Renewable Energy Group Inc. on Wednesday completed its previously announced acquisition of substantially all the assets of Imperium Renewables Inc. REG paid Imperium $15 million in cash and issued 1.675 million shares of REG common stock in exchange for substantially all of Imperium’s assets, including the 100 million-gallon nameplate biodiesel refinery and terminal at the Port of Grays Harbor, Wash. Ames-based REG assumed $5.2 million of Imperium’s debt from Umpqua Bank, which has agreed to provide the newly named REG Grays Harbor LLC with an additional loan capacity of up to $5 million to fund capital expenditures and improvements at the facility.