The many meanings of "Smart Grid"

America seems to have decided that a "smart grid" is what we need to solve the problems of our electric power system. But, what exactly is a "smart grid"? The answer is that it is many different things. Some of the things that get talked about are relatively inexpensive and can go a long way toward solving key problems. Others will likely be very expensive, and at this stage may better be left to the realm of research.