When Ron Bowen planted his first prairie for a landowner over three decades ago, the client’s motivation was pretty clear. “The main question was, ‘Is it pretty?’ It was an ornamental prairie,” recalls Bowen, the founder and owner of Minnesota-based Prairie Restorations, Inc. But Bowen knew the benefits of prairie ecosystems were more than skin deep. They provide wildlife habitat, build soil, help keep contaminants out of water, fix nitrogen and, as it’s become clear in recent years, trap carbon. If people were willing to get a prairie system established on their land because it gussied up the landscape, so be it. All the hidden benefits would come along for the ride. But an ecosystem’s good looks can only take it so far in a world where competing interests for land are increasing sharply. To evolve beyond an odd planting here and there to a major part of the landscape, it has to earn its own way economically. That’s why Bowen and other prairie enthusiasts are pleased to see in recent years a keen interest in “functional restoration”— establishment of prairies to provide numerous services to society, including things like stabilization of lakeshores or hunting habitat for pheasants. And they are even more excited by the latest task prairies are being asked to perform: serve as a source of biomass energy.
In its seemingly endless search for new sources of energy, the world is now seriously considering the potential of utilizing plants and plant products. So far, that interest has manifested itself almost exclusively in the form of ethanol—mostly from distilling corn kernels into a fuel additive for gasoline. But as concerns over the environmental and food supply impacts of raising so much corn for fuel have emerged, energy experts, environmentalists and rural communities have increasingly looked at actual plant parts as sources of energy. In the Upper Midwest, some of that interest has centered on the plants found in prairie lands.
The viability of tapping into prairies as an energy source received a significant boost in 2006 from a University of Minnesota study published in the journal Science. The 10-year study found that mixes of 16 native prairie plant species yielded on average 238 percent more biomass than land planted to a single species. An added bonus was that the greater diversity increased carbon sequestration, provided more stable annual yields and significantly reduced the need for pesticides, herbicides and fertilizers such as nitrogen, which can be supplied to the prairie via legume species. The study stopped at 16 species and research is being done to see if even more diversity can be as productive.
Studies like this are good news for fans of a system that prior to European settlement formed the largest ecosystem in North America—it stretched from Canada to Mexico and from the Rockies to Indiana. At one time a third of Minnesota and 80 percent of Iowa was covered by prairie.
Today, well less than 1 percent of those native prairies have escaped the plow and bulldozer. We’ve also lost the ecological services that came with the deep-rooted grasses, forbs and legumes found in prairies, and the results have been predictable: increased erosion, less wildlife, more released carbon and more polluted water.
Prairie hay can be used to generate energy in many ways: burned to generate electricity, burned or gasified for heat or gasified and chemically combined to make ethanol. There is also a lot of buzz over the possibility of breaking down the cellulose in plants and fermenting the resulting sugars into ethanol. Cellulose is the most abundant naturally occurring organic molecule on the planet; harnessing it as a source of commercially viable energy would be nothing short of revolutionary.
Getting energy from legumes, forbs and grasses on a regular basis could provide an economic incentive to restore millions of acres of prairie to the landscape. But major questions remain as to how viable it will be to restore, raise and harvest millions of acres of prairie plants for energy. And how can it be done without making prairies just another industrialized source of commodities? After all, energy generation, like any industrial process, has mostly relied on a narrowly focused drive to maximize production from a single resource. Healthy prairie systems, on the other hand, rely on diversity.
So the question remains: can a complex polyculture serve the needs of a system based on a simplified monoculture? Can we meld the two, or will yet again single-minded monoculture overwhelm multifunctional diversity?
First, the seed
Firms like Prairie Restorations have proven that thriving perennial grassland systems can be returned to the landscape. But Bowen and other prairie experts caution that to ratchet up prairie production to meet the needs of even one major power plant won’t happen overnight, and could take as long as a decade.
“To get to the point were we are producing electricity for the grid just in Minnesota, it is probably going to take a couple of million acres, some projections go up to five million acres,” says Bowen. “Right now, I would guess the industry produces enough seed to plant 50,000 acres in Minnesota.”
Daryl Smith, Director of the Tallgrass Prairie Center in Iowa, estimates it would take 100,000 acres of prairie just to generate electricity for Cedar Falls, Iowa, a city of around 37,000. Less than 28,000 acres of prairie grow in the entire state of Iowa today.
“There’s been a lot of questions about if biomass kicks in will there be enough seed available? In particular, local seed,” Bowen says.
Seed corn, which has been domesticated to within an inch of its life, can be produced in South America during winters in the Northern Hemisphere. But if native prairies are to remain native prairies, it’s important that prairie plant seed match the local ecology. For instance, taking big bluestem grass that originated in Missouri and planting it in Minnesota may result in a prairie plot that’s not as cold hardy.
There are also concerns that non-local prairie seed will produce a different ecosystem, and simply not be the prairie nature intended. Bowen and Smith say it’s important to match seed to the local ecotype, but that the definition of what constitutes “local” may have to be loosened a bit if we are to increase prairie plantings significantly. One definition of what is “local seed” is something that originated within a 50-mile radius.
