Carbohydrate-rich and fast-growing seaweeds such as the S. japonica species are increasingly becoming the 3rd generation biomass of choice. Environmentally friendly as well as economically sound processes for biofuel production are essential if the benefits of these novel marine feedstocks are to be harnessed. This study features an experiment-based process design that combines a fluidized bed fast pyrolysis reactor system, non-intensive pretreatment, and a Bryton power cycle in an, energy-wise, nearly self-sustainable system, considerably reducing the utilization of fossil fuel-derived utilities. Complex liquid products of pyrolysis and catalytic upgrading were modeled using a specialized software ensuring strict adherence to experimental data, hence retaining a highly realistic simulation. Results of comprehensive techno-economic and market uncertainty assessments have shown a capital investment of 170 mil. USD, and a minimum selling price range of 1.534-1.852 USD/L. When compared to traditional oil and gas extraction and refining processes, the designed process yielded a 12.8-fold reduction of the total CO2 emitted, indicating a superior process in terms of environmental sustainability.