Concentrating Solar Power

Power Tower

Power tower technology is considered to be at medium maturity within concentrated solar power technology. The first commercial power tower plant using power tower technology was installed by Abengoa Solar and it is successfully celebrating its 2 years in operation.
The second generation, Abengoa Solar-built, like the first, recently began operational start-up, and the third is based on the technology used in high-temperature demonstration plants.

Introduction to Technology

On tower systems, a heliostat field comprised of movable mirrors, is oriented according to the solar position in order to reflect the solar radiation concentrating it up to 600 times on a receptor located on the upper part of the tower. This heat is transferred to a fluid with the purpose of generating steam that expands on a turbine that is coupled to a generator to produce electricity.

Operating Scheme for tower technology

Tower technology operation is based on three main features: heliostats, receptor, and tower.

Heliostats have the function to capture solar radiation and direct it to the receiver. They are composed of a reflective surface, a supporting structure and mechanisms used to orientate them, following the sun’s movement (which involves the necessary systems for the heliostat movement as well as control systems). The most used reflective surfaces today are glass mirrors.
- Heliostat Sanlucar 120
- Heliostat Sanlucar 90
The receiver which transfers received heat to an operating fluid (which could be water, molten salts, etc.). This fluid is in charge of transmitting hear to other parts of the C.S.P. plant, generally to a water deposit, obtaining high temperature steam to produce electricity through the action of a turbine.
Latest advances and research are centered to obtain high temperature towers, with heat transporting fluids, such as air, salts, etc.
The tower acts as support for the receiver which should be located at a certain height above the heliostats level to avoid, or at least reduce, shades and blockings.

PS20, Eureka ( hight temperature
tower) and PS10.

Today, the first and second commercial solar power tower are in operation at the Solucar Platform. Abengoa Solar is committed to technology having research teams focused on tower technology.

At Abengoa Solar, is committed to technology having research teams focused on tower technology.

For more information, please download our Tower Technology White-paper

High Temperatures, Good Yield

The high temperatures that could be obtained with this technology (over 1832 º F [1000ºC]) allow to aim to higher yields on electricity generation, even above 25% on the transformation of solar radiation into electricity.

Hybridation and Storages

When using tower technology, energy storage could be added. As from such storage, the system could provide energy, even in cloudy conditions or at night. Today, the most used solution is the usage of water/steam or molten salt storage tank that stores energy to be then distributed. Consequently, the plant needs to be over-dimensioned.

Another application used on tower technology is hybridation.

Requirements

To install tower technology plants, there are certain requirements, such as:

Climate (DNI). The economic viability of a solar thermal project is directly dependent on the direct solar irradiation values recorded annually in the location under consideration for implementation.
Orography: A surface area with favourable orography facilitates the work involved in construction and maintenance of the solar field. Tower plants can in any case adapt to land diverse in orography, ranging from certain undulations in the area for implementation, as in the case of PS20, to include land characterized by more complex orography, which may involve valley slopes for positioning solar fields if they suitably face the south in latitudes in the Northern Hemisphere.
Availability of electrical power grid connection.


PS10 Tower	PS10 Aerial View

Land requirement for 20 MW Plants

The following table shows the total surface needed to construct an installation. Besides area data needed (acres - hectares), width (x en ft) and length (y in ft) of the rectangular area.