LONGMONT - Biofuel company Sundrop Fuels Inc. is partnering with ThyssenKrupp Uhde Corp. to build the nation's first "green gasoline" plant in Alexandria, La.

ThyssenKrupp, based in Germany, has an American engineering and contracting subsidiary, Uhde Corp., based in Bridgeville, Pa. More than 70 engineers from the two companies are working together to design the Sundrop Fuels plant, which is expected to start construction later this year, according to a news release from Sundrop.

The plant is expected to cost $450 million to $500 million to build and could employ 150 people, Sundrop said last year. It will be financed, in part, by tax-exempt private activity bonds, which require no public funding.

Sundrop Fuels plans to use forest plant matter and natural gas to make bio-based "green gasoline."

Sundrop plans to use ThyussenKrupp Uhde's High Temperature Winkler gasification process at the new plant, the company said. The company also will use its own patented RP Reactor, a high-temperature technology.

The production plant is planned to have a capacity of 3,500 barrels of renewable gasoline per day.

In 2011, Sundrop announced $155 million in backing from Chesapeake Energy Corp. Other investors include venture capital firms Oak Investment Partners, with offices in Connecticut, Minnesota and California, which invested $20 million in July 2011; and Kleiner Perkins Caulfield & Byers, which has offices in California and in China and invested an undisclosed amount.