Analysis of Multi-Biofuel Production during Cultivation of the Green Microalga Tetraselmis subscordiformis

Abstract

Research to date has mainly focused on the properties and efficiency of the production of selected, individual types of biofuels from microalgae biomass. There are not enough studies investigating the efficiency of the production of all energy sources synthesised by these microorganisms in a single technological cycle. The aim of this research was to determine the possibilities and efficiency of the production of hydrogen, bio-oil, and methane in the continuous cycle of processing T. subcordiformis microalgae biomass. This study showed it was feasible to produce these three energy carriers, but the production protocol adopted was not necessarily valuable from the energy gain standpoint. The production of bio-oil was found to be the least viable process, as bio-oil energy value was only 1.3 kWh/MgTS. The most valuable single process for microalgae biomass conversion turned out to be methane fermentation. The highest specific gross energy gain was found after applying a protocol combining biomass production, hydrogen biosynthesis, and subsequent methane production from T. subcordiformis biomass, which yielded a total value of 1891.4 kWh/MgTS. The direct methane fermentation of T. subcordiformis biomass enabled energy production at 1769.8 kWh/MgTS.