Can the next generation of electric vehicle batteries make the jump into grid energy storage? This week saw Nissan and Sumitomo form a JV to recycle partly spent car batteries (like those from Nissan’s upcoming Leaf sedan EV) for other purposes, including potential grid applications. Then BYD, the China-based, Warren Buffett-backed EV startup, announced a MOU with Los Angeles Department of Water and Power to build batteries to back up wind power. That’s similar to a project lithium-ion battery maker A123 has with Southern California Edison — in fact, A123 has a significant presence in grid storage. Still, the economics of batteries make them hard to justify for most grid energy storage applications.