To complete the response to James, please read the following post: EWPC: People Coordinating and Cooperating with Electrons Part 6.
Having reserves available is insufficient. Active and reactive reserves need to be dispatched and deployed in the correct places to keep the system synchronized. Lack of enough reactive reserves leads to voltage collapse, which fuels the dominoe effect.
Because the US grid was not designed for Model 2, a comprehensive design based on ultraquality is a must. Investments required under Model 3 are much smaller than with Model 2, as "connected networks" are very expensive.
A flawed market design and architecture that increases boom-bust behavior is probably the culprit on excess capacity in some regions of the USA.
Please take any follow up discussions to Part II.