Protein separation and characterization from Neochloris Oleoabundans

21 
 
 
Fig. 1.4. The picture represents the distribution of various products from microalgae on a base scale of 100 kg of 
microalgal biomass (Wolkers, Barbosa, Kleinegris, Bosma, Wijffels, & Harmsen, 2011) 
The production of methane from microalgae has been proposed since the 50’s using wastewater 
as inoculums, however not much work has been done in this field. Recently the U.S. Department 
of Energy listed three main biobased fuels as the main ones from microalgae, namely: 
i. Production of methane gas via biological or thermal gasification 
ii. Production of ethanol via fermentation 
iii. Production of biodiesel 
A potential fourth option would be burning directly the biomass to produce steam and 
electricity. However, it would miss the transportation fuel purpose and its emphasis as an 
environmentally sustainable fuel, which is one of the most important issues for developed 
economies (i.e. USA ). (Sheelan, Dunahay, Benemann, & Roessler, 1998) 
Microalgae store organic matter through the photosynthesis. Microalgae find CO
2
 in atmosphere 
as well as anthropogenic gases like flue gases from fossil power plants. SunChem process was 
designed to produce methane from gasification of microalgae. It is mainly composed by 5 
different steps as shown in Fig. 1.5. The first step is represented by the production of the 
biomass in the PBR (photobioreactor). In this stage the fixation of CO
2
 via the photosynthesis 
leads to the synthesis of biomass. In the second step excess water is removed mechanically and 
recycled to the PBR. The algae concentration reached is approximately 20 wt% dry mass. The 
biomass is then liquefied by heating it up to 450°C at a pressure of 30 MPa . In the fourth step 
the organic stream is catalytically gasified under hydrothermal conditions to Bio-syngas, with 
methane as the main product. In the last step methane is separated from CO
2
, that is recycled to 
the PBR and methane is partially used to provide the heating needed in the process. (Haiduc, 
Brandenberger, S., F., Bernier-Latmani, & Ludwig, 2009).