ClearFuels Technology Inc., an 'Aiea company developing biorefineries, said it sold a 25 percent ownership stake to Rentech Inc., a Los Angeles company that has a patented process that can be used for producing synthetic fuels and other products.

The investment coincides with a strategic partnership with Rentech that ClearFuels said will expand its capabilities for biofuels facilities development to include renewable synthetic diesel and jet fuels.

"We plan to establish our technology at demonstration scale and accelerate our commercial deployment by developing projects jointly with Rentech," Eric Darmstaedter, ClearFuels chief executive officer, said in a press statement.

ClearFuels was established in 1998 and has looked at using its technology on Kaua'i as well as begun project development of commercial scale biomass-to-energy projects in the Southern U.S. and internationally.

The technology it uses can convert biomass feedstocks such as sugarcane bagasse and wood waste into ethanol and other alternative fuels at a low cost.

The Hawai'i company also received an exclusive license for use of Rentech's proprietary synthetic fuels technology for production of biofuels from bagasse, and for use of the process with wood waste at up to 12 U.S.-based projects.

"Our investment in ClearFuels was the result of a review of dozens of other gasifier technologies and companies," said D. Hunt Ramsbottom, Rentech president and CEO.

"The addition of the ClearFuels process to our technology portfolio strengthens our renewable strategy and increases the deployment opportunities for our technology for the production of renewable synthetic fuels from rural biomass sources."

In its transaction with Rentech, ClearFuels received warrants to buy up to 5 million shares of Rentech common stock. The first tranche of the shares carry an exercise price of 60 cents each. Rentech's shares rose 1 cent to 59 cents each in stock market trading yesterday.