The amount of solar energy striking the surface of the earth in two hours is enough to supply all of humankind’s needs for an entire year. For this reason, it is widely thought that solar energy should be our primary source of electricity. If this is to happen, however, there must be cost-effective ways to obtain solar electricity regardless of the time of day, weather, or seasonal changes. Essentially, there must be ways to store the energy from the sun to use it when we need it.
