means (such as flotation processes as elaborated upon in the patents US7022509B2
and US6000551), pulsed electric field (US20110107655A1 and US20040224397),
electromagnetic radiation (US2009087900A1 and WO2009142765A2), pulsing
ultrasonic waves (US20120125763, US8043496B1, and US20100151540A1), or
even through genetic manipulation (autolysis as elaborated upon in the patent
US20170022436A1 and US20160130627). In addition, the procedure may use at
least one enzymatic (such as a cellulose, protease or glycoproteinase) or physicochemical treatments to disrupt the cells (WO2010039030A1 and
US20120238732A1), followed by repetitive steps to separate different cell compounds which finally leads to extract the oil. No-solvent cell lysis or single step
extraction protocol is always promising since the extracted oil can be released from
wet microalgae, directly entering the subsequent steps. More information on this
methodology can be found in the patents US20120040428A1, US20160265011,
and US20110107655A1.
Compared with conventional and mechanical means of oil extraction, in which
cells into should be transformed into dried granules and different solvents are used,
alternative methods have been developed with an aim to further save time and
financial resources (see the patents US2012065416 and US2011225878). For
example, FAs can be simultaneously extracted and saponified from dry biomass
using ethanol and hydroxide sodium in an argon atmosphere at 75–90 °C
(ES2289898A1). Even wet microalgae biomass can be extracted directly
(US2009227678A1 and US5928696A). A US patent publication 2014/0113363
entitled “process of producing oil from algae using biological rupturing” introduced
an oil extraction bioreactor operatively connected to algae growth reservoirs. In this
system, for biologically rupturing algal oil vesicles, a structured enzyme system
such as a cellulosome was claimed. Different patents, i.e., US8450111B2 and
US20110076748A1, claimed that utilizing a single hydrophilic ionic liquid was
effective for a one-step process for the lysis of microalgae cell walls and separation
of the lipids contained for use in biodiesel production.
Overall, diverse strategies have been put forth claiming success in oil extraction
from diverse set of dried and/or wet algal materials. To draw a distinction, patents
US20130210093 and WO2010039030A1 made a comparison among the methods
described in the other patents, from routine solvent extraction to supercritical fluid
extraction and a modified Bligh and Dyer method. The findings reported showed
that more long-chain omega-3 FAs could be obtained using a solvent miscible with
water in comparison with the supercritical fluids extraction and hexane extractions.
4 Conclusions
In this chapter, patents published since 70s on biofuels production from microalgae
were reviewed and discussed in order to shed light on the state of the art of algal
fuel production. Overall, a significant number of patents could be found on various
aspects of biofuels production from microalgae with a sensible increase in their
304
A. F. Talebi et al.
and US6000551), pulsed electric field (US20110107655A1 and US20040224397),
electromagnetic radiation (US2009087900A1 and WO2009142765A2), pulsing
ultrasonic waves (US20120125763, US8043496B1, and US20100151540A1), or
even through genetic manipulation (autolysis as elaborated upon in the patent
US20170022436A1 and US20160130627). In addition, the procedure may use at
least one enzymatic (such as a cellulose, protease or glycoproteinase) or physicochemical treatments to disrupt the cells (WO2010039030A1 and
US20120238732A1), followed by repetitive steps to separate different cell compