In this work, the gasification of the black liquor is proposed as an alternative ammonia production route. Due to the seasonal variation of the energy prices, a multi-time integration approach that combines different technologies and energy inputs is used to identify the most suitable operating conditions and arrangements that minimize the energy resources consumption. As a result, the integration of technologies such as power-to-gas systems, carbon capture and injection units, along with liquid fuel storage, may help offsetting the intermittency of the renewable energy resources and increasing the economic revenues of the integrated pulp and ammonia plant. The optimal CO2 management and synthetic natural gas storage may ensure a reliable operation even during the strained periods of the electricity grid. Also, the credits obtained from the injection of biogenic CO2 emissions may compensate for the investment cost associated to the implementation of these new technologies.