Ramez Naam has done lots of research/writing about "learning rates" for power technology. Here's a writeup from late last year on lithium ion batteries: http://

Ramez Naam has done lots of research/writing about "learning rates" for power technology. Here's a writeup from late last year on lithium ion batteries: http://rameznaam.com/2015/10/14/how-cheap-can-energy-storage-get/ http://rameznaam.com/2015/10/14/how-cheap-can-energy-storage... There are two different studies, one which shows a 15% and one which shows a 21% learning rate (decreased price due to volume). One thing that's worth noting is that lithium ion energy density (Wh/kg) has not increased appreciably in the past few years (~200 Wh/kg) - we're probably maxed out w/o switching chemistries. Oxis and Sony are targeting 500 Wh/kg Li-S batteries for 2019/2020, but I'll believe it when I see it - most of the Li-S research is super gee-whiz (lots of coated nanotubes, nanocomposites, etc) but that stuff never tends to make it outside of the labs, and if it does, will be quite expensive.