I don't think modulating the loads would really help anybody, since most people should be charging at night anyway. Count me among the people who wish for V2G. If charge COULD flow out (and I think it cannot) THAT is your big opportunity to make a difference in aggregate. I suspect just being able to smooth out very small peaks and valleys is valuable and it wouldn't have to cycle batteries that much. Just take a plugged in car, have it start discharging for 5 min (say 1-2% of charge) and then recharge in the next 5 min. I believe batteries are not much harmed by small cycles in the middle of their range. (Of course owners would be opting in for this)
I'll leave it to Tesla engineers to figure out what uses the batteries can tollerate, and certainly if the price is right we would all tollerate a little abuse. For example, if the utility is paying $600/kWh, I'll be willing to sell 40 kWh. If this happen a couple of times, it pays for the whole battery.
For night charging, selling variable load should be quite valuable to a utility. Suppose the utility has 1000 MW of really cheap base capacity. Suppose demand varies from 800 MW to 1000 MW, and averages 900 MW. Without batteries, the utility throttles base capacity back to 800 MW, but has to keep 200 MW of stand by capacity and use on average 100 MW of this more expensive capacity. Now suppose that Tesla has a large enough fleet that needs to charge at an average of 100 MW for 10 hours. (100,000 EVs need about 10 kWh per nightly charge, about 1000 GWh.) So if this fleet we all aggregated, it could easily vary load from 0 to 1000 MW. So the utility could run cheap baseload at 1000 MW all night. The aggregate batteries would vary the load from 0 to 200 MW as needed. Thus, the utility needs practically no stand by power at all, only enough to cover unusual circumstanstes where demand exceeds 1000 WM. So the utility is able to get much better utilization out of its most efficient base load generators.
Now if the fleet can be called upon to discharge 1 kWh for every 3 that it charges, then a much smaller fleet can provide this regulation service. Suppose the fleet is just 50,000 vehicles, and it needs 500 MWh. Then the base load could be set at 950 MW, while the fleet varies from providing 50 MW power to absorbing 150 MW. The net demand varies from 800 to 1000 MW, so practically no stand by power is required. So the question is this arrangement is more beneficial than the other.
From the utility's perspective, they get better utilization and sell more power with the 100,000 vehicle fleet than the 50,000. The utility does not need to finance these assets, so fewer cycles per battery is really noon of their concern. From the EV owner's perspective, the large fleet scenario induces no incremental wear and tear, otherwise, they would need to be compensated for that. Thus, either they fail to get Suffield compensation and suffer an economic loss, or the utility winds up paying for that cost. So again 100,000 EVs providing load only is probably the cheaper and most equitable deal for both EV owner and utility. The EV owner winds up paying less per kWh than the baseload cost of that power, quite close to free, whIle all ratepayers benefit from lower rates.
So 100,000 EVs against average nightly power demand of 900 MW may seem like a lot, but really we are talking about powering a service area with about 1 million homes. Thus, if just 1 home in 10 had an EV, that would suffice. So long term, I definitely see this level of EV penetration. So past about 5% EV penetration in the US, there may be little need for bi-directional V2G, load only should suffice. In the US I think we could hit this point around 2025. Imagine how mainstream EVs could become when aggregation programs enable participants to charge nightly for less than 2 c/kWh, or less than $10 per month.
As a variation on this, suppose that business provides charging to customers and employees during the day. If these charging facilities are also aggregated so that the utility can offset the need for stand by power. The need for stand by is much greater in the day, so a business could provide effectively offer free variable rate charging. The business would need to determine if it is in their interest to provide the facilities, but the cost of energy could work out to have practically nothing. In deed, if the penetration of solar power is high enough, it can induce negative prices on the spot market. So aggregated EV charging can actually earn money for absorbing surplus power, and this is in addition to the value of taking taking stand by power off line. So if EV charging is well aggregated, then the need for stand by power and grid batteries can be greatly reduced. But if EV charging is not aggregated, than the need for stand by power can actually increase. So it is in the interest of all ratepayers, to see that regulatory road blocks to this sort of aggregation are removed.
)
