Microgrids: Self-Sufficient Energy Islands
Originally published September 11, 2015
Microgrids, small energy systems that can run independently of the main grid, can turn communities into self-sufficient energy islands. The technology may have been made popular by a devastating storm, but public power utilities have been creating electricity islands since before it was cool. Microgrids are positioned to grow quickly, with public power utilities leading the way, thanks to their unique position in their communities.
When Superstorm Sandy roared up the East Coast in October 2012, it not only knocked out power to about 8.5 million customers in the Northeast and Midwest and caused an estimated $65 billion in damage — it propelled one utility segment into the limelight: microgrids.
“Superstorm Sandy was a watershed moment,” said Michael Burr, director of the Microgrid Institute, an organization focused on microgrids and distributed generation. “It marked a point where microgrids became a solution that people were more aware of.”
Microgrids are small energy systems that can run separately from the grid, making them ideal for facilities or wider areas that can’t afford to see their power go down. The U.S. Department of Energy defines microgrids as “a group of interconnected loads and distributed energy resources with clearly defined electrical boundaries that acts as a single, controllable entity with respect to the grid and can connect and disconnect from the grid to enable it to operate in both grid-connected or island mode.”
Public power pioneers
While Superstorm Sandy and other storms may have jump-started the interest in microgrids, the technology is as old as some of the first public power utilities that sought to bring the benefits of electricity to parts of the country that were unconnected to larger grid systems.
“Many of our public power utilities started out as separate grids with their own generation, serving their own communities,” said American Public Power Association President and CEO Sue Kelly at the association’s National Conference in June. “As public power is already owned by our customers and our sole mission is to serve our own communities, you could argue we are in fact the original microgrids. As the saying goes, “Been there, done that, got the T-shirt”— and we did it over 100 years ago.”
Those first municipal utility microgrids included diesel engines and a basic distribution system. Starting about a decade ago, microgrids were typically set up on university campuses, at hospitals and at military bases to provide backup power.
A typical microgrid includes several core technologies, Burr said. A control system is used to balance generation and demand within the microgrid. A distributed generation system provides the electricity from one or more power sources, which can, for example, include natural gas-fueled combined heat and power, solar panels, geothermal systems and small-scale biomass. A microgrid might also include demand-side management technology, Burr said.
In recent years, the technology used in microgrids has become more sophisticated and less expensive, expanding their appeal, Burr said.
A moving target
So, where are we today? Currently, there is about 1,250 MW of microgrid capacity in the United States, according to a July report from GTM Research. The firm expects microgrid capacity to increase to about 2,800 MW in 2020, with renewable energy making up about a quarter of the capacity.
About 80 percent of microgrid capacity is centered in seven states, which are led by New York with about 220 MW. The other top states in order are Georgia, Texas, California, Maryland, Oklahoma and Alaska, according to GTM Research.
Some of the factors driving the microgrid market include increased customer demands, maturing technologies, the reduced cost of renewables and changing regulations, GTM Research said.
The outlook for microgrids has quickly shifted. “We’re moving into full-scale deployment with microgrids,” said Peter Asmus, an analyst with consulting firm Navigant Research.
In 2009, about two-thirds of all microgrids were pilot or research and development projects, he said. At the time, there were questions about their feasibility and many utilities expressed concerns about the idea of customers being able to island off the grid, according to Asmus.
The outlook, however, changed with more utilities setting up microgrids, Asmus said. Further, at least in the near-term, Asmus said he expects public power utilities to play a larger role with microgrids than investor-owned utilities, partly because they can move faster and don’t need to get project approval from public utility commissions.
U.S. public power microgrid capacity will likely grow from a negligible amount last year to about 100 MW by 2017 and to then roughly double by 2023, Asmus said.
Resiliency and control
The New York Power Authority is one of the utilities getting a jump on microgrids. Last year, NYPA released a plan for how it would help transform New York’s utility industry, partly by giving customers greater control over their electricity. NYPA sees improved resiliency through microgrids as one element of that plan.
NYPA finished building a microgrid this year for the New York City Department of Corrections’ Rikers Island that is centered around a 15-megawatt cogeneration plant, according to Randy Solomon, NYPA’s director of energy services delivery.
The project was spurred by a 2006 blackout in Queens, New York, which led to grid instability in the area for about three weeks, affecting the prison facility, Solomon said. In the future, Rikers Island will be able to keep operating with full power during a wider power outage. The microgrid can send power out of its system and could potentially help stabilize nearby areas if needed, Solomon said.
With an eye toward protecting facilities from power outages, NYPA is studying the feasibility of several other microgrid projects, including one for a New York City wastewater treatment plant, one for a group of state office buildings in Albany, New York, and one at the Stony Brook University Research and Development Park on Long Island, Solomon said.
One of the latest microgrid trends expands on the concept used at Rikers Island to include a wider community, which could include dispersed facilities and multiple generating sources, said the Microgrid Institute’s Burr. A community-microgrid may include multiple property owners that hope to see benefits besides backup power, he said. Benefits can include the use of local, renewable energy sources, economic development, lower costs and a modernized grid that offers improved services, he said.
In a version of a community-microgrid, late last year, Norwich Public Utilities and the Connecticut Municipal Electric Energy Cooperative, a joint action agency, finished a $9 million, 10-MW project to supply backup power to the Backus Hospital and critical facilities near the site in Norwich, Connecticut. The other facilities include schools, emergency shelters, a fire station, a shopping center and other buildings.
The project was partly a response to Superstorm Sandy and Hurricane Irene, which caused widespread outages in the Northeast in 2011, said Chris Riley, a utility spokesman.
Meanwhile on the West Coast, investor-owned utility San Diego Gas & Electric has been running its 4.6 megawatt Borrego Springs demonstration project since 2009. The microgrid covers part of a small, isolated town about 75 miles west of San Diego. The project uses a mix of local generation, energy storage and automated switching to keep the power on in the outage-plagued town.
SDG&E is expanding the project so it includes all its customers in Borrego Springs and is powered mainly by a 26-MW solar project. If the project’s batteries run down, SDG&E will use conventional generation to power the town. The utility plans to finish expanding the microgrid in mid-2016 and is looking at other areas in its service territory that could benefit from a microgrid.
Not far from Borrego Springs, the Marine Corps’ Camp Pendleton set up what is called a fractal microgrid, where the base-wide microgrid is made of sub-systems that have a similar design. The overall Camp Pendleton microgrid includes four interoperable microgrids that scale up from 4 kilowatts to about 1 MW. Each grid is able to island off from the others. The project includes solar and diesel generation as well as battery storage.
Like Camp Pendleton’s fractal grid, nested microgrids are another type of emerging microgrid, Burr said. A nested microgrid includes multiple systems within the microgrid that can be operated independently. The nested microgrid might include critical facilities spread around a community, with the overall microgrid being managed as a portfolio to balance generation and demand, he said. During a power outage, each node within the microgrid would operate by itself.
New York State, which is in the early stages of revamping its utility industry through the Reforming the Energy Vision initiative, plans to spend $40 million to support community-microgrid systems. The state expects to ultimately help sponsor up to seven microgrids.
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