[zeristor]

“I'm not sure I'd want the lifetime of the most expensive component in my car being used to supplement the grid.”

I’d imagine that a service like that would be paid for, indeed. Tesla has talked about setting up a system to orchestrate grid support from car batteries and powerwalls.

As I understand it there is more money to be earnt to maintain grid frequency, than to shift load. I guess with more battery storage on the grid the variability in price at higher frequency will calls being made for seconds and minutes will dip.

There’s storage over the day night cycle but earning once a day will take longer to generate income.

But seasonal variability will be generating income a lot more slowly unless the price goes very high, but there would probably be other problems at that point.