I just completed a project analysing the construction of a concentrated solar power plant, using sodium as a working fluid and thermal energy storage mechanism;

I just completed a project analysing the construction of a concentrated solar power plant, using sodium as a working fluid and thermal energy storage mechanism; we found that it is a very practical solution, and believe that such a system would allow for solar power plants to provide power on a more continuous basis, at a reasonable cost. Sodium will allow for energy storage on a much larger scale than is possible with any other current technology, due to its favourable characteristics. It seems that thermal energy storage is one of the most practical methods of storing large quantities of energy, but I am unsure as to when such a system will be deployed at scale, though some (fast breeder) nuclear plants use a sodium coolant system.