I would have to agree steam is how almost all electrical energy is produced today however I would make it a hybrid of several type of boilers the fresnel is nice but a standers fire belly works forever cloudds or not . the real issue is going to be storage how do we keep the power going long after the suns gone down or a week of cloudy if no one stokes the belly.
as a design of the city having steam ducted below the surface to heat the homes in winter or to turn the massive amount of compresors in summer depending on the climate would be nice all the systems integrated to avoid wasting any valuable energy the final outlets for the ducted steam would be into the greenhouse/garden areas for the tropical species plants.
I propose a pulse dc power grid high frequency dc pulses alternating polarity should serve to deliver maximum power at lowest drain to the batteries, this should serve all our lighting and general needs only a few things may need a something different like things with sensitive timer chips and such. as a side note the steam generator can also be used to purify the water for drinking and use the stored potential energy of a column of water for backup power.
