Switching to Switch Grass?
By Stall, Sam
Not long ago, the innocuous prairie grass known to scientists as Panicum gatum was of interest only to a handful of researchers. But, in 2006, the woody perennial catapulted from eyesore to national savior.
During his 2006 State of the Union Address, President Bush called the plant – better known as switchgrass – a potential biofuel powerhouse that could help end the country’s dependence on foreign oil.
As quickly as you can say “hype,” it became the poster plant for the biofuels movement.
Far from the limelight, a cadre of hardworking experts – many of then based in Indiana – have struggled for years to help switchgrass live up to that billing. If they can work. out the remaining technological, logistical, and economic kinks, it might indeed be used as everything from feedstock for the production of cellulosic ethanol to a cleaner-burning additive at coal-fired power plants.
But the devil – a big, complicated, expensive devil – is in the details.
Consider the task before Dr. Klein Ileleji, assistant professor and extension engineer in the agricultural and biological engineering department at Purdue University. His objective seems straightforward: Find a way to burn some switchgrass along with the coal that’s used to fire one of the four boilers powering the Purdue campus. Nothing drastic just enough of the stuff to account for 5 percent to 10 percent of the unit’s output.
“But you can’t just say, ‘I want to use switchgrass,’” Ileleji offered. “You have to re-engineer your entire system.”
Switchgrass is so bulky compared to coal that one must burn bales and bales of the stuff to produce significant energy. Those bales must be ground into small pieces to fit into the boiler, but the little pieces tend to clog pipes. And because those bits bone-dry switchgrass are bascially kindling, they have to be processed with kid gloves so they don’t catch fire before they’re supposed to.
“There’s a chance we could pelletize it, but it’s expensive,” Ileleji said. “That’s an option we might go to in our tests.”
Those tests will begin in earnest if he manages to raise the roughly $1.5 million needed to modify the boiler and put in switchgrass-friendly handling equipment. All this effort and coin so that Purdue can, to put it diplomatically, burn a bunch of weeds. But Ileleji thinks the program could generate environmental rather than. economic savings.
Switchgrass is “carbon neutral,” because when burned it only releases the carbon dioxide that it extracted from the environment during its growth. Replacing 10 percent of coal at any given plant sounds insignificant, but if it were done nationwide, the carbon reduction would be significant.
“When we look at a fuel mix like this, we need to look at all sides of the issue,” Ileleji said. “It might not be economical from an energy standpoint, but you reap environmental benefits.”
Only if you retrofit pretty much every coal-burning boiler in the nation, however.
The other, more widely known application is as biomass for the production of cellulosic ethanol. To be fair, there are other plants besides switchgrass in the running for this role – wood chips, the agricultural residue from corn, even some types of fast-growing trees.
“It’s just the one that gets the most media attention,” says Wally Tyner, professor of agricultural economics at Purdue University. “President Bush has settled on it, but the scientists haven’t.”
Figuring the costs
Yet switchgrass is a strong contender. It’s extremely hardy and fast-growing, providing lots of cellulose for the so-far- theoretical cellulosic ethanol industry. Today, almost all ethanol is produced by fermenting food crops such as corn and (in the tropics) sugar cane. Cellulosic ethanol is derived using special enzymes or bacterias that are added to big vats of cellulose-rich plant material, which is then broken down into ethanol.
The advantages of the process over straight fermentation are huge. First and foremost, the feedstock comes from non-food sources that can be grown on marginal land. And, secondly, those crops are located in the United States, as opposed to Iran or Venezuela or Saudi Arabia.
There’s just one problem: Cellulosic ethanol is still too expensive to undersell even $120-a-barrel crude.
“We could build a plant today if someone said, ‘I’ll buy your $4 or $5 (per gallon wholesale) ethanol,’” Tyner said. “One of the jokes in the business is that everybody wants to build the third cellulose ethanol plant. No one wants to build the first or second one, because its incredibly risky.”
The problem is that no one can say for sure how much the stuff will cost until a decent number of commercial facilities go online.
“For example, one of the critical enzymes in the enzymatic conversion process is now about $1 a gallon,” Tyner said. They hope to get that down to 25 cents a gallon, but it’s not there yet. Now if you get some plants running, you get a lot of enzyme being produced, then maybe you get economies of scale. But how far it will come down we don’t know.”
What he can say with some certainty is that, unless oil prices skyrocket to ridiculous heights, a gallon of cellulosic ethanol will probably still cost more on the wholesale market than a gallon of regular gas. Plus, ethanol contains only 69 percent of the energy of the same amount of gasoline, further widening the price difference.
That’s where the government comes in.
