The inimitable Tom Murphy weighed in on the physics and cost challenges of battery technology on Friday. His analysis was spot on in pointing out the specific energy challenges of batteries, referring to the fact that per kilogram, even a lithium-ion battery gets max about 180 Wh/kg compared to 13,800 Wh/kg for gasoline. Energy density is a real issue for batteries as is the problem that even though the cost of electricity winds up being much lower than gasoline, when the cost of the battery is factored in, batteries are typically more expensive. I’ve written before about how energy storage remains the holy grail of the smart grid, transportation, renewable energy, the entire energy economy. The barriers to a breakthrough in batteries are large because major physics problems are not well understood, but folks like Vinod Khosla have pointed out that a battery breakthrough would be so incredibly disruptive that major initiatives like the entire smart grid and all it entails would not be necessary. That’s certainly a reason for some hefty government research programs and some VC for the most promising tech.