One of the problems with alternative energy sources such as wind and solar is their intermittent nature. Sometimes the wind is blowing and sometimes it isn’t. And the sun goes down every night. This is one of the reasons why fossil fuel plants are still a mainstay for any major power utility.
This problem has led to a quest for ways to store energy such that an alternative fuel power plant can supply energy on demand. One such method uses compressed air, while another has large batteries. More recently, a company named SolarReserve has received a $737 million loan guarantee from the US government for the construction of a round-the-clock solar power plant in Nevada—a plant that uses molten salt to store energy accumulated during daylight hours.