While researching this I found a tremendous resource that goes in to pretty good depth of all the alternatives for grid level storage: http://www.sbc.slb.com/S

While researching this I found a tremendous resource that goes in to pretty good depth of all the alternatives for grid level storage: http://www.sbc.slb.com/SBCInstitute/Publications/~/media/Files/SBC%20Energy%20Institute/SBC%20Energy%20Institute_Electricity_Storage%20Factbook_vf.ashx http://www.sbc.slb.com/SBCInstitute/Publications/~/media/Fil...