The whole point of their study was to determine what kind of mix would work. They made no claims that intermittent renewables could provide 100% of energy needs

The whole point of their study was to determine what kind of mix would work. They made no claims that intermittent renewables could provide 100% of energy needs all the time. Intermittent production is why they include hydro as one of the technologies: http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity If there is a strong shift to grid-charged electric vehicles (as opposed to hydrogen fuel cells), that also holds great potential as a buffering mechanism for intermittent energy production. Just because we don't do it now doesn't mean it can't be done.