabolic Mirror to capture the Suns heat,
this heat would be MUCH higher than Passive Solar Heating for houses,
the soil would be absorbing 100c ...

from there you could go one of two directions ....
1. use a Lower Boiling Temp. liquid (ammonia?)
or 2. increase the Temp. further ... a Higher Boiling Temp. liquid or
somehow a Parabolic Mirror... ???

BUT it has been proven that you CAN store Heat in the soil IF it is
Insulated and Waterproofed, ... then it could store Temps. in excess
of 100c .... which then opens up the possibilities of using the heat
to generate electricty .....