SBIR-STTR Award

Stretched membrane mirror structures are under development as a potential significant improvement for solar concentrator mirrors for heliostats and dishes. The planned multibar rim drive concept is a similar potential improvement for supporting and steering these mirror structures. The drive concept could be incorporated into the present generation of heliostat designs; however, it is expected that it would be more beneficial when used with the stretched membrane structural concept. The primary improvement is that it carries the loads directly from the rim to multiple points on the ground, thus eliminating the need to carry the loads back to a center post. In addition the multibar concept allows the mirror to be stowed in a face-down position, which may prove mandatory to protect the thin membrane reflective surface from hail.Anticipated Results/Potential Commercial Applications as described by the awarded:Development of the multibar rim drive should result in significant structural weight reduction and corresponding cost savings for stretched membrane heliostat solar collectors. These improvements should contribute to the implementation of membrane heliostats.

Phase II will continue development of the multibar heliostat rim drive mechanism that was successfully demonstrated in Phase I. The program consists of the following major objectives: (1) develop a structural and mechanical design for an optimally sized membrane heliostat incorporating the multibar rim drive concept, (2) perform collector system integration studies to assure the applicability of the heliostat to commercial solar central receiver projects, (3) derive cost data for economic evaluation of the concept, and (4) design and fabricate a 26 ft (7.9 m) diameter prototype heliostat to evaluate and demonstrate the concept. The multibar drive supports the mirror module at the rim and carries wind and gravity loads directly to the ground through a series of linkages. In addition, the drive allows the mirror module to be stowed in a face-down position close to the ground. In conjunction with stretched membrane solar concentrators, the multibar rim drive holds the potential to reduce the cost of central receiver solar power systems significantly. This cost reduction is accomplished by more efficient use of structural materials, elimination of expensive gear systems, and by taking full advantage of the unique characteristics of stretched membrane mirror modules.Anticipated Results/Potential Commercial Applications as described by the awardee: This project will result in a fully-integrated, low-cost, light-weight, stretched-membrane heliostat. This heliostat will be marketed for commercial solar power generation and process heat applications to utility companies as well as to industrial energy consumers. Topic 22: Solar Thermal Technology