Study Finds Vermont Yankee Shutdown Could Strain Grid

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(Host) The shutdown of Vermont Yankee could strain the New England transmission grid and require upgrades to keep the network stable.

That’s a key finding of a recent report that looks at a scenario without Yankee in the region.

But as VPR’s John Dillon reports, the situation is not as dire as first feared.

(Dillon) Yankee is far and away the largest power generator in Vermont. The electrons it pumps into the grid helps keep the transmission system stable.

That’s why ISO-New England – which oversees the regional grid – wanted to look at what happens if Yankee shuts down as scheduled next year.

(Johnson) "The good news here is that we have time."

(Dillon) Kerrick Johnson is a vice president with the Vermont Electric Power Company, which runs the statewide transmission network. Johnson says he and other officials were worried that the closing of Vermont Yankee could require new power plants to be up and running quickly. But based on the ISO study, that doesn’t appear to be necessary.

(Johnson) "It’s a very conservative view. And so when you start with it may be that it’s so bad that we would have to wheel in emergency generation. That has proven not to be the case, thankfully, because that’s expensive and dirty and noisy. As a matter of fact it now appears that we will have time to effect and execute the solutions required to ensure system reliability."

(Dillon) Johnson says transmission operators have two or three years to work out a plan. Johnson says the solutions could be transmission upgrades and measures to control demand.

(Johnson) "It’s likely we’ll need some transmission, probably installation of equipment at existing substations, what are called capacitors and reactors to handle respectively over voltage situations and low voltage situations, as well as we might have to build some transmission, some new transmission lines. But those appear to be modest in nature, in existing rights of way and in parallel to existing lines.

(Dillon) The ISO study was based on situations that could threaten the grid, such as the loss of a major generator coupled with a large power line failure.

If two of these mishaps happen at once, ISO says transmission lines could overheat and regional blackouts could occur. The report says the system needs work, with or without Vermont Yankee.  But it says Yankee’s shutdown could make things worse.

For VPR News, I’m John Dillon in Montpelier.

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