The energy situation in both process industries andpower plants is changing. It is becoming interesting toperform system analysis on how to integrate gasificationinto chemical recovery systems in the pulp & paperindustry and into the CHP systems in power plantapplications to complement with production ofchemicals aside of heat and power. The potentialchemicals are methane, hydrogen, and methanol. It isalso interesting to estimate the potential to introducecombined cycles with gas turbines and steam turbinesusing both black liquors and other type of biomass likepellets, wood chips etc. To perform such type ofanalysis, it is vital to have relevant input data on whatgas composition we can expect from running differenttypes of feedstock. In this paper, we focus on blackliquors as feedstock for integrated gasification systems.The experimental results are correlated into partial leastsquares models to predict major composition of thesynthesis gas produced under different conditions.These quality prediction models are then combined withphysical models using Modelica for the investigation ofdynamic energy and material balances for completeplants. The data can also be used as input to analysisusing e.g. ASPEN plus and similar system analysistools