IV. Structural constraints: Limits of the transmission system.

There seem to have been few questions raised regarding the capability of the existing transmission system to support this project. Without a detailed transmission integration study by the ISO New England, it is difficult to say with any certainty what the transmission constraints on such extensive new power generation in southern Vermont may be. Nonetheless, a few conclusions can be drawn from examining the capacity of the transmission system in the region and the location of current generating units.

NEPOOL has identified the 345 kV transmission tie from Vermont Yankee south to Northfield as a potentially limiting interface. This means that this line does not have much extra capacity to deliver energy south into Massachusetts beyond its current commitment. In addition to power from Vermont Yankee flowing south, New England draws power from Hydro Quebec and New York from northwestern Vermont. This need to import electricity, through Vermont, to meet growing demand in the rest of New England constrains the system considerably. We do know, as discussed above, that most of the energy from these plants would have to be exported from Vermont since the local market cannot absorb 1,350 MW of additional power. The primary interface from southern Vermont to the rest of NEPOOL is through the Vermont Yankee line to Northfield. Since this link is already a potential bottleneck, it is inconceivable that this interface can absorb all that additional output. The interconnection with New York from the Rutland region is quite weak and could carry only a small fraction of the output of the Rutland plant.

Another constraint is the transmission tie between Vermont Yankee and the Rutland area. While this particular tie may be sufficient to carry a portion of Vermont Yankee's 500 MW of output to the Rutland area, it is probably not capable of carrying the bulk of the power from the proposed Rutland plant south to Massachusetts.

The capability of the transmission system in this context is not easily determined. It requires an analysis that lies far beyond the scope of this paper. Nonetheless, these observations about capacities of the existing transmission lines in the area should be regarded as a major potential obstacle in the path of the proposed project. The sheer size of the proposed power plants, and the lack of available markets in the Rutland and Bennington areas, are likely to require the construction of new transmission lines to carry the energy to the rest of New England. To minimize impact from such a project, it would be beneficial to site the transmission alongside the gas pipeline. However, this may not be a viable solution because the southwestern portion of Vermont does not have the strong interconnection with the rest of New England that would be needed. A connection with the New York - Massachusetts 230 kV line is possible, but again, it is altogether unclear whether this connection, combined with existing ties out of Rutland would be sufficient.

New generation would potentially displace some of the power currently being imported from New York and Hydro-Quebec. In that sense it is possibly better to bring the generation closer to the where the greatest demand is, which is Massachusetts. However, this does not resolve the underlying transmission constraint in the inter-tie with Massachusetts.

Another problem is that if the proposed plants were built, they would have to curtail the availability of power from Hydro-Quebec because transmission capability is limited. This may seem fine in context of current prices for Quebec power. Nonetheless, considering the low cost-base of this power, the likely re-negotiation of contracts or other new arrangements at some point in the future, and the fact that high-voltage lines to Quebec are already in place, it may not be in the long-term interest of Vermont to restrict access to this source. Building the Rutland plant would be a further hindrance to increasing such imports unless transmission capacity south of Rutland were expanded dramatically.