Microgrids improve resilience, efficiency

After Hurricane Irene in 2011 knocked out power to nearly 1 million Connecticut homes and businesses, state officials began examining how to better steel communities against powerful storms that could become more frequent in a changing climate.

Based on the recommendations of a state task force, the legislature enacted a program a year later to help protect the power supply for critical municipal services through microgrids.

Fairfield, a town of 60,000 with five miles of coastal shoreline, became the state’s first municipal microgrid system to go online in 2015. A state grant, town funds, and technical support from Schneider Electric all helped launch the project. The microgrid powers the town’s police and fire headquarters, emergency communications center and nearby cell tower, and a homeless shelter. If the main grid shuts down, the microgrid can operate in island mode, keeping the power on.

“Fairfield’s microgrid project is an example of how a municipality can help protect public safety and minimize hardships to their residents and businesses during power outages,” Katie Dykes, deputy commissioner of the state Department of Energy and Environmental Protection, said in a press statement.

To define terms, a microgrid is a lot more than a simple emergency generator. It’s a relatively small, controllable power system composed of one or more generation units connected to nearby load that can be operated with, or independently from, the local distribution and bulk transmission system. Microgrids can run on a variety of power sources – renewables, natural gas-fueled combustion turbines, or even emerging sources such as fuel cells.

In the case of Fairfield, there is a 300-kilowatt natural gas generator, 47-kilowatt solar photovoltaic system, and a 60-kilowatt combined heat and power generator that are tied together and can provide up to 120 percent of peak power use for the facilities.

To tackle the project, Fairfield needed funds and know-how. For the former, it received a $1.1 million state grant and chipped in $130,000. For the latter, it turned to Schneider Electric, an international electric management company with U.S. headquarters in Andover, Mass. Schneider was chosen through a request for proposals to help Fairfield apply for the state grant and engineer the project.

Philip Barton, senior director of Schneider Electric’s Microgrid Competency Center, said that connecting the three buildings – the police/fire headquarters, communications center, and homeless shelter – required digging conduits under the streets between them, “a fairly expensive construction project.” The state changed its laws to avoid right-of-way issues that otherwise would have made it difficult to do the work. (We outline other legal and regulatory hurdles to microgrids.)

Since the microgrid system was installed, no storms have knocked out the main commercial grid. The microgrid, however, is tested routinely to make certain it is ready to run on its own. Meanwhile, upgrades to the town’s power generators are paying dividends.

Ed Bowman, assistant director of public works in Fairfield, estimates the town is saving about $60,000 a year in electric expenses and about $10,000 a year in heating costs. The new generator at police and fire headquarters runs on natural gas that is cleaner-burning and more efficient than the diesel generator it replaced, complementing Fairfield’s green energy efforts. Heat produced by the generator is recovered and used to heat and cool the buildings and help heat water. The microgrid control system also is designed to be cost-effective by taking power from the cheapest source available between the commercial power grid and the locally-generated alternatives.

Microgrids currently provide a tiny fraction of U.S. electricity (about 1.6 gigawatts, or less than 0.2 percent). They aren’t a traditional infrastructure investment for utilities, and the power industry isn’t set up to facilitate development of microgrids by non-utilities. But interest is growing due to microgrids’ ability to keep the lights on in a widespread natural disaster, improve efficiency, and integrate renewables. Microgrid capacity is expected to more than double in the next three years.

Public-private partnerships, like the one in Fairfield and elsewhere, are helping to pave the way. For example:

  • Montgomery County, Maryland, recently entered a public-private partnership with Duke Energy Renewables and Schneider Electric to develop two microgrids to power county facilities. Ratepayers won’t have to foot the bill, and the government will get more resilient and affordable power with environmental benefits.
  • In the Denver suburbs at Peña Station Next, a public-private partnership with the city, county, Panasonic, Xcel Energy, and Younicos is developing a microgrid that uses solar panels and battery storage.
  • In Alaska, the state with the most microgrids, the city of Anchorage is about to deploy a project by ABB for the Chugach Electric Association that will use two energy storage technologies and help the area integrate more wind power.

Fairfield and Schneider Electric have teamed up on a second microgrid project, expected to be completed by summer 2018, for the town’s wastewater treatment plant and an animal shelter. A $2.5 million federal grant will fund a new cogeneration unit – fueled by biogas produced at the wastewater treatment plant – to provide heat and electricity to the facility. The microgrid will also incorporate solar power, and during normal operations will control the power delivered based on using the greenest available source.

For cities considering a similar project, Barton and Bowman offer the following advice:

  • Optimize sustainability, resiliency, and efficiency in any microgrid project.
  • Talk to local utilities early in the process to ensure power generated on site can connect to the grid. (Fairfield found its solar generators could not be used during a commercial power outage.)
  • Bigger isn’t always better. A larger power system can run into additional regulatory requirements that can add time or money, so a 1 megawatt generator may be preferred over a 1.2 megawatt generator.

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