Renewable waste-based fuels may decrease the resource use and environmental impact of the road transport sector; one of the options is biogas produced via anaerobic digestion of waste streams from pulp and paper mills. This paper describes process simulation and economic assessments for two options for integrating anaerobic digestion and production of liquid biogas in a typical Nordic Kraft pulp mill: (1) a high-rate anaerobic reactor in the wastewater treatment, and (2) an external anaerobic stirred tank reactor for the treatment of primary and secondary sludge as well as Kraft evaporator methanol condensate. The results revealed an annual production potential of 26-27 GWh biogas in an average Nordic Kraft pulp mill, which is equivalent to a daily production of 7600 L of diesel in terms of energy, and the production cost was estimated to €0.47-0.82 per litre diesel equivalent, comparable with the Swedish price of €0.68 per litre diesel. However, for the cases with liquid biogas (LBG), a discounted payback period of about 8 years may not be considered profitable by the industry. Other pre-requisites may, however, improve the profitability: a larger mill; production of compressed biogas instead of liquid biogas; or, for case 1, a comparison with the alternative cost for expanding the wastewater treatment capacity with more process equipment for activated sludge treatment. The results reveal that anaerobic digestion at pulp mills may both expand the production of renewable vehicle fuel but also enable increased efficiency and revenue at Kraft pulp mills.