The computer simulated assessment from the Independent System Operator (ISO) New England reports Vermont and New York could face overloads -- defined as more electricity flowing through the system's equipment than it can handle, which could lead to the lines heating up, sagging, possibly melting and eventually shutting down -- in the system if the nuclear facility goes out of service once its license expires in roughly 17 months.
New Hampshire lines could face severe overloads with certain combinations of large transmission lines out of service, according to the early assessment on the region's transmission grid and its reliability.
Advocates for the 38-year-old Vermont Yankee point to this document as further evidence of the facility's importance to the energy grid. Opponents are not surprised with the assessment, saying that any time a generating source is taken offline there is always a temporary energy shortage.
But local electric companies are reaching out to stakeholders and other interested parties to inform them about the context of Vermont Yankee's possible closure and its impact at the regional level.
Chris Dutton, CEO of Vermont Electric Power Company, Inc. (VELCO), said problems within the state would likely revolve around low voltage issues -- such problems are likely resolvable with minor equipment modifications in different substations.
"In New Hampshire, however, it appears the situation is more acute and that there will actually be lines that overload if Vermont Yankee is not relicensed," he said. "The impacts are greater in New Hampshire in part because the load centers in New Hampshire are closer to the plant than is the load center in Vermont, which is in Burlington."
However, simulated findings showed potential deficiencies were expected to rise under certain conditions in 2018 absent improvements to the grid, which were similar with or without Yankee in operation.
The most recent Vermont Needs Assessment was partially in response to the February vote by the State Senate to block plant owner Entergy Corp.'s relicensing bid. The report was designed to analyze scenarios of the potential affects of Yankee permanently going out of service.
An updated needs assessment focusing on a future without Yankee online is currently under way and is expected to go public at the end of the year. A follow-up solutions assessment report is likely to be released in the first quarter of 2011.
According to Dutton, the idea behind the assessment is to gauge the entirety of the system and test its robustness both in a steady state, but also assuming the largest negative effect that may occur as well.
"Whatever would cause the most disruption; they assume that occurs and they see how the system responds to that adverse affect. That is called the ‘N-minus-1,'" he said.
"They have engaged in this N-minus-1 approach, and what they're doing is they're looking 10 years out to 2020 and they're assuming Vermont Yankee is not relicensed," Dutton added. "And then they look at the system with what they think are appropriate assumptions about the generating plants that are running and the state of the transmission system at that time as they anticipate it would be, and then they say, ‘OK, let's assume the event that has the single biggest impact occurs, how does the system respond?'"
The follow-up assessment expected to come up later this year will also chronicle if another crisis happens in addition to the N-minus-1 approach.
Vermont Yankee, located in Vernon on the banks of the Connecticut River, has generated power since 1972. Energy officials have claimed portions of the regional grid have been built around the plant, so consequently, its closure would have an adverse affect on the New England power supply.
Yankee spokesman Larry Smith concurred with the ISO findings, saying the nuclear facility has a reliable and stable record during its operation.
"We agree with the ISO assessment that there could be some instability within the grid with the loss of Vermont Yankee and its 650 megawatts of baseload power," he said.
VELCO has not taken a position regarding the future of Vermont Yankee as Entergy has lobbied to extend the site's license for 20 years.
"That's a position that we take with every power source and we're required to take. We can't show favorites based on kinds of fuel -- we are zealous protectors of system reliability," said Kerrick Johnson, VELCO's vice president for external affairs.
But given the timing, VELCO must plan as if Yankee is not going to operate past its licensing date, Johnson added.
"It is our job to make sure the system is reliable and we assume that Vermont Yankee is there. We find that it has benefit to the grid when it runs ... but it is our responsible simply to make sure the system stays reliable," Dutton said.
Sandy Levine, senior attorney for the environmental nonprofit Conservation Law Foundation (CLF), said the loss of Vermont Yankee's energy was expected; as it would be when any significant power supply goes offline.
"It highlights some change that need to be made to address Yankee no longer producing power," she said. "It also highlights some transmission upgrades to address that. It's possible to address any problems with the grid through generation and energy efficiency that is more local to the power demand."
Groups such as CLF and NEC, both of whom oppose the relicensing of Yankee, also describe the recent assessment as "unalarming" because of a continuing excess of power in the region, claiming the grid does not require the nuclear facility in its long-term power supply needs.
http://www.reformer.com/localnews/ci_16538647
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