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This article addresses the simulation and life cycle assessment of a biogas-to-liquid plant for the coproduction of synthetic fuels (diesel and gasoline) and electricity. The system comprises a biogas dry reforming process to produce syngas, Fischer-Tropsch synthesis, and a combined-cycle process. A detailed reaction model of the dry reforming process is implemented in the simulation of the system in Aspen Plus (R). Inventory data obtained mainly through process simulation are used to evaluate the environmental performance of the system in terms of global warming, cumulative non-renewable energy demand, ozone layer depletion, acidification, and eutrophication. In particular, the life-cycle environmental profile of synthetic biodiesel as the main product of the biogas-to-liquid plant is calculated and compared with that of conventional diesel. Overall, the performance of the synthetic biodiesel product is not found to be environmentally favourable, which suggests the need for further optimising the biogas-to-liquid system to make it competitive with conventional systems. In this sense, biogas production and direct emissions to the air from the biogas-to-liquid plant arise as the main sources of impact.