“This creates a huge challenge,” says Bowen. “The smaller that circle gets, the more I say wait a minute, that’s not practical. I’ve expanded that circle to a couple hundred miles when I obtain seed for plantings.”
“I don’t think you want to mix Utah seed with Iowa seed or Minnesota seed,” Smith adds. “But purists are sometimes too narrowly focused. I think it’s more important to match habitat type than geographic type.”
Some compromises on how diverse restored prairies for biomass production are may be needed as well. The original native prairies that have never been plowed count the different species of grasses, legumes and forbs in the hundreds. Today, a more affordable restoration project consists of between a dozen and 20 species.
“We may need to accept a less than perfect prairie if we’re going to get the growth we need for biomass,” says Jim Falk, a farmer and seed dealer in western Minnesota. “Why wouldn’t 15 species work as a start? If they get into a big argument about this, we will get nowhere.”
One concern is that if some sort of compromise is not reached over issues such as local seed and diversity of prairies, the biomass industry will bypass diverse prairies and source their material from monocultures of say, switchgrass. A study out of Nebraska created a stir within the agriculture community earlier this year when it reported that switchgrass monocultures managed for high yield (fertilizer applications, for example) produced 93 percent more biomass than diverse prairies receiving low inputs. A monoculture of high-yielding switchgrass may provide year-round cover to soil formerly left bare by row crops, but it will lack many of the other ecological services native prairies produce.
A waiting game
Even if the definition of “local seed” is expanded and less than perfect prairies are acceptable, a lot of seed must be produced and many acres planted and nurtured before these ecosystems can begin feeding the biomass industry.
Prairie seed propagation can be a painstaking process. First, it must be collected from remnant native prairies—some no larger than a suburban backyard. Then each species must be raised as a monoculture in carefully managed plots. Once the cultivated plants produce seed, they can be made part of prairie mixes and planted. Establishing a prairie doesn’t simply consist of tossing seed on bare ground. Whatever is growing on the land must be killed, generally with herbicides. If the land was planted to row crops such as corn, it’s actually easier because of the absence of perennial weeds. If it’s former pastureland or another perennial system, it can be tougher. Once the prairie seed is planted, usually with a no-till drill, weeds must be mowed. By the third year, a viable prairie can be established.
By the time prairies are established from the seedstock, it could be another three to seven years before there’s enough prairie biomass available to supply several processing plants.
“You’re talking about a 10-year window before you get anything,” says Bowen.
That’s a huge investment in time and resources for an endeavor that may or may not have a processing/market system in place by the time the product is ready. Falk, who has 100 acres of native prairie that’s never been plowed on his own farm, says seed dealers like himself would “jump on board” to supply a prairie plant biomass industry. But before taking such steps, the seed industry needs an assurance that some sort of viable market will be there. “If that commitment isn’t there, it’s going to be awful tough to take that gamble,” says Falk.
It will also be a fair roll of the dice on the part of the farmers who would establish prairies on former crop acres. For one thing, it can cost anywhere from $300 to $400 per acre to get prairie established on old crop ground, depending on how diverse the seed mix is. The price can be as high as $600 if it’s in old pasture. Per-acre prices can range past the $1,000 mark for very diverse mixes.
Getting little or no economic return from land for three years while prairie plants get established is next to impossible for most farmers to pull off. And when one considers that same land could be growing corn or soybeans, which are pulling down record prices these days, the draw of prairie hay gets even weaker.
But Bowen points out that once that prairie is established, it doesn’t have to be re-planted each spring, and if managed properly, next to no inputs such as fertilizer are required.
“Getting a prairie established is expensive, but then you’re done. Once it’s planted, it’s planted,” he says.
Also, some shortcuts have been learned over the years in terms of getting prairies established. “It’s not quite as much of an art as it once was,” says Smith. “One thing we’ve learned is to mow the weeds that first year down to four or five inches so the sun-hungry prairie plants can get a good start. It used to be the recommendation was to mow at 10 inches, and weeds would shade out the prairie plants.”
Bowen says one way to get some economic value off of land while transitioning it to prairie is to sow prairie seed and plant corn over it as a cover crop. The corn can be harvested in the fall and by next spring the prairie has gotten off to a good start.
Another issue farmers have to deal with is harvesting and getting that product to the processing plant. As anyone who has made hay can attest to, the bulky nature of forage makes it a very inefficient product to handle. One estimate is that in Minnesota, it doesn’t make economic sense to haul biomass more than 50 miles from field to processing plant.
Several biomass processing plants have been proposed in the Midwest, and some are even creating energy from plant material on an experimental basis. But the bottom line is corn can be sold at the local elevator on any given day; prairie hay cannot. And if and when biomass processing plants get established, it will take some time before they are as ubiquitous and handy as the elevator in town.
“With bioenergy you need large volumes of hay and so we have all the problems associated with transporting hay,” says Jason Hill, a research associate in the University of Minnesota’s Department of Applied Economics. Hill has studied the economics of using diverse prairie ecosystems as sources of biofuels.
