WASHINGTON – The demand for alternatives to petroleum-based fuels is steadily rising. Corn and soybeans – the dominant feedstocks for ethanol and biodiesel production in the United States – grow well in the central regions of the country.
But are these the only available sources? What options exist for U.S. growers in other regions? How can corn and soybean feedstocks be improved?
Answers. Scientists at the Eastern Regional Research Center in Wyndmoor, Pa., are answering these and other questions about renewable fuels production.
Their research focuses on four major areas: biodiesel, ethanol, thermochemical processes and cost analysis.
Said center director John Cherry, “This is a particularly exciting time, because so much of our research work is being adopted and used by industry.”
What do animal fats, rendered materials, and restaurant grease have in common? Besides ready availability and limited marketability, they’re all subjects of Eastern Regional Research Center biodiesel research headed by research leader Bill Marmer.
Scientists in his group have demonstrated that products of the rendering industry can be used as low-cost feedstocks for biodiesel production.
Trap grease. Biochemist Mike Haas and biologist Karen Scott are working with the Philadelphia Fry-o-Diesel company to demonstrate that trap grease – waste grease that restaurants and food companies collect from their drains – can be converted into a clean-burning, renewable fuel source.
Haas and Scott helped characterize trap-grease samples, advised the company on operation design, and analyzed the products of trial runs.
They have successfully produced fatty acid methyl esters, the chemical compounds that make up biodiesel, from the grease.
The esters are being tested to determine whether they meet accepted biodiesel standards.
These researchers are also developing a method to produce biodiesel directly from oil-bearing materials, including soybean flakes and rendered products.
The oils or fats in the feedstock are treated with 18 percent methanol, forming biodiesel as the extractant.
This would eliminate the need to isolate the oil before converting it to fuel, thereby reducing production costs, and would expand the amount of available fuel feedstocks.
Glycerol. Another objective of biodiesel research is to find uses for glycerol, a coproduct of biodiesel production.
“For every 100 pounds of biodiesel produced, you get 10 pounds of glycerol,” said chemist Tom Foglia.
“Current markets are saturated.”
Concerned that increased biodiesel production could result in a hyperglutted glycerol market, researchers are investigating alternative uses for the compound.
Molecular biologist Dan Solaiman and microbiologist Rick Ashby have found that crude glycerol can be used to support microbial cell growth and production of polyester biopolymers, which can be used as plastics or adhesives, and biosurfactants, which are used in detergents or as antimicrobial agents.
This is particularly important because crude glycerol is less marketable than pure glycerol.
In related studies, chemist Victor Wyatt demonstrated that glycerol could be used to produce a new class of prepolymers for making such products as coatings, resins, foams and agents for remediation of polluted environments.
These alternative uses for glycerol have proved successful on a trial scale.
Now the scientists are testing them at an industrial level through a cooperative research and development agreement with an international consumer products company.
Ethanol. Affordable, available, and easy to work with, corn is the main feedstock for ethanol in the United States. As ethanol production increases, so does the demand for suitable feedstocks.
To avoid overburdening the corn market, ethanol producers have two options: increase conversion efficiency or use an alternative crop.
Several Eastern Regional Research Center projects have demonstrated how these can be done.
Food technologist David Johnston is investigating new processes using protease enzymes from microbial and fungal sources to produce ethanol more efficiently.
In trials, Johnston found that adding enzymes during fermentation sped up the process and increased ethanol yields.
“The enzymes make more nutrients available for the yeast. They expedite the fermentation process and can also make it easier to separate liquid from solids after the ethanol has been removed,” Johnston said.
Efficiency. “This is important because the more efficiently you separate the free liquid from the solids, the more energy efficient the process can be.”
Corn isn’t the only available feedstock for ethanol.
Research leader Kevin Hicks is collaborating with biotechnology company Genencor International; Virginia Tech, in Blacksburg, Va.; and members of the barley industry to explore barley’s potential as a feedstock in regions of the United States where corn is not the principal crop.
Hicks estimates that barley grown in North America could supply about 1 billion gallons of ethanol per year.
The crop is well suited to the Mid-Atlantic, where it could be grown as a winter crop in rotation with soybeans and corn in two-year cycles.
Currently, barley yields less ethanol than corn does, and the ethanol from barley is more expensive. Barley’s physical properties – an abrasive hull and low starch content – impede production efficiency.
Hurdles. But Hicks and his colleagues are overcoming these hurdles with research.
With Genencor, the researchers are developing new enzyme technology that could improve the speed, efficiency and cost of barley-based ethanol production.
They also collaborated with Virginia Tech researchers to develop barley varieties with higher starch content and a loose hull that generally falls off during harvest or grain cleaning.
Initial studies suggest such varieties have promise as a feedstock.
Biomass. There are two main processes, or “platforms,” for making fuels from biomass: sugar and thermochemical conversion.
The sugar platform involves breaking down complex carbohydrates in the biomass – materials such as sawmill waste, straw and cornstalks.
Then, yeasts metabolize, or consume, the simple sugars to make alcohol.
Breaking down those complex carbohydrates requires a lot of energy, Hicks said, and special microorganisms are required to convert some sugars into ethanol.
And, ironically, the process creates a lot of carbon dioxide – the greenhouse gas that’s helping to spur the biofuels movement.
The thermochemical platform involves heating the biomass in a reactor and converting it into liquid (bio-oil) and synthetic gas.
Chemical engineer Akwasi Boateng has led much of the Eastern Regional Research Center research on this process.
Reactors. In a study with research leader Gary Banowetz and colleagues in Corvallis, Oregon, Boateng converted grass seed straw into synthetic gas using small-scale gasification reactors.
Built to serve a farm or small community, these reactors could provide an environmentally friendly and economic use for the 7 million tons of straw produced by the grass seed industry every year in the Pacific Northwest.
Neither the sugar platform nor the thermochemical platform has been perfected yet, Hicks cautions.
“Each one has technical and economic hurdles that must be solved through research,” he said.
“We’re trying to compare the processes and determine which, if perfected, would give the most useful energy from a given amount of biomass.
“We’re working with international experts to make intelligent decisions on where to focus our efforts.”
STAY INFORMED. SIGN UP!
Up-to-date agriculture news in your inbox!