What if an offshore wind farm was up and running last winter? 

Analysis shows the benefits and limitations of wind power 

Last year at this time, New England was gripped by a blast of unusually cold weather that went on for 16 days. The prolonged low temperatures increased demand for natural gas for both heating and electricity, which with the region’s pipeline constraints led to sharply higher wholesale electricity prices and forced power generators to burn more oil in the brief period than they had in the previous two years combined.

Now the operator of the region’s power grid, at the request of the Massachusetts Clean Energy Center, has engaged in a bit of “what if” analysis. What if a wind farm had been operating off the coast last winter?

The analysis indicates a working wind farm last winter would have reduced the region’s carbon dioxide emissions and wholesale electricity prices, but not enough to eliminate the impact of the region’s pipeline constraints. The analysis also shows that a wind farm’s energy production is highly variable, going up and down fairly dramatically over the course of a day.

Stephen Pike, the CEO of the Clean Energy Center, said in a statement that he was encouraged by the analysis, which showed that offshore wind would provide “a significant source of clean energy to the grid that would help shave peak demand, save ratepayers millions of dollars, and reduce the region’s greenhouse gas emissions.”

In doing the analysis, the region’s power grid operator, ISO New England, relied on wind speed data gathered by the Clean Energy Center at three offshore sites from December 24, 2017, through January 8, 2018. The ISO used that data to estimate wind power production for an 800 megawatt wind farm (the size of the project being built by Vineyard Wind) and a 1,600 megawatt farm, and then extrapolated what impact wind farms of that size would have on the region as a whole.

The data indicate wind farms of those sizes would have generated about 70 percent of the power they were capable of generating over the 16-day period, partly because the wind wasn’t blowing hard all the time and partly because at times it was blowing too hard. On three separate occasions, according to the analysis, the turbines would have had to be shut down completely to avoid damage caused by wind speeds in excess of 55 miles per hour.

The analysis estimated the wind farm would have supplied 3 percent (with an 800 megawatt wind farm) or 7 percent (at 1,600 megawatts) of New England’s power needs and reduced carbon dioxide emissions by 5 percent or 11 percent over the 16-day period. The wind farms would also have saved New England ratepayers between $40 million and $85 million in avoided fuel costs, depending on the size of the wind farm.

The takeaway from the analysis is that a wind farm would have had a beneficial impact, reducing emissions and cutting wholesale electricity prices. But the wind farm would not have displaced all coal and oil use during the extreme cold period. The analysis estimated oil use would have been reduced, but only by 4 to 7 percent depending on the size of the wind farm. Coal use would have fallen even less, between 3 percent and 4 percent. Still, as more and more renewables are added to the grid, displacing oil and coal, the impact of a wind farm on coal and oil use should increase.

The other big lesson is that the variable nature of wind power makes it difficult to count on when power supplies are tight. That’s why the development of battery storage and other technologies that would make it possible to store electricity for use when needed is so important.

In the meantime, wind farms have to be conservative when promising how much power they will be able to deliver. The Block Island Wind Farm, for example, is capable of producing 30 megawatts of power at maximum capacity, but for 2021-2022 it is promising ISO New England it will produce an average of 6.8 megawatts during the four summer months and 14.1 megawatts the rest of the year.

Meet the Author

Bruce Mohl

Editor, CommonWealth

About Bruce Mohl

Bruce Mohl is the editor of CommonWealth magazine. Bruce came to CommonWealth from the Boston Globe, where he spent nearly 30 years in a wide variety of positions covering business and politics. He covered the Massachusetts State House and served as the Globe’s State House bureau chief in the late 1980s. He also reported for the Globe’s Spotlight Team, winning a Loeb award in 1992 for coverage of conflicts of interest in the state’s pension system. He served as the Globe’s political editor in 1994 and went on to cover consumer issues for the newspaper. At CommonWealth, Bruce helped launch the magazine’s website and has written about a wide range of issues with a special focus on politics, tax policy, energy, and gambling. Bruce is a graduate of Ohio Wesleyan University and the Fletcher School of Law and Diplomacy at Tufts University. He lives in Dorchester.

About Bruce Mohl

Bruce Mohl is the editor of CommonWealth magazine. Bruce came to CommonWealth from the Boston Globe, where he spent nearly 30 years in a wide variety of positions covering business and politics. He covered the Massachusetts State House and served as the Globe’s State House bureau chief in the late 1980s. He also reported for the Globe’s Spotlight Team, winning a Loeb award in 1992 for coverage of conflicts of interest in the state’s pension system. He served as the Globe’s political editor in 1994 and went on to cover consumer issues for the newspaper. At CommonWealth, Bruce helped launch the magazine’s website and has written about a wide range of issues with a special focus on politics, tax policy, energy, and gambling. Bruce is a graduate of Ohio Wesleyan University and the Fletcher School of Law and Diplomacy at Tufts University. He lives in Dorchester.

The ISO issued a statement saying it is working to incorporate more energy into the region’s power system. “These efforts include implementing new market rules and operational procedures to account for the variability of intermittent resources to ensure the region benefits from renewable energy when it is available, but also ensure the grid remains reliable when the sun isn’t shining and the wind isn’t blowing,” the statement said.