Do-it-Yourself Oil Extraction

The conventional wisdom has always been that combining oil crushing and biodiesel production is too expensive for all but the largest producers. That thinking has put biodiesel producers at the mercy of a volatile and capricious oil market. A California engineering firm says it's found a way for biodiesel makers to take control of their feedstocks.
By Jerry W. Kram | January 17, 2008
Excessive feedstock costs have been a thorn in the side of the biodiesel industry for more than a year. Small producers in particular have been at the mercy of oilseed crushers who have passed along higher oilseed costs. Biodiesel manufacturers could have more control over their processes if they could extract their own vegetable oil and perhaps even diversify their feedstocks. Mechanical crushers have lower capitol costs, but leave about one-third of the oil in the oilseed cake. The alternative, solvent extraction, removes almost all of the oil from the meal. However, economies of scale have prevented all but the largest biodiesel plants from doing their own solvent extraction.

Murrieta, Calif.-based SRS Engineering Corp. says it's changing that dynamic. SRS says its solvent extraction system can economically cash flow for biodiesel plants as small as 15 MMgy to 20 MMgy. "We are finding out that for biodiesel plants to become profitable it is necessary for them to look at securing feedstocks directly from farmers," says George Hawranik, SRS's senior engineer. "What they have to do then is come up with a method to extract the oils."

SRS provides complete engineering, design and production services for multiple industries, including the biodiesel industry. According to Hawranik, the company has been in business 25 years and has worked in the biodiesel industry the past four years. Its primary business is distillation columns for glycerin strippers and methanol recovery, pretreatment systems and plant development.

SRS is building two facilities that will utilize its solvent extraction system. One, near Birmingham, Ala., will have the capacity to produce 20 MMgy of biodiesel with a 12 MMgy solvent extraction plant. The other plant, to be located north of Fresno, Calif., will be a 60 MMgy biodiesel plant with a 24 MMgy solvent extraction plant. The company is in discussions to start construction on another five to six plants in the coming year. Hawranik says the SRS system can also be retrofitted onto existing plants and incorporated into new construction.

Along with the lower oil yield, mechanical extraction has other drawbacks, Hawranik says. The hydraulic presses that squeeze the oil from the oilseeds require large electric motors to power them, which in turn leads to higher operating costs. "A mechanical system can take as much as five to ten times more electricity in some cases than a solvent extraction system," he says. "To make money in the biodiesel business, energy is a big, big factor." Mechanical systems also require more material storage and handling, more maintenance, and additional workers to operate them.

Offsetting these advantages are the higher capital costs of a solvent-based system. Hawranik says most solvent systems cost double that of mechanical systems. With its design and manufacturing capabilities, SRS can build a solvent extraction system at a price competitive with a mechanical extraction system. "We can produce this equipment and install it far more cheaply than everybody else out there," he says. "We are slightly more expensive than mechanical crushers and way lower than other solvent extraction systems." He estimates that other solvent extraction systems cost about $1.50 per gallon of capacity while mechanical systems were closer to 50 cents per gallon. SRS's costs were closer to the average for mechanical systems than to other solvent extraction systems, Hawranik says. A solvent extraction system also requires additional land for siting. A 12 MMgy system will require an additional eight to 10 acres.

SRS has several advantages that allow it to create a system that is less expensive than its competitors. The company has a large engineering office plus a manufacturing facility in India where SRS can design and produce its own equipment. "We control our own costs," Hawranik says. "A lot of companies out there are buying combinations of equipment from around the world. Their equipment is from different manufacturers so everyone is getting a cut of the pie. In our case, the pie is basically in our court, so to speak." The company also controls the intellectual property over its designs so it doesn't have to license technology from other companies.

Because of the high capital cost of solvent extraction systems, it has been the conventional wisdom that only large plants producing more than 100 MMgy could make such a system cash flow. The lower cost of the SRS system makes it practical for plants as small as 15 MMgy. "If you go to some of the big companies out there, a 60 MMgy plant will cost $100 million or more to install a system just to process the feedstock," Harwanik says. "Ours is more affordable for a 20 MMgy plant."

How the System Works
In the SRS system, oilseeds are cleaned, cracked and cooked with steam, before being flaked and dried. Oil is extracted from the flaked seed with hexane to create an oil-hexane mixture called miscella. The hexane is recovered for reuse from the miscella in an evaporator. The oilseed cake is steamed to remove the residual hexane, toasted and dried. It is screened and any lumps are crushed to a uniform size, and then mixed and packaged for livestock feed.

The crude vegetable oil at this point contains gums, waxes and other impurities that make it unsuitable for biodiesel production. The oil is degummed by adding phosphoric or citric acid and sending it through a separator. The degummed oil is sent through a bleaching system and is then filtered. Finally, the bleached oil goes through a deacidification column to remove free fatty acids (FFAs). The FFA-free oil and FFA distillates can then be made into biodiesel. "A lot of solvent extraction systems do caustic washing," Hawranik says. "That actually removes the FFA from the soy oil. Soy oil can be anywhere from 2 percent to 4 percent FFAs. Our system actually converts the FFAs to usable oil. Other systems basically water wash their oil, which lessens the quality right off the bat."

The company tested its oil pretreatment system on other potential feedstocks such as chicken fat and turned feedstocks with as much as 15 percent FFAs into 100 percent usable oil, Hawranik says. "I would recommend that every plant being built today have a pretreatment system," he says. "It will pay for itself very quickly. The only pretreatment system I would recommend is one that converts FFAs to oils. You are throwing your money away if you are paying for 4 percent FFAs and you have to dispose of it. It doesn't make economical sense when you can convert it to usable oil and get money for it. If you take 4 percent of 60 million gallons that is millions of gallons of usable oil, or something you have to dispose of. It isn't a very complicated choice."

The oil produced by the SRS system could be considered even better for biodiesel production than commercial vegetable oils because the FFAs and water are removed. "The biggest challenge in building these systems is to prepare it to minimize the amount of rework and cost to condition the biodiesel," Hawranik says. "Our engineering concept basically started with the first drop of oil right through to the first drop of biodiesel. We look at every feature in between to minimize soap content, to minimize the use of methanol and methylates, and Magnesol or ion exchange. People are finding out there that they are getting a lot more methanol than they suspected in the biodiesel. They are using a considerable amount of Magnesol, which is very costly, to bring it up to spec. So we have specifically designed equipment to treat the oil before it gets to the Magnesol." This dedication to quality on the front end makes a difference to the bottom line, Hawranik says. "It makes our plants more efficient," he says. "These are challenges that we have worked on for the past four years."

Hawranik believes it's time for this technology to be widely adopted. When the biodiesel industry was just starting, the people getting into it found that solvent extraction was expensive, which is why the industry became largely dependent on the crushing industry for feedstock. Now that vegetable oil costs are becoming prohibitive, producers are looking for alternatives. "People are researching it," he says. "We know of a couple of mechanical extraction systems going in. We are just joining the game now. We are working with an Indian manufacturer to combine our system and their system to make the whole thing less expensive."

As feedstock sources become more diverse, the SRS system will allow biodiesel producers more flexibility to use the most economical feedstock available, whether imported or domestic. "I think a lot of the feedstock will be coming from counties like Mexico, where there is undeveloped land that can grow jatropha oil," Hawranik says. "We have a party with several thousand hectares available that wants to start doing pilot testing on growing jatropha. We are also working with the University of Tijuana which is helping us put in a plant in the Mexicali area."

Jerry W. Kram is a
Biodiesel Magazine staff writer. Reach him at jkram@bbibiofuels.com or (701) 738-4962.
 
 
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