Microalgae-to-biofuel process skips extraction

By Lisa Gibson | May 31, 2010
Posted July 14, 2010, at 4:54 p.m. CST

Illinois-based Unitel Technologies Inc., says it has developed a microalgae-to-biofuel process that skips drying and oil extraction altogether, representing a faster, cheaper and less energy-intensive route to clean fuels.

Instead of focusing on the algae oil, Unitel's patent-pending technology uses fatty acids in biofuel production. That's a night-and-day difference from most microalgae processes, whether manufacturing jet fuel, green diesel, or other fuels. "They all start with the oil," said Unitel CEO Serge Randhava. "But getting to the oil is expensive." Unfortunately, the energy required to extract a drop of algae oil can be more than the amount of energy that drop represents, he added.

So instead, the Unitel process allows continuous treatment of the algae slurry in a special hydrolysis reactor to yield a fatty acid product, a sweet water stream that contains glycerol, and the deoiled algae biomass, according to Randhava. The fatty acids are then catalytically decarboxylated and converted into paraffinic hydrocarbons that go through mild hydrocracking and hydroisomerization to make biojet fuel. "Our focus is to forget oil and just get to the fatty acid," he said. "The fatty acid is a starting point for all the same things as oil." The other streams are not wasted in the process, as the glycerol can be reused in the algae tanks as a carbon source and the algae biomass can be dried and used in animal feed or gasified.

Some of the features of the technology can be traced back to the 1990s when Unitel designed and built slurry-based coal liquefaction and supercritical carbon dioxide extraction demo units, according to Randhava. "The slurry pump loop and the depressurization module are two examples," he said. "The high-efficiency heat interchange system was developed in 1994 when I was chairman of Xytel-Bechtel in Houston."

Randhava has not developed a timeline for commercialization of his process, as the news of its completion is "hot off the press," he said. "What I'm hoping to do is see if I can generate enough interest in the biomass community to enlist three or four strategic partners," he said, adding that developing a pilot or demonstration-scale system would be the ideal next step. "I'd like to see a strategic partnership over the next few months to take this ball and run with it," he said.