Survey of Potential Low-Cost Concentrator Concepts for Use in Low-Temperature Water Detoxification

Several different concentrator concepts have been considered for use in the detoxification of chemically contaminated water. The reactions of interest are predominantly photocatalytic in nature and are driven by low concentrations (between 1 and 50 suns) of UV radiation in the 300-to 385-nrn wavelength range. Optical performance characteristics of these concentrators are thus somewhat differentcompared to concentrators developed for industrial process heat and electrical energy production. Relaxed optical tolerances might lead to reductions in concentrator cost that, when integrated into overall field system cost, could make the solar driven process competitive with current UV lamp technology. Aspects of the concentrator system that might realize cost reductions include theconcentrating element, the support structure, the tracking and drive system, the manufacturing processes, and the installation procedures. Several ideas have been resurrected from earlier research in the Solar Thermal Program where the need for more stringent optical performance requirements led to a decline or even an end to further investigation. In light of this new application, the mostpromising of these ideas are presented, including a description and a discussion of the cost and performance trade-offs. In addition, the results of recent investigative research on several of these concepts will be presented. The concepts include a low-cost parabolic trough, the inflatable line-focus concentrator, and the holographic concentrator.