Transmission

Before industry restructuring and creation of ISO New England in the 1990s, New England saw little investment in transmission infrastructure. Over the past 20 years, the ISO’s continuous study and analysis of the transmission system has helped guide cooperative regional investment to fix weak spots and bottlenecks on the system that greatly improved its economic performance and maintained reliability of service. This investment has also enabled the interconnection of power plants with lower emissions, as well as the more efficient flow of low-cost power across the region.

Today, New England’s electricity consumers, who share transmission project costs, benefit from reduced risk of blackouts, lower wholesale energy costs, and less air pollution, all while the grid is being positioned to become greener and more flexible. Because of this investment, fewer projects for reliability purposes are expected going forward; transmission development will largely shift to projects needed to integrate renewable energy being procured by the states. (Learn more about ISO New England’s responsibility for power system planning.)

Regional Transmission Investment

Based on the needs described in the ISO’s Regional System Plans, New England’s transmission owners have initiated projects reinforcing transmission-serving areas that have experienced significant load growth, such as northwestern Vermont. Projects have also been initiated in critical load pockets, such as Southwest Connecticut and Boston, allowing the import of power from other parts of the system. New interconnections with neighboring power systems also have been placed in service. Together, these interconnections enable the import of competitive and emergency supplies of electricity from New York and eastern Canada. The region met 17% of its energy needs with imported electricity in 2018.

As of the March 2019 Regional System Plan Project List, 797 project components had been placed in service and an additional 72 projects were anticipated over the next 10 years to ensure that electricity continues to move reliably and efficiently across the region.

Fast Stats
  • 9,000 miles of high-voltage transmission lines (115 kV and above)
  • 13 transmission interconnections to electricity systems in New York and Eastern Canada
  • 17% of region’s energy needs met by imports in 2018
  • 797 project components placed in service across the region since 2002 to fortify the transmission system; 72 planned, proposed, or under construction, as of the March 2019 Regional System Plan Project List
  • 17 Elective Transmission Upgrades (ETUs) proposed as of the January 2019, ISO Generator Interconnection Queue, totaling nearly 14,000 MW of potential transfer capability, which would help access non-carbon-emitting resources

New transmission investment in New England

Improvements Have Lowered Energy Costs

Transmission system upgrades have contributed to striking decreases in congestion costs in the New England energy market and have, with the aid of low natural gas prices and other factors, helped drive down and mitigate “uplift” payments to run specific generators to meet local reliability needs. Additionally, since 2010, the ISO has not had to rely on special reliability contracts with older, less efficient generating resources in weak areas of the transmission system.

New England Costs for Congestion, Uplift, and Reliability Agreements

Positioning for a Hybrid Grid: More Wind and Hydro Power Means More Wires

Additional investment in transmission infrastructure will be fundamental to meeting the states’ policy directives for renewable energy and to reliably decarbonizing millions of vehicles, households, and businesses.

Of the roughly 13,500 MW (nameplate) of wind power being proposed regionally (as of January 2019), about 9,500 MW would be offshore of Massachusetts, Rhode Island, and Connecticut, with most of the remaining 4,000 MW located onshore in Maine. (Historically, almost 70% of proposed new megawatts in the ISO Generator Interconnection Queue have ultimately withdrawn.) Read more about proposed new resources in the region.

Because of the large distances from some of the proposed onshore wind power projects to the existing grid, major transmission system upgrades will be needed to deliver more of this power from these remote, weaker areas of the system to far-away consumers. Proposed offshore wind projects closer to New England load centers may require fewer upgrades to the existing grid, but building wind turbines offshore is typically more costly than placing them on land.

Representative of the types of projects announced for the region in recent years

Refining the Elective Transmission Upgrade (ETU) Process to Support State Efforts to Connect More Renewables

In 2015, the ISO improved its interconnection study process for elective transmission upgrades (i.e. not reliability-driven upgrades) and introduced new rules that ensure that renewable resources are able to deliver capacity and energy into the wholesale electricity markets. ETUs are transmission lines funded by private parties—not through regional cost-sharing. While not necessary from a reliability standpoint, they can help enhance generator deliverability or facilitate the integration of renewable resources, such as remote wind resources, by enhancing portions of the grid.

Today, private developers are competing in state procurements to build transmission projects that would enable the delivery of thousands of megawatts of clean energy, mostly from wind resources in northern Maine and hydro resources in Canada (not all proposed wind projects in New England would be delivered through ETUs). As of January 2019, more than 15 ETUs were proposed to be built over the next four to eight years. State procurement programs will be major deciders of which projects will move forward. Coordination of energy policy among multiple states is challenging, particularly when infrastructure needs to be built across multiple states.

In 2017, the ISO implemented a new “clustering” methodology that enables interconnection requests from multiple generators and ETUs in the same area to be studied together. This is helping to advance the requests in northern and western Maine where thousands of megawatts of proposed new resources, mostly wind, are seeking to interconnect to the regional grid. It may also help generators save on interconnection costs. The first cluster of resources is proceeding through the interconnection study process on the basis of these new rules.

Read more about the ISO’s responsibility for long-term transmission system planning on the Power System Planning page.

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