You may have heard about the new technology that promises to extend solar power production into previously unknown territory: darkness. The key ingredient is a type of salt that acts as a thermal mass, becoming molten during the heat of the day and then releasing that stored heat at night to provide steam to power turbines for energy production. The New York Times blog Green Inc. offers a good look at the details of the Nevada solar plant being planned around this technology, and a good sum-up of how it will actually work:

Huge fields of mirrors called heliostats focus the sun on the receiver, which heats the salt to 1,050 degrees. The liquefied salt flows through a steam-generating system to drive the turbine and is returned to the receiver to be heated again.

A planned power plant in Nevada projects being able to store up to 12 hours of energy with this method, enabling the utility company purchasing the power (NV Energy) to better distribute this variable renewable resource. A second plant, providing 150 MW of solar power for California’s PG&E, will have 7 hours of storage.