Economic evaluation on bio-synthetic natural gas production integrated in a thermomechanical pulp mill

In this study, biorefinery as a concept is applied to thermomechanical pulp (TMP)-based paper production to evaluate the possibility of co-production of synthetic natural gas (SNG), electricity and district heating in addition to mechanical pulp and paper. The combined heat and power plant (CHP) associated to TMP is replaced by a biomass-to-SNG (BtSNG) plant. Implementing BtSNG in a mechanical pulp production line might improve the profitability of a TMP mill and also help to commercialize the BtSNG technology by taking into account of some key issues such as biomass availability, heat utilization, etc. A TMP + BtSNG mathematical model is developed with ASPEN Plus. The model prediction shows that the scale of the TMP + BtSNG mill and SNG price are two strong factors for the implementation of BtSNG in a TMP mill. A BtSNG plant associated to a TMP mill should be built at a scale above 100 MW of biomass thermal input. For the case of Swedish economic condition, commercialization of SNG production as a transport biofuel has not matured yet. Political instruments to support commercialization of transport biofuel are necessary