Why Vermont wind projects aren’t powering as much as they could 

In the world of electric transmission it’s called “curtailment.” At Sheffield and Lowell Mountain, it’s meant that even on the windiest of days the regional power grid operator, ISO New England, pulled the plug on power production because there was just too much available from other sources. Newer, non-baseload sources like Lowell got yanked first.

“We’re concerned and we think ISO New England needs to do a better job at integrating these renewables,” said Chris Recchia, the commissioner of the Vt. Department of Public Service.

After more than a year of operation, Sheffield has operated at about 23 percent of its planned 32 percent capacity; part of that shortfall is caused by curtailment. Green Mountain Power officials– operators of Lowell Mountain– say it’s too early to gauge efficiency.

“The entire plant went online at the end of last year. And with any new plant there are lots of things you still need to do, a lot of maintenance, startup maintenance, we had some sound testing. So, we’ve been doing well with that. It’s not at the same capacity as we expect to get next winter,” said Dotty Schnure, the spokeswoman for GMP.

GMP plans to install a $10 million device to help ease the transmission issues. But even that won’t completely solve the problem. State officials say it’s disappointing to see so much wind capacity left on the table.

“I would like to see the priority given to the distributed renewables first and to adjust things like gas and oil, and to not have those running when they don’t need to be,” Recchia said.

Along with the region’s shortcomings in infrastructure, like 60-year-old power lines, transmission planners say the realities of the power market don’t always jibe with renewables.

“So it isn’t that it wasn’t foreseen, it was based on the information you know and can try to and foresee, but it’s an extremely dynamic environment– Maine, Vermont, New Hampshire, Massachusetts, Connecticut– those states are seeing an explosion in renewable energy, smaller-scale renewable energy,” said Kerrick Johnson of VELCO.

The developer of the Seneca Mountain wind proposal in the Northeast Kingdom this week said they are scaling back from 35 turbines to around 20, primarily because of overcapacity concerns.

“We cannot carry any more large wind capacity on those lines,” Johnson said. “Everybody knows this. Seneca has publicly made aware that they’re aware of this. In the end it all boils down to how much money are you willing to spend to ensure system reliability to accommodate your project.”

Washington Electric Co-op purchases power from Sheffield. Co-op officials say technology and infrastructure should not be considered limitations, and that Europe provides a good example of how to successfully incorporate renewables.

“So that you can take the wind when the wind is blowing, take the solar when the sun is shining and have your backup sources fill in as they do now,” said Avram Patt of the Washington Electric Co-op.

Some say until the curtailment problem is addressed, the prospect of future big renewable projects will, in a way, be self-limiting.

Beyond wind, the Public Service commissioner says issues of blending new power sources into the grid, including the fast-growing popularity of solar net-metering, will need to be addressed.