Power engineers can calculate it and they (along with grid managers, FERC and electrical reliability organizations) will call out any schemes that actually put the grid at risk (having learned from California’s initial debacle with restructuring). In a fully integrated grid of the future, the bulk of electric vehicle charging would be done at night when loads are much lower and more lower-cost generating capacity is usually available. In this scenario, a vast number of electric vehicles also would be plugged in during the day while many people are at work and would take relatively small amounts of power from the grid when needed to maintain a full charge; they would also serve as storage for the grid and inject power back into the system when needed and cheaper than running the next increment of more expensive generation.
If and when all this happens is still up for debate—it will require a massive investment in infrastructure—but it’s almost certainly not going to be your grandfather’s power grid any more.
The ability of anything to inject power into the utilities power lines, to power a down grid especially is not going to happen. At least for a very long time.
There are a whole bunch of technical and organizational challenges that will have to be overcome, long prior to that happening.
From a technical standpoint we require that the switchgear that connects small generators (pick your technology, but mostly solar) to fully disconnect from the grid in the event of a grid disruption. This is vitally important because the linemen making repairs need positive isolation and grounding to safely make repairs.
Yes, maybe someday in a popular science conceptual way this kind of thing might happen, but we are so far away that it is literally a popular science magazine topic.
Where I see the industry going is that we will end up with more solar generation at the individual customer level as the technology matures. That will help us burn less hydrocarbon, but that is about it. I also see more localized generation as technology improves. This reduces the problems and the expense of long distance energy transmission.
Few people know that almost all of our nations major power outages have been caused by transmission lines tripping out of service. Local generation solves that issue.
Things like fuel cell technology at the local level, and even possibly microturbine technology will allow local competivly priced generation.
The next thing for the indstry to work on is utility scaled storage for solar energy. Solar is wonderful energy who’s cost per megawatt is droping quickly. The problem is that it is not currently storable at a reasonable price.
In a recent class I learned (but have not personally verified this) that at certain locations there is so much solar power available during peak solar times that there is an excess of energy Vs load and that utilities have been required to sell those megawatts even to the point of paying for the sale (negative pricing), because we are required to accept all the solar produced. Again I have not personally verified this, but during a class on grid disruption analysis I attended this spring, that was presented as an issue.
