Imagine a farm on which both traditional crops and recent introductions, such as switchgrass, miscanthus and willow, are thriving. The farm features a bedded pack barn for dry cows constructed from building materials obtained from woody products grown on the farm. The loafing area uses biochar, also from woody crops, to filter water as it leaves the barnyard area. The barn is bedded with highly absorbent materials grown on the farm, and the same crops provide cover for a variety of wildlife species. And when it’s time for a lunch break in the field, the farmer uses a compostable plate and cup.
The concept isn’t that far-fetched, and researchers are working on developing biomass for such uses. While bioenergy crops like willow, switchgrass and miscanthus were first grown primarily for energy, new research shows promise for these crops in a variety of consumer applications.
Many bioenergy crops are suited for cultivation on marginal land and help address environmental concerns, especially water quality. However, there’s a lot for the new grower to ponder. Establishing a crop is just one aspect — harvesting, handling, transportation to the market or plant, and conversion to energy must also be considered.
If the purpose of growing bioenergy crops is to produce renewable energy, why should farmers look at other markets?
Most farmers who are growing renewable energy crops are relatively new to the game and have entered the field with the prospect of an expanding market for renewable energy. Alternative marketing options allow farmers to experiment and plant fewer acres as they learn how to grow bioenergy crops.
“Supply chains for energy crops have two ends,” said Dr. Tom Richard, director of Pennsylvania State University’s Institutes of Energy and the Environment. “Feedstocks [are] at one end and markets [are] at the other end. Putting them together is tricky. There are a lot of different relationships. It’s important to understand what the competitive advantages and contractual relationships need to be to make sure that everyone along the su
pply chain makes money and that products work.”
Richard said that renewable energy crops are bulky and can be expensive to establish, harvest, store and transport. New markets allow farmers to develop strategies for managing crops from seed to harvest on a small scale while emerging markets are developing.
Richard explained, “There are business and technical aspects. Considerations include when and how to harvest; whether to put in an intermediate storage system on the farm or store off the farm; how to move materials to the end market.” He noted that there is both full-scale and simulated research in each of these areas for perennial grasses and willow, with the goal of finding cost-effective solutions. He referenced the Bioenergy Knowledge Discovery Framework (www.bioenergykdf.net) as a partner and source of data sets, collaboration efforts and mapping tools.
While switchgrass and miscanthus may look similar to traditional hay crops in the field, they are quite different. Switchgrass is a perennial warm-season grass that’s native to the U.S. It’s widely adapted to a variety of growing conditions and suitable for reclaimed land such as mines. A healthy, well-established stand of switchgrass is productive for up to 20 years.
Miscanthus, also a perennial grass, is related to sugarcane. Sterile hybrids grown from rhizomes are cultivated for biomass. Miscanthus grows up to 12 feet tall, and mature stands produce as much as 10 to 12 tons per acre. This crop has the potential to yield more biomass annually than other bioenergy crops and may meet biofuel goals without displacing food production.
Shrub willow cultivation for biomass differs substantially from growing giant grasses. After site preparation, 6 to 8-foot-long willow whips are cut into 10-inch pieces and put into the ground. Most willow is planted in double rows, with 5 feet between rows and 2.5 feet between pairs. After the first summer, the willow is mowed, or coppiced, which encourages new growth. New shoots from the coppice create a dense shrub that fills in the space. After several years of growth, the coppice is harvested in winter. Following harvest, the willows send up new shoots that can be harvested again in several years. Richard noted that some existing willow stands have been harvested as many as seven times, but with improved genetics, growers will likely opt to establish new stands.
One potential alternative use of bioenergy crops is in the mushroom growing industry. Mushroom growers use commercially produced compost that is made close to major mushroom growing areas such as Kennett Square, Pennsylvania.
Dr. Dan Royse, professor emeritus, Penn State Department of Plant Pathology and Environmental Microbiology, said the mushroom industry is big and uses a lot of biomass. In 2013, more than 1 ton of biomass was used to nurture Agaricus, the species that accounts for 98 percent of mushroom production in the U.S.
Royse noted that producing the compost required for growing mushrooms is a stinky process; European mushroom growers use biofilters for odor control. “Gases are blown through a straw-based biofilter, which collects ammonia and sulfur compounds,” Royse explained. “After several months, the biofilter material can be used as part of the compost material.”
Spent mushroom substrate (SMS), the material that remains after mushrooms are harvested, is high in nitrogen and organic matter, and it can be used as a soil amendment. “It’s a sustainable cycle,” Royse said. “We can take spent mushroom compost, put it back on farmland and grow another crop. If you apply SMS to a cornfield, you can harvest the corn, then use the corn stover in the mushroom compost.”
Calvin Ernst, who has been growing switchgrass seed for conservation projects for more than 30 years, said that residential heating was the original target market when he started production with Ernst Biomass in August 2012. As the company expanded, Ernst realized there were other applications and markets for switchgrass.
Switchgrass makes suitable bedding for dairy cattle, horses and poultry, and it can be used for compost and mulch. Current research into switchgrass includes applications for biopackaging (plastic substitute or replacement) and building materials. Switchgrass also shows promise as an industrial absorbent, primarily in the expanding oil and natural gas industries.
Dr. David DeVallance, who teaches sustainable construction at West Virginia University, said there’s potential for using biomass products in the building industry; however, biomass products won’t compete with existing traditional wood products.
“These short-rotation crops won’t compete with solid lumber,” DeVallance said, noting that the U.S. green building market is expected to increase in value. “They will be in the same category as wood residues that are already being used for products such as particleboard. But if we can make new, more efficient products, we can reduce energy use in homes.”
should short-rotation woody crops and perennial grasses have to be beneficial to the construction industry? “Improved thermal performance, added value to locally sourced wood and biomass, and reduced construction time and carbon footprint,” said DeVallance. “The USDA has a certified biobased product program, so an interior composite panel that is at least 55 percent switchgrass would qualify for certification.”
Some biomass crops require treatment to optimize the end use benefits of the crop. Torrefaction is heat treatment of woody biomass, such as willow or poplar, that results in a high-quality biofuel with higher energy density than the original material. The end product is hydrophobic, or water-repellent, and can be pelletized for easier handling and storage.
WVU is currently working on a heavy-use livestock loafing area that employs a layered biomass chip filter. “We have 12 inches of gravel, and on top of that we’re putting layers of different biomass,” DeVallance explained. “We’re using white oak layered with different levels of torrefied chips and/or biochar. We want to see if we can improve [the] quality of runoff water.” After completion of laboratory studies, the group is now working on a field project in which three loafing pads will be compared.
Another area in which biomass crops can be used is in packaging. “A lot of people are interested in a product that farmers may be able to s
upply,” said Dr. Judd Michael, Penn State professor of sustainable enterprises. “Packaging comprises about 30 percent of all plastic uses, and packaging stakeholders are trying to get people away from limited natural resources such as petroleum-based products. This could be solved with bioproducts.”
Developing new markets for biomass requires a concerted effort by farmers and industry stakeholders. The Northeast Woody/Warm-Season Biomass Consortium (NEWBio) is a network of universities, private industry and governmental organizations aimed at creating sustainable chains for biomass energy in the Northeast. NEWBio research focuses on switchgrass, miscanthus and coppice production of willow. The efforts of NEWBio and other organizations will help develop reliable and sustainable biomass for a wide variety of applications, including fuel, that will help the U.S. further its goal of energy independence. For more information on NEWBio partners and projects, visit www.newbio.psu.edu.
Photo 1 by Wolfgang Hoffmann.