With regional electricity demand projected to climb as much as 11% over the next decade, the oldest transmission line in New England is about to undergo a $470 million, multi-year rebuild.
National Grid said its A1/B2 Transmission Line Project will facilitate increased energy capacity in Central Mass. and modernize aging infrastructure that’s more prone to outages and other problems. The project involves upgrading more than 570 structures dating to 1909 along a stretch of approximately 47 miles from the New Hampshire border through Franklin and Worcester counties ending in Sterling. It connects into 6.8 miles of upgraded lines already completed in New Hampshire and Vermont.
The utility company said the line was originally constructed to deliver hydropower from Vermont to towns in northern Franklin and Worcester counties. The line supported industrial growth and major infrastructure development in the early 1900s, including the construction of the tunnels necessary to expand the water supply for Boston from the Quabbin and Wachusett reservoirs.
“While the lines continue to serve the region, they no longer meet modern reliability and capacity needs. Due to their design and configuration, the existing system is more susceptible to outages caused by lightning, vegetation, and other environmental factors and its design limits access by modern equipment for maintenance and upgrades, which can lead to more frequent interruptions and longer restoration times for customers,” National Grid said. “Additionally, the lines and associated infrastructure lack sufficient capacity to support future energy demands, accommodate new customer load, or integrate additional distributed energy resources.”
ISO New England, the operator of the New England electric grid, said last spring that increasingly widespread electric heating and transportation is projected to push demand on the grid up about 11% by the mid 2030s. Annual energy use in New England grew steadily between 1995 and 2005, driven primarily by increased economic growth and the use of air conditioning, ISO-NE said. Since 2005, net annual energy use has trended downward mainly due to an increase in efficiency.
The new corridor — which originates in Vernon, Vermont, and travels through Hinsdale and Winchester, New Hampshire before continuing into Warwick, Royalston, Winchendon, Gardner, Westminster, Fitchburg, Leominster, and Sterling — is expected to be completed and in operation by late 2030. National Grid said it would initially operate at 69kV but with the capability to support 115kV, which it said is the modern standard for transmission infrastructure.