MANKATO — When it comes to capturing and storing the sun's energy, wetlands might be the most efficient of any ecosystem around, according to Minnesota State University biology Professor Gregg Marg.
So with industry and science looking at plant matter as a replacement for foreign oil, Marg is studying whether wetlands could be a new source of ethanol. Marg and chemistry Professor James Rife have obtained a federal grant to convert wetland plants into ethanol and measure how feasible and productive the process might be.
For biomass produced per acre, wetlands are extraordinary, Marg said.
"Northern wetlands are some of the biggest producers, along with rain forests," he said, something that's even more remarkable because northern wetlands generate all of their growth in about six months of the year.
Marg cautions that the research isn't aimed at potentially fueling cars by harvesting the nation's last remaining natural wetlands.
"We're talking about wetlands that don't exist currently and that we could re-establish," he said.
Along with being an energy source, the reconstituted wetlands could provide enormous environmental benefits, according to Marg. Wetlands clean pollutants from water before it enters rivers, they help restore aquifers and they reduce flooding along rivers.
And because wetlands created for the ethanol industry would be harvested in late fall, they would still be a valuable habitat for waterfowl — which nest in the spring and would likely have migrated by harvest time, Marg said.
Of the millions of acres of wetlands once sprinkled across Minnesota, fewer than 2 percent remain because so many have been drained for farming and development. If restoring wetlands produced dependable income for farmers, many of those former wetlands could be brought back.
"I've got to think it's possible at least, or I wouldn't spend my time on it," Marg said.
Ears of corn — not cattails and bull rushes — is what comes to mind when most Americans think of sources for ethanol. But scientists and energy companies are focusing on new raw materials for producing ethanol as a replacement for gasoline.
Switch grass is high on the list and was even mentioned in President Bush's last State of the Union Address. An ethanol plant that will use corn stalks, leaves and cobs is being planned. Another intends to use wheat straw. Trees and wood waste from lumbering are also possible inputs for ethanol plants.
In a study published Friday in the journal Science, University of Minnesota researchers suggested prairie grass could be a good replacement for corn in future ethanol plants. A mix of several native prairie grass species, including switch grass, produces more energy per acre than corn or from switch grass alone, according to the study.
And the prairie grasses also act as a sponge for greenhouse gases that contribute to global warming. The study predicts that the prairie grasses grown on marginal land without fertilizers and pesticides would yield 51 percent more energy per acre than corn cultivated on fertile land using chemicals and fertilizer.
In addition, the prairie grasses are perennials, meaning farmers could avoid the cost in time and fuel of replanting each spring. And after the first year, the fields require minimal work other than harvesting.
With so many alternatives to corn, why bother looking at wetland plants? Marg said it's because of the wetlands enormous ability to produce biomass, because the nation's demand for food and energy might require better use of marginal lands and because there are environmental benefits to restoring wetlands.
"It's just an alternative," Marg said.
One of the challenges of any of the ethanol alternatives mentioned is turning the biomass into alcohol. It's called cellulosic ethanol, and it requires a more complicated process than the relatively simple task of converting corn starch to sugar to alcohol.
David Tilman, the U of M regents professor who led the study of the mixed prairie grasses, has said that a cellulosic ethanol facility is roughly equivalent to reproducing what happens in the digestive system of a cow.
"To a certain extent, that's true," Marg said.
Cows use a bacterial colony in their stomachs to produce the enzymes needed to turn cellulose into sugar. Similar enzymes would be used in a cellulosic ethanol plant.
It can be done. Facilities in Iowa and Idaho are expected to be doing it soon on a large scale, and Marg and Rife and a few students will be doing it at MSU on a smaller scale — probably by next summer.
The more detailed scientific study won't be completed for a couple of years or more. When it's done, farmers and policy makers and energy companies will have a better idea if reconstituted wetlands might be worth investing in. And someone will need to develop harvesting equipment that will work in a soggy environment.
"Before we spend a lot of money developing this other stuff, does it even make sense doing it?" Marg said, summarizing the question behind the more than $100,000 grant.
The answer will be determined by the amount of cattail moonshine Marg, Rife and their team of students can produce.
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