What is the effectiveness of the production of electric energy by the evaporation of water using the sun (Solar Tower)?

What do you mean by effectiveness? Do you mean efficiency? Are you looking for a yearly energy production rate (capacity factor)? In which area? What material for the mirrors and receiver? Is there storage available as well? which technology of storage? There is a lot involved but in general solar to electric efficiencies can't go above 20%. There are losses everywhere: collector, receiver, storage, turbine, generator, etc. I suggest you reading the following report by NREL:http://www.nrel.gov/docs/fy04osti/34440.pdf