Within the carbon constrained world biomass based power production is expected to abatement. However, within the framework of a constitute one of the candidates for CO2 liberalized energy market, biomass power system must be competitive from efficiency and cost point of view for their successful commercial breakthrough. Integrated Gasification Combined Cycles based on pressurized biomass gasification, coupled with economical acceptable hot gas clean up systems, are one of the most promising options. Within this study, a technical and economic assessment is carried out of alternative power plant concepts with the aid of computer simulation tools. Different gas turbine plant sizes are considered ranging from 10MW up to 70MW and their performance is evaluated. Apart from stand-alone power e e systems, we complement our study with cases linked with a coal-fired power plant by parallel integration of a gas turbine with the existing steam cycle. Power plant simulations enabled us to discuss issues associated with the optimum integration of the different plant components as well with the operation of the turbine burning low calorific value syngas fuel instead of natural gas. An economic analysis has also been carried out in order to examine the economic viability of the proposed concepts. The different process configurations were evaluated on a Cost of Electricity (COE) basis. During the implementation of this method, the effects of CO2 allowances has also been included in the economic evaluation in order to examine alternative options to enhance the economic attractiveness of biomass power production.