Excellent Grist article!  The focus on cost and capacity factor is really on the mark.  Adding solar furnace molten salt storage and/or geothermal heating to the CAES system might eliminate most of the natural gas use.  Then maybe waste stream biogas could make up most of the extra power needed.

Especially if the waste stream biogas were first used to generate electric power in a solid oxide fuel cell.  The 800 degree waste heat from the 50% efficient fuel cell would then be used to heat the CAES compressed air before it enters the turbine generator.

Then of course when natural gas was needed it would also be used in the fuel cell turbine system, at many times the efficiency of the turbine system alone.  Add in an HVDC national power distribution system, smart grid technology, and backup battery storage in homes and buildings, that also stores electric power from building mounted solar, and it all fits together.

And it would be much more reliable than a central generating power grid, the kind we have now that shuts down in storms, sometimes for weeks.  Each home, neighborhood, local area, and region would be independent.  But connected through the smart grid so power could go from where there was a surplus to where it is needed.

I maybe need to write a new article on superconducting magnetic energy storage.  Wisconsin Public service here in northern wisconsin has been using it on a small scale for decades.  The superconduction technology used in high energy physics research provides all the necessary data to scale this technology up to local and national grid size. 

Let's get the government funding flowing to do this yesterday!  But employ CAES with solar furnace and compression heat storage coupled with biogas/natural gas fueled solid oxide fuel cell powerplants backing up wind/solar through a smart grid. 

A good plan, the SMES R&D goes on, it can be added later on, making solar our main energy source.  A 600kv HVDC power backbone acting as a kind of national battery, with large scale SMES plants along the supergrid located regionally, to make independent loops.  Finally, perfect reliability without any combustion.