Forestry biomass – The Southeast U.S. is heavily forested; Alabama, Georgia, North Carolina, South Carolina, and Virginia average approximately 65 percent forest coverage. Georgia’s total acreage is 37,068,000 acres, of which 65 percent is forested. Of Georgia’s 23,631,000 timber acres 750,000 acres are in national forests and the remainder is privately held. In addition to forested land another 16 percent of the land (5,800,000 acres) is devoted to agriculture or grazing. A long growing season coupled with over 50 inches of rain, soil with low cation exchange capacities, and low water and nutrient holding capacities are characteristic of the state and the region.
The Southeastern U.S. has an abundance of wood and wood byproducts that are available for use as energy feedstocks. Many areas within the southeast are currently growing 50% more wood than is harvested each year, and chip prices generally range from $40 to $60 per dry ton delivered.
The Georgia Forestry Commission estimates that 700 million gallons of ethanol per year could be produced from the clean pine fiber coming from small merchantable trees (5 million tons/yr) plus other trees now classified as non-merchantable (3.8 tons/yr); if the conversion rate of 80 gallons per dry ton is achieved. This calculation excludes 19 million tons per year of current other (non-energy) uses of wood yet does not factor in the many wood chip to electricity plants now being planned and developed in Georgia. Given that tree biomass accumulates at an average rate of 2.5 to 3.8 for slash and loblolly pine (the main planted pine species in Georgia) it is likely that some forested acreage will be converted to the higher biomass producing perennial grass crops to serve some of the energy enterprises.
Dedicated Biomass Crops – When compared to other parts of the country the Southeastern US agriculture has a long growing season with reasonable rainfall (50+ inches/yr), which is often supplemented by irrigation from ground and surface water sources. Many soils of the region have a low cation exchange capacity and are relatively shallow. Over the past five years Dr. Bill Anderson, a Tifton USDA-ARS plant breeder, and Dr. Dewey Lee, UGA extension plant scientist have been examining plant species which show promise as dedicated bioenergy crops. Several of the perennial grasses include Napiergrass (Pennisetum purpurem), energy cane (Saccharum sp.), giant reed (Arundo donax), bermudagrass(Cynodon sp.), sorghum, and Miscanthus. Yield trials of these grasses have been promising, with many of the trials indicating yields in excess of 22 Mg/ha/yr (10 tons per acre) are possible with minimal inputs. Sub-tropical species perform well in the Southeast in comparison to switchgrass, but some species such as napiergrass need greater inputs to sustain yields. Breeding efforts are underway to improve yields and increase nutrient and water use efficiency.
Learn more about bioenergy crop research hereand our partners at New Energy Farms.