The Other Ethanol
Researchers are going beyond corn
in the push for more ethanol.
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A pile of harvested poplar trees at Kellogg Biological Station. The lab plans to examine the potential of poplar trees as a source of cellulosic ethanol. |
America’s love affair with corn-based ethanol has been strong since the 1970s. But since last December’s passage of a new energy bill mandating 36 billion gallons of ethanol be produced annually by 2022, researchers are looking for new ways to fuel cars. “It’s a very ambitious target,” said Jerry Schmidt of external affairs at the National Renewable Research Laboratory in Colorado. “It’s going to be difficult, but with the right resources and consistent support, our researchers believe that it can be done.”
As corn takes more of a toll on the environment and the U.S. food supply, scientists are pushing the food crop to the back burner and researching other options. Most similar to corn is sugarcane—both processes involve the conversion of either the kernels or sugar into starch or glucose, which is then fermented to release ethanol.
While the sugarcane process is widespread in Brazil, it has not been explored much in the United States even though sugarcane yields more energy than corn. It’s a matter of climate, not technology, said Kenneth Keegstra, professor of chemical and molecular biology at Michigan State University and scientific director of the Great Lakes Bioresearch Center in Wisconsin. There are only three states—Hawaii, Lousiana and Florida—where it’s conceivable for sugarcane to become a large part of ethanol production.
More promising but difficult is cellulosic ethanol—ethanol made by breaking down plant cell walls. In a process called hydrolysis, enzymes break the cellulose into sugars which are fermented into ethanol. The process is inefficient and expensive as the research is relatively new. “Five years ago I wasn’t working on biofuels, but our research in plant biology was relevant, so suddenly I’m engaged in this activity,” Keegstra said.
The sources for cellulosic ethanol are numerous and include trees, grass, corn husks, stalks and even waste wood found in landfills. The Great Lakes Bioresearch Center is researching perennial grasses, such as switchgrass, which require little fertilizer and aren’t in competition with food cropland, said Keegstra. Researchers estimate that switchgrass ethanol averages 94 percent lower greenhouse gas emissions than gasoline.
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| Poplar stumps in a recently harvested research plot. |
Oak Ridge National Laboratory in Tennessee is looking into poplar trees as another option. The lab will soon sample several thousand variations in poplar plants, said Brian Davison, coordinator for biomass characterization and modeling at Oak Ridge. “Poplar trees and switchgrass are on everyone’s list of top biomass crops—one or both of them can be grown potentially productively in almost every biomass-producing region in the country,” Davison said.
Analyzing these plants will hopefully yield results that answer important questions in cellulosic ethanol production: how to modify plant cell walls to break them apart easier, and how enzymes break apart components and use their sugars.
The problem is that while there is a wealth of sources for cellulosic ethanol, the cellulose itself is difficult to break apart. Even the human body cannot digest cellulose. “It’s a complicated process and set of problems,” Keegstra said. “It’s a matrix of conditions: different plant biomasses by different treatments by different enzymes to find combinations that work.”
Since it’s so complicated and new, the costs are great, said Seth Snyder, section leader at Argonne National Laboratory in Illinois.
“With ethanol made from corn grain, the final ethanol is about 12 to 15 percent alcohol, like wine. If you make it from cellulose, it’s about 5 to 7 percent, like beer, so more initial material is required to recover the same ethanol from fermentation.”
Although the cellulosic ethanol industry is growing, it will be awhile before the ethanol can be commercially produced. However, the U.S. Department of Energy and private companies are already starting to fund new cellulosic plants. “Concrete is being poured, steel is going up—we think it will be commercialized in five to six years,” said Schmidt.
Mascoma Corp., formed two years ago to produce cellulosic ethanol, recently announced a new plant in Michigan because of the state’s hardwood sources. Jay Niles, vice president of business development at Mascoma, hopes to see commercialization within the next few years. “With wood, the supply chain already exists in Michigan,” Niles said. “It allows the quantities to be available at the magnitude the industry will eventually require.”
Beyond cellulosic ethanol, perhaps an even better source of ethanol is algae. The National Renewable Energy Laboratory had an algae program a number of years ago, but with shifting federal research priorities, the program went away. Schmidt said the federal agency is getting back in the business and looking at different ways algae can be used to produce biofuels.
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| The Kellogg Biological Station has more than 5,000 plant samples. |
Some experts, including Davison of Oak Ridge, believe that algae isn’t a particularly effective way to make ethanol because it is expensive and grows in limited areas. But talk of algae is picking up. Snyder of Argonne said he would like to see his laboratory begin serious research on algae. Algae’s benefits include its ability to grow in water, which gets around some of the land issues. It also has a high oil content which makes it easier to convert to ethanol than sugar, Snyder said.
Most research into algae has occurred in Arizona where stations have been set up to experiment with growing algae on a large scale. Companies are experimenting near power plants because carbon dioxide emissions from plants can accelerate algae growth. In the fall of 2006, the Arizona Public Service and GreenFuel Technologies of Massachusetts grew algae and turned it into ethanol at Redhawk, a natural gas power plant in Arizona. However, most researchers agree algae has a ways to go before it can be used on an industrial scale in producing ethanol.
Down the Wrong Path?
Despite all the new and ongoing research into ethanol, it might not be an ideal fuel. Ethanol cannot be carried in existing pipelines. “Ethanol is a very different solvent than petroleum—if you put the first ethanol into an existing pipeline, it would clean the pipeline and 40 years of residues could get washed out,” said Davison. This would render the first ethanol almost useless. Also, ethanol is transported by truck, and if the distance is great enough, “you could spend all your energy just driving the truck to get to ethanol stations.”
One solution is to concentrate biofuel crops within 10 miles of biorefineries. Each state has a biomass resource such as eucalyptus, willows, sycamores, silver maples, poplars and switchgrass, which can be used for ethanol, Schmidt said. “Every state could contribute to the nation’s fuel needs by growing an indigenous biofuels industry within that state.”
This localization of the industry could improve sustainability, which should be the goal of any fuel program, said Phil Robertson, professor of ecosystem science at Michigan State University and program leader for sustainability at the Kellogg Biological Station in Michigan. Researchers there are looking into diversifying sources of biofuel and into how to get rid of extra water, waste and energy loss while making ethanol. Robertson said he’s afraid the high goal set by the government will only intensify environmental problems because the focus will be on technology, not sustainability.
“If we just go down the path blindly without considering sustainability, we’re likely to have the same systems that we have now—business as usual with all the current problems,” he said.
Business as usual is already occurring. Billions of dollars in subsidies are still given to farmers to produce ethanol from corn. As more corn is grown, more nitrogen fertilizer will be applied, causing problems as diverse as oxygen-depleted coastal areas and greenhouses gas production. Even though the government is putting money into cellulosic ethanol, the goal may just encourage more corn production to reach the 36 billion gallons.
There seems to be agreement that ethanol is part of the answer but far from the whole one. Ethanol is perhaps a short-term solution, but a long-term solution should also include multiple players such as bio- and green diesel, wind, solar and wave energy, plug-in hybrids, and biomass, said Keegstra.
“I don’t think anybody believes ethanol is the entire answer,” he said. “The energy crisis in the United States is too big to have a single answer.”
Amanda E. Peterka is a junior studying journalism at MSU. This is her fourth appearance in EJ. Contact Amanda at peterkaa@msu.edu.
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