Single and dual purpose nuclear desalination

The use of single purpose water production and dual purpose electricity and water production plants is discussed. An expression for the combined water and electrical production is derived. The total cycle efficiency appears as a sum of the electrical production efficiency and the water production efficiency weighted by the ratio of the absolute heat addition temperature to the water cycle to the absolute heat addition temperature to the electrical cycle. The underlying thermodynamic considerations reveal that the water production and electricity production processes are competitive rather than complementary processes from the overall cycle´s efficiency perspective. Improving the water production process would be at the expense of the electrical production process, and vice versa. It follows that a dual purpose plant rejecting heat from the electrical production process to a water plant would not necessarily be more efficient than a single purpose water production plant. This suggests the need for a close consideration of the needed water electricity mix for such plants at the design stage to accommodate different situations.