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Concentrated solar power, also called solar thermal, is a means of gathering solar energy distinct from the use of photovoltaic (PV) panels. Instead of directly converting solar energy to electricity, as in PV panels, concentrated solar power concentrates sunlight onto a relatively small point, which heats a medium. The heat from the medium is then either transferred directly to the target to be heated, such as a swimming pool, or connected to a generator for producing electric power.
Unlike commercial PV panels, which have an efficiency of about 17-19%, concentrated solar power efficiency ranges from 40-60%. There are three types of concentrated solar power devices -- low temperature devices (used to heat pools), medium-temperature devices (used to heat water for commercial or residential use), and high-temperature devices (used to generate electricity).
Concentrated solar power is cheaper than solar panels, as it primarily consists of mirrors to concentrate the sun's rays, rather than photovoltaics, an electronic system which requires high-purity silicon to produce. Both must regularly be cleaned, or they loose their energy-generating power.
In recent years, several large-scale concentrated solar power plants have been built. SEGS (Solar Energy Generating Systems), a solar thermal plant run by the Israeli company Solel, covers 1000 acres. The largest solar power plant of any kind, this plant produces 90% of all commercially available solar power -- 354 megawatts, about 1/6th of a major nuclear power plant, and about 1.5% of the Three Gorges Dam, the world's largest power plant of any kind. At the Solel plant, mirrors concentrate solar power onto tubes filled with oil, which are heated to generate electricity.
In 2006, about 21 million square feet of concentrated solar power systems were built in the United States, 16 million of it the low-temperature variety used to cheaply heat swimming pools. These use either warm water or air as a medium to transfer heat.
The term "concentrated solar power" is most often associated with high-temperature solar thermal collectors, such as those used in the Solel plant. These use steam or gas turbines to generate electricity from superheated fluid.
Frequently Asked Questions
What is Concentrated Solar Power (CSP)?
Concentrated Solar Power (CSP) systems generate electricity by using mirrors or lenses to concentrate a large area of sunlight onto a small area. The concentrated light is then used as heat, which can be converted into electricity through a steam turbine or heat engine driving a generator. CSP is distinct from photovoltaic solar power, which converts light directly into electricity without the heat stage.
How does CSP differ from traditional photovoltaic (PV) solar panels?
While both CSP and PV technologies harness solar energy, they operate differently. PV panels convert sunlight directly into electricity using the photovoltaic effect. In contrast, CSP uses mirrors or lenses to concentrate sunlight to heat a fluid, creating steam that drives a turbine connected to a generator. CSP is typically used for large-scale power plants, whereas PV can be used for both small-scale residential and large-scale applications.
What are the main types of CSP technologies?
There are four primary types of CSP technologies: parabolic troughs, which use curved mirrors to focus sunlight onto a receiver tube; central receivers or solar towers, where a field of mirrors concentrates light onto a central collector; linear Fresnel reflectors, which use flat or slightly curved mirrors; and parabolic dishes, which resemble satellite dishes and focus light onto a receiver at the dish's focal point.
What are the advantages of CSP over other forms of renewable energy?
CSP systems offer the ability to store thermal energy for power generation when sunlight is not available, providing a more consistent and controllable electricity supply. According to the International Renewable Energy Agency (IRENA), CSP with thermal storage can deliver power for up to 15 hours after sunset, enhancing grid stability and reducing the need for backup fossil fuel power plants.
Where are CSP plants usually located, and why?
CSP plants are typically located in areas with high solar irradiance, such as deserts. These locations receive a large amount of direct sunlight, which is necessary for the efficient operation of CSP systems. For instance, the Mojave Desert in the United States is home to several CSP plants due to its abundant sunshine and vast open land.
What is the future potential of CSP technology?
The future potential of CSP is significant, especially for regions with high solar resources. The cost of CSP is expected to continue to decrease as technology advances. The International Energy Agency (IEA) projects that with appropriate investment and policy support, CSP could meet up to 11% of global electricity demand by 2050, making it a key component in the transition to renewable energy.