Comparison of the performances and costs of alternative applications of biosyngas

VTT, in close co-operation with Finnish-based industrial companies, is developing an advanced process for producing multi-purpose synthesis gas (syngas) from solid biofuels. To have a common basis for comparing different bio-syngas applications with one another, a relatively simple model of synthesis-gas conversion was developed. The model splits the conversion into three basic calculation steps: (1) the extent of conversion of syngas, (2) the extent of uptake of the chemical energy of the converted syngas in the synthesis products and (3) the selectivity of the synthesis towards the desired main product(s). The model was applied to the following end-products: Fischer-Tropsch liquids, methanol, synthetic natural gas and hydrogen. Useful comparisons of the production efficiencies and the production costs of these different compounds were derived. The model was also used to elucidate the sensitivities of the performance and cost estimates to such variables as the cost of the feedstock, the composition of the synthesis gas and the value of the by-product energy. The economics of bio-syngas production based on the process concept under development at VTT appear very promising.