Process Optimization for the Hydrothermal Production of Algae Fuels

Abstract

In this work, the production of liquid fuels from algae via hydrothermal liquefaction has been analyzed. The process consists of algae growing and harvesting, biomass liquefaction, hydrocracking of the biocrude, and the separation of the products into fuels. Surrogate models for all of the units are developed to evaluate the optimal operating conditions including the nutrient and light effects on algae growth rate. The yield and distribution of the products of hydrothermal liquefaction (HTL) and the hydrocracker are predicted using kinetic and yield data, and the operation of the column is determined using both rules of thumb and experimental data. The model is optimized aiming at selecting the algae composition, HTL, and hydrocracking product distribution. In particular, the algae should have 53% lipids, 30% proteins, and 15% carbohydrates for the production of a mass with 51% biocrude that is cracked into 18% kerosene, 24% gasoline, and 59% diesel. The estimated facility investment costs add up to 130 M€ with a production cost of 0.64 €/gal. These results are competitive with renewable-based Fischer−Tropsch (FT) fluids and biodiesel.

Techno-Economic and Life Cycle Analyses of Thermochemical Upcycling Technologies of Low-Density Polyethylene Waste

“…Life cycle assessment (LCA) has also been performed for producing power and syngas . Hydrothermal liquefaction (HTL) is also exploited for treating plastic waste using steam, , but TEA and LCA for HTL have mainly focused on moist organic residues, such as municipal organic residues, biomass, , and algae , rather than plastics.…”