Using Highly Concentrated Sunlight in Space

The techniques of nonimaging optics are particularly valuable in space or lunar environments in which the use of solar thermal energy has obvious advantages. Earlier preliminary studies have ex­plored this concept for the production of cement from lunar regolith and for solar thermal propulsion in space. For example, extremely high temperatures, in the range of 1700-1900 °C, are necessary for the production of cement from lunar minerals. Such temperatures will in turn require very high levels of solar flux concentration. Energy budgets for the support of permanent manned operations on the lunar surface are expected to be limited. For high-temperature thermal (i. e., >300 °C) end uses, direct solar energy has obvious advantages over most other practical power sources. Conventional combus­tion processes are clearly impractical, and conversion of electricity (either solar or nuclear generated) to high-temperature heat represents a very wasteful use of high-quality energy. On the other hand, solar radiation is abundant and nondepletable. Most importantly, it is readily converted to heat with high efficiency, although at high temperatures this requires high concentration, as will be discussed subsequently. In the late 1970s, a small proj ect was undertaken, with the support of the Jet Propulsion Laboratory, to investigate the potential of nonimaging designs for PV concentration in space. The project did establish that nonimaging design techniques could provide significant advantages and that the concepts were compatible with many other features thought to be important for deployment of concentrators in space (e. g., the use of large, lightweight reflecting membranes).

Updated: August 22, 2015 — 3:58 am