Production of jet fuel from microalgae biomass cultivated in saline domestic wastewater.
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Date
2018
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Abstract
Jet fuel from crude petroleum oil is known as the most efficient energy carrier for the aviation
sector. Environmental concerns and economic pressure drive major industries to adapt to
current global revolution towards alternative, sustainable, and clean fuels. In this study
conversion of algae biomass to jet fuel is presented as a novel technology of low carbon
footprint and a cost-effective jet fuel. In this current study, it is reported that there is a
possibility of substantially converting microalgae oil into aviation fuel by adapting and
applying the same processes used for the conversion of fossil crude petroleum oil into
conventional jet fuel. The drawback, however, remains the low oil output from used species of
microalgae and the general operating costs which are still at developmental stages.
A part from the introduction and the literature review making respectively chapter 1 and
chapter 2, this study, therefore, has focused on the magnification of lipid production and the
simplification of the conversion processes in chapter 3. Microalgae cells were physiologically
stressed by totally depriving them of all growth nutrients for three days aiming to modify their
genetic physiology which in turn will favour the yield of lipid and bio-oil. An elaborate
experiment was established from algae biomass cultivation to jet fuel production. The
experiment involved biomass cultivation, harvesting and bio-oil extraction using a solvent
mixture made of methanol and chloroform. Thermal cracking without catalyst or pyrolysis of
crude bio-oil were undertaken to break down the carbon chains in order to complete the
fractionation. ASTM methods and standards related to aviation fuels were used to generate the
relevant data.
The conceptual design with a simplified conversion process undertaken in chapter 4 was
established based on the experiment completed in chapter 3. It suggested to cultivate the
species in domestic wastewater ponds or use the seawater/saline water because the used species
was comfortable in saline or marine environment. Parameters such as density, kinematic
viscosity, flash point, freezing point, total sulfur, net heat of combustion and distillation were
evaluated during the experiment in chapters 3 and 4. It was found that the majority of
parameters analysed regarding the algae-based jet fuel from the laboratory was complying to
ASTM standards. However, it will require additional processes such as upgrading and
reforming to enhance the quality of jet fuel and improve the level of some parameters such as
density and freezing point which were not rigorously complying with ASTM standards. Also,
the improvement involves the use of the same additives used for conventional jet fuels for flow
ability and freezing at higher altitudes. The scaling up of the production process is still a
challenge due to operating costs. In this regard, blending algae-based jet fuel and the
conventional jet fuel in 50/50, 80/20 and 20/80 ratios was carried out and evaluated in
Chapter 5 and Chapter 6 as an alternative approach for sustainability.
Description
Doctoral Degree. University of KwaZulu-Natal, Durban.