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. Two Kansas State University engineers are assessing systematic production methods that could lower the costs of algae oil production. They plan to grow algae in the ocean on very large, supporting platforms.
Current algae growing methods use ponds and bioreactor columns, and algae float around suspended in water. Harvesting such a moving target systematically requires using costly inputs like centrifuges and electricity. Even with these best technologies for algae growth and production, the end product biodiesel is expensive at about $56 a gallon.
Wenqiao Yuan, assistant professor of Biological and Agricultural Engineering, and Zhijian Pei, professor of Industrial and Manufacturing Systems Engineering, do not think food production land should be used to produce algae for fuel. The two are studying the feasibility of large-scale algae production in the ocean and how to engineer the production systems. They are imagining a long, continuously rolling surface like a conveyer belt.
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.
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. Once the algae attach, they grow very well, producing a green clump several millimeters thick.
"We are doing very fundamental research now," Yuan said. "We need to understand the algae attachment mechanism before we can select species more likely to attach to a solid support."
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.
