William Widmer for The New York TimesThe cutting room floor at a factory in Eunice, La., that processes alligator meat. The leftover fat may have a novel new use: serving as an ingredient of biofuels.
Researchers at the Lafayette campus of the University of Louisiana are looking for green substitutes for diesel fuel. The prime one now in use is soybeans, which are used to make biodiesel oil. But soybeans are also needed for human consumption and animal feed. The United States uses 45 billion gallons of diesel a year; making just one billion gallons from soybeans would use up 21 percent of the American crop, the scientists point out.
Now the researchers think they have identified a potential source for biodiesel that currently goes straight to landfills: alligator fat, about 15 million pounds of it every year.
Alligators are grown and harvested for their meat and for their skins before the fat heads to landfills, noted Rakesh Bajpai, a professor of chemical
engineering at the university. They are not endangered or threatened. (Crocodiles are, but those are not part of the researchers’ equation.)
And alligators are plentiful in the wild, Dr. Bajpai said. “If you start seeing alligator roadkill, you’ve arrived in Louisiana,’’ he said.
The fat has very limited uses. “When I talk to local people, they say, ‘Grandma used to use it for every purpose,’” he said. Often, Dr. Bajpai said, it was used as a cure-all like cod liver oil. But even that use has died out, he said.
That is in contrast to alligators’ skins, which are fashioned into wallets, belts and shoes, or their meat, which is commercially available and which shows up on restaurant menus, often as a deep-fried appetizer. “They say it’s very good,’’ Dr. Bajpai said. “I don’t know. I am a vegetarian.’’
In a paper published on Wednesday in the journal Industrial Engineering Chemistry Research, Dr. Bajpai and five collaborators report on lab experiments in which they converted 61 percent of the alligator fat to liquids that would be usable in biofuel.
Some 15 million pounds could become 1.25 million gallons of fuel, with an energy content about 91 percent as great as that of petroleum diesel. A large plant could produce the fuel at $2.40 a gallon, Dr. Bajpai said, not counting the cost of the fat, which would presumably be zero, or the cost of transporting the fat to the plant.
And for each gallon of biodiesel produced, the refinery would also make a few ounces of glycerol, a chemical valuable in industry, he said.
That would appear to make alligator fuel competitive with commercial diesel, which sells for a little more per gallon than gasoline. And various quotas and credits are available to encourage biodiesel use.