The 20 off-grid microgrids Mission Critical Group delivered in October 2024 to a telecommunications provider expanding its network in Alaska were tested, assembled, broken down, crated and aerially lifted to 20 new telecommunication towers, many located on mountain tops.
Mission Critical Group, a power systems integrator, had to grapple with difficult terrain, extremely hot and cold temperatures —down to -50 degrees Fahrenheit —and high elevations to power telecommunications provider OTZ's 630-mile microwave network from Coldfoot Camp to Kotzebue, Alaska.
In some cases, the towns had no reliable power or connectivity, said Matt Coffel, chief commercial and innovation officer at Mission Critical Group. The microgrids will provide both primary and backup power for OTZ’s telecommunication towers.
About $40 million in funding for the project came from the federal Bridging the Digital Divide program, which aims to ensure everyone in the U.S. is connected to affordable, reliable internet by 2030.
Batteries keep microgrids operating for a week without sun
The 10-kW microgrids, which Mission Critical Group started deploying a year ago but are being added as OTZ expands its network, include solar along with lithium-iron phosphate batteries that generally keep the microgrids running for about a week if the sun isn’t shining, Coffer said. Low-emission propane generators serve as backup.
Mission Critical Group often uses fuel cells as backup for its microgrids, but the cold temperatures made that too difficult, Coffer said. And it’s not possible to get hydrogen up to the mountain tops for refueling.
Adding 10-kW wind turbines is an option in the future. One worry is that if a wind turbine snaps off the tower and flies into the communications equipment, it’s expensive to repair, he said.
Keeping the telecommunications tower powered is important to Alaskan residents and businesses for a number of reasons.
Expanding mine needed connectivity
For Red Dog Mine, located in Alaska’s Northwest Arctic Borough and the largest global producer of zinc, the connectivity provided by OTZ is critical to supporting the mine’s expansions, Coffel said.
The OTZ network also helps lower costs for people living in the towns along the microwave network who are paying high prices for phone and connectivity, he said.
An alternative to the microgrids would have been either air fiber–a wireless, point-to-point connection installed 300 feet in the air–or undersea cable. The undersea cable option would have been expensive, especially considering that only about 3,000 people live in the towns along the network, Coffel said.
“It's 1,500 miles by water around the island chain to get over there. So 1,500 miles of subsea connectivity to beef up connectivity and save 3,000 people money wouldn't be fiscally possible,” he said.
The number of cell phone towers powered by microgrids is on the rise
Increasingly, cell phone towers are being powered by microgrids. The towers are often located in remote locations with no central grid connection – or an unstable one. Frequently, remote facilities depend largely on expensive and polluting diesel generators. Microgrids can provide a cleaner, more resilient and less costly option, especially as cell phone usage increases.
Not only are rural areas in Alaska looking to deploy microgrids to power cell towers. In these areas, community leaders are also interested in using microgrids to transition communities away from diesel power.
Most power systems in Alaska are not connected to the transmission grid. They are generally microgrids that range in size from a few kilowatts to multiple megawatts and include a mix of energy resources, including diesel generators.
The town of Hughes is working to wean itself off diesel, and with about $1.2 million in funding from the federal Department of Energy’s Office of Indian Energy, added solar and storage to its off-grid diesel microgrid.
In 2020, the town began installing a 120-kW solar array and 337-kWh battery system to the existing diesel microgrid and by the fall of 2021, the microgrid was operating four to five hours a day without diesel. It expanded its “diesel-off” time to 11 hours during the summer after adding controls to the system.
Searching for the right generation sources
For Mission Critical Group’s project in Alaska, powering with diesel in the cold climate was not an option. After considering several possibilities, the company decided that solar microgrids with batteries, along with propane backup, made the most sense.
“I have installed diesel in all sorts of cold climates, but cold is -20 or -30 degrees Fahrenheit, not minus 50,” said Coffer. “And you have to keep additives in the fuel. You can't get the fuel up there, so diesel's a non-starter. There's clearly no natural gas lines up there, despite a lot of it being in the ground. We looked at hydrogen fuel cells and methanol fuel cells, and the reliability wasn't there.”
About the Author
Lisa Cohn
Contributing Editor
I focus on the West Coast and Midwest. Email me at [email protected]
I’ve been writing about energy for more than 20 years, and my stories have appeared in EnergyBiz, SNL Financial, Mother Earth News, Natural Home Magazine, Horizon Air Magazine, Oregon Business, Open Spaces, the Portland Tribune, The Oregonian, Renewable Energy World, Windpower Monthly and other publications. I’m also a former stringer for the Platts/McGraw-Hill energy publications. I began my career covering energy and environment for The Cape Cod Times, where Elisa Wood also was a reporter. I’ve received numerous writing awards from national, regional and local organizations, including Pacific Northwest Writers Association, Willamette Writers, Associated Oregon Industries, and the Voice of Youth Advocates. I first became interested in energy as a student at Wesleyan University, Middletown, Connecticut, where I helped design and build a solar house.
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