Currently, most of the methods, which require the extraction of immobilized oil from algal biomass for developing biofuels-from-algae, are energy and cost intensive, with the amount of energy consumed for oil extraction exceeding the energy value of the end product in some cases, the company said.
Unitel claims that it addresses this issue by developing a method that focuses its attention on the production of algal fatty acids instead of algal oil extraction.
The Unitel process involves continuous treatment of the feedstock – a slurry or ‘soup’ of water and cultivated algae (1% to 20% by weight) in a hydrolysis reactor to yield a fatty acid product, a ‘sweet’ water stream containing glycerol and other solubles, and de-oiled algal biomass. A small fraction of the fatty acid product is fed back into the reactor as catalyst.
The ‘sweet water’ goes back into the algae propagation tanks, where the carbon in the glycerol helps the growth of phytoplankton. The de-oiled biomass (consisting primarily of proteins and carbohydrates) is dried for use as a food ingredient for animal consumption.
The algal fatty acid product is converted into paraffinic hydrocarbons (alkanes) by being catalytically de-carboxylated, followed by mild hydrocracking and hydroisomerization to make biojet fuel consisting of C10-C15 branched paraffins.
