Biomass for Energy Production

Research Issue

Increasing emphasis on renewable energy sources has resulted in renewed attention to using forest and agricultural biomass for energy.  The recently revised report from the Billion-ton study [pdf - you may download a free pdf reader from Adobe] examined the feasibility of U.S. forest and agriculture resources to replace a third of the country's present petroleum consumption with energy produced by at least one billion dry tons of biomass annually.  Using biomass for energy has the potential to reduce net carbon emissions associated with climate change. Woody biomass is an abundant, widely distributed, low-cost, local source of renewable energy that is commonly used for residential-heating, commercial electricity, and industrial heat and power.  Currently woody biomass only provides the equivalent of three percent of U.S. energy consumption.  Barriers to increased large-scale use of woody biomass for energy include uncertainty about the long-term availability, cost, and potential environmental impacts.  Native perennial grasses such as switchgrass (Panicum virgatum L.), big bluestem (Andropogon gerardii Vitman), and Indian grass (Sorghastrum nutans (L.) Nash) also have the potential to be used as low-input biomass energy crops.  If integrated into management systems that include trees, these grasses have the potential to produce earlier revenue while the tree crop matures. Integration of trees and bioenergy grasses will provide a number of environmental benefits including greater carbon sequestration, protection of soil and water resources, improved wildlife habitat, and increased landscape diversity. 

Our Research

NRS scientists are exploring current and future woody biomass availability from multiple perspectives including estimation of available wood residues from harvest operations in native forests, options for plantation production of woody biomass, biomass resources in proximity to coal-fired electricity plants that have the capacity to co-fire with wood, the apparent effects of policies related to utilization of biomass for energy, factors affecting utilization of woody for residential heating, and long-term effects of intensive biomass on forest soil nutrients. 

Co-firing with woody biomass in existing electric utilities is a relatively low-cost way to increase use of woody biomass for energy within the existing infrastructure.  Our analyses show that partial replacement of coal with woody biomass appears feasible in many locations, but the clustered spatial arrangement of existing coal-fired electric utilities limits the capacity to co-fire with wood from surrounding forests. We analyzed factors associated with electric utilities that currently co-fire with woody biomass to identify locations that appear promising for establishment of co-fired or wood-fired electric utilities.  Other analyses show that wood energy used for residential heating has declined precipitously over the past century but is still responsive to the costs of alternative energy sources. Substantial increases in other sources of residential heating fuel trigger an increase in wood heating. Highly efficient residential wood and pellet stoves that are currently available can convert a greater portion of woody biomass to useful energy than existing electric utilities that co-fire with woody biomass. 

We are also evaluating the productivity of both trees and grasses when integrated into various agroforestry practices.  In cooperation with the University of Missouri Center for Agroforestry, we are screening native grasses such as big bluestem (Andropogon gerardii Vitman), little bluestem (Schizachyrium Nees), eastern gamagrass (Tripsacum dactyloides (L.) L.), and switchgrass (Panicum virgatum L.) for shade-tolerance to select the most promising cultivars for integrating into agroforestry alley-cropping systems.  Other studies are evaluating the flood-tolerance of different trees and grasses for planting along riparian or on bottomland sites.  Management for bioenergy crops on these sites will require selection of trees and grasses that have the capacity to withstand flooding by both backwater and flowing water to minimize establishment costs and harvesting after a killing frost to minimize nutrient depletion.

There is much we do not yet understand about the long-term nutrient dynamics associated with repeated harvests of biomass from energy plantations or native forests. Consequently we are using existing and new field experiments to measure nutrients extracted from sites during repeated woody biomass harvests and the associated long-term changes in soil nutrients. This includes experimentally testing the effectiveness of best management practices designed to sustain habitat biodiversity and soil productivity.

