Neptune Regional Transmission System is a developer of the Neptune Project, a high voltage direct current (HVDC) transmission project.

Northwestern Mutual executive vice president and CIO Ron Joelson said Neptune represents a significant addition to the company’s infrastructure equity platform that it has formally launched in 2013 within Northwestern Mutual Capital.

"The combination of current yield from an asset with strategic importance to the power markets of the Northeastern United States is very attractive. Our investment objective is to generate superior returns while maintaining a well-balanced and diversified investment portfolio to preserve the company’s exceptional financial strength," added Joelson.

The Neptune system comprises a 65-mile high-voltage, direct-current underwater transmission cable connecting Sayreville, New Jersey to Long Island, New York.

With operations launched earlier in 2007, the Neptune System’s 660MW capacity is contracted to the Long Island Power Authority (LIPA) under a 20-year agreement.