Battery crunch coming
 

Volkswagen says it needs the equivalent of 40 "gigafactories" worth of batteries by 2025 for 3 million electric cars/ year. 200GWh per year.
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"Assuming other automakers prepare similar electric-vehicle sales goals, VW predicts a total of 1.5 terawatt-hours will be required within the global automotive industry."
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Do we have enough Lithium? Cobalt? We need to focus on gravity/ railroad for grid storage (and nuclear which needs no storage) to save the batteries for transportation.
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VW says it needs '40 gigafactories' for electric-car batteries by 2025
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Good for him. Save the human race. And make a few bucks.

It seems silly to have battery backup for the home. Excess solar can be sold back to the grid, so that negates the need for storing excess production.

I'd like to see a system that can connect an EV to the house in case of a power outage. This would completely eliminate the need for home power storage or power generators.

Never mind the batteries and the Lithium. What about the mains electricity to charge them all? Bye bye hydrocarbons, hello nuclear.

Battery grid storage seems silly now but what about when solar and wind become more than just a drop in the bucket of the base load? This is the aspect that the anti nuclear crowd is totally unaware of (ignorant bliss). The grid doesn't function unless it is rock solid or things start browning out and burning up.

I'm still against chemical storage. Seems it would be more efficient to use pumped hydro or other potential kinetic energy storage such as your railcar suggestion.

How efficient is decomposing water into H2? This is one of the few chemical storage solutions I could see being practical.

H2 conversion forth and back not good. Ammonia has also been used. Rail cars should be quite cost effective if there is an appropriate grade. I'm surprised Tesla hasn't jumped in on this since the Gigafactory1 is surrounded by hills. Save the batteries for transportation.

Yes save the world by strip mining it for battery materials.

I think the answer is smaller batteries and on the road charging. One experimental bus line in Salt Lake City is using the bus stops to inductively charge small sets of batteries. Fewer batteries required. We could inductively charge cars while they drive. Technology is already here.

Also what about the super capacitor cars?

It takes an enormous amount of copper wire to make an inductive charge road. The cost is prohibitive.

Although induction charging might work for buses that run a known route and spend a decent amount of time at stops, it's just not practical for passenger vehicles.