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Squeezing fuel from oranges

Orange juice makers  needed a new use for the leftovers. So USDA researchers found one: ethanol for your vehicle.

By WILLIAM R. LEVESQUE
Published May 30, 2006


Orange juice processors needed someone to invent the better mousetrap.

For decades, processors had made dry pellets out of the orange peels left over from juice production, selling them as cattle feed for a small profit, much of it to European farmers.

Then in the early 1990s, the bottom fell out of the feed market. Prices fell; production costs increased.


That’s when juice processors approached U.S. Department of Agriculture researcher Karel  Grohmann, based in Winter Haven, and posed a deceptively simple question: Can anything besides cattle feed be created from those messy orange peels?

His solution was ethanol, a natural biofuel more commonly extracted from corn and sugar cane.

“The citrus peel was a natural to make ethanol,” said Grohmann, who is now retired.

Today, USDA researchers partnered with a private ethanol company are in the midst of a large-scale experiment that scientists say is proving that ethanol extracted from citrus waste is a profitable, technologically feasible alternative for helping rid the industry of up to 3½ tons of waste each year.

Bill Widmer, a chemist at the USDA Citrus and Subtropical Products Laboratory in Winter Haven, said the citrus industry could produce up to 55-million gallons of ethanol annually based on current citrus production figures.

That’s a drop in the bucket compared with the 4.3-billion gallons of ethanol produced in the United States, mostly from Midwestern corn. But for citrus processors, it would provide revenue where they currently take a loss.

Up to 95 percent of all oranges grown in Florida are used to make juice.

“We view it as very promising,’’ said Scott Stevenson, owner of Renewable Spirits, a Delray Beach ethanol company funding the USDA research.

“It’s very economically appealing with a return on an initial investment in just two to three years. Processors are just giving away (the waste) right now.”

Widmer said processors would earn three times more money from ethanol than they currently get from selling waste product as cattle feed, which earns them from 2 to 4 cents a pound.

“They’re just happy to get rid of it, even as cattle feed,” he said. “It would cost them much more to take it to the landfill. And they’ve got to get rid of it somehow. They don’t have a lot of choice.’’

The USDA research, headed by Widmer, has previously shown on a small scale that it was technologically viable and profitable to produce ethanol from citrus pulp. Now, they’re proving it on a larger scale.

Earlier this year, the USDA built a 10,000-gallon pilot facility at a Bartow juice processor and surpassed a milestone that was the ethanol equivalent of the four-minute mile: The USDA produced four gallons of ethanol for every 100 gallons of liquid waste pulp. Widmer said the process is profitable at that level.

Smaller-scale tests have been even more encouraging, with five gallons produced from 100 gallons of waste pulp.


Widmer said he expects to reach five gallons in the 10,000-gallon facility. Tests earlier this year used grapefruit waste by-products, which don’t produce as much ethanol as orange pulp, he said. Late this year, the large facility will begin processing orange peels.

“In the last few months, we’ve heard processors talk a lot more about ethanol production,” said Widmer, who said startup costs might be several million dollars. “And the value of the product is only going to go up, along with gasoline prices.’’


He said ethanol generally sells at about the price of gasoline. If gas prices were ever to plummet, the process might not be so attractive.
Florida Agriculture Commissioner Charles Bronson last month challenged Florida farmers to produce more ethanol.

“I know we can do it,” Bronson told a gathering of stockholders for Farm Credit of South Florida, according to the Palm Beach Post. “We can have 2-million acres worth of crops for fuels if we can get enough plants built so we can turn it into ethanol.’’
Processors certainly have taken notice, said Dan King, who until recently was the interim executive director of the Florida Citrus Processors Association.

“They’re in a wait-and-see mode,’’ said King, who now works for the Florida Department of Citrus. “They need to see better evidence that there will be a positive return on any investment.”


Renewable Spirits in recent months has shown data to processors that it says proves the technology can pay for itself … and then some.

Stevenson said he is looking to partner with a company to produce ethanol to prove to all that it can work outside the laboratory.
Florida’s Natural Growers, a Lake Wales processor, is currently reviewing the technology but is undecided about its future.

“Producing ethanol from (citrus waste) is a very interesting idea,” said Don Gray, the company’s senior engineering manager. “We’re still in the process of evaluating it economically. I can say it doesn’t look real far off that it will be economical. We have to dispose of that waste in some manner.”

What makes an orange peel attractive to produce ethanol is that it is full of sugars. Once the sugars are fermented by microscopic yeasts and a bacterium introduced into the enzyme-laden process, ethanol is produced.

In previous years, the costs of those enzymes was enormous.

“If it cost $15 in enzymes to produce $1 of ethanol, where’s the economics in that?’’ Widmer said.

The process still allows processors to extract a peel oil from the waste product, which can then be sold for a variety of uses, including use as a degreaser in machinery.

“Processors are still saying, 'Show it to me, prove it to me,’ ’’ Widmer said of his waste-to-ethanol process. “I don’t blame them. If I were going to plunk down millions on a plant, I’d want an assurance that it would work 100 percent.’’

William R. Levesque can be reached at (813) 226-3436 or levesque@sptimes.com.