3D model of the AT solar power tower 1A. The solar power tower is placed in a pit in the soil so as to take advantage of the increased insulation provided by the soil. A reflective surface is added (ie thin metal surface) to redirect any sunlight falling into the pit towards the pyramid. Additional sunlight can be provided to the pyramid by means of heliostats (placed on buildings). The inside of the pyramid is filled with water, which is transformed to steam due to the heating. This steam in turn is used to drive a piston which generates electricity. The AT solar power tower also functions as a mere water heater aswell, providing hot water for several buildings around town. A (seperated) water ring serves as a water store for incoming (cold) and outgoing (hot) water. Cold water comes in from the right half of the ring, hot water goes out the left side. On the left, there is also a condensor hooked up to a pipe that conducts excess steam (valve is opened when there is overpressure). The pyramid is also made directional, so it must be oriented towards the south (in areas in the northern hemisphere) or towards the north (in areas in the southern hemisphere). See the 'Purchasing_the_models' link at appropedia's AT_CAD_Team for additional information on the model