"Wind and solar energy are called intermittent sources, because the power they produce can suddenly disappear when a cloud bank moves across the Mojave Desert or wind stops blowing through the Tehachapi Mountains, for example. In just half an hour, a thousand megawatts of electricity -- the output of a nuclear reactor -- can disappear and threaten stability of the grid."

Well Ralph you're using California as an example, one that has been skewed by the experiment of deregulation of the power market in 1999. A lot of standby power was lost when it was mandated utilities "divest" themselves from the generation market. Good ol' Jerry Brown at his first turn at the helm killed the Sun Desert nuclear plant that was to be built near Blythe CA in 1976, there's your loss of 1GW of available baseload power that is NOW unavailable thanks to Jerry. The national power grid needs upgrading on a mass scale, it has served since the 1950's and needs to be brought into the new millennium. Until massive power storage units are brought online along the power grid, power will be at the mercy of weather, floods, earthquakes, fires. The cascading failure of the grid supposedly caused by a utility worker at a switching station in Yuma Arizona, that affected the grid from Imperial County to Orange County is a prime example of how fragile the grid is now. Being able to store power generation and keeping generation online instead of faulting in cascade fashion is a necessary step in the strengthening of the power grid. As for baseload sources of power generation, Concentraited Solar with heat storage or more Geo-thermal could be used as a spinning, baseload resource.