You can see the line of mirrors lower in the photo as a blue line stretching across the view from left to right. The mirrors reflect the suns energy upward to the pipe at the top of the towers. That's why the tops are so lit up and bright. The pipe at the top contains liquid salt (I am guessing here) and the stored energy can drive steam turbines day and/or night.
Linear parabolics are more economical to build since you track the sun only on one axis. Heliostats track the sun in two axis, are more efficient from an energy in/energy out point, but are more expensive to build and maintain.
Engineer by necessity, weldor by choice.
On edit: Missouri Mule, I sometimes claim to be from Missouri. SHOW ME!