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The purpose of this paper is to present greenhouse gas study results for biofuels produced with partial qualified utilisation of pulp wood or forest residues when integrated into kraft pulp mill systems. The impact of considering biogenic carbon on the results is also presented.

The material and energy balances of the integrated ethanol production were simulated for the study with a mill‐wide simulation model. Data for the simulation were obtained from prehydrolysis and cooking experiments. The life cycle model for greenhouse gas calculation was created based on the simulation results. In this paper, the change of forest carbon stock caused by residue removal from forest soil and carbon delay of forest growth after stand felling were also taken into consideration, to discuss the true greenhouse gas emissions of forest biomass utilisation.

The emission reduction levels achieved with these ethanol fuels derived from forest biomass ranged from 80 to 90 per cent when biogenic carbon emissions were neglected.

The findings indicate that in both cases a significant percentage of the side flows containing energy can be utilised to produce excess electricity when the ethanol plant is integrated into the pulp mill. The findings also indicate that the carbon storage impact of forest biomasses affects significantly the emission values of both studied fuels and overturns the emission savings of prehydrolysed chip based ethanol.