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'Hydro' alter ego: Duckweed

Part wastewater purifier, part protein shake, an aquatic plant named “duckweed” could make a splash as another big source of starch for the world’s growing appetite for biofuel.

Feasting on the organic and inorganic nutrients suspended in livestock wastewater (and thereby helping to clean it), the tiny green plant Lemnaceae can produce five to six times more starch per acre than corn. According to North Carolina State University researchers Jay Cheng and Anne Stomp, facilities used to process corn into ethanol can easily do the same with duckweed. Even the energy footprint of the ethanol production could shrink, since the tiny duckweed plant — a few millimeters in diameter — doesn’t require the requisite mechanical grinding that corn does.

With high amino acid and protein contents under the right growing conditions, duckweed is a potential high-protein feed for cattle, poultry or even fish. Reviewing past research, Cheng and Stomp estimate duckweed in a year produces at least six times the protein per acre that soybeans do and 10 times that of rice and corn — all common animal feeds. Past studies have shown that animals fed a vegetarian diet with duckweed supplements have higher growth rates than those fed a regular diet.