1 Introduction
The World Meteorological Organization confirmed that 2016 was the hottest year
on Earth; the global temperature rise is almost 1.1 °C higher than the value in the
pre-industrial period (World Meteorological Organization 2017). In 2016, 195
countries ratified the Paris climate agreement including a commitment to keep the
global warming below 2 °C before 2100. The global climate change is the result of
a rise in Earth’s temperature due to the presence of greenhouse gases from human
activities. The limited availability of fossil resources, such as petroleum, and the
strong dependence on the production of fuels and other chemicals provoke environmental, social, political, and economic concerns. Similar to the oil refinery,
where the crude oil is processed and refined into different products of high and low
values (liquefied petroleum gas, gasoline, naphtha for olefins and aromatics, kerosene, heating fuel, diesel, heavy fuel oil, and bitumen), the biorefinery is one of the
most promising alternatives to obtain biofuels and chemicals from renewable
sources (Chew et al. 2017). Biorefinery involves transformation of raw materials
obtained from agriculture, silviculture, organic wastes, or any biomass through
various unit processes to convert them in a wide range of products (Postma et al.
2016). Some definitions of biorefinery include the one provided by the National
Renewable Energy Laboratory (NREL) “A biorefinery is a facility that integrates
biomass conversion processes and equipment to produce fuels, power and (organic)
chemicals from biomass” and by the International Energy Agency (IEA) “A
biorefinery is the suitable processing of biomass into a spectrum of marketable
products (food, feed, materials, and chemicals) and energy (fuels, power, heat)” (de
Jong et al. 2012; Budzianowski 2017). Biorefineries are classified according to the
biomass feedstock generation (Saai-Anuggraha et al. 2016; Hossain et al. 2017):
The first-generation biorefineries use sugarcane, corn, or soybeans to produce
value-added products for feed, food applications, fuels, and specialty chemicals.
Almost all current biofuels (mainly ethanol, butanol, and biodiesel) and bio-based
chemicals (lactic acid, itaconic acid, 1,3-propanediol, etc.) are produced in this type
of biorefinery. The second-generation biorefineries are based on lignocellulosic
materials, and they are composed of three main sections to convert lignocellulose
into biofuels. The main product is the cellulosic ethanol; however, the biomass
conversion by thermochemical platform involves the gasification of biomass to
produce syngas (CO, CO 2 , H 2 , and CH 4 ), which can then be converted into various
chemicals, such as ethanol, methanol, and butanol. The most advanced is the
third-generation biorefinery that can use a mixture of biomass to produce a multitude of products using a combination of technologies. Microalgae biomass is
considered as the most promising feedstock for the third-generation biorefineries.
The microalgae might contribute to reduce the oil dependency and the rise in
Earth’s temperature. They have the ability to transform solar energy into chemicals
by capturing CO 2 and releasing O 2 . It is known that microalgae are one of the best
technologies for carbon dioxide sequestration (Wiesberg et al. 2017) and their use
as renewable energy source was long ago proposed by scientists. The patents and
90
P.-L. Gorry et al.
The World Meteorological Organization confirmed that 2016 was the hottest year
on Earth; the global temperature rise is almost 1.1 °C higher than the value in the
pre-industrial period (World Meteorological Organization 2017). In 2016, 195
countries ratified the Paris climate agreement including a commitment to keep the
global warming below 2 °C before 2100. The global climate change is the result of
a rise in Earth’s temperature due to the presence of greenhouse gases from human
activities. The limited availability of fossil resources, such as petroleum, and the
strong dependence on the production of fuels and other chemicals provoke environmental, social, political, and economic concerns. Similar to the oil refinery,
where the crude oil is processed and refined into different products of high and low
values (liquefied petroleum gas, gasoline, naphtha for olefins and aromatics, kerosene, heating fuel, diesel, heavy fuel oil, and bitumen), the biorefinery is one of the
most promising alternatives to obtain biofuels and chemicals from renewable
sources (Chew et al. 2017). Biorefinery involves transformation of raw materials
obtained from agriculture, silviculture, organic wastes, or any biomass through
various unit processes to convert them in a wide range of products (Postma et al.
2016). Some definitions of biorefinery include the one provided by the National
Renewable Energy Laboratory (NREL) “A biorefinery is a facility that integrates
biomass conversion processes and equipment to produce fuels, power and (organic)
chemicals from biomass” and by the International Energy Agency (IEA) “A
biorefinery is the suitable processing of biomass into a spectrum of marketable
products (food, feed, materials, and chemicals) and energy (fuels, power, heat)” (de
Jong et al. 2012; Budzianowski 2017). Biorefineries are classified according to the
biomass feedstock generation (Saai-Anuggraha et al. 2016; Hossain et al. 2017):
The first-generation biorefineries use sugarcane, corn, or soybeans to produce
value-added products for feed, food applications, fuels, and specialty chemicals.
Almost all current biofuels (mainly ethanol, butanol, and biodiesel) and bio-based
chemicals (lactic acid, itaconic acid, 1,3-propanediol, etc.) are produced in this type
of biorefinery. The second-generation biorefineries are based on lignocellulosic
materials, and they are composed of three main sections to convert lignocellulose
into biofuels. The main product is the cellulosic ethanol; however, the biomass
conversion by thermochemical platform involves the gasification of biomass to
produce syngas (CO, CO 2 , H 2 , and CH 4 ), which can then be converted into various
chemicals, such as ethanol, methanol, and butanol. The most advanced is the
third-generation biorefinery that can use a mixture of biomass to produce a multitude of products using a combination of technologies. Microalgae biomass is
considered as the most promising feedstock for the third-generation biorefineries.
The microalgae might contribute to reduce the oil dependency and the rise in
Earth’s temperature. They have the ability to transform solar energy into chemicals
by capturing CO 2 and releasing O 2 . It is known that microalgae are one of the best
technologies for carbon dioxide sequestration (Wiesberg et al. 2017) and their use
as renewable energy source was long ago proposed by scientists. The patents and
90
P.-L. Gorry et al.