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Microgrids are electric power systems that let a community make its own power without drawing from the larger electric grid. During an emergency, microgrids can disconnect from the wider grid, keeping the lights on through events that affect power generation and transmission.
Microgrids can serve an area as small as a single neighborhood, an apartment complex, or the campus of a hospital, business or university. But the same idea can also scale up to serve an entire city. A microgrid can also power just a key portion of its area, such as emergency services and government facilities.
Microgrids and the clean energy transition
For most of its history, the electric grid has relied mainly on large, central power stations, using resources like coal, hydropower and nuclear power. These stations make enormous amounts of electricity—often enough to supply millions of homes. Far-flung networks of substations and transmission lines connect these stations to consumers, so that just a few power plants can supply wide regions with cheap electricity.
But as the world builds new forms of energy, including small generators and sources that don’t contribute to climate change, this model is changing. Today, the focus is on clean energy technologies such as solar panels and wind turbines. These can easily be built at a very small scale, down to a few solar panels on a rooftop. And because large tracts of land are needed to make solar and wind farms that produce as much energy as central power plants, it is often more practical to build them as smaller, “distributed” resources.
This, in turn, makes it easier to build microgrids. Not every community can host a large power station, but it is relatively easy to build enough solar and wind energy to meet local needs. Emerging forms of energy storage, like advanced batteries, can also be built on a small, local scale, providing another source of backup power that can unhook from the grid.
Automated grid controls have also made microgrids more practical. In a blackout, a microgrid must stop transmitting electricity to and from the wider grid quickly, before its equipment is affected. Computerized systems can now spot early signs of an impending blackout and make the decision to disconnect automatically.
Microgrids and extreme weather
Small power stations are not a new invention, and there have been many cases going back decades of small campuses with their own power supply disconnecting from the grid to get through a blackout. MIT itself has generators that kept the main campus running during the Northeast Blackout of 1965.
The idea of building microgrids as a deliberate strategy, however, is fairly new.
In large part, that’s because climate change has brought new risks to the electric grid. Transmission lines can be damaged in intensifying hurricanes, heatwaves and wildfires; worsening droughts can lower the output of hydropower stations, or leave nuclear and coal plants without enough water for cooling; rising seas leave coastal areas’ power plants more prone to flooding. In a grid that relies on moving electricity long distances from a few plants, these events can cause widespread outages.
At the same time, society has grown more dependent on having a reliable supply of electricity at all times, including to keep life supporting equipment in operation.
Microgrids can help vulnerable areas adapt to these changes. And because they play well with modern clean energy technologies, they can go hand in hand with remaking our energy system to produce fewer climate-warming greenhouse gases. In the most ambitious vision, whole regions can become networks of interconnected microgrids, working together to provide cheap, efficient electricity in normal times, and disconnecting in emergencies to keep blackouts from spreading.
Published January 29, 2024