In Alaska we have wind - diesel set ups where the wind turbine generation offsets the use of diesel in a generator or the wind is paired with hydro. If the wind drops down you want to ramp up the hydro or diesel so you have a consistent amount of power. Large fly wheels are used to even out the load. When would supercapacitors be more cost efficient than fly wheels in general and what would there specs need to roughly look like? Based on the recent advances in graphene superconductors in the link.

http://www.technologyreview.com/view/521651/graphene-supercapacitors-ready-for-electric-vehicle-energy-storage-say-korean-engineers/