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A. Zhang and C. Li
biomass from the culture water and drying it for subsequent oil collection. Relatively
low algal biomass concentrations and the small size of microalgae make separation
challenging and energy intensive. A meta-analysis of published studies shows that
more than 40% of the total energy required for biodiesel production can be attributed
to harvest and product collection [35].
Purity of the algal lipid is an important parameter for processing into liquid transportation fuel. Inorganic materials that stay with the oil are a concern, and the method
of harvest and collection can influence the impurity levels. Inorganic salts and phospholipids are two known impurities that could affect processing. Inorganic salts are
in the culture medium and occur naturally in algae, but they also can be introduced
as flocculants.
Evaluating the sustainability of algal cultivation systems for biofuel production
requires examining the various material and energy inputs needed for the cultivation systems to maintain scalable productivity, maximize system robustness, and
minimize costs. Scalable productivity refers to a cultivation system’s ability to maintain productivities with respect to algal biomass and algal product (mass/area-time
or mass/volume-time) from the laboratory scale to the commercial scale. System
robustness refers to a cultivation system’s ability to reliably and dependably deliver
consistent productivity and avoid system crashes or failures as a result of either biological or physicochemical causes. Costs pertain to capital and operating costs for a
cultivation system.
3.3 Hydrocarbon-Rich Fuel Produced by Pyrolysis
of Vegetable Oil
3.3.1 Reaction Mechanism of Catalytic Pyrolysis
Pyrolysis of oil refers to the process of breaking the chemical bond in triglycerides to
produce small molecule substances under almost oxygen-free and high-temperature
conditions. The molecular weight of animal and vegetable oil, which is generally
larger, can be decreased by pyrolysis that helps to reduce the viscosity of raw oil. The
pyrolysis of oil, known as a complicated process, includes molecular bond rupture,
molecular isomerization, and polymerization, and we can obtain the products in different distributions of molecular weight by altering pyrolytic temperature, pyrolysis
time, reaction atmosphere, and heating rate [36].
Catalytic cracking of oil refers to the high-temperature cracking of animal and
vegetable oils and waste oils to produce low-carbon alkanes, olefins, etc., after catalyst addition. The addition of the catalyst not only reduces the activation energy
of the cracking reaction, increases the reaction rate, increases the yield of the lowcarbon alkyl alkene, but also increases the flexibility of the distribution of the cracked
product, changes the distribution of the reactants, and improves the selectivity of the
target product.
A. Zhang and C. Li
biomass from the culture water and drying it for subsequent oil collection. Relatively
low algal biomass concentrations and the small size of microalgae make separation
challenging and energy intensive. A meta-analysis of published studies shows that
more than 40% of the total energy required for biodiesel production can be attributed
to harvest and product collection [35].
Purity of the algal lipid is an important parameter for processing into liquid transportation fuel. Inorganic materials that stay with the oil are a concern, and the method
of harvest and collection can influence the impurity levels. Inorganic salts and phospholipids are two known impurities that could affect processing. Inorganic salts are
in the culture medium and occur naturally in algae, but they also can be introduced
as flocculants.
Evaluating the sustainability of algal cultivation systems for biofuel production
requires examining the various material and energy inputs needed for the cultivation systems to maintain scalable productivity, maximize system robustness, and
minimize costs. Scalable productivity refers to a cultivation system’s ability to maintain productivities with respect to algal biomass and algal product (mass/area-time
or mass/volume-time) from the laboratory scale to the commercial scale. System
robustness refers to a cultivation system’s ability to reliably and dependably deliver
consistent productivity and avoid system crashes or failures as a result of either biological or physicochemical causes. Costs pertain to capital and operating costs for a
cultivation system.
3.3 Hydrocarbon-Rich Fuel Produced by Pyrolysis
of Vegetable Oil
3.3.1 Reaction Mechanism of Catalytic Pyrolysis
Pyrolysis of oil refers to the process of breaking the chemical bond in triglycerides to
produce small molecule substances under almost oxygen-free and high-temperature
conditions. The molecular weight of animal and vegetable oil, which is generally
larger, can be decreased by pyrolysis that helps to reduce the viscosity of raw oil. The
pyrolysis of oil, known as a complicated process, includes molecular bond rupture,
molecular isomerization, and polymerization, and we can obtain the products in different distributions of molecular weight by altering pyrolytic temperature, pyrolysis
time, reaction atmosphere, and heating rate [36].
Catalytic cracking of oil refers to the high-temperature cracking of animal and
vegetable oils and waste oils to produce low-carbon alkanes, olefins, etc., after catalyst addition. The addition of the catalyst not only reduces the activation energy
of the cracking reaction, increases the reaction rate, increases the yield of the lowcarbon alkyl alkene, but also increases the flexibility of the distribution of the cracked
product, changes the distribution of the reactants, and improves the selectivity of the
target product.