ENERGY EFFICIENCY IN BIOREFINERIES - A CASE STUDY OF FISCHER-TROPSCH DIESEL PRODUCTION IN CONNECTION WITH A PULP AND PAPER MILL

A problem arises in integrated production plants, where several products are produced simultaneously, when different plants are evaluated in respect to their own energy efficiency indicators. Energy efficiency is measured as the ratio of energy input to products produced. In a mill that produces pulp and paper products, heat, electricity, and liquid transportation fuels, the challenging problem is how to define a millspecific energy efficiency indicator and how it can be compared to corresponding indicators in other mills. In this study, energy efficiency figures were calculated for a stand-alone Fischer-Tropsch (FT) plant and for a case in which the same stand-alone plant is connected to an integrated pulp and paper mill. In addition, the study also evaluated CO2 emission efficiencies. The results clearly indicate that the introduction of the FT plant into an integrated pulp and paper mill is beneficial from the perspective of primary energy and biomass use. When considering CO2 emissions, the benefit depends on the definition of the plant boundary and the degree of optimization of the integrated process. TURO HAIKONEN*, MARI TUOMAALA, HENRIK HOLMBERG, PEKKA AHTILA ENERGY EFFICIENCY IN BIOREFINERIES—A CASE STUDY OF FISCHER-TROPSCH DIESEL PRODUCTION IN CONNECTION WITH A PULP AND PAPER MILL