Evaluation of Potential Bioenergy Feedstocks for the Southeast

This project involves the assessment of numerous perennial and annual crop plants for conversion to liquid fuels, namely ethanol.  Yield and conversion efficiency are the primary areas of assessment for generally tall bunch grass species that grow well in middle and southern Georgia.  Crop production practices include both conventional and minimum input strategies. 

Crop species and cultivar improvement are determined based on yield and conversion methodologies.  Sweet sorghum and energy cane are feedstock species that produce sugar for direct fermentation and distillation to ethanol.  Current research involves assessment of sweet sorghum varieties and production practices that are adapted to Georgia and produce high concentrations of sugar and biomass.  Energy cane is being assessed for yield and cold tolerance for production in Georgia.  Once germplasm has been evaluated, breeding efforts will attempt to incorporate genes from other sorghum germplasm sources for pest resistance, faster maturity and seed production traits.

Perennial grasses are also an excellent feedstock for conversion of cellulose to bio-fuels.  We are presently testing numerous species for biomass yield and persistence in Georgia.   To date, napiergrass and energy cane have produced an average of 12 to 14 tons dry matter/year versus 5 to 6 tons for switchgrass for the first two years of a long term test at Tifton.   Numerous conversion technologies have been researched for efficient conversion of cell wall material composed of cellulose, hemi-cellulose and lignin to bio-fuels.  For enzymatic conversion, that relies on the breakdown of cell walls by various pretreatments and enzymatic conversion of cellulose and hemi-cellulose to fermentable sugars, we are determining species, varieties and plant parts that have lower lignin and higher degradability.  To some extent, germplasm that is highly digestible for use as forage appears desirable for enzymatic conversion to ethanol.  For thermochemical processes (conversion of biomass to syngas to conversion to bio-fuels), cell wall composition has less importance than traits such as ash and contaminant contents.  However, research will continue in this area.

The primary interest of the geneticist is to assess the genetic variability of some of the common or potentially useful warm-season grasses for biomass conversion.  Bermudagrass and napiergrass were the first species researched in this area, for two main reasons.  1) Bermudagrass is the primary forage grass currently grown in the South, where there are already good production and cultural systems in place.  Genetic improvements in yield and digestibility, in relation to biomass conversion, have already been improved.  Napiergrass has been worked on in Florida and appears to have greater yield potential than all other warm-season grasses, including switchgrass in the South.  2) Significant genetic variability exists from world wide collections for both bermudagrass (over 600 accessions) and napiergrass (over 100 accessions) at Tifton.

Additional Resources:
Bioenergy Feedstocks from Agricultural Crops (18.56 MB .pdf)

Bermuda Grass for Bioenergy? (314 KB .pdf)

Elephant Grass for Bioenergy? (840 KB .pdf)

Project Leader: Bill Anderson
Contact Info:
Affiliation: USDA/ARS Crop Genetics and Breeding Research Unit
P.O. Box 748
Tifton, GA 31793
(229) 386-3170