Bermudagrass for Biofuels: Effect of Two Genotypes on Pyrolysis Product Yield ² A. A. Boateng,* ,‡ W. F. Anderson, § and J. G. Phillips ‡ USDA-ARS, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PennsylVania 19038, and USDA-ARS, Coastal Plain Experiment Station, 115 Coastal Way, Tifton, Georgia 31793 ReceiVed September 11, 2006. ReVised Manuscript ReceiVed NoVember 13, 2006 Bermudagrass is a perennial grass used as forage for livestock and harvested as hay on 10-15 million acres in the southern United States. It has potential as an energy crop for the production of biofuels through the lignocellulosic conversion program. Coastal was released in 1943 and was the primary forage genotype until the development of Tifton 85 which has greater yield and quality for ruminants. Pyrolysis of these two genotypes harvested at the same maturity and separated into leaf and stem was carried out to establish their effect on the yield of pyrolysis products. The pyrolysis was carried out in an analytical pyrolysis-gas chromatography system at 500, 700, and 900 °C temperatures. The noncondensable gas yielded, comprising CO, CO 2 ,H 2 , and low molecular weight hydrocarbons, was estimated between 10 and 12.5 wt %. The char yielded ranged between 5.5 and 16 wt % with remainder, comprising condensable aerosols that constitute bio-oils when condensed, was 73-82 wt % estimated as the difference between the biomass and the produced gas and char. Statistical analysis of variance showed no significant difference between pyrolysis products due to genotype or whether the sample was leaf or stem. However, there was a strong significant effect of pyrolysis temperature on the product yields with the maximum gas yield and minimum char yield occurring at 900 °C. The calorific value of the gas reached 2300-2500 kcal/kg for both genotypes, about 20-25% of the heating value of natural gas. The study helps to ascertain that when harvested at the same maturity, the effect of bermudagrass genotype and plant part on pyrolysis gas and char yields may not be significant during thermochemical conversion. However, the condensable liquids were not analyzed. 1. Introduction Bermudagrass (Cynodon spp.) currently covers over 10 million acres of land in southern United States and is primarily used as a forage for livestock. Some of this pasture is cut for hay. Because of the vast acreage of bermudagrass currently grown in the US, it can be a potential biomass feedstock for biofuel production. The planting of bermudagrass as a forage began after the development and release of the Coastal bermudagrass genotype in 1943. Coastal has been the standard forage bermudagrass against which all cultivars have been measured since 1943. Through the years, other improved forage bermudagrass hybrids have been released. The most recent genotype, Tifton 85, yields 20% higher biomass (Table 1) and has 10% higher digestibility than Coastal. Tifton 85 is currently the bermudagrass of choice for growers who are taking row crops out of production and replacing them with pasture in much of the southern U.S. These two cultivars are very distinct grasses. Coastal is a cross of a local Cynodon dactylon landrace “Tift” and a C. dactylon from South Africa. It has moderately fine stems and leaves. Tifton 85, however, has much coarser stems and leaves. It is a cross of Tifton 68 and a plant introduction from South Africa with fall armyworm resistance. Parent Tifton 68 was developed from a cross between two C. nlemfuensis introductions that had the highest digestibility by ruminants among over 400 accessions tested. Thus, Tifton 85 also has very high digestibility. Two potential conversion platforms are currently being considered under the biomass initiative program. The first, known as the sugar platform, is the bioconversion by simulta- neous saccharification and fermentation (SSF) of lignocellulosic feedstock. The second is the thermochemical conversion platform for the production of synthesis gas (syngas), pyrolytic oils, and related fuels and chemicals. Sun and Cheng 1 carried out enzymatic hydrolysis of acid-pretreated bermudagrass found in the southeastern US for the purpose of bioconversion of the lignocellulosic material into reducing sugars. In their work, cellulases supplemented with -glucosidase were used as the biocatalysts to obtain about 45% ethanol conversion efficiency. ² Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. * Corresponding author. Tel.: 215 2336493. Fax: 215 2336559. E- mail: Akwasi.Boateng@ars.usda.gov. ‡ Eastern Regional Research Center. § Coastal Plain Experiment Station. (1) Sun, Y.; Cheng, J. Enzymatic hydrolysis of rye straw and bermuda- grass using cellulases supplemented with -glucosidase. Trans. ASAE 2004, 47 (1), 343-349. Table 1. Average Forage Yield of Coastal and Tifton 85 Bermudagrass at Griffin, Calhoun, and Tifton, GA, in 2003-2005 a kg/ha oven-dry forage varieties Griffin Calhoun Tifton state-wide avg Tifton 85 14606 C 19868 C 15395 C 16623 Coastal 13015 D 14251 D 12801 D 13355 CV b (%) 7 12 7 LSD.05 778 1390 844 a Any two means in the same column with no letter in common are significantly different (p < 0.05) by the Bonferroni least-square difference (LSD) technique. b cvscoefficient of variance. 1183 Energy & Fuels 2007, 21, 1183-1187 10.1021/ef0604590 This article not subject to U.S. Copyright. Published 2007 by the American Chemical Society Published on Web 12/29/2006