[thackney]

In truth, I don't think California and NY would be able to meet the 70%.

Or RI or Conn. or Delaware or Maryland or Mass. or Eastern PA etc. Also isolation as you suggested requires each grid to have 100% plus the spare capacity to handle planned & unscheduled outages (simultaneously) plus handle growth. Load can grow faster than Power Plants can be built if conservative long range planning is not done. By combining several small grids into larger grids, they can "share" the spare capacity.

a handful of conventional missles striking a few select locations could wreck the grid for a long time

This problem is exasperated in smaller grids. Larger grids have greater capacity to reroute power.

[taxcontrol]

This problem is exasperated in smaller grids. Larger grids have greater capacity to reroute power.

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I still do not understand how you feel that what I said would have less ability to reroute power. Regional grids (I'm thinking 9 regional grids across the US) would interconnect local (I'm thinking statewide for local).

[taxcontrol]

Also isolation as you suggested requires each grid to have 100% plus .....

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Why?

Let's assume 2 lines of capacity X (which is load plus reserves).

In the simplist model, I would now have 1 line from grid A carrying 1/2 X and I would have the 2nd line now from grid B that would carry 1/2 X.

Why would I need to essentually double capacity?