The energy use of the macroalga pelagic Sargassum in the Mexican Caribbean

Abstract

The potential of the pelagic Sargassum as feedstock for energy and substrates production is evaluated from an engineering point of view to determine if the macroalgae is a source of renewable biomass at a large-industrial level. This alternative could be a solution to mitigation and adaptation for the influx problem in the Caribbean coastline of Mexico (and other Caribbean countries). Recent research and experiments suggest that macroalgae can be processed by biorefinery systems like Hydrothermal Liquefaction (HTL) that makes suitable the use of the Pelagic Sargassum as a source of renewable energy and a substrate of potential products and services. Two different process scenarios, with or without a heat exchanger unit, are simulated in Aspen Plus to evaluate the physical, chemical, and cost feasibility of the macroalga continuous HTL to obtain bio-crude oil, an aqueous phase, gaseous phase, and char, as valuable products at an industrial production with a potential use such as biofuel, and fertilizer. Both cases are thermodynamically, energetically, and economically evaluated with a macroalga sludge feedstock of 2.79 M t/year, a total product sales of $14.94 M USD/year, and a payback period of 5.54 years in one of the scenarios considering the total capital, and utility costs of the integrated system and its boundaries. The production of 1.87 PJ/year of energy equates to 0.05% of Mexico's primary energy production from crude oil in 2019. This study stands for an opportunity for adaptation and mitigation of the problem that is affecting the Caribbean zone, as well as for an opportunity of synergy between the scientific, private, and government sectors.