When adding electric usage, you need to "bill" it at the marginal costs to generate that electricity
Yes, but marginal analysis requires identifying the correct margin. If you charge your car during the day at work, you are increasing peak load, which is often coal. If you charge your car at night, you are contributing to base load. This might not even require building new plants! This works great if you have nuclear plants. With a sufficiently smart grid, it makes erratic sources like wind much more useful.
Yes, but marginal analysis requires identifying the correct margin.
I do agree using the rate for coal is pessimistic.
On further research, I discover that Li-ion batteries are very energetically expensive to produce. Their net lifetime energy in production and then recycling is about 430 kWh per kWh of battery. Li-ion can be recharged 300-500 times. Using 430 recharges, amortizing production costs across all uses of the battery we see that we have 1 kWh of production energy used for every 1 kWh of storage the battery accomplished during its lifetime...
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.