SL, I have a personal history in the area, I married a native Nantucket'r in 1975, after being stationed on Nantucket Island while serving in the USCG. The island was then served by several large diesel generators located downtown near the harbor, and a half dozen above ground tanks that contained "bunker fuel", a viscuous substance that had to be heated before it could be injected into the diesel cylinders, as it is on large marine diesel engines.
The relatively small size Nantucket power plant meant that power was costly. There was also an acute safety issue, the power plant was surrounded by frame structures clad in cedar shingles, the mandated "historic architectural style". They would have burned like kindling, in fact fully a third of the town of Nantucket did burn in the mid-19th century whaling era, because they were storing wooden casks of whale oil in warehouses that were located in the same area as the power plant tank farm.
Nowadays, there is an underwater power feed from the mainland. Power is still relatively costly, averaging twice what it costs in most of the USA. Most of the mainland power comes from coal burned in classic high pressure steam turbine type power plants. These were until recently scheduled for retirement as part of Obama's "Clean Power Plan".
Renewables are NOT becoming major players in New England. In fact even though Nantucket is 35 miles offshore, and has near ideal prevailing wind conditions which caused NOAA to add it to the "Top Ten Wind Power Sites" list, the people don't want wind farms. Most of the classic high power steam turbines will be replaced by more efficient "combined cycle" power plants, still fueled by coal, but with stack scrubbing that will turn air pollution into toxic "fly ash".
I know this because I lost $7500 I unwisely invested in the Cape Wind offshore wind farm back in 2007 when Obama touted it as a "shovel ready" green energy project he would "fast track" as soon as in office. He said this during his first presidential campaign, and I believed him. Cape Wind would have occupied totally unused space on the Nantucket shoals and would have been only barely visible from either the island or the mainland:
https://www.capewind.org/ (the link appears dead today, before that was not updated for 2+ years)
The problem was "NIMBY". The view of the offshore wind turbines would have been:
...however, note the Cape Cod town called "Hyannis" on the map above. That is the location of the "family compound" of the powerfull Kennedy/Shriver clan, who refer to it as their "cottage", although it is about 11,000 square feet in three or more large structures. (Look for one of their finer moments when the movie "Chappaquiddic" premieres Friday this week.)
THEY didn't want to look at wind turbines offshore. So they formed a powerfull political alliance with the arch-conservative Republican "Koch Brothers", the fossil fuel magnates who own the large majority of coal contracts for the 80-odd New England area coal plants. Strange bedfellows, to say the least - but this alliance stopped the Cape Wind project dead in it's tracks via lawsuits. My $7500 is gone, which is why I remember this whole sorry story.
Note that the primary benefit of Cape Wind would have been the saving of an estimated 1200 people annually, who die from the asthma, emphysema, and other ailments caused by the coal effluents. That small area on the densely populated East Coast accounts for fully 10% of the 12,000 power plant fatalities that the USA experiences each year. Plus about twice that many who experience respiratory diseases but are only sickened and not killed.
But hey, those approximately 13,200 people that have died since 2007 did so for a reason, so that the Massachusetts royal family did not have to endure the "horror" of the above view of wind turbines on the horizon. But it does positively frost my butt with rage when the Democrats try to paint themselves Green to win an election.