The DOE has some great resources, I can't the one I'm thinking of, but this document: http://energy.gov/sites/prod/files/2013/12/f5/Grid%20Energy%20Storage%20D

The DOE has some great resources, I can't the one I'm thinking of, but this document: http://energy.gov/sites/prod/files/2013/12/f5/Grid%20Energy%20Storage%20December%202013.pdf http://energy.gov/sites/prod/files/2013/12/f5/Grid%20Energy%... On page 30 has a matrix of the different attributes of different energy storage systems (but unfortunately not cost or capacity).