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(THE CONVERSATION) The electric grid is an amazing integrated system of machines spanning an entire continent. The National Academy of Engineering has called it one of the greatest engineering achievements of the 20th century.

But it is also expensive. By my analysis, the current (depreciated) value of the U.S. electric grid, comprising power plants, wires, transformers and poles, is roughly US$1.5 to $2 trillion. To replace it would cost almost $5 trillion.

That means the U.S. ele...