Transactions of the ASAE Vol. 47(5): 1689-1696 E 2004 American Society of Agricultural Engineers ISSN 0001-2351 1689 FIXED- BED GASIFICATION OF FEEDLOT MANURE AND POULTRY LITTER BIOMASS S. Priyadarsan, K. Annamalai, J. M. Sweeten, S. Mukhtar, M. T. Holtzapple ABSTRACT. The U.S. cattle industry is a $175 billion industry with an estimated 100 million cattle. About 10 million head of these cattle are in feedlots producing harvestable manure. At the same time, the U.S. poultry industry is the world’s largest producer and exporter of poultry meat. Not surprisingly, one outcome is the production of a large quantity of manure byprod- ucts, with approximately 60 million tons of dry harvestable animal manure produced annually from confined livestock and poultry. This article describes a method of extracting energy from feedlot manure or poultry litter biomass either individually or combined with each other. High-ash (approximately 45% dry weight basis) feedlot biomass (HFB) and poultry litter bio- mass (HLB) were gasified in a 10 kW (thermal) fixed-bed, counter-current atmospheric pressure gasifier to generate a mix- ture of combustible gases that could be further burned to generate heat. This article discusses the effect of the biomass particle size on the composition of the product gas leaving the gasifier, the temperature profiles in the fixed bed, and the ash fusion of HFB and HLB during gasification. Air-blown gasification of the biomass fuels yielded a low-Btu gas with a higher heating value of 4.4 ±0.4 MJ/m 3 and an average product gas composition (dry basis) of H 2 : 5.8 ±1.7%, CO: 27.6 ±3.6%, CH 4 : 1.0 ±0.5%, CO 2 : 6.7 ±4.3%, and N 2 : 59.0 ±7.1%. The overall average equivalence ratio was 2.82 ±0.43 on a dry ash-free basis. The experimental results also show that high-alkaline content fuels, such as HLB (Na 2 O + K 2 O = 16.7% of ash), can be gasified by blending with lower-alkaline content fuels, such as HFB (6.0%), to reduce agglomeration in the fuel bed without significantly affecting the heating value of the product gas. The gasification of HLB and HFB yields a low-Btu gas that can be combusted to generate heat for steam or power generation. The process has potential for reducing transportation costs for traditional cropland-based manure application in some regions. Keywords. Agglomeration, Co-gasification, Feedlot biomass, Fixed-bed, Gasification, Manure, Poultry litter, Renewable energy. nimal waste disposal is a major problem faced by all nations across the globe. In the U.S., the annu- al production of collectable cattle manure in feed- lots, i.e., feedlot biomass (FB), is approximately 12 million dry tons, while that of broiler litter, i.e., litter bio- mass (LB), is almost 8 million dry tons (Sweeten, 1992). Col- lectable FB and LB account for approximately 20% and 13%, respectively, of the total collectible animal waste measured as dry solids generated in the U.S. (Sweeten, 1992). The po- tential renewable energy from this harvestable manure is approximately 258 × 10 15 J (245 × 10 12 Btu) of heat energy, Article was submitted for review in September 2003; approved for publication by the Structures & Environment Division of ASAE in June 2004. Presented at the 2003 ASAE Annual Meeting as Paper No. 034135. The authors are Soyuz Priyadarsan, Graduate Student, and Kalyan Annamalai, ASAE Member Engineer, Professor, Department of Mechanical Engineering, Texas A&M University, College Station, Texas; John M. Sweeten, ASAE Member Engineer and Fellow, Professor and Resident Director, Texas Agricultural Experiment Station, Texas A&M University Agricultural Research and Extension Center, Amarillo, Texas; Saqib Mukhtar, ASAE Member Engineer, Assistant Professor and Extension Specialist, Department of Biological and Agricultural Engineering, Texas A&M University, College Station, Texas; and Mark T Holtzapple, Professor, Department of Chemical Engineering, Texas A&M University, College Station, Texas. Corresponding author: John M Sweeten, Texas Agricultural Experiment Station, Texas A&M University Agricultural Research and Extension Center, 6500 Amarillo Blvd. West, Amarillo, TX 79106; phone: 806-677-5600; fax: 806-677-5644; e-mail: j-sweeten@tamu.edu. which is nearly 2% of the total annual energy consumption of the U.S. This is approximately equivalent to the annual en- ergy consumption of approximately 19 million single-family households in the U.S. Traditionally, animal manure is utilized as an organic soil fertilizer for farmland applications, with the application rate generally determined by the nitrogen requirement of the soil. Since poultry litter contains higher amounts of phosphorous relative to nitrogen than required by the crops, it results in phosphorus accumulation in the soil. Runoff of this excess phosphorous accumulated in the soil can result in eutrophica- tion of receiving waters such as lakes and streams. The industry has realized the severity of the potential problem and is taking steps to reduce the environmental impact of such wastes. Animal manure yields energy with no net increase in carbon dioxide or greenhouse gas equivalents. A feasible method of extracting energy from animal manure is needed. Animal waste has the potential to be used as an alternate fuel in different combustion technologies such as boiler burners and fluidized-bed burners to reduce the dependence on fossil fuels and reduce greenhouse gas emissions (Anna- malai et al., 1987a; Annamalai et al., 1997; Annamalai et al., 2003a; Sweeten et al., 1986; Frazzitta et al., 1999). However, these technologies require dry animal waste (<10% moisture) along with low ash and fine particle size distribution (<300 mm for boiler burners and up to 50 mm for fluidized- bed burners), which invariably requires grinding of animal manure. However, the low energy, high ash, and high moisture content of animal waste along with grinding A