Techno-economic aspects of different process approaches based on brown macroalgae feedstock: A step toward commercialization of seaweed-based biorefineries

Brown macroalgae, so called seaweed, has shown promising potential to produce biofuel and biobased chemicals. However, a single-product biorefinery producing biofuel from seaweed at an industrial scale has many economic obstacles, hindering its commercialization. In the present contribution, a model-based process analysis was performed in which (1) the main economic barriers of an only-fuel approach were studied extensively, (2) an innovative biorefinery approach was applied to remove the economic impediments and pave the way to the commercialization of a seaweed-based biorefinery. Nizimuddinia zanardini, a natural and widely available brown macroalga in Iran, was chosen as the plant's feedstock. In the only-fuel approach, the seaweed was used to produce fuel ethanol and electricity exclusively. In the biorefinery approach, an integrated process was applied to produce fuel ethanol, electricity, and high-value chemicals, i.e., mannitol, alginate, and protein. Simulations were conducted by Aspen Plus (R), and the results were employed to perform an economic analysis. Considering the internal rate of return of 20% for the plant location, the profitability indices of both process frameworks were calculated. Based on the profitability indices, the only-fuel approach was economically unviable, mainly due to the low conversion rate of ethanol from seaweed carbohydrates. On the other hand, the biorefinery approach was cost-effective, having produced highly valuable chemicals. Therefore, it is much more lucrative to produce highvalue chemicals besides biofuel than to exclusively produce biofuel from seaweed feedstock. The maximum allowable dry seaweed price (MDSP) was -64 and 374 US$ per ton of dry seaweed for the only-fuel and biorefinery approaches, respectively. MDSP of the biorefinery approach can be used to set a benchmark price for future studies on seaweed cultivation.

Automated summary

Translation of the text reveals that while a single-product biorefinery for biofuel production from seaweed faces economic obstacles, an innovative biorefinery approach can potentially pave the way for commercialization by producing high-value chemicals alongside biofuel.