Concentrated Solar Power
Focusing the suns energy for large scale power generation
August 2009
Concentrated solar power (CSP) is a method of electric generation fueled by the heat of the sun, an endless source of
clean, free energy. Commercially viable and quickly expanding, this type of solar technology requires strong, direct solar
radiation and is primarily used as a large, centralized source of power for utilities. In contrast, photovoltaic cells are
effective in a wider range of regions and applications. CSP plants generate power best during the late afternoon
during peak demand and can displace the use of fossil fuel plants that emit the greenhouse gases that cause climate
change. As energy storage technology continues to advance, more CSP plants will be able to provide baseload power
throughout the night.
TECHNOLOGY
CSP, also called solar thermal power, uses mirrors to focus sunlight onto a heat transfer medium. The steam produced
from the heat transfer medium powers a turbine or engine that generates electricity.
Depending on the type, CSP
plants can supply up to 100 megawatts (MW) with a potential to produce up to 300 MW, on par with other utility scale
power plants.
Effective CSP requires solar radiation of at least 5.5 kWh/m2/day California averages 6.75 8.25
kWh/m2/day1 and functions best in arid, flat locations. The U.S. Southwest, Sahara Desert, and Australia have the
highest potential capacity for CSP in the world.2
TYPES OF CSP SYSTEMS
Parabolic Trough: Long, curved mirrors pivot to concentrate sunlight onto
tubes filled with a heat transfer fluid, generally oil or water, whose steam
moves a power generating turbine. These systems are the most developed
CSP technology and have operated in the United States since the 1980s.
Optimal capacity size is 150 250 MW enough to power 44,000 homes
although 80 MW is the largest plant size today. Alternately, one U.S. company,
Sopogy Inc., has created a Micro CSP system that uses a scaled down
parabolic trough system for distributed generation o