Regional electric utility and grid operators say they are being forced to curtail power sources and that new development may not be possible due to energy grid saturation in northern Vermont.
“During periods of a high generation or low consumer demand, ISO New England must curtail some resources in order to maintain safety and comply with reliability standards,” Matthew Kakley, ISO-NE spokesman told True North Reports on Wednesday. “These curtailments are meant to ensure that transmission lines are not overloaded beyond their physical capacity.”
Managing the power grid in the age of unpredictable wind and sunshine adds a new challenge for the energy supply side. On the demand side, increased efficiency for heating and other appliances also poses a challenge.
“You need some balance — you want the generation of electricity to match the demand of the energy. You don’t want it to be out of sync,” said Andrea Cohen, manager of Government Affairs for the Vermont Electric Cooperative. “More and more generation and not that much demand, that’s not good for the system.”
According to the Vermont Electric Power Company’s (VELCO) overview of the Sheffield-Highgate export interface (a power-saturated portion of the northern grid), curtailment is already unavoidable.
“Seeking to prevent generation curtailment at all times would lead to disproportionately costly projects compared to the marginal benefit that can be achieved,” the document states.
According to VELCO’s grid document, curtailment usually happens during the mid-day, during periods of high generation, or at planned maintenance outages, and coinciding with periods of lowest demand. Such periods often occur at the same time as high wind and hydro generation, leading to waste.
Vermont Electric Co-op CEO Christine Hallquist says efforts in Vermont to increase energy efficiency, while looking good on paper, have an unintended negative effect.
“It’s not so simple anymore,” Hallquist said. “With distributed generation, sometimes increased efficiency can go against our goals. We actually need more demand. The more demand we can get, the more generation we can put out. Generation kind of pushes out on the wire and demand pulls it in.”
Hallquist said there might be some opportunity for better grid efficiency during nighttime hours when around just 10 percent of the energy available is actually used. For instance, this might be a good time for electric car batteries to recharge or for electric heat-pumps to warm up homes, all with energy which otherwise goes to waste.
ISO-NE is working hard to make grid upgrades. Since 2003, the region has invested more than $8 billion in transmission upgrades to ensure reliability, with another $4 billion in reliability upgrades expected in the coming years. These upgrades have provided the region with improved reliability.
“While these upgrades were designed to address weaknesses in the transmission system and to shore up reliability, they’ve eased the flow of power around the region, enabling lower-cost, more efficient generators to be used more,” Kakley said.
Annette Smith, executive director of Vermonters for a Clean Environment, said there are projects pending by Vermont renewable energy developer David Blittersdorf that need more scrutiny for grid impact.
“He’s proposing projects all in grid-constrained areas,” Smith said.
“The Swanton Project is not in the Highgate-Sheffield constrained area, but it’s in a different area that would perhaps curtail Georgia Mountain (Wind) and McNeil Biomass (an incinerator in Burlington). That’s why the utilities are opposing that one, especially Burlington Electric,” she said.
Smith added that the Holland and Irasburg wind turbine proposals would most likely curtail existing Sheffield and Lowell turbines.
“The big question is, why does Blittersdorf keep trying to do things in that grid-constrained area?” she said. “There is capacity in other places. I just don’t get it.”
Hallquist says the over-saturation means new energy projects simply have to look elsewhere.
“Any developers that want to build new projects up there, well now we’ve reached the limits of the system, now the answer is to move it to other areas of Vermont where there’s capacity available,” Hallquist said.
Hallquist reaffirmed VEC’s commitment to Vermont’s renewable energy goals, including 90 percent renewable energy use by 2050.
“We are going to continue to have these public policy debates around what does it take for Vermont to reach its long-term renewable goals that are defined in the Comprehensive Energy Plan,” Hallquist said. “That’s something that Vermont wants, we’re here to serve, and we’re here to help Vermont achieve those goals.