Evaluation of heliostat field/receiver configurations

This report evaluates and compares north heliostat field/cavity receiver configurations and surround heliostat field/external receiver configurations. The receiver coolants are molten nitrate salts and liquid sodium. Both field/receiver configurations use molten salt thermal storage; the sodium receiver is thermally connected to thermal storage by a sodium-to-salt heat exchanger. The heliostat filed size is fixed at 1,000,000 square meters of reflective area, and the delivered molten salt temperature is fixed at 566/sup 0/C. The delivered thermal power varies from 500 to 600 MW/sub t/, depending on the overall system efficiency. The generic north heliostat field/cavity receiver configurations were found to be 6 to 10 percent efficient than a generic surround field/external receiver configuration. There was little or no difference found in the transient performance of a molten salt receiver compared to a sodium receiver connected to a sodium-to-salt heat exchanger. Four configurations were of particular interest: (1) a north heliostat field/single cavity molten salt receiver, (2) a surround heliostat field/external cylinder molten salt receiver, (3) a surround heliostat field/external cylinder liquid sodium receiver, and (4) a north heliostat field/single cavity liquid sodium receiver. It was found that the surround field/liquid sodium external receiver configuration may provide energy at a 14 percentmore » lower levelized energy cost than a north field/molten salt cavity receiver configuration. However, the cost advantage of the surround field/liquid sodium external receiver is not conclusive because of uncertainties in system component costs.« less