Simulation and life cycle assessment of biofuel production via fast pyrolysis and hydroupgrading

A biofuel process chain based on fast pyrolysis of hybrid poplar and subsequent hydroupgrading of the obtained bio-oil is simulated using Aspen Plus®. The simulation includes the pyrolysis plant and the biorefinery with its hydrotreating, hydrocracking, distillation and steam reforming sections. All parts of the process are modeled with a high level of detail, using 83 model compounds and a kinetic reaction model for the pyrolysis plant. A cross-check with published experimental data is included in order to validate the model. Based on the simulation results, a Life Cycle Assessment (LCA) is conducted for the biofuel products, identifying the processes with the highest contribution to the environmental impacts. The obtained synthetic biofuels are compared with their fossil fuel equivalents in order to quantify their potential environmental benefits. LCA results show greenhouse gas (GHG) savings of 54.5% for the produced fuel mix compared to conventional gasoline and diesel. Electricity consumption is one of the keys for reducing the overall environmental impact, while GHG savings could be enhanced by improving the thermal efficiency of the combustion processes in the plants. The biofuel pathway assessed is found to be an interesting option to produce second-generation biofuels with optimization potential in all phases of the system.