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From Peas to Ethanol
AEN News
Washington - So you don't like eating peas? Then how about fueling
your car or truck with them? That's a possibility Agricultural
Research Service (ARS) scientists are exploring--using a type of
fuel called ethanol, made from the legume's starch.
Ethanol is among the cleaner-burning alternatives to petroleum, and
is credited with reducing tailpipe emissions of carbon monoxide
and other pollutants when added to gasoline.
In 2004, some farmers contacted ARS microbiologist Nancy Nichols
about new ways to add value to their field pea crops. Most peas
grown in the northern United States and elsewhere are fed whole
to animals as a rich source of protein. The remainder is sold
for human consumption as split peas. Besides protein, field
peas also contain lots of starch. The farmers thought they
might earn more if the crop's starch could be used to make
ethanol for fuel, while still using the leftover protein
as high-value feed for animals.
To find out, Nichols teamed with Bruce Dien, a chemical engineer;
Victor Wu, a chemist (formerly with ARS, now retired); and Mike
Cotta, a microbiologist--all at ARS' National Center for
Agricultural Utilization Research, Peoria, Ill. There, they
put whole peas through a three-step process.
First, they dry-milled the peas into flour. Next, they separated
the protein and starch. Finally, they used enzymes and yeasts
to ferment the starch's sugars into ethanol.
During studies, the fermented pea starch produced somewhat
less ethanol than corn (1.7 gallons per bushel versus 2.8),
because the legume had less starch to begin with. But the
pea starch fermented just as easily as corn starch.
Potentially, the high yield of enriched protein, together
with the fermentation leftovers, could be sold as livestock feed.
Economic modeling studies are now under way to determine whether
using pea starch could be profitable to commercial ethanol plants,
especially those located in areas where the legume is grown.
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