Metrology-Assisted Robotic Mirror Alignment for Parabolic Trough Collectors

High performance parabolic trough solar collectors are well-suited to generating industrial solar steam.Their thermal efficiency is greatly determined by the accuracy with which they are assembled.State-of-the-art designs require placement of dozens of mirror panels to sub-millimeter accuracy so that the focused reflected light hits its narrow target.That painstaking mirror placement is performed today by skilled labor using expensive, massive, non-mobile fixtures that results in high costs.The main goal of the project is to develop an automated process that can reduce the assembly cost of large parabolic trough collectors by $6/m2 (equal to that of all the raw material used for the collector’s structure).Our patented robotic automated assembly method, derived from modern aerospace techniques, lowers costs, improves quality, and can be easily mobilized to new construction sites.In Phase I, we established the technical and economic feasibility of the robotic assembly process by component-level testing and cost analysis.Most critically, we showed that the metrology techniques we identified were capable of providing positional data to a robot in an outdoor environment with direct sunlight and the presence of a vibrating platform.We also showed evidence that commercial robots could be used outdoors.We were therefore able to overcome the primary challenge of extending indoor aerospace metrology-guided robotic techniques to the outdoors.We further showed that the processes we designed and their associated equipment costs were consistent with meeting the cost reduction goal.In Phase II, we will synthesize and demonstrate a complete process solution by having a robot position brackets on a full-scale collector prototype.We will show that the system costs less than $400,000, can install brackets in less than one hour, that no collector is damaged due to collisions with a robot, and that the assembly achieves the rigorous submillimeter tolerance requirements.Following Phase II, we will deploy the mobile robotic assembly platform to commercial project sites where we will be installing hundreds of collectors for solar steam production.The reduced installation cost gives us a competitive advantage in selling solar steam at prices competitive with natural gas.With natural gas at historically low prices in the USA, policies that encourage solutions to global warming help to internalize the negative externalities of carbon emissions.The market- based policies effectively drive up the cost of natural gas for industrial customers.These market forces compel our customers to consider the lowest cost renewable alternatives.