 

Expected Outcomes

• A better understanding of the spatial distribution of woody biomass resources relative to existing electric utilities that have the potential for co-firing with wood.
• Identification of locations with relatively abundant woody biomass resources and other infrastructure needed to support electric generation with woody biomass. 
• A more realistic estimation of the possible regional contributions of woody biomass for energy production relative to total energy consumed.
• Field trials to test the productive capacity of energy plantations for alternative woody and herbaceous plants.
• Methods to measure the nutrient dynamics associated with short-term and long-term biomass harvesting in native forests.
• Identification of native shade-tolerant perennial grasses as bioenergy crops within several agroforestry practices.
• Quantify growth of trees when grown in association with native grasses or man-made prairies to include native legumes when harvested as bioenergy crops.
• Better guidance for managers on how to harvest biomass while protecting the productive capacity of soils.

 

Research Results

Aguilar, F.X.; Song, N.; Shifley, S. 2011. Review of consumption trends and public policies promoting woody biomass as an energy feedstock in the U.S. Biomass & Bioenergy. 35: 3708-3718.

Kabrick, J.M.; Goyne, K.W.; Fan, Z.; Meinert, D. 2011. Landscape determinates of exchangeable calcium and magnesium in Ozark Highland Forest soils. Soil Science Society of America Journal 75(01):164-180.

Ponder, F., Jr. 2011. Contrasting the effects of organic matter removal and soil compaction on root biomass of 9-year-old red oak, white oak, and shortleaf pine in a Missouri Ozark forest. . In: Fei, S.; Lhotka, J.M.; Stringer, J.W.; Gottschalk, K.W.; Miller, G.W. (eds.) Proceedings: 17th Central Hardwood Forest Conference; NRS-GTR-P-78. Newtown Square, PA: USDA Forest Service, Northern Research Station:  323-331.  

Van Sambeek, J.W.; McGraw, R.L.; Kabrick, J.M.; Coggeshall, M.V.; Unger, I.M.; Dey, D.C.  2007.  Developing a field facility for evaluating flood tolerance of hardwood seedlings and understory ground covers.   In: Buckley, D.S.; Clatterbuck, W.K. (eds.) Proceedings: 15th Central Hardwood Forest Conference.  SRS-GTR-101.  Ashville, NC: USDA Forest Service, Southern Research Station:  727-733. 

Van Sambeek, J.W.; Navarrete-Tindall, N.E.; Garrett, H.E.; Lin, C.-H.; McGraw, R.L.; Wallace, D.C.  2007. Ranking the shade tolerance of forty-five candidate ground covers for agroforestry plantings.  The Temperate Agroforester 15(4): 1-9.

Van Sambeek, J.W.; Garrett, H.E.  2004.  Ground cover management in walnut and other hardwood plantings.  In: Michler, C.E.; Pijut, P.M.; Van Sambeek, J.W.; and others.  Proceedings: 6th Black Walnut Symposium. NC-GTR-243.  St. Paul, MN: USDA Forest Service, North Central Research Station: 85-100.

Research Participants

Principal Investigator

• John M. Kabrick, Research Forester, US Forest Service, Northern Research Station
• Felix Ponder, Jr., Research Soil Scientist (retired), US Forest Service, Northern Research Station
• Stephen R. Shifley, Research Forester, US Forest Service, Northern Research Station
• J. W. Van Sambeek, Research Plant Physiologist, US Forest Service, Northern Research Station

Research Partners

• Franciso X. Aguilar, Forestry Department, University of Missouri at Columbia
• Keith W. Goyne, Department of Soil, Environmental and Atmospheric Sciences, University of Missouri at Columbia
• Michael Goerndt, Forestry Department, University of Missouri at Columbia
• Nianfu Song, Forestry Department, University of Missouri at Columbia
• H.E. Garrett, University of Missouri at Columbia
• Shibu Jose, University of Missouri Center for Agroforestry
• Douglas C. Wallace, National Agroforestry Center, USDA Natural Resource Conservation Service 
• Elsberry Plant Materials Center, USDA Natural Resource Conservation Service