Storing solar heat

The photovoltaic materials needed to turn the sun's rays into electricity are still relatively expensive, given the power they can produce. And, since the sun doesn't always shine, solar energy must be stored if it is to provide a continuous stream of electricity. A recent NYTimes Science article describes a technology that collects solar energy as heat, and stores the heat to enable 24-hour-a-day power generation.

Using mirrors and lenses, the sun's rays are reflected and focused on to a tank of molten salt. The salt reaches temperatures high enough to boil water. It's a lot cheaper to store energy as heat than it is to store it as electricity. The article cleverly points out that a coffee thermos and a laptop computer battery can store roughly the same amount of energy; and the battery cost 30 times more. By cooling the hot salt, steam is made continuously, rain or shine, night and day. The steam powers conventional electric generators. link