Macroalgae valorization for the production of polymers, chemicals, and energy

The increasing awareness of man-made environmental impact of our modern highly industrialized societies has led to an increasing demand of natural products representing additionally a key element within the transition towards a circular bioeconomy. In this sense, macroalgae constitute a renewable and abundant natural resource with high usage potentials in a wide range of very diverse applications. In addition to the respective useable bioactive compounds varying between species and more significantly between the three taxonomic groups, macroalgae are characterized by additional promising properties such as high growth rates, simple cultivation and harvesting strategies, and no competition with fertile lands. These are only some reasons why macroalgae have been used for centuries as a raw material in very different application fields; the food sector is only one prominent example. Furthermore, new macroalgae-based products have been developed over the last decades; this is true for hydrocolloids, nutra- and pharmaceuticals as well as biomaterials. Additionally, nowadays macroalgae are also a potential feedstock for green energy production in the form of gaseous and liquid biofuels such as biogas, bio-oil, or bioethanol. Within this context this review provides an analysis of the main compounds with possible economic potential obtained from green, red, and brown macroalgae as well as an evaluation of the global macroalgae market and the existing obstacles. Additionally, it also provides an overview of the macroalgae potential in new applications and as a source of green energy.