Microgrids: electricity goes local

When Hurricane Sandy hit New York in 2012, most of lower Manhattan went dark, and it was almost two weeks before most of the power was restored. But in one building in Greenwich Village, the lights stayed on and the heat kept working (and the building’s population doubled). That’s because, as University of Wisconsin engineering professor Thomas Jahns explained, that building had “its own miniature version of a utility grid”: a microgrid.

Big Old Power Grid

The trillions of watts of electricity used every year in the United States are delivered by just three huge power grids. The grids’ size and interconnectivity make electricity cheap and accommodate differences in supply and demand between different regions, but it also leaves the whole network vulnerable — like the time a glitch in an Ohio control room caused a $10 billion blackout in the Northeast and parts of Canada. Or when a worker in Arizona accidentally tripped a power line, and a power outage swept from Southern California to Mexico. The number of major outages like these is rising, and because climate change is expected to increase the frequency of extreme Sandy-like storms, the problem is only going to get worse.
Meanwhile, the demands on the grid are climbing as its aging infrastructure is getting more and more fragile. The average U.S. power plant is 30 years old, and the average power line is 25 years old. Transformers that were only designed to last 40 years have been in service much longer. And even if all those elements were replaced, the grid in its current form was mostly designed in the first half of the twentieth century, when electricity was first a novelty, then a luxury. It was never intended to support a country dependent on air conditioning, computers, and millions of personal electronic devices.