Argo Plans Major Redevelopment of Cross-Sound HVDC Cable
Argo Infrastructure Partners has announced that Cross-Sound Cable Company, LLC is initiating a project to significantly upgrade and expand its electric transmission system — Cross-Sound Cable (CSC), a critical HVDC transmission system connecting the electric grids of New England and Long Island.
CSC is a 24-mile submarine transmission cable with 330 MW of bi-directional capacity linking the ISO New England electric grid with New York ISO's Zone K, with HVDC converter stations located in New Haven, Connecticut and Shoreham, New York. Originally developed by TransÉnergie U.S., a subsidiary of Hydro-Québec, the system was provided by Hitachi Energy as a complete 330 MW ±150 kV HVDC Light® transmission system, with commercial operation beginning in mid-2003. CSC has operated reliably for more than twenty years, including over a decade under Argo's management. CSC's current capacity is 100% contracted to Long Island Power Authority and at times provides approximately 7% of the electricity needed by Long Island electrical power users.
As part of its planned redevelopment, Argo has initiated a targeted process to select a transmission redevelopment partner for CSC. Marathon Capital has been engaged to support this process, which is focused on identifying a partner with experience in transmission development alongside infrastructure capital to support a comprehensive modernisation and expansion. The contemplated initiative aims to enhance resiliency and reliability and bring significant incremental transmission capacity.
CSC is described as ideally situated to support the U.S. Department of Energy and the Federal Energy Regulatory Commission's stated goal of expanding inter-regional transmission.
Argo's managing partners have underscored the strategic importance of the asset. "Cross-Sound Cable is a critical interregional transmission platform, regulated by NY's PUC, that delivers reliability, cost benefits and, for Long Island, access to cleaner energy resources," said Jason Zibarras, Founder and Managing Partner of Argo. Michael Madia, Managing Director of Argo, stated that CSC is "uniquely placed to serve as a foundational component of a broader Northeast transmission network, supporting reliability, economic growth and energy resource flexibility."
Argo's broader transmission portfolio includes Hudson Transmission, a 660 MW interconnection between the PJM grid and the NY ISO (Zone J) grid in New York City, and Smoky Mountain Transmission, a ~90-mile system supporting ~400 MW of hydroelectric power in North Carolina and Tennessee, linking into the transmission systems of both TVA and Duke Energy. As of December 2025, Argo manages approximately $7.5 billion in assets.
Argo expects that the redevelopment of CSC will support regional workforce development and specialised construction activity during modernisation and upgrade phases, while strengthening long-term energy security for customers.
