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Microgrids can be thought of as small-scale power stations, connected to one another in a way that mimics our current power grids.

While the current grid can fail if part of it goes down or gets overloaded, microgrids can switch into a mode that allows each individual station to focus only on its local area.

This means that power outages related to major events such as storms can be mitigated or avoided. And when the power does go out, it can be restored far more quickly.

Oak Ridge National Laboratory and UT have a team of experts in the study and improvement of microgrids, including joint UT-ORNL Governor’s Chair for Power Electronics Yilu Liu, Min H. Kao Professor Leon Tolbert, and joint UT-ORNL Professor Fred Wang, all faculty in UT’s Min H. Kao Department of Electrical Engineering and Computer Science.

Tolbert recently addressed the topic of microgrids and the promise they hold.

What are the major advantages of microgrids?

They are smaller, more localized, and much easier to control and repair if needed. If there is a loss of power we can get it restored in hours rather than weeks or months.

What impact could they have in the wake of natural disasters or other events that might normally cut off the power supply?

Microgrid stations aren’t just connected to the grid but also have back-up power sources for when the rest of the grid goes down. It varies, but they can have solar panels, fuel cells, diesel, even batteries—whatever it takes to keep them running in their particular environment. Because of that, the critical areas could keep power running—places like shelters, hospitals, emergency services, even things like campuses or apartment blocks.

Do they automatically turn on, or is that something that has to be controlled from a center?

They switch on automatically in case of a traumatic event, but you can also plan ahead to switch them from a grid function to a local function. If you can plan ahead . . . you can balance the power more smoothly. If it’s unplanned, that takes a little bit to work itself out.

How do they compare to normal power stations?

Right now, microgrids can produce 10 megawatts in perfect situations, but typically they produce less than that. A common power plant like a nuclear plant or hydroelectric produces 100 megawatts. So the big plants produce more, but then you have to run transmission lines everywhere, and they are all connected back to that one source. With microgrids, you synch a series of them up like a grid for overall power, but since they all have their own areas to serve, one glitch or one microgrid going down doesn’t crash the network as it can in current systems.

How do we know they work?

Right now, rural places like Alaska, and areas in the US West, and select spots in Africa that aren’t connected to a major grid system use them, so we know they work.

If they hold such promise, why aren’t they in use elsewhere?

The big thing in the past has been the cost, but the price of materials has come down. Solar panels, fuel cells, and batteries are becoming cheaper all the time. They are now practical; they just have to be implemented.

When might we see them gain more use in the US?

We are working on a couple of projects right now—one in Tennessee, one in South Carolina. The Tennessee project involves setting up a solar- and battery-powered microgrid at a public airport, while the one in South Carolina is in partnership with a power company to provide a microgrid at a civic center.


David Goddard (865-974-0683,