Evaluation of Micro-Scale Syngas Production Costs through Modeling

Abstract

Feasibility of biomass gasification is very much dependent on the cost of the gasification facility and its operation. A cost analysis model was accordingly developed to analyze the unit cost of syngas production from micro-scale biomass gasification facilities. Costs considered included all capital and operating costs. The model was applied to evaluate a scenario for Mississippi in 2008. Results of the modeling indicated that operating cost was the major part of the syngas production cost, and the single-shift operating cost could be up to 83.64% of the total annual cost of syngas production at the 60 Nm3 h-1 capacity level. Labor cost was the largest part of the operating cost and the total annual cost. The labor cost could be up to 73.60% of the total of annual operating cost and 61.56% of the total annual cost of syngas production. The unit cost and energy cost of syngas production of the 60 Nm3 h-1 facility were $0.55 Nm-3 and $0.095 MJ-1, respectively, which were higher than the $0.357 Nm-3 and $0.009 MJ-1 natural gas average retail prices in the U.S. in the fourth quarter of 2008. When the production capacity increased, the total syngas production annual cost continually increased, but the syngas unit cost markedly decreased. Therefore, the effective way to reduce costs is to plan for a higher-capacity micro-scale facility. Sensitivity analysis showed that, from the lower bound to the upper bound of the production capacity range tested (60 to 1800 Nm3 h-1), there was a shift from labor cost to equipment cost as the factor of greatest influence on syngas unit cost. Such information provided by the model identifies considerations for planning and/or operating micro-scale gasification facilities. The model can be a tool for analyzing the economics of syngas production and, in that regard, it can generate useful information for the design of smaller gasification plants.