Pyrolysis of algal biomass

The pyrolysis of algal (Laminaria digitata, Fucus serratus and mix macroalgae species from Black sea) and lignocellulosic (safflower oil cake and grape seed) biomasses was studied at 500 °C in a fluidized bed reactor. The yields of pyrolysis products (char, liquid and gas) were quantified. Pyrolysis condensates were produced in two separate phases; aqueous phase and oil. The yield and composition of products from seaweed pyrolysis were compared with those obtained from terrestrial biomass. Chemical compositions of pyrolysis products relevant to fuel applications were determined. In addition, oils and aqueous phases were analyzed by GC–MS and HPLC. The oil yields from seaweeds varied between 11 and 17%, whereas yields from lignocellulosic biomasses were in the range of 23–40%. The oils from lignocellulosic biomasses showed a higher heating value (30.04–31.25 MJ kg−1) than that of oil from seaweeds. The aqueous phase yields from lignocellulosic biomasses and seaweeds were about 19–21% and 17–26%, respectively. The pyrolysis gases with a yield of about 17–37% were composed of mostly of carbon oxides. The yields of char were in the range 29–36% for seaweeds and 23–26% for lignocellulosic biomass. Due to the higher content of ash (41–52%), the char obtained from seaweeds had a lower heating value than those from grape seed and safflower oil cake.

► The oils from lignocellulosic biomasses has higher calorific value than that of oil from seaweeds.
► Although the chars obtained from seaweeds can not be used as solid fuel or feedstock for gasification, it can be used as fertilizer due to the high K content.
► Production of fuels by pyrolysis seems not possible from seaweeds.