“What Congress has done is pass a renewable fuel standard that mandates that cellulose be used,” Tyner said. “And so if people perceive that that’s credible, then the oil companies will be obliged to buy it. The standard says that if somebody produces it, you’ve got to buy it and you’ve got to blend it (with gasoline, usually in a 10-percent mix called E10). So whether it’s economical, in the sense that it can compete with gasoline, is less relevant than the standard.”
But even if a government-mandated market already exists, filling it with switchgrass products could take some time. For one thing, someone will have to start growing the plant. Right now, the number of Hoosier acres planted in switchgrass is close to zero.
The sheer bulk of that notional harvest would also present problems. Tyner calculates that a 100 million-gallons-per-year cellulosic plant would gobble up a dozen 13-ton truckloads of biomass every hour of the day.
“That’s a truck every five minutes that has to be unloaded and the material moved into the system,” he said.
Cellulosic production facilities don’t come cheap, either. Putting one up from scratch would cost between $200 and $400 million. Existing plants that process corn would have to be extensively retrofitted to handle switchgrass and other forms of biomass.
But there’s another problem.
Current regulations mandate selling a blended E10 fuel that’s 10 percent ethanol and 90 percent gasoline.
“This year, we’re probably going to produce 11 billion to 12 billion gallons of corn ethanol (nationally),” Tyner said. “We consume 140 billions of gasoline annually. So with the 10 percent blend that’s used the United States, we only need 14 billion tons of ethanol. Once we get there, we hit what we call in the business ‘the blending wall.’ Even if every drop of gasoline sold in this country is blended, all you need to do that is 14 billion gallons of ethanol. Right now we’re in a. position where our production is about up to what the market can absorb.”
All without harvesting the first acre of switchgrass.
There are several ways to stimulate further demand, the simplest being to bump up the required per-gallon ethanol content to 15 percent or even 20 percent. But the car companies worry this new blend could damage their engines.
“The ethanol people say there’s no problem, but the automobile people say ‘Wait, I’m not sure I want to warranty these fuel systems designed for E10 for E20,’” Tyner said. “So there are problems. I’m not saying they’re insurmountable, but there are hurdles that have to be jumped in order to go beyond E10.”
A switchgrass scenario
He figures that cellulosic energy production will begin something like this: The first producers will initially make ethanol from “corn stover,” the readily available field residue that’s left over when the corn harvest it taken in. There’s a lot of this sitting around in northern and central Indiana, and it costs around $40 per dry ton. Later, if the process catches on, less-desirable land in southern Indiana could be planted in switchgrass, which can be had for about $60 per try ton.
“We could have 400 million to 800 million gallons of cellulosic ethanol 20 years from now, just from Indiana,” Tyner said.
This sounds like a huge amount, but it seems a lot less significant when one considers that 400 million gallons would only satisfy U.S. gasoline needs for one day.
It makes one appreciate oil. It. comes from the ground, it’s easy to handle, and it yields a high-energy, easy-to-handle fuel. But the price keeps going up – and not just at the- pump.
“Sometimes I start my talks with a piece of information from the National Petroleum Council,” Tyner said. “One of the things they say is that in 2030 we’re still going to be getting three-quarters of our energy from oil, gas and coal. But then they say that there are accumulating risks – I love that term – for continuing to expand their use. There are accumulating risks for continuing to rely on oil and gas as much as we have in the past. To attenuate those risks we need to diversity our profile. That’s what we’re in the process of doing.”
Also known as: Wobsqua grass; blackbent; tall prairie grass; thatchgrass; tall panic grass.
Appearance: Woody, tall (up to nine feet), perennial grass native to the North American Great Plains.
Characteristics: Grows in poor soil, Tolerant of drought and heat. Self-seeding. Requires less fertilizer than standard food crops and minimal care. Cannot be harvested the first season after planting, but can be harvested for 10 years thereafter. The plant is mowed like hay or alfalfa.
Advantages: Can be grown on land unsuitable for traditional crops, abrogating “food vs. fuel” controversies. Ample roots inhibits soil erosion. Switchgrass stands are favored by game birds, which eat the plant’s seeds.
Other uses: Occasionally employed as an ornamental grass by gardeners. Excellent forage for cattle – though not goats, sheep and horses, which find it somewhat toxic.
Potential fuel yield: As much as 1,000 gallons of ethanol per acre, compared to 665 gallons for sugarcane and 400 gallons for corn.
Drawbacks: Difficult to transport enormous bales of switchgrass to processing plants. So far, the cellulosic ethanol extraction process hasn’t been economically viable.
Source: Purdue University
Copyright IBJ Corporation Jun 9, 2008
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