Amber Waves of Gas?: Gasoline Alternative May Be Found in Prairie Grass

[RedEarth]

The jockeying for the alternative energy source of the future is like a horse race with a staggered starting order. Corn got out to a big lead on the back of government subsidies, but it's been brushed back by reports that it actually generates more fossil fuel emissions during its transformation to ethanol than it avoids as a fuel. This realization caused soybeans and switchgrass to catch up. Suddenly, technological advances allowed waste products such as straw and corn stover to zoom into the picture. Now, a new class of biomass is making a dash: Jockeyed by a team of ecologists and economists at the University of Minnesota, highly diverse mixtures of low-maintenance prairie grasses have officially entered the contest. The group, reporting in tomorrow's issue of Science, says these diverse grassland species constitute a carbon-negative source of energy that could alleviate 19 percent of global electricity consumption and 13 percent of the world's petroleum consumption.

Ecologist David Tilman notes that in five to seven years, the source of biofuels such as ethanol or biodiesel will expand from just corn grains and soybeans to cellulose, a plant sugar known to be an ethanol-rich source. "When we turn that corner," Tilman says, "we want to have available the most efficient way of producing cellulose to be a biomass feedstock." Based on his work with crops grown over 10 years at Minnesota's Cedar Creek Natural History Area and on estimates in other scientific papers, Tilman calculates that nitrogen-poor, degraded land planted with a mixture of perennial prairie grasses--such as goldenrod, Indian grass, big blue stem and switchgrass--can actually provide up to 238 percent more bioenergy than the same land planted with only one species. (Switchgrass, when grown alone in the poor soil, returned only one third of the energy of a diverse plot.) In addition, when compared with ethanol from corn grown in fertile soil, he claims his plots can return 51 percent more energy per acre

The kicker to Tilman's finding: his process is reportedly carbon-negative--meaning the plants can store more carbon in their roots than they will create during their conversion to biofuels or electricity. Tilman says this negativity occurs because prairie grasses have complex root systems underground that typically make up two thirds of the plant total biomass, making them efficient carbon sinks: "When they grow, they have to a lot of carbon to keep their roots alive and to make these very extensive root systems," Tilman speculates that these diverse systems may use more nitrate, "the limiting nutrient" in the soil, which starves bacteria that decomposes carbon, allowing the plants to better maintain their roots. All told, the Minnesota group estimates from its own soil sampling that, per acre, these grasslands could result in the sequestration of up to 1.8 tons of carbon dioxide per year.

Bruce Dale, a biomass conservation researcher at Michigan State University, believes that although Tilman "provides an interesting perspective on the use of degraded lands," he makes a critical "apples-to-oranges comparison": pitting the production of ethanol from corn, an actual working industry, to ethanol production from grasses--currently hypothetical, due to economic constraints. If grasses do become viable sources for ethanol, he notes that the technology will also be applicable to the unused parts of corn, such as stalks. Tilman counters that although breaking down the stover will result in more ethanol, it will further shift the carbon balance of corn. "If you take the stover off of the corn field and use it for bioenergy, you're going to decrease the carbon storage in the soil," Tilman explains. "We're trying to find something the gives us energy at the same time that it gives us a reduced greenhouse gas emission benefit."

Alex Farrell, a professor in the Energy and Resources Group at the University of California, Berkeley, says that the entry of prairie grass into the alt-fuel marathon is exciting, but it's likely to take several years to determine how best best to use this new resource--be it for electricity or biofuels. "Even if we were to find an environmentally appropriate way to use this resource, it will still be only part of any solution," he cautions. "It's not a silver bullet."

http://www.sciam.com/article.cfm?chanID=sa003&articleID=5EE06FDA-E7F2-99DF-3C6DEDB5F5F4518D

[no_hypocrisy]

1. Provided that global warming doesn't dry up the ground that

grows the grain . . .

[jpak]

6. Diverse natural prairie plant communities are extremely drought resistant

They specifically evolved to withstand heat, drought and extreme cold (something the Dust Bowl generation found out the hard way).

Natural prairie/bison agricultural systems for animal protein and biofuels will be part of our GW solution/salvation...

[RedEarth]

7. You're exactly right...... it's very drought resistant

Oklahoma State University as well as numerous other universities are involved in extensive research in using prairie grass/switch grass as an alternative fuel. They haven't come up with all the answers, but they are making headway.

[Botany]

2. Thanx for the post

[Bitwit1234]

3. I wish for this each day.................

Because if the United States could find an alternative energy to fuel their vehicles, it would sure knock a hole in the oil supplies in the Middle East. Of course oil would still be used for other things but if it dropped to 10 dollars a barrell the Middle East would not be so violent. There would be no need to beat each other up trying to get the oil..

And of course it is a religious thing also, but oil if fueling most of the conflict. Each country wanting to be sitting in the control booth. If they didn't have anything to control, the money for wars would dry up also.

[democraticinsurgent]

4. Ironic

All of the ethanol development is essentially "fueled" by the $70 per barrel oil prices. The irony in which is that the Iraq War likely drove the run-up.

[applegrove]

5. Thanks for the post!

[JohnWxy]

8. Switchgrass really looks good for the future and it looks like the research is

going to get us to a place where this will be technically as well as economically feasible.

But I am surprised to see an obviously incorrect statement in this article about starch based ethanol:

"but it's been brushed back by reports that it actually generates more fossil fuel emissions during its transformation to ethanol than it avoids as a fuel." This is simply false.

And: "This realization caused soybeans and switchgrass to catch up." There is no such realization. Soybeans are a realistic current source for ethanol. But throwing swithcgrass in with soybeans as "catching up" - what is this guy talking about. Important research is being done re cellulosic ethanol and we are hopeful it will be developed into a practical source for ethanol. but work still needs to be done. This article sounds like it was written for a high school newspaper.

Those 'reports' are articles by Pimentel (entomologist) and Patzek (UC Oil Consortium) which have been debunked (jan 2006 , Science - Farrell and Kammen , Univ Calif, Berkeley) over and over again. The work of legitimate researchers and recognized authorities such as Michael Wang (Argonne National Laboratory - Dept of Energy), or Bruce Dale, Michigan State University, and researchers at U.S. dept of Agriculture has shown concusively that there is a net energy gain in making ethanol from corn.

I'm very hopeful re cellulosic ethanol. But one thing it is not. IT is not economical now. It is not producing ethanol for sale right now. Waiting until it is economically viable, and then waiting to scale it up to significant volumes (figure at least 10-15 years for that) is not an option when you have a way to reduce GHG and reduce dependence on imported oil which is economically valid and available to you right now.

Another thing about expanding corn/sugar cane/soy bean based ethanol now is that by building the infrastructure for the manufacture of ethanol for starch based ethanol now you will foreshorten the time required to get cellulosic ethanol cost effective as a big part of that equation is just making the product at large enough volumes. with the manufacturing facilities already in place when cellulosic ethanol is ready, that will reduce the time needed to scale up cellulosic ethanol to become economically viable.

[bhikkhu]

9. I would hope to see it in my lifetime, but...

"building the infrastructure" may be the crux of the matter, rather than the comparatively miniscule expenses of R&D. Given the knowable expenses (or best guesses) of the inputs and outputs, it is hard to imagine any near-term large scale private or government investments in what would be, realistically, the small scale production of oil equivalents at $200 to $300 a barrel. I would only hope - long term - that the technology might be developed for more ease of localized production/refinement, bypassing the massive geopolitics of energy production and transport.