Keeping Nantucket Powered is a Challenge as Electricity Demand Rises

Nov 24, 2014

A file photo from December 2005 shows the installation of one of Nantucket's two undersea cables at Jefferson Avenue beach.
Credit Rob Benchley

Keeping an island 30 miles off the mainland supplied with fuel and electricity is hard enough, and on Nantucket, there’s also the need to account for the seasonal population that creates a short but significant surge in the demand for energy. It's a complex energy system that is constantly evolving with advances in technology and transportation.

The public beach at the end of Jefferson Avenue on Nantucket looks pretty much the same as the rest of the beaches along the island’s calm north shore. But there’s one big difference, one you can’t see. Buried beneath the sand are two massive cables capable of carrying up to 74 megawatts of electricity. They stretch nearly 30 miles beneath Nantucket Sound to substations on Cape Cod, and deliver all the island’s electricity – think of them as Nantucket’s extension cords to the mainland.

But in the not too distant past, Nantucket generated its own electricity at a downtown power plant along the waterfront. As Nantucket’s demand for electricity increased in the early 1990s, the island suffered 20 to 30 blackouts every year. Dave Fredericks is the former manager of the power plant, which he said was powered by six massive diesel generators.

“We really ran the power plant like a ship at sea,” Fredericks said. “It was loud, it was noisy, most of these units were built in the 1960s, so they were already 25 and 30 years old, and they required enormous amounts of maintenance, enormous amounts of oil.”

The two undersea cables that replaced the generators are part of a complex system of infrastructure and transportation that keeps this island powered up. Above the water, a fleet of barges, ferries and tanker trucks crisscross the Sound to deliver Nantucket’s liquid fuels and gas. It’s a system primed for change thanks to transportation improvements, the evolving nature of Nantucket’s waterfront, and the island’s surging demand for electricity.

A barge delivers 50,000 gallons of fuel oil, which is pumped into the Nantucket's downtown fuel tank farm.
Credit Jason Graziadei

And while there is huge potential for renewable energy on the island, it has gone mostly untapped as islanders have struggled to balance the history and natural beauty of Nantucket with the visual impact of wind and solar energy systems.

As it stands today, just one of the undersea cables generally has more than enough capacity to handle all of Nantucket’s electricity demand. But not always. The island’s peak load, the point during the summer when electricity use is at its highest, has continued to grow. 

“July of 2013, Nantucket’s peak load hit an all-time high, which was 45 MW, and it was up 12.5 percent from a year before,” said Lauren Sinatra, the town of Nantucket’s energy coordinator. “That definitely caught National Grid’s attention -- 12.5 percent in one year.”

That spike is part of a five-year trend in which the island’s energy demand climbed 3.6 percent annually. By comparison, the statewide growth rate for Massachusetts was just 0.6 percent during the same period. That kind of demand led National Grid to start talking about the possibility of a third electric cable to the island – something both residents and National Grid hope to avoid.

George Aronson, the town’s senior technical advisor on energy, said that without a third cable, the island could be at risk during times of peak demand. 

“But if one of the cables goes down…,” Aronson said. “Last summer, Nantucket actually saw a 45 MW peak and that’s obviously greater than the capacity of either of the cables, and if that combination happens, you lose a cable at exactly the hot point of the summer where your peak is greater than the capacity of the cable, there’s a short term problem and that’s the problem that needs to be addressed.”

This town of Nantucket infographic shows how liquid fuel is delivered to Nantucket, where it is used and where it is stored.
Credit Town of Nantucket website

  For its part, National Grid is working to avoid – or at least delay – a third undersea cable. National Grid’s Tim Roughan said it could be done with what he called the “non-wires alternative.”

“Non-wires alternative is essentially, instead of the electric company putting up a bigger wire, we rely on resources behind the customer meter to manage their load,” he said.

The non-wires alternative includes initiatives like increasing participation in energy efficiency and incentive programs, time-varying rate structures, even a voluntary program in which customers would allow National Grid to control their thermostat and air conditioning units.

But the final piece of National Grid’s non-wires alternative? Renewable energy: an option with huge potential, but one that has proven to be a minefield on Nantucket.

The island is blessed with one of the strongest wind regimes on the East Coast, and more than 60 percent of the island is dedicated as open space. But you won’t find a large solar installation on Nantucket, and there’s only two operating wind turbines dotting the island’s landscape at the high school and Bartlett’s Farm. Nantucket voters have rejected proposed wind energy projects at the municipal landfill during three consecutive town meetings between 2012 and 2013, and a series of proposed solar installations on town buildings never materialized.

Despite its abundant natural resources, the island simply hasn’t reached consensus on how to harness them, and on what scale.

George Aronson, the town’s energy advisor, said it’s no surprise an island that takes such pride in historic preservation and conservation might have issues with the development of renewable energy projects.

“Nantucket as a historic district is very proud of its look and feel it’s managed to preserve - the old buildings, the cobblestones,” he said. “And there are many people on the island who feel a larger wind turbine, vertically on the skyline, would be a disturbance to that feel, and that will always be an issue of contention on Nantucket. The visual impact of solar on a building is something that is jarring to many, whether or not that’s compatible with the historical view of the island is a big subject of discussion.”

Every month, the island receives 200,000 gallons of fuel oil and diesel fuel delivered by barge. John Stackpole, the president of Harbor Fuel Oil Corporation, the company that charters the barges and distributes the fuel, remembers when the island’s deliveries were even larger.

“Back in the late 60s and 70s,” he said, “all product came in from New Jersey and New York on barges from Mobil Oil Corp. - kerosene, gasoline, diesel fuel, heating oil all at once, some times as much as 500,000 gallons at a whack. It was called a ‘drug store load’ in those days because it was so many different products.”

A view of the south side of the island's tank farm in downtown Nantucket.
Credit Jason Graziadei

  All of the fuel is stored in an aging tank farm on the edge of Nantucket’s historic downtown. The 11 tanks, located directly behind the Stop & Shop and the wharves lined with stores and restaurants, are licensed to hold 975,000 gallons of fuel. It’s a situation that poses all kinds of issues and concerns: from safety and aesthetics, to the danger of transporting so much fuel through the harbor, where a major spill could threaten one of the last remaining wild scallop fisheries on the East Coast.

Then there’s the question of whether there are better uses for the prime real estate along the waterfront of downtown Nantucket.

“The tank farm has been a controversy for quite a few years,” Stackpole said. “It’s become like an airport, where people have moved around it and suddenly decided that it shouldn’t be there. It’s controversial and people feel it’s not safe, which is not true, it’s very safe facility, there’s never been problems. It was put there originally because everything was waterborne by transportation.”

Town officials have been talking about moving the tank farm out of the downtown area for almost 30 years. Only now does there appear to be real movement toward that goal, and there are several reasons why. More products such as gasoline are now being delivered by tanker trucks on the Steamship Authority boats rather than by barge, so there’s less need for bulk storage. There’s also the fact that the Steamship now runs its vessels to Nantucket from Hyannis rather than New Bedford, and the increased frequency of its freight boats – factors that have changed the equation for fuel delivery to Nantucket, according to Nat Lowell.

“We’re not far away anymore,” he said. “In the old days, theoretically, we were 200 miles away from our fuel source in New York.  Now we’re 26 (miles) with three trips per day.”

Perhaps more important is the fact that surrounding property owners are seriously looking at the redevelopment potential of the tank farm and the former power plant property – two extremely valuable pieces of real estate.

The island’s selectmen also recently issued a request for proposals from companies interested in building and operating a new bulk fuel facility near the airport.

Whether the tank farm eventually moves, or if a third undersea cable someday snakes its way to Nantucket, the island’s distance from the mainland isn’t going to change. And that means keeping the island powered up will likely remain a complicated and expensive puzzle.

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