Techniques for Processing Macroalgal Biomass in Energy and Food Production

Macroalgae are commercially available as both food and energy sources. Macroalgae are a diverse group of photosynthetic eukaryotic marine organisms. Unlike unicellular microalgae, macroalgae are multicellular and have plant-like characteristics. Macroalgae are classified as Phaeophyta or brown algae, Rhodophyta or red algae, and Chlorophyta or green algae based on the composition of photosynthetic pigments. The food industry makes extensive use of macroalgae, which are also used to produce biofuels and bioethanol. It is also used as animal feed, fertilizer, and soil conditioner. The aim of this chapter is to provide an overview of thermochemical and biochemical biomass conversion technologies that are employed currently. A growing interest exists in the production of various biofuels. Based on the requirement for drying before processing, the extraction of energy from seaweed biomass can be divided into two types: bioenergy production from the dry seaweed biomass by direct combustion, pyrolysis, gasification, or transesterification and from the wet biomass by hydrothermal treatments, enzyme hydrolysis, fermentation to bioethanol/biohydrogen/biobutanol, and anaerobic digestion. The well-established techniques for the biomass conversion into energy and food products are combustion, fermentation, anaerobic digestion, and biorefining approach. Agar and alginate from seaweed are used as food products.