By CHRIS HUBBUCH
Wisconsin State Journal
APPLETON, Wis. (AP) — Proponents of a less-centralized electric system envision a future in which residents, businesses and municipalities own and operate solar panels augmented with batteries and other generators joined together in so-called microgrids.
So what exactly is a microgrid?
It’s a self-contained electric system that can seamlessly connect and disconnect from the main power grid, said Bob Lasseter, the UW-Madison professor who coined the term in the early 2000s.
Lasseter helped pioneer the technology after seeing a small natural-gas-powered generator be outfitted with a system to capture heat given off by its engine. Instead of going to waste, the energy could be used to heat and cool a building.
By moving generators closer to where electricity is needed, Lasseter realized, designers can eliminate a lot of the waste now generated in the current system made up of remote power plants connected by long wires.
“I got really intrigued and started realizing that small energy sources … are actually going to have an impact,” he said.
Microgrid technology is expected to play a big role in attempts to increase the use of solar electricity and make the grid stabler, the Wisconsin State Journal reported.
Unlike generators, which produce electrical current by spinning magnets around coils of wires, most solar panels rely on the electrical grid to function.
“If the power goes out it just shuts down,” said Tom Jahns, professor of power electronics and electrical machines at UW-Madison.
If there is a small number of solar panels in a system, there’s no cause for concern; but when solar arrays start to outnumber spinning generators, Jahns said, “the system gets more wobbly.”
Microgrids also increase electrical systems’ resilience to natural and human-made disruptions. When power goes out, a microgrid will automatically disconnect and keeps operating as an “island,” Jahns said. Microgrids can also help get the larger grid back up and running.
The cost of microgrid controllers is still too great for many applications, but the technology is becoming more common. Navigant Research has identified more than 2,250 projects that had been planned or installed by the end of 2018.
One such project, built by Faith Technologies, has been running for the last year at the Gordon Bubolz Nature Preserve in Appleton.
On an overcast day in early May, with temperatures around 50 degrees, two fields of solar panels were kicking out a little more than twice what was needed to supply an 18,000-square-foot lodge, an instructional center and a handful of outbuildings.
Most of the excess was being used to charge a 100-kilowatt battery, which also drew from a natural-gas fired microturbine that doubled as a heater. An extra 2.5 kilowatts was being fed into utility power lines, although the project was too large to receive payments for its excess generation.
“We’re very generous,” said Caramy Biederman, the lead project engineer.
With its combination of generation and storage — there’s a fuel cell, powered with hydrogen that is produced from excess solar power, and a backup natural-gas generator — the grid is controlled by a central computer, which balances supply and demand in much the same way as the large grid.
The $3 million system, believed to be the first of its kind in Wisconsin, can produce more power than is needed but allows Faith to experiment with different configurations.
“We basically built several microgrids into one,” Biederman said.
For example, it might be more efficient to run the microturbine all-out and store the extra energy; or to use utility electricity at night when it’s cheaper and save the batteries for a cloudy afternoon.
Faith Technologies gave the system — along with the new lodge — both to help Bubolz and to demonstrate its microgrid systems for potential clients, usually commercial or industrial companies looking to reduce their energy costs.
Steve Nieland, director of energy solutions at the company, said in most cases a microgrid system can pay for itself in 10 to 15 years.
“Microgrid technology and the grid really are things that work hand in hand together,” Nieland said. “We like to think microgrid technology is going to help the grid and provide more resiliency while reducing that carbon footprint.”