Tao's Team

By Jessica Williams | July 01, 2004
As a professor in the Department of Agricultural and Biological Engineering at Purdue University, Bernie Tao has worked on several experimental projects that challenge biomass parameters.

Over the years, Tao and his students have explored changes in plant microbial behavior to create useful products that people can use. One example is biodegradable plastics made with animal fat. The U.S. government has also asked Tao to look at vegetable oils and soybeans to create renewable products that would replace petroleum, a limited resource. For him, the projects aren't about repeating what scientific advances have already been made, such as renewable fuel, but discovering new products that perhaps no one had thought of before.

"We didn't have any use in making biodiesel fuel because it's pretty simple," Tao said. "But people would approach us and ask, 'What else can you do with this?' So we began to look at what other things you can make with it."

As Tao and his students have proven, the possibilities seem endless.

Getting the most out of biodiesel
The highest value petroleum product in the energy sector is aviation fuel, according to Tao. It differs from ground transportation fuel, and the main challenge is its cold temperature behavior. A biodiesel-fueled car has no problem running in weather 5 or 10 degrees below zero. However, biodiesel in airplane engines would easily crystallize with temperatures in the atmosphere between 40 and 58 degrees below zero. To obtain a more ideal aviation fuel, Tao and his students created an efficient fractionation method for biodiesel, extracting the materials that would quickly freeze in the fuel. Tao's improved biodiesel is being tested in commercial airline engines at Purdue University Airport, where Tao's students measure thrust, emissions and power of various biodiesel blends.

"There's really no other competitors [other than biodiesel] in this area," Tao said. "For cars, you can use fuel cells, coal and ethanol. Biodiesel is the only thing that can work on aviation."

Biodiesel can supply many other useful materials when broken down. Glycerin, obtained from triglycerides in fatty acids, is a sweet-tasting ingredient that can be used to make pharmaceuticals. It can also be added to food in small amounts. Tao said the market for glycerin in those areas is very small and saturated. So he posed the question: "How do we make money from glyceride and not sell it for pharmaceuticals?"

Tao knew glyceride absorbs water very well. He realized it could make an ideal anti-freeze agent. Traditional anti-freeze products, made up of ethylene glycol, are toxic and currently being phased out by propylene glycol. Propylene glycol isn't as harmful but is more expensive. Both are made from petroleum or natural gas. Thus, Tao and his students found a way to use glycerin in anti-freeze as a cheaper and more biodegradable alternative. The glycerin-based anti-freeze works as a deicer for airplanes. One could spray it on the outside of a plane and not worry about contaminating the ground or sewer. Tao is currently talking with a company to commercialize the product.

Tao and his students have also been looking at solvents in biodiesel, such as methyl esters. Methyl esters can be applied to waste such as polystyrene or Styrofoam, and those materials would dissolve into a harmless solution. But what could be done with the leftover solution? Since products that treat wood and protect other materials from erosion, corrosion and weather elements are petrochemicals that emit unpleasant odors and damage the environment, Tao and his students found the polystyrene solution to be an adequate replacement for the petrochemical.

Tao has done experiments with the source of biodiesel: oilseed plants. These plants contain both oil and water, which plants naturally separate by storing the oil in tiny balls called oil bodies. The oil bodies are coated with a unique hydrophobic protein that protects them from water. To give this natural occurrence a boost forward, Tao and his students cloned the protein and genetically modified the oil body with enzymes and catalysts in order to cause the same chemical reaction used to produce biodiesel in production facilities. Tao's altered plants allow for the chemical reaction to occur while the oil is still in the plant. This process, called post-synthetic modification, saves money and gives a full yield of oil production.

Hexane use in the biodiesel production process also posed a challenge for Tao and his students. Hexane is a petroleum alkane added to the oilseed crushing process and then evaporated to create biodiesel. In order to avoid using the explosive, flammable and inedible chemical in the process, Tao and his students created a way to extract the oil using water, which is cheaper. Unfortunately, the process only yields 80 percent to 85 percent oil, whereas the hexane process yields approximately 94 percent. Tao's research at least offers producers a choice: should a cheaper process be used or one that yields the most oil?

Undergrads get creative
Tao said he likes to see where society has a need and discover how he can fill that need with an environmentally-friendly product that can make a profit. He decided to pass that aspiration to his undergraduate students through an entrepreneurship class that demands creativity and smarts to produce a usable product.

The students have responded with a wide variety of products. For example, one woman was concerned about crayons in China that were made from hazardous petroleum material. So she made crayons out of soybeans. Tao said the soy-based replicas are so safe that one could eat them. Another student created soy-based candles that burned twice as long and produced less smoke. An avid skier made ski wax out of soybean oil to replace the regular ski wax that puts harmful chemicals into the environment. A vegetarian student made soy-based gelatin to replace gelatin made from cow bones, a possible source of mad cow disease. Another student made a healthy, protein-based cereal without starch or wheat gluten.

"The kids are so creative and now it's in the market," Tao said. "It's an economic benefit."

Tao also spread his bioscience interests to primary and secondary education institutions. Tao helped develop a science kit that teaches kids to make glue and other adhesives using natural products. The students also make ethanol and biodiesel, run the fuels in an engine and do solvent experiments. Tao said approximately 65,000 kits are distributed across Indiana per year. About 95 percent of elementary schools in the state use them.

Advocating a renewable fuel
Tao knows of the major advantages to using biodiesel. For example, he said biodiesel's lubricity and low sulfur content is ideal. The alternative fuel benefits the environment on a variety of levels, including low air emissions. It's renewable; farmers can grow the feedstock used to produce the biodiesel every year. Economically, it boosts the domestic and industrial markets.

On the down side, biodiesel is currently more expensive than traditional fuels. However, Tao pointed out that as petroleum becomes harder to get, it will become more expensive as well. Consumers have already noticed an increase in fuel prices this summer.

"We can't quit using it," Tao said. "Where are the resources going to come from? The obvious answer is we're going to grow the stuff. Suddenly, we become the supplier."

Tao hopes biorefineries will replace oil refineries in the near future, drawing the fuel market from southern states like Texas to the agricultural Midwest. The experiments Tao does in Indiana edge that concept closer to reality.

"The most interesting aspect of renewable fuel is the merging of biology life sciences and engineering technology," Tao said. "Let's put down the natural laws that govern biology and how they work with technology and what ramifications come with that."
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