Vegetable Oil—The New Fuel?

By John Roach
for National Geographic News
April 22, 2003
As the world watches the price of crude oil fluctuate in response to the conflict in Iraq, chemists and advocates for alternative energy technologies are training their sights on the grease used to cook French fries.

They say that oils derived from soybeans, corn, and other vegetables hold promise as a cleaner and renewable alternative to the finite resource sucked up from the ground.

"It is time for us to start getting sane about how we produce energy and how we use energy," said Charris Ford, an alternative fuels advocate in Telluride, Colorado who drives a modified diesel truck fueled by used vegetable oil that he collects from local restaurants.

Ford is a leader of what he hopes will be a revolution based on the use of vegetable oils to do everything from power cars and protect their engines to serve as the primary lubricant for industrial applications such as the operation of heavy machinery.

Unlike petroleum-based products, vegetable oils are biodegradable, nontoxic, and are derived from a renewable resource. When used as a fuel, they produce nearly 100 percent less greenhouse gases than petroleum-based diesel fuels (see sidebar), and when used as motor oil they improve gas mileage by more than 3 percent and reduce smog-forming nitrogen oxide emissions by 75 percent, according to Ford.

Despite such benefits, however, vegetable-based oils currently comprise less than one percent of the North American market share, according to statistics compiled by the Canadian Agricultural New Uses Council.

One of the roadblocks to the market appeal of vegetable-based lubricants is their unreliability at both high and low temperatures. When they get too hot they oxidize and break apart, and when they get too cold they solidify. Neither of these scenarios bodes well for the engines the oil is meant to protect. Another problem is the high development cost of vegetable-derived motor oils relative to petroleum-based products.

Several teams of researchers are developing technologies to roll over these obstacles. The most recent advance comes from chemists with the U.S. Department of Agriculture's National Center for Agricultural Utilization Research (NCAUR) in Peoria, Illinois.

"Through chemical modification, what we tried to do is make certain changes in the molecular structure," said Atanu Adhvaryu, an associate research scientist with NCAUR and a leader of the project team developing chemically modified vegetable oil for use in car engines and industrial machinery. The team discussed their project Monday at a meeting of the American Chemical Society in New Orleans, Louisiana.

The NCAUR researchers say their chemically modified soybean oil is a simple, cost-effective method for enhancing the temperature stability and lubricity of vegetable oil, while retaining its basic chemistry. Such a development, they believe, has huge market implications that could take hold within the next five years.

Ford, who stars in the independent film French Fries To Go on the use of vegetable oil in lieu of petroleum, spends his days promoting the market potential for vegetable-derived oil products. He is excited by the research being conducted by the NCAUR team and others and its potential application to vegetable-derived motor oils.

"I have spent a great deal of time speaking with folks who are developing this technology and hope one day to use it in my own vehicle as well," he said. "In fact, I hope to one day offer veggie oil changes to the customers at my Grassolean Stations."

Chemical Modification

Like all vegetable oils, soybean oil is made up of what are scientifically known as triglyceride molecules, which under a microscope look like the capital letter E, said Adhvaryu. These molecules are very similar in structure and contain multiple double bonds.

When these molecules containing double bonds are exposed to oxygen from the air and high temperatures, they readily condense together, oxidize and sometimes break apart. At cold temperatures the molecules easily stack together, forming little crystals that join together, eventually rendering the liquid oil a mass of solidified gunk.

What Adhvaryu and his colleagues did was chemically alter the symmetrical structure of the molecules so that they no longer consist of multiple double bonds and are also unable to stack together at cold temperatures.

The result is an inedible vegetable oil product that is more stable at both hot and cold temperatures, which is a key requirement for using it as a stand-alone engine oil, industrial fluid, and specialty grease. In addition, the chemical modification also improves the oil's lubricity.

"In due course of time, five or six years of time, there is going to be a major, major demand for these kinds of fluids," said Adhvaryu.

In addition to use in motor oils, he says veggie oil and its derivatives have a wide range of industrial applications, including hydraulic fluids, lubricants for heavy machinery, and functional fluids for processing metals.

Environmental Benefits

Advocates for the use of vegetable oils say they are easier on the environment because they are much more biodegradable than conventional, petroleum-based oils. When spilt or disposed of on the ground, vegetable oil will decompose by upwards of 98 percent. Petroleum based products only decompose 20 to 40 percent, said Adhvaryu.

Additionally, vegetable oils are a renewable resource. When supplies are low, more crops such as soybeans and corn can be planted to make up the shortfall, which is an added bonus to agricultural economies, according to the NCAUR Researchers. Petroleum, on the other hand, is a finite resource.

Ford says that one of the common arguments he hears about the use of vegetable-based lubricants and biofuels is that there are currently not enough of them to meet the demand for fuels and lubricants.

"I always answer them by saying, 'guess what, we don't have enough petroleum either,'" he said. "We didn't leave the stone age because we ran out of stones; we would be foolish to wait until we run out of petroleum to begin creating an alternative fuel based infrastructure."

A switch to vegetable-derived oils would also preserve finite petroleum resources for other uses, such as the manufacture of plastics, said Ford.

"Conservation should not just be reserved for baby seals," he said. "We need to conserve the sticky black stuff too. Why burn petroleum and poison our air when we're going to need it for computers, auto parts, and CDs?"

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