Microgrids: Big Power, Small Grids

Researchers are exploring how to leverage microgrids to strengthen the nation’s power grid, work that could help homes and regions maintain power independence and become more efficient day-to-day.

Bob Hebner spends his days researching how next-generation energy technologies, so-called microgrids, could help the nation avoid rolling blackouts, secure an airport during a natural disaster and deliver energy to a hospital during an emergency.

“Microgrids give greater reliability during an emergency and greater efficiency during normal day-to-day activities,” said Hebner, director of the Center for Electromechanics and professor in the Department of Mechanical Engineering.

Watch an animation of how microgrids work.

In the last 10 years, the technology to support these souped-up versions of power grids, or microgrids, has evolved, creating both challenges and opportunities. UT Austin’s Cockrell School of Engineering is working to address these through theoretical modeling using super computers, as well as testing in real-world environments.

In a microgrid, computers manage the two-way flow of power and information for operators and users. They can alternate power sources depending on availability, store or return excess energy and disconnect from the larger grid.

These technologies are called microgrids because the regions they serve are much smaller than entire states or sets of states served by conventional grids. Today, many towns and villages in the state of Alaska operate on microgrids.

Similar to a power grid, a microgrid’s job is to manage a load — the amount of electricity that consumers require — by providing available energy. But a microgrid operator can set limits on how much power it delivers, depending on various factors such as time of day.

Unlike a conventional power grid, a microgrid offers greater local control because it allows for different types of local power sources, such as solar, wind and natural gas. A home on a conventional power grid might also produce solar energy, but it would have to send that power to a local utility company’s substation before it could be used as electricity. Homes on a microgrid aren’t reliant on the big grid to use the energy they produce.

For instance, when faced with a shortage of electricity, a standard power grid can only deliver at the full 100 percent capacity or shut off completely.

But in the case of a microgrid, “instead of going to zero, those served by microgrids will be able to still use, say, 60 percent power to avoid rolling blackouts,” Hebner said. “Using home management systems, you can choose how to use and conserve that power — what to have on or off and for how long.”

In theory, a neighborhood on a microgrid could send excess power it produces to a nearby hospital that might need power during a hurricane or other emergency, though this use is still far from being in practice.

In the not-so-distant future, the integration of microgrids could significantly change people’s energy habits to take advantage of available energy when it’s less costly.

“Rather than just using your washing machine, your house would negotiate with the microgrid as to when the power was available to use it,” Hebner said. “In times of shortage, it may be better to do laundry or dishes at 4 a.m. rather than at peak times when everyone uses electricity.”

For all its benefits, a fundamental problem with this new technology is figuring out how to integrate self-contained microgrids into conventional power grid systems, which developed their basic operating principles before today’s technologies were available.

“Microgrids allow us to design power systems a fundamentally different way,” Hebner said. “Fifty years from now, we hope to have a system that’s greener, less intrusive and much more reliable. What we are really trying to understand is how a microgrid can work in the future.”

To that end, Hebner and other faculty members established an informal microgrid work group that brings together faculty and researchers across engineering disciplines at UT Austin to discuss their work. Right now, there are four engineering faculty members and about 20 engineering graduate researchers working on various microgrid projects, from electric ships to energy security on military bases.

One big advantage for UT researchers is being able to test on a functioning microgrid, which can be tied to electric and solar power. The microgrid is housed on the J.J. Pickle Research Campus. Another advantage is the connection to Pecan Street Inc., a nonprofit consortium that lets researchers apply the monitoring and control methods they develop to an actual commercial development in East Austin.

Later this year, Hebner and his team are heading to Alaska for field-testing. In a partnership with The University of Alaska Fairbanks, the team is modeling the use of geothermal energy to run both a town and a gold mine, which itself requires about as much electricity as the entire town to operate.

Meanwhile, electrical and computer engineering associate professor Alexis Kwasinski and his research team are working on several microgrid-related projects, including modeling the effects of natural disasters on conventional power grids. Other researchers are looking at microgrids to provide energy security at airports, manufacturing installations and military bases.

John Ekerdt, associate dean of research for the Cockrell School, said that the work being done at UT has implications for everything from hospitals to remote communities.

“As we evolve to more efficient microgrids for managing energy use, this research will guide the infrastructure, design and investment decisions for power grid operators and end users,” Ekerdt said.