Okay, fossil fuels aren't an option. Let's quit them completely and go 100% renewable.
Just to keep the numbers easy, I'm going to say we'll need 40,000 MW of grid generational capacity, especially during the overnight hours when people charge their cars. Suppose it all has to come from renewable sources. The sun doesn't shine at night (duh) wind generation is unreliable and other sources are just too small to really matter, so we need batteries.
If all 40,000 MW came from batteries, we'd need a battery with 400,000 MWh capacity (40,000 MW * 10 hours). Since it's not good to charge/discharge batteries completely and so often, perhaps we should round it up to 500,000 MWh just to keep things safe and to ensure a long service life before degradation sets in.
Batteries are expected to cost $100/kWh within a few years, so 500,000 MWh of battery capacity would cost approximately $50 billion, not including any of the inverters, switchgear, transmission lines, etc.
In order to "fill up" said battery during the daytime, we'd need a major excess of solar capacity. We only get about 6 hours of solid daylight in the middle of winter, so again, to keep the math easier, let's say we need ~66,666 MW of excess generation (400,000 MWh / 6 hours) to match the nighttime energy drain. At $0.20/watt, that's about $13 billion in PV solar panels, again, not including inverters, switchgear, transmission lines, etc.
Lastly, we'll need to greatly increase the number of charging locations. Costs vary wildly, but let's assume the average cost to install a L2 charger is $1,000 (it personally cost me $2,500 to install my TWC + DCC box). There are 10 million homes in California. That's $10B in charging infrastructure.
So far, my "back of the napkin" calculations are getting close to $75B in costs. And since projects like tthese are never completed in time and always come in over budget, maybe we should just pad it up to a nice, round $100B.
$100B is a pretty tough nut to swallow.