Eric Woodford, who operates a custom baling business in Minnesota’s Redwood and Renville counties, has worked on biomass feasibility projects in recent years. He says utilizing plant material for energy could be a huge market for custom balers such as himself. But it has to be a localized market in order for it to work, especially with today’s rising fuel costs.
“The collection costs can be quite steep,” he says. “Usually the limiting factor is how much feedstock can be collected in a certain radius. With fuel prices going up, it could become not feasible.”
Researchers have studied more efficient ways of transporting forage to processing plants. It turns out large rectangular bales, as opposed to round bales, increase transportation efficiencies significantly. Even better, says Hill, is increasing the density of the material through cubing or pelleting. Portable pellet mills are on the market today and Hill says they could be transported from farm-to-farm to process the prairie hay, much like threshing machines did a century ago. There is even talk of using a process called pyrolysis to heat the biomass in a portable microwave-type apparatus, creating a liquid substance that would be easier to handle. Farmers in a community could pool resources and buy or lease such equipment.
“There is almost inherently a need for cooperative work in this area,” says Hill.
How much cutting can it take?
One other key issue to address is how often prairie lands can be harvested for biomass without being depleted. Sure, bison harvested prairie plants for centuries. But they also returned nutrients to the soil via their manure, and in some cases didn’t come back to the same spot to graze for a couple of years.
If an entire prairie plot is cut every year, there’s the possibility that nutrients will be so depleted that fertilizer will need to be added to the land. That adds to the expense the farmer has already taken on establishing the prairie, and negates one of the environmental pluses of such a system: fewer chemicals.
“In our particular instance, I do not think it would work,” says Brad Hodgson, who, along with his wife Leslea, raises beef cattle on grass in southeast Minnesota. The Hodgsons attended two focus groups last year on prairie plant-based biofuels. “If you take all that matter off and burn it, you’re losing all that nutrient content and you become reliant on inputs again. You’re right back in the situation of mining off minerals again.”
Prairie experts concede they’re not sure what will happen if prairies are harvested every year. Another concern is harvest timing: is it better to harvest in the fall, or wait until the following April when wildlife no longer need the prairie plants for winter shelter and feed?
The Tallgrass Prairie Center’s Smith says harvest frequency and timing are two of the areas his researchers are examining in a project launched this spring. The Center planted 100 acres of prairie on former corn ground and is hoping to replicate as closely as possible what a real farm would face when undertaking such an enterprise, all the way to transporting it to a stoker furnace in Cedar Falls, 20 miles away.
One area Smith and his colleagues are investigating is how to get multiple uses out of prairie plots, something farmers have shown a lot of interest in. He says one strategy could be to harvest a prairie plot for biomass one year, and graze it the next, or harvest/graze part of the plot each year in a rotational pattern (wildlife experts recommend cutting/grazing in alternating blocks, rather than strips to provide more safe habitat for animals). Established prairies could also produce other sources of income through fee hunting or carbon credits.
Egging it on
In the end, prairie-based biofuel production faces the ultimate “chicken or the egg” quandary. Economists have another term for it: “the coordination problem.”
Getting a new industry started from scratch won’t be solved by simply building a bunch of processing plants, or, for that matter, establishing millions of acres of prairie. A bioenergy company doesn’t want to take the risk of building a biomass plant without the assurance of a consistent supply. And in turn, seed producers, farmers and even custom balers and haulers can’t afford to invest in this new venture without a consistent market. Corn ethanol didn’t have a coordination problem to this extent—corn was already being raised for livestock and other uses when ethanol came along. The ethanol industry simply soaked up the excess corn at first, and then later, when farmers saw there was money to be made raising extra product, provided the incentive for more to be raised.
“We have all these systems that need to shift and they need to shift together,” says Nick Jordan, a University of Minnesota crop/weed ecologist who is researching perennial plants and biofuels.
That’s why if society decides an energy system based on perennial polycultures is worth getting off the ground, it needs to prime the pump in a coordinated fashion.
In Minnesota such an opportunity was missed during the last Legislative session, when lawmakers failed to pass funding for an initiative called Reinvest in Minnesota (RIM)-Clean Energy. This program would help farmers establish diverse native prairies for biomass production. RIM-Clean Energy would pay farmers a percentage of the market rate for biomass during the contract period. Just as importantly, it would make payments to farmers in areas where biomass energy facilities are already being proposed. Payments would also be targeted at watersheds where getting more perennial plants on the land would provide the most environmental bang for the buck. This is about as close to “coordination” as you’re going to get.
On the bright side, RIM-Clean Energy still exists as a program, and could get off the ground in the future if the Legislature and Governor decide to fund it.
But for now, the people in power are continuing to place their bets on row crop-based bioenergy. While snubbing RIM-Clean Energy in 2008, the folks at the Capitol mandated that biofuels included in diesel fuel increase from 2 percent to 20 percent by 2015. Soybeans, which by the way are an annual row crop that can be highly erosive and dependent upon chemicals, are the primary source of biodiesel.
“The Legislature really missed a key opportunity to send a signal to the market and the public in general that energy production based on perennial systems is important,” says Falk, the seed dealer. “Given how long it takes just to propagate prairie seed, we can’t afford to miss many more opportunities like this.”