TC Energy agreed to sell the Portland Natural Gas Transmission System to Blacrock for $1.14 billion. : TC Energy Corp. and its partner Northern New England Investment Co. Inc., a subsidiary of Energir LP, have agreed to sell the Portland Natural Gas Transmission System (PNGTS). TC Energy said in a media release that a purchase and sale agreement was signed to sell the asset to BlackRock, through a fund managed by its Diversified Infrastructure business and investment funds managed by Morgan Stanley Infrastructure Partners.