February 5, 2010

US researchers to extract oil for biofuel through marine sources

Researchers from the University of Missouri have designed a system that extracts oil for use as biofuel by using algae, brine shrimp and tilapia.

The system has the potential of reducing greenhouse gas emissions, said the researchers.

Microalgal biomass production could reduce emissions by providing biofuel replacement of fossil fuels as well as carbon-neutral animal feeds, said David Brune, bioprocessing engineering professor at the University of Missouri.

He said algae were proven to produce 100 times more fuel than soy oil, but they are hard to extract and convert into usable fuel.

Brune and colleagues developed a biomass cultivation model for a proposed 50-megawatt natural-gas-fired power plant in Southern California. In the researchers' design, sludge-fed algae would be cultivated in large raceways. Paddle wheels would hasten reproduction by moving the water. This is where the brine shrimp and tilapia come in.

The brine shrimp will eat the algae and convert it into a consistent, high-quality protein and oil, Brune said. Tilapia consumes the algae to prevent overproduction, reduce zooplankton and clean up algal waste to provide clean water.

The shrimp are harvested and separated into high-protein feeds and oils. The shrimp waste is collected and fermented in an anaerobic digester.

If 100% of the algal biomass consumed by the shrimp were harvested and fermented, the resulting biomass production could replace 26% of the plant's natural gas usage, according to Brune. 

Earlier research by Brune at Clemson University showed that brine shrimp feeding on algae could produce up to 500 gallons of biodiesel per acre per year with little environmental waste.

Microalgal biomass production offers several advantages over conventional biomass production, he said. In addition to higher productivity, this method can use otherwise nonproductive land, reuse and recover waste nutrients, and use saline or brackish waters.