Solar Plants That Work Without Sun

What’s the Latest Development?

A California energy company has developed technology that allows thermal solar power plants, rather than conventional photovoltaics, to generate electricity even when the sun isn’t shining. The key is energy storage. By storing the sun’s heat energy in molten salts inside a tank—the salts are typically a combination of sodium and potassium nitride—the energy can be called upon after the sun goes down to power steam turbines. Thermal solar power plants work by using mirrors to concentrate heat energy on a central water tank.

What’s the Big Idea?

If solar energy is to compete with conventional forms of energy production, the process must become more efficient. While the price of photovoltaic technology has been falling, the system, which converts sunlight directly into energy using familiar solar panels, loses much of its effectiveness once the sun goes down. Energy storage will help thermal solar power compete with photovoltaics by lowering energy production costs and “by increasing the price that utilities are willing to pay for the electricity.”