Biofuel production from microalgae by means of hydrothermal liquefaction: Advantages and issues of the promising method

The use of microalgae for biofuel production is one of the promising ways for substitution of fossil fuels. There are a number of microalgae-to-biofuel conversion methods with different target products (biodiesel, bioethanol, biobutanol, bio-oil, biochar, biomethane, biohydrogen, etc.). One of the promising technologies demonstrating a significant increase of references in the literature in the last few years is hydrothermal liquefaction (HTL) of microalgae with bio-oil production. In the present paper, we discuss the advantages of the HTL method and its current important issues. One of the main problems of HTL is the search for optimal strains and cultivation conditions that provide high biomass productivity with optimal biochemical composition. In the case of HTL, the reduction of nitrogen content in feedstock is one of the important issues. The possibility of obtaining the optimal microalgae biochemical composition for the processing that includes HTL is considered. It takes into account our own experience in microalgae cultivation. Also, we analyze the processing ways, which include HTL, and the influence of extraction of high-value compounds from microalgae on the efficiency of bio-oil production and on its quality. © 2017 by Begell House, Inc.