Isle of Light: How a New England Island Is Gaining Power Independence

Published On
Sep 12, 2018

The little island of Isle au Haut lies about six miles off the coast of Maine, and a single power cable strung across the ocean floor is its electrical lifeline. With that cable already 15 years past its anticipated 20-year lifespan, island residents know their lights could go dark at any time. A solution in the works could make the local resident-owned utility independent from mainland resources and present a new model for the ways artificial intelligence (AI) can make all utilities smarter operators.

While simply replacing the cable is an obvious option, that effort’s estimated $1.7 million price tag is more than the small Isle au Haut Electric Power Co.—really, a for-profit cooperative—can afford. The entire system encompasses approximately 150 meters, with only 42 year-round households, according to the 2010 census. So, the company will pair a new 1-acre solar array and a battery-based storage system with its existing diesel generator as a backup. Also, a network of air-to-water heat pumps will be added to provide an additional form of energy storage during the winter months.

This might sound like the kind of microgrid popping up in isolated communities and military bases across the United States. However, it’s a sophisticated solution that will provide multiple benefits to the small island, including an economic boost. The system won’t require centralized controls. Instead, AI-based distributed sensors and controls will optimize operations in real time to ensure the best use of available power using price signals from each node in the network.

The design of the new system is the brainchild of Dynamic Grid Systems, a joint venture that combines the efforts of Putney, Vt.-based renewable-energy developer Dynamic Organics and Introspective Systems of Portland, Maine, which creates distributed sensor and control networks for a broad range of applications. Solar engineering is being completed by Solar Design Associates of Harvard, Mass.

“We’re developing a system that’s an interesting hybrid of connected and islanded,” said Morgan Casella, CEO of Dynamic Grid Systems and managing partner of Dynamic Organics.

While the existing submarine cable is still working, the power it supplies will be just one more node to be priced into the network. During the winter, that cable will allow the electric company to net meter power back to the mainland grid. However, Casella said the utility is ready to be cost-effective when the cable does fail.

The system’s post-cable economics are based on the addition of air-to-water heat pumps, starting with units to serve municipal buildings and a few selected residences. The solar array is sized to support the island’s larger summer population, which would mean significant excess generation during the longer off-season. Once the cable fails, selling those kilowatt-hours back to the mainland won’t be an option. The new heat pumps will take that excess power instead.

Currently, residents use either fuel oil or kerosene for heating, and they pay a significant premium over the prices paid on the mainland. Plus, that money goes to off-island businesses. The new heat-pump customers will be getting insulation upgrades to ensure efficient operation, and then their much-reduced heating payments will stay on the island as add-ons to their monthly electric bills.

The expected $1 million price tag for the rebuilt grid is still more than the utility can afford on its own. The project, if begun by the end of 2018, is eligible for a 30-percent federal tax credit, but the company’s tax liability is too low for that benefit to be helpful to its own balance sheet. So, to finance the plan, the company plans to pass ownership to a group of passive investors who will be able to make use of the credit, along with accelerated-depreciation benefits. Once costs have been recouped, Isle au Haut’s resident utility owners will buy it back at a reduced cost.

It’s important to note that the ingenuity behind this new plan’s design and financing is nothing new for this tiny community and its utility. The electric company and its distribution lines were largely the work of a small crew who dug their own post holes and strung their own lines in return for stock in the company back in the late 1960s and early 1970s. The route for the now close-to-failing submarine cable was designed in 1983 by a local diver and his partner, with the cable laid from the barge of another resident.

In rebuilding their supply network, today’s Isle au Haut Electric Power Co. managers might be turning to outside help for a change. But this new plan, with its highly renewable (and local) sourcing, and added benefits for locals’ heating bills shows a similar emphasis on meeting real community needs. Its high-tech, real-time control system represents just the latest iteration of a commitment to bring power to the island’s people in a very literal fashion.

About the Author

Chuck Ross

Freelance Writer

Chuck Ross has covered building and energy technologies and electric-utility business issues for a range of industry publications and websites for more than 25 years. Contact him at

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