US Edition RBS, which is 84pc-owned by the taxpayer, has been forced to slim down and sell off a string of assets to appease European competition regulators after it received billions of pounds in state handouts during the financial crisis. RBS owned 51pc of the joint venture, with San Diego- based Sempra Energy the minority partner.
The bank sold the bulk of its Sempra business to JPMorgan for $1.6bn earlier this year, but the US bank did not pick up the energy trading unit because of fears US regulators would clamp down on risky trading assets.
Noble Group will also assume $265m in debt associated with Sempra Energy Solutions under the deal, which is expected to close before Christmas. The division employs 200 people and sells energy to commercial and industrial customers in 16 US states.
Bruce Van Saun, RBS's finance director, said: "The sale of the Sempra Energy Solutions business line out of our JV with Sempra Energy represents another step in divestiture of this asset as agreed with the European Commission.
"Noble represents a strong strategic fit and a good home for this business."
RBS and Sempra are in advanced talks over the sale of the last remaining assets of the joint venture – its North American wholesale power and natural gas business.