Aquatic Biofuels

Up to now you may have only heard of growing micro-algae for fuel at experimental large scale in either open pond systems or Photo Bio-Reactors (PBR).  However, two engineers from Kansas State Universitiy Wenqiao Yuan and Zhijian Pei, are designing systems to grow and harvest algae more efficiently and successfully in the open seas. The idea is to grow algae in the ocean on very large, supporting platforms. They have been awarded over $98, 000 as a Small Grant for Exploratory Research by the National Science Foundation.

Both professors who teach industrial manufacturing and systems engeneering at Kansas State claim that land from food production should not be used to grow and harvest algae for as feedstock for fuel. Studies are being carried out in their laboratories of the feasibility to grow large scale algae production in the ocean on specifically made production systems.

Professors Pei and Yuan are currently working to identify oil-rich strains that are inclined to grow on solid surfaces, this will make it easier to grow and harvest the algae once it has been produced.

“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. Professor Yuan went on to say that 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.

In their studies two species of algae have been identified, these are particularly rich in oil content and fast growing and both have shown to attach well to the stainless steel film (dimpled) used as a platform, once the algae attach to the dimpled film they grow very very well. It was also shown that the chosen algae cannot grow as well on smooth surfaces and prefer a rougher more textured surface.

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.

The system works pretty much in this way:  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.

How feasible do you think such a system would be? What about transporting the harvest from the sea to the land and processing it, the cost of processing would not change, but only the drying mechanisms would (drying out at sea and not on land).

The main advantage of such a system seems to be land use – with this system there would be no land used to grow and harvest the algae. This is not really an issue with algae growth anyway as marginal and desert land is mainly used. Only if costs of production and investment are lower than open-pond or PBR’s  systems then this could be a viable option.

Please leave any comments you may have below.

Tony Piccolo – Aquatic Biofuels Specialist, Rome-Italy