Technologies

Offices, plants and installations

Concentrated Solar Power

Power Tower

Power tower technology is considered to be in a médium maturity within concentrated solar power technology. The first tower generation has been installed by Abengoa Solar and is celebrating these days its first 4 months in operation successfully.
The second tower generation is currently under construction and the third is based on the technology used on the high temperature demonstration plant.

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.

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.

The first commercial tower of the world is PS10, of Abengoa Solar. Today, a second tower - PS20 – is under construction. 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:

• Topography: the site needs to be level
• Irradiation: the direct normal insolation (DNI) should be a high as possible
• Water Availability: water is needed for cooling in the power block
• Electric Transmission: electric lines and transmission capacity are needed to convey solar power from the plant to the consumer

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.

20 MW	Basic Tower
Land requirement *	235 acres= y=3300m x=3100 ft

* For radiation conditions of 2120 kWh/m²year

Links

Download our White Paper on Tower Technology