可以设计一个最初可在微咸水上运行，后来可转换为在海水上运行的电厂；然而，由于操作参数的极端变化，它的成本效益不高。在本案例中，如果处理海水的能力在经济上不可行，则可以使用替代水源。在其他情况下，如果存在微咸水透镜体，但补给速度较慢，则可能更可行的方法是首先安装微咸水系统并运行电厂，直到水质开始恶化。然后，微咸植物的产量可以降低到可以通过补给率维持的水平。由于微咸水处理厂产能减少而导致的产量不足，必须由新海水处理厂的产能来替代。

It is possible to design a plant which can be initially operated on brackish water and later converted to operate on seawater; however, because of the extreme variation in the operation parameters, it is not very cost effective. In the case presented, an alternate water source was available, providing the capability to treat seawater was not economically viable. In other cases, where brackish water lenses exist but have slow recharge rates, it may be more feasible to initially install a brackish water system and operate the plant until the water quality begins to deteriorate. Then the production from the brackish plant could be reduced to levels which could be sustained by the recharge rate. The shortfall in production resulting from reduced brackish water plant capacity would have to be replaced by capacity from a new seawater plant.