Central Electric Cooperative lineman Jonathan Noles inspects Central's microgrid. (Photo courtesy Central Electric Cooperative)
Central Electric Cooperative lineman Jonathan Noles inspects Central’s microgrid. (Photo courtesy Central Electric Cooperative)

In the midst of the past decade’s shale gas boom, an electric cooperative in Oklahoma suddenly found itself with a glut of far-flung industrial load that co-op officials say was like serving 350 Walmarts in the middle of nowhere.

“In 2011, our peak was 110 megawatts,” says David Swank, CEO of Central Electric Cooperative. “We received requests that would have tripled our demand. And it was a challenging load for us—very high on the front end, and falling off quickly.”

Meeting this volatile, isolated demand with conventional grid infrastructure could have cost upwards of $100 million, Swank says.

The dilemma got folks at the Stillwater-based co-op thinking about non-traditional approaches to serving the load.

Swank says there were two key outcomes.

One was the development of a custom “capacity integration” engineering model that “cascades” energizing load in tandem with the drop-off rate of other loads. Swank says the innovative solution saved the co-op some $50 million in new capacity infrastructure.

The second was ultimately never built, but would start the co-op on a path to grid rethinking that could one day transform the co-op’s entire system.

Swank says Central Electric meticulously designed and engineered an “energy park” microgrid solution for the shale gas region that would have used distributed energy resources, battery storage, demand response, and back-up fossil-fuel generation to meet the load at a fraction of the traditional cost.

The project, which included input from oil and gas producers, a local university, and the Oklahoma Corporation Commission, was halted in late 2014 when fossil fuel prices plummeted. But Central Electric wasn’t going to let all that engineering design work go to waste. The co-op’s board of trustees agreed to take what they had learned and build “Innovation Pointe,” a cutting-edge, micro-grid-powered commercial and residential space surrounding its new headquarters building.

The Innovation Pointe microgrid comprises a solar field, two substations with automatic switching capabilities, battery storage, and backup power generation fueled by diesel and natural gas. Space conditioning will be provided by a common ground-source heat pump loop.

All facilities will be LEED-certified and boast a range of modern amenities, including campus-wide Wi-Fi, leasable electric vehicles, and access to drones, a technology center, and 3-D printing.

Although the microgrid will provide value to the co-op and its membership, Swank says “the most important thing is the ability for us to truly participate in the transformation that is happening in our industry.”

Central Electric, the park’s first tenant, expects groundbreaking for other business construction will begin in the first quarter of 2018. And the co-op is exploring how similar projects might deliver safe, reliable, affordable power throughout its territory.

Microgrid Pioneers

Lee Ragsdale, NCEMC senior vice president, discusses the Ocracoke microgrid among a rooftop solar array built to withstand winds up to 140 mph. (Photo by Cathy Cash)
Lee Ragsdale, NCEMC senior vice president, discusses the Ocracoke microgrid among a rooftop solar array built to withstand winds up to 140 mph. (Photo by Cathy Cash)

Many consider electric cooperatives to be the pioneers of microgrids.

Most of the larger co-ops today began in the 1930s and ’40s as very small, highly localized systems functionally similar to modern microgrids. Over the years, as populations grew, co-ops merged or became interconnected to share resources, strengthen reliability, and boost efficiency.

“When it comes to microgrids, co-ops are ahead of the curve in the power sector,” says Tom Lovas, technical liaison and consultant to NRECA. “Remote places are always looking for ways to improve efficiency and reduce costs. The cooperative community is really out in front.”

Microgrids are such specialized entities that they defy easy definition, Lovas says. Essentially, a microgrid is a power system that is detached from the main electric grid either full time or for a specific period or event, like an outage. It has a source of generation (fossil fuels, renewables, storage), a means of distribution, and a control platform that manages generation to cost effectively meet load and keep the system stable.

“Every microgrid is custom designed,” says Venkat Banunarayanan, associate director for distributed energy at NRECA. “Nothing is off-the-shelf.”

Alaska Leads

Lithium-ion battery storage at Kotzbue Electric Association. (Photo courtesy Kotzbue Electric Association)
Lithium-ion battery storage at Kotzbue Electric Association. (Photo courtesy Kotzbue Electric Association)

Because of its remote villages and lack of access to a central grid, co-op-rich rural Alaska has been a hotbed of microgrid activity for years.

Alaska Village Electric Cooperative (AVEC) operates 49 rural microgrids with an average load of less than 200 kW, similar to a modest neighborhood in the lower 48. Diesel-fueled generation is the backbone.

“The local microgrid is the only option we have to serve these communities,” says Meera Kohler, CEO of Alaska Village Electric Cooperative and NRECA’s Alaska director.

A typical AVEC microgrid has three generators for redundancy. The co-op buys and stores a year’s worth of fuel for each system because frozen waterways prohibit shipments for more than half the year, and flying in fuel is extremely expensive.

About a dozen of AVEC’s microgrids include wind power, and fewer have solar energy installations, Kohler says. None have battery storage because of high construction and replacement costs.

That could change soon, though.

AVEC and nearby Cordova Electric Cooperative are part of a three-year innovation project with the Department of Energy (DOE) and three national labs that aims to bolster the resiliency and cybersecurity of small microgrids in harsh weather conditions. DOE awarded $6.2 million to a project dubbed RADIANCE that will be based in Cordova and will test multiple networked microgrids and energy storage.

“This project is anticipated to make significant advances to microgrid technology applications, from the smallest rural Alaskan utilities to the continental American power grid,” says Cordova Electric CEO Clay Koplin.

Kotzebue Electric Association (KEA) in northwest Alaska has been among the most ambitious co-ops in pushing the capabilities of its microgrid. The co-op serves about 3,200 people in the village of Kikiktagruk using a combination of reciprocating diesel gensets, two 900-kW wind turbines, and lithium-ion battery storage rated at 1.2 MW. The co-op’s total load is 1.5 to 2.5 MW during summer and 2 to 3.5 MW during winter.

“The battery provides nondiesel spinning reserve to allow us to utilize higher levels of renewable penetration, up to 90 percent,” says Matt Bergan, project engineer at Kotzebue Electric.

During periods of high wind, the co-op sends excess wind power to a local hospital to run electric heaters. Since the wind-to-heat system went on-line in December 2016, Maniilaq Health Center has saved more than 25,000 gallons of fuel—about $50,000 a year in savings for the hospital, Bergan says.

“By utilizing wind power and battery reserve, we are aiming to achieve 30 percent fuel savings over the year,” he says. “It’s during the harshest weather that we get the most wind power, so we like harsh weather. But when it gets too harsh and wind power begins to shut down, our control system can dispatch battery power and additional diesel generation automatically to maintain power for the community.”

Rural Microgrids Shape the Future

North Carolina EMC's microgrid campus on Ocracoke Island includes diesel generators, battery storage, and solar generation. (Photo by Cathy Cash)
North Carolina EMC’s microgrid campus on Ocracoke Island includes diesel generators, battery storage, and solar generation. (Photo by Cathy Cash)

“Ocracoke is still a little sleepy town compared to other places,” says Byron Miller, a lifelong resident, as he fishes in the surf off the southernmost island of North Carolina’s Outer Banks. “There are not a lot of places like it.”

Yet this village community of less than 1,000, accessible only by boat or plane and vulnerable year-round to hurricanes and nor’easters, is waking to new energy technologies with a microgrid designed to deliver reliable power and cost savings for members.

G&T North Carolina Electric Membership Corporation (NCEMC) worked with Tideland EMC, which serves the island, to install the facility in February 2017.

“As cooperatives, we want to be shaping the future as we continue the mission of empowering people,” says Lee Ragsdale, NCEMC senior vice president for grid infrastructure and compliance. “We are learning from this microgrid. We hope to replicate these lessons and expand to other areas.”

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The microgrid includes a 3-MW diesel generator and 62 rooftop solar panels that have a 17-kW capacity and are built to withstand winds up to 140 mph. Ten cabinets of Tesla batteries sit on a concrete platform built 4-feet high to stay out of the reach of storm surge. Fully charged, the batteries store 1,000 kWh and dispatch up to 500 kW. An inverter takes the DC power from the batteries to AC power for the grid.

The controller is installed on the island but can be operated remotely from NCEMC’s headquarters in Raleigh.

The system remains connected to the main grid through transmission fed from the north by Cape Hatteras Electric Cooperative, based in Buxton, North Carolina. Transmission is submerged under Pamlico Sound from Hatteras Island and then strung overhead on Ocracoke.

The Ocracoke microgrid also offers co-op members a role. Residents and small businesses on the island have acquired 183 Wi-Fi-connected thermostats, and 50 water heater controls have been installed for load curtailment and balance.

NCEMC believes the microgrid will improve electric reliability on the island and reduce costs. It will also allow the co-ops involved to research microgrid operability and test system components for future energy needs.

As a Tideland EMC member who manages several rental properties on Ocracoke, Miller was an early adopter of the connected thermostats and water heater controls. He says he can control heat and air conditioning on his rental properties via his mobile phone, even during a demand-response situation or drastic weather.

He believes more members will sign up for smart thermostats and water heater controls, and he expects island residents to embrace the microgrid as a means of “saving money and helping the island get power back from a surprise situation.”

“The Tesla batteries and solar, having that here is pretty cool. Using the batteries to supplement during times of high demand would be good for everybody,” he says.

The Electric Load of Tomorrow

Linemen Jonathan Noles (left) and Larry Gordon have seen their skillsets expand to service Central Electric's new microgrid. (Photo courtesy Central Electric Cooperative)
Linemen Jonathan Noles (left) and Larry Gordon have seen their skillsets expand to service Central Electric’s new microgrid. (Photo courtesy Central Electric Cooperative)

Back at Central Electric in Oklahoma, the oil and gas industry now makes up about 60 percent of the co-op’s total load. CEO Swank says the pressure of having to rapidly add some 300 MW of capacity to supply a frenzied gas exploration boom helped the co-op “be smarter about what the demand is, what load characteristics look like.”

“Residential and commercial loads are becoming more disruptive in nature, so whether co-ops explore microgrids or not, they have to become smarter, more analytical, and nimble at the distribution level,” he says.

Swank says the Innovation Pointe project goes beyond building the microgrid and energy supply. It’s the co-op’s first foray into the urban planning concept of “placemaking,” a model that advocates the creation of self-sustaining communities.

“This campus will serve as a laboratory,” he says. “It will be able to be replicated within Central’s territory and other locations across the country. We are working with some large master developers and will be making some big announcements in coming months.”

He says the ultimate goal is for the park to be able to run off-grid, noting that the trailblazing microgrid successfully “self-healed” during a recent outage.

Swank says Central Electric’s high-profile embrace of new technologies and new ideas has required fresh commitments to training lineworkers, educating staff and board members, and soliciting and reacting to feedback from consumer-members.

“We as co-ops have to adapt,” he says. “The greater challenge is, do we have the capacity within our organization to harness it?”

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