Rand Paul underground electric fence idea

It's hard to take Rand Paul seriously, and with plans like this one that's getting some media attention, a billion dollar underground electric fence between the U.S. and Mexico is really hard to take seriously. As pointed out by several sources, including this one:

Rand Paul wants to bury a wire on the border and run electricity through it. As soon as somebody crosses the electric fence, choppers will be dispatched to dispatch the offending illegal back to whence they came.
Apparently Paul has a way to detect the difference between iguanas and other wildlife that is currently allowed to cross the borders unimpeded.
“My plans include an underground electric fence, with helicopter stations to respond quickly to breaches of the border,” state the Kentucky candidate for Senate on his website.
“I have not heard that. “Underground? What would happen? How would that work?” said National Republican Senate Committee Chair John Cornyn.