Jim Clair - Academia.edu (original) (raw)

Papers by Jim Clair

SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems

CSP Ganged Heliostat Technologies Investigations in a Tensile Based Non-imaging System Abstract: ... more CSP Ganged Heliostat Technologies
Investigations in a Tensile Based Non-imaging System
Abstract:
Background
Concentrating Solar Power (CSP) and specifically Power Tower or Beam Down type systems achieve high levels of solar concentration and efficiency. Collecting fields comprise a large fraction of the system installation and maintenance costs. Technological advances promise economically competitive solar power. Skysun, LLC proposes a ganged heliostat to significantly reduce these costs.
Method
Typically, a heliostat requires one each of the following: mirror module, support structure, dual axis drive, post/pedestal and foundation. Each of Skysun, LLC’s heliostats require: mirror module, reduced support structure and a single axis drive, eliminating the need for a pedestal and foundation for each heliostat. The ganged heliostat consists of two cables supporting a plurality of single-axis actuated heliostats. The cables act both as a supporting structure and as a translator of focusing motions to the many heliostats. The cables terminate to an actuated rotational member supported by a substantial post. Cable tension may be variable. This configuration reduces the ratio of posts and foundations to heliostats, and eliminates dual axis drive actuators, substituting single axis actuators instead. The ganged heliostat may be rotated to the vertical for ease of robotic cleaning and water reclamation. The ganged heliostat may also be inverted, with the reflective surface downward, to protect against weather events such as hail. Finally, the ganged heliostat may be secured to protect against high wind conditions.
The reflective surface, which can be deformed by cable and heliostat orientation, provides an efficient means to form a large concave collecting surface laying principally in the horizontal. Reflected incident rays, being non-normal, suffer from astigmatism. Novel deformations of the reflective surface eliminate astigmatic aberration. A toric - shaped deformation of the reflective surface reduces the size of a chosen astigmatic focus, yielding higher concentration. Latitudinal and longitudinal deformations maintain focus upon a fixed receiver. In the ideal, the astigmatic focus is reduced to a point.
Conclusion
The goal of this paper is to outline the relatively inexpensive methods utilized by Skysun’s ganged heliostat prototype and how the methodology may be scaled up. Skysun, LLC proposes a ganged heliostat to significantly reduce collecting field costs to $75/m2 installed.
Key words: solar concentrating CSP Power Tower Beam Down heliostat astigmatism deformation ganged

SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems

CSP Ganged Heliostat Technologies Investigations in a Tensile Based Non-imaging System Abstract: ... more CSP Ganged Heliostat Technologies
Investigations in a Tensile Based Non-imaging System
Abstract:
Background
Concentrating Solar Power (CSP) and specifically Power Tower or Beam Down type systems achieve high levels of solar concentration and efficiency. Collecting fields comprise a large fraction of the system installation and maintenance costs. Technological advances promise economically competitive solar power. Skysun, LLC proposes a ganged heliostat to significantly reduce these costs.
Method
Typically, a heliostat requires one each of the following: mirror module, support structure, dual axis drive, post/pedestal and foundation. Each of Skysun, LLC’s heliostats require: mirror module, reduced support structure and a single axis drive, eliminating the need for a pedestal and foundation for each heliostat. The ganged heliostat consists of two cables supporting a plurality of single-axis actuated heliostats. The cables act both as a supporting structure and as a translator of focusing motions to the many heliostats. The cables terminate to an actuated rotational member supported by a substantial post. Cable tension may be variable. This configuration reduces the ratio of posts and foundations to heliostats, and eliminates dual axis drive actuators, substituting single axis actuators instead. The ganged heliostat may be rotated to the vertical for ease of robotic cleaning and water reclamation. The ganged heliostat may also be inverted, with the reflective surface downward, to protect against weather events such as hail. Finally, the ganged heliostat may be secured to protect against high wind conditions.
The reflective surface, which can be deformed by cable and heliostat orientation, provides an efficient means to form a large concave collecting surface laying principally in the horizontal. Reflected incident rays, being non-normal, suffer from astigmatism. Novel deformations of the reflective surface eliminate astigmatic aberration. A toric - shaped deformation of the reflective surface reduces the size of a chosen astigmatic focus, yielding higher concentration. Latitudinal and longitudinal deformations maintain focus upon a fixed receiver. In the ideal, the astigmatic focus is reduced to a point.
Conclusion
The goal of this paper is to outline the relatively inexpensive methods utilized by Skysun’s ganged heliostat prototype and how the methodology may be scaled up. Skysun, LLC proposes a ganged heliostat to significantly reduce collecting field costs to $75/m2 installed.
Key words: solar concentrating CSP Power Tower Beam Down heliostat astigmatism deformation ganged