Making costs of algae oil production more reasonable

Washington, November 4: Two Kansas State University engineers are assessing systematic production methods that could make the costs of algae oil production more reasonable, helping move the US from fossil fuel dependency to renewable energy replacements.

The idea by K-State's Wenqiao Yuan and Zhijian Pei is to grow algae in the ocean on very large, supporting platforms.

Compared to soybeans that produce 50 gallons of oil an acre a year, some algae can average 6,000 gallons, but it's not cheap to produce.

Current algae growing methods use ponds and bioreactor columns, and algae float around suspended in water.

Harvesting such a moving target systematically requires using very costly inputs like centrifuges and electricity.

Pei and Yuan are working to identify oil-rich algae species that are inclined to settle down and grow en masse on a solid surface, a characteristic that will make algae production manageable and harvesting much simpler.

"We think there is tremendous potential for algae oil production if we grow it on big platforms and incorporate the ocean into the system," Yuan said.

"Half the cost of growing algae is in providing a steady supply of food and water, the growth medium. Ocean water offers those in abundance," he said.

Pei said the research team has achieved some exciting results.

In studies of two species of algae characteristically high in oil content and fast growing, both species attached very well to a stainless steel, thin film surface that was slightly dimpled.

Furthermore, once the algae attach, they grow very well, producing a green clump several millimeters thick.

"Our results indicate that the algae attach better on a slightly textured surface," Yuan said.

"We need to understand the algae attachment mechanism before we can select species more likely to attach to a solid support," he said.

Pei and Yuan think large-scale algae production done on very large support surfaces in ocean water is quite feasible.

They are imagining a long, continuously rolling surface like a conveyer belt.

"Right now, we really are thinking in terms of a large-scale biological and mechanical production system," Yuan said.

As Yuan describes the system, the algae would grow on the thin-film surface submerged under the ocean.

At some point, the growth surface rolls up into the sunlight and the algae dries.

A harvesting knife at the end of the conveyer system scrapes off dried algae, at which point the surface submerges to become home to the next growth of oil-rich algal material.

--ANI