Ethanol Research News
News Item 1: Glue Made From Ethanol-Production Leftovers May Be Worth More Than The Fuel Itself, Researcher Says
Mixing up a batch of ethanol from alfalfa or switchgrass isn't nearly as efficient as creating it from corn, but that doesn't mean growing grass crops for fuel won't pay, according to Paul Weimer.
Rather than dwelling on finding ways to squeeze extra ethanol out of biomass from crops such as switchgrass, Weimer is concentrating his research on the leftovers. He thinks that the large heap of fermentation residue from the ethanol-making process -- what many people consider a byproduct -- could be far more valuable than the ethanol itself.
"A lot of people want to do the same thing with biomass material that we've been doing with corn," said Weimer, a research microbiologist at U.S. Department of Agriculture's (USDA) Agricultural Research Service Dairy Forage Research Center and associate professor of bacteriology at the University of Wisconsin-Madison. "They want to hit it with enzymes to break it down into sugars, and ferment those sugars into ethanol."
The problem with this, he explains, is that the enzymes needed to break down celluose biomass are very expensive, and they don't work nearly as effectively as the enzymes used to convert starch.
In fact, Weimer added, both corn and cellulosic biomass must be subjected to costly pretreatment to maximize the ethanol yield.
"Our philosophy is a little bit different," Weimer said. "We think that the fermentation residue may actually be more valuable than the ethanol. And it may mean that we can do without pretreatment."
According to a Sept. 27 announcement, he came to this conclusion as he took a closer look at the residue -- the fermentation leftovers. He determined that the organisms that he uses to convert biomass do their job by sticking to the cellulose fibers with a glue-like substance called a glycocalyx.
"Because glycocalyx works so effectively at holding organisms to cellulose material, we found that we couldn't get the glue off of the fibers without destroying the glue," Weimer said. "So, we took the entire fermentation mixture -- the glue, plus the bacteria, plus the rest of the cellulosic biomass -- and used it as an adhesive."
Specifically, they used it as wood glue. To explore the glue's potential as value-added product for biomass crops, Weimer set out to test it by enlisting help from a research team at the USDA Forest Products Lab led by adhesive scientist Chuck Frihart. Their primary performance concerns were pressure and durability in wet conditions.
"One of the biggest drawbacks of any bio-based adhesive is that it will stick stuff together well but falls apart once it gets wet," Weimer said.
While Weimer's bio-based adhesive does have this problem if used as a standalone product, it works well when mixed with another adhesive, a commonly used petroleum-based resin. In some applications the researchers have successfully used a mix in which up to 73 percent of the resin was replaced with the bio-based adhesive.
Although the adhesive appears to have great potential, there are still a few hurdles. For one, it's quite viscous. For use in an industrial application, the glue would need to be made easier to apply. A second challenge is to bring the process to a larger scale. A third is to develop formulations that incorporate the bio-based glue into other types of adhesive mixtures. These challenges, says Weimer, will simply take time.
Weimer hopes to get the wood products industry interested in replacing half of the phenol formaldehyde (PF), a petroleum-based adhesive now used to make plywood, with the biomass-based adhesive.
"The PF that the fermentation process would partially replace sells for considerably more that ethanol, and the fermentation would still generate ethanol on the side," he said.
But the economic incentive is only part of the picture, according to Weimer. "We'd like to keep alfalfa on the landscape because it has a lot of environmental benefits," Weimer said. "It's a good cover crop, it's drought-tolerant and fixes nitrogen. But because farmers are moving away from it as a dairy feed, we're trying to find another use, and we think this glue might be a solution."
News Item 2: Researchers Working To Take Natural Gas Out Of Ethanol Production
It takes a lot of natural gas to run an ethanol plant. A plant needs steam to liquefy corn starch and heat to distill alcohol and more heat to dry the leftover distillers grains.
Burning natural gas to produce all that heat is the second largest expense at most ethanol plants -- trailing only the cost of the corn used for ethanol production. One estimate says Iowa's annual production of more than one billion gallons of ethanol accounts for about 16 percent of the state's demand for natural gas.
That has Iowa State University researchers working with an Ames company to develop a renewable and cost effective alternative to the natural gas burned by most ethanol plants, according to a Sept. 26 announcement.
The technology involves partial combustion of biomass -- that could include corn stalks, distillers grains, waste wood or other biorenewables -- to produce a mixture of hydrogen, carbon monoxide, methane and other flammable gases. The resulting mixture is known as producer gas and it can replace natural gas in an ethanol plant's heaters. The producer gas can also be upgraded to what's known as syngas, a mixture that can be converted into high-value transportation fuels, alcohols, hydrogen, ammonia and other chemicals.
Producer gas is made by injecting biomass into a fluidized bed gasifier, a thermal system that pumps air up through a bed of hot sand, creating bubbles and a sand-air pseudo fluid. A reaction between the biomass and the hot sand-air mixture produces flammable gases. The process also generates its own heat to sustain the reaction. It's a system that's reliable, produces few emissions and can be efficiently integrated into a plant's existing natural gas boilers and dryers.
Iowa State researchers Robert C. Brown, the Bergles Professor in Thermal Science and Iowa Farm Bureau director of the Office of Biorenewables Programs; Ted Heindel, a professor of mechanical engineering; and Francine Battaglia, an associate professor of mechanical engineering, are working with Frontline BioEnergy, an Ames company that produces biomass gasification systems, to study and design a gasifier large enough to produce energy for an ethanol plant. The project is partially supported by a $132,274 grant from the Grow Iowa Values Fund, a state economic development program.
Heindel will work with Nathan Franka, a master's student in mechanical engineering, to observe and measure a fluidized bed in action. They'll use Iowa State's $640,145 X-ray flow visualization facility to see through a test bed that's six inches in diameter. They'll be looking to see what happens inside the fluidized bed when biomass is injected. Heindel will take X-ray radiography, X-ray computed tomography and X-ray stereography images of the flows to measure local conditions.
Battaglia will work with Mirka Deza, a doctoral student in mechanical engineering, to simulate the results of Heindel's tests using computational fluid dynamics. The idea is to run simulations and compare the results with data from the fluidized bed experiments. If the results don't match, the researchers will have to figure out why and the computational models may require modifications. Iowa State's "Lightning," a new high-performance computer capable of 1.8 trillion calculations per second, will provide the computational power for the simulations.
Battaglia said the validated computer models can help Frontline BioEnergy make appropriate design changes. Using the computer models to assist with the design work is much cheaper and faster than building prototypes and running experiments, she said. That's because designers can change parameters and quickly analyze how each change affects performance. Besides, she said, researchers can't look inside a real gasifier to see what's happening.
John Reardon, the research and development manager for Frontline BioEnergy, said the Iowa State research will provide the company with insights about the mixing that happens inside a fluidized bed gasifier. That will help the company design improved commercial-scale gasifiers capable of processing 300 tons or more of biomass per day. A diagnostic tool developed as part of the research project will also help the company avoid problems in the fluidized bed and maximize the reliability of those gasifiers.
All that can be a boon to an industry that produces an alternative to fossil fuel.
"Using biomass to fuel an ethanol plant can reduce ethanol costs," Reardon said. "It also hedges against volatility in the natural gas market and also doubles the renewable energy ratio of the ethanol product."
This article originally appeared in the 10/01/2006 issue of Environmental Protection.