Concentrating Solar Power Technologies Overview

Concentrating solar power (CSP) uses arrays of mirrors to generate large amounts of heat from concentrated sunlight. The heat is then used in a conventional power cycle or other heat engine to produce mechanical power that drives an electrical generator.  The heat can also be efficiently and cheaply stored to produce electricity when the sun is not shining.  Typically, CSP power plants generate large amounts of power (hundreds of megawatts) for utility-scale applications.

CSP has three generic system architectures: line-focus (trough and continuous linear Fresnel reflector [CLFR] systems), point-focus central receivers (power towers), and point-focus distributed receiver (parabolic dish-engine systems). These three approaches are shown schematically and described in more detail below.

• Linear Concentrators
• Point-Focus Central Receiver
• Point-Focus Distributed Receiver

Linear Concentrators

The sun’s energy is concentrated on an fluid-filled tube (current operators usually use a synthetic oil) running along the focal line of the parabolically shaped trough.

• Parabolic 2-D shape or linear Fresnel approximation
• Tracks East to West
• Focal length:  approximately 3 m
• Concentration factor:  approximately 30 to 40

Point-Focus Central Receiver

Large sun-tracking mirrors, called heliostats, focus the sun’s energy on a receiver located atop a tall tower.

• Parabolic 3-D shape
• Heliostats track in azimuth and elevation
• Focal length:  100s of meters
• Concentration factor:  approximately 800

Point-Focus Distributed Receiver

The sun’s energy is concentrated on a receiver and generator located at the focal point of the parabolic dish.

• Parabolic 3-D shape
• Tracks on sun in azimuth and elevation
• Focal length:  approximately 4 m
• Concentration factor:  3000