Energy Crops and the Environment

Biomass energy crops are trees and perennial grasses grown specifically to provide raw materials (feedstocks) for energy producers and industry. The U.S. Department of Energy's Bioenergy Feedstock Development Program (BFDP) conducts and funds research on a variety of trees and switchgrass. The Program has determined that hybrid poplars, hybrid willows, and switchgrass have the greatest potential for dedicated energy and raw material (fiber) crops across a wide geographic range. Agricultural, forest and municipal wastes and residues, and recycled paper, are valuable short term “bioenergy” resources, but alone do not provide the long term advantages of dedicated tree and grass energy crops. Together, bioenergy from waste sources and dedicated crops can provide substantial contributions to the Nation’s energy use mix. The main goal of dedicated crops is to provide energy and material sources while providing environmental benefits and increasing opportunities for rural economic development. These biomass energy crops provide environmental benefits such as improved water quality, native wildlife habitat, and increased soil conservation compared to traditional agricultural row crops.

Trees and perennial grasses can often be grown on farm land that is less suitable for conventional crops and can soil stabilization. Although energy crops could potentially be grown on any of the nearly 400 million acres of cropland available in the U.S., energy crops must be economically competitive with traditional crops. Recent studies have used an agricultural simulation model to estimate how energy crops (switchgrass, willow, and hybrid poplar) would compete with traditional crops at a farmgate price of about $40/dry ton. In this analysis, about 42 million acres of switchgrass could be competitively grown and sold for bioenergy by 2008. The potential regional distribution of switchgrass production is shown in the map below. For additional details on this analysis, please visit http://bioenergy.ornl.gov/papers/wagin/

• Rural agricultural development
• Domestic energy supply
• High yield per unit of area
• High energy output/input ratios
• Predictable supply
• Possible coproducts: pulp and paper, chemicals, forage
• Multiple crops and harvesting options
  • Grasses harvested once or twice annually
  • Trees harvested on 3-10 year cycles

• Water quality improvements
• Relatively low chemical inputs (fertilizers, herbicides, pesticides)
• Carbon sequestration
• Wildlife habitat
• Stabilization of streambanks
• Environmental sustainability

The BFDP is investigating how growing energy crops on agricultural lands can decrease erosion and runoff compared to agricultural crops. Field studies at sites provided and maintained by cooperators are being done to determine if the extensive rooting systems of trees and grasses will provide

• Soil stabilization
• Nutrient retention
• Carbon sequestration
• Channels for water infiltration
• Stabilization of riverbanks
• Decrease bank erosion
• Decrease sediment deposition in rivers and streams
• Intercept nutrients and sediment in runoff

Researchers have established several heavily monitored test sites to learn how energy crops can contribute to improvements in surface water and groundwater quality as a result of

• Reduced herbicide and pesticide requirements which may decrease the potential for chemical runoff into surface water and infiltration into groundwater
• Extensive Roots of both trees and grasses which may:
• Intercept nutrients which could migrate into groundwater
• Reduce nutrient runoff and surface water contamination

• Natural forests provide the best habitats for birds and small mammals
• Tree crops provide habitat of similar value as natural forests
• Tree and switchgrass plantings support more bird species than traditional row crop plantings
• Plantings with greater vegetation variation and more groundcover are more attractive to small mammals
• Tree and switchgrass plantings provide habitat for species of concern

• Characterizing soil physical and chemical changes over time following biomass energy crop establishment
• Quantifying soil losses from biomass energy crops compared with agricultural crops
• Determining nutrient transport and water quality
• Determining the potential of biomass energy crops as filter strips
• Determining the use of agricultural wastes as nutrient sources for biomass energy crops
• Wildlife diversity questions on larger scale plantings
• Determining the carbon sequestration potential of biomass energy crops

For more information about the environmental sustainability research efforts, contact

Bioenergy Feedstock Development Program
Oak Ridge National Laboratory
P.O. Box 2008
Oak Ridge, TN 37831-6422
telephone: (865) 574-7364; fax: (865) 576-8143