Evaluation of Alternative Biochemical Routes for Energy and Fuel Production from Brown Algae: An Energy, Economic, and Environmental Assessment

In this study, main routes for biochemical conversion of seaweed into energy and biofuels are assessed based on their economic performance, energy requirements, and CO₂ emissions during plant operation. These routes include: sugar platform (SP), methane platform (MP) and volatile fatty acids platform (VFAP). In SP, sugars produced from hydrolysis and saccharification of carbohydrate part of biomass is utilized by bacteria to produce ethanol. In MP, all parts of biomass including carbohydrates, proteins, and lipids are digested to produce methane. The produced methane gases are used as fuel source for electricity production in a power plant. In VFAP, further degradation of VFAs to methane are inhibited by addition of inhibitors allowing to have VFAs as end products of fermentation. VFAs can be recovered and further processed into mixed alcohols. The process alternatives are simulated in Aspen plus v 8.6 and simulation results are used to develop techno-economic models. Maximum dry seaweed price (MDSP) is calculated using techno-economic model to reach a breakeven point after 20 years of plant operation. MDSP is used as an economic index to identify the economic strength of each route. Sensitivity analysis are performed to identify the main parameters affecting the economics, energy requirements, and carbon footprint of the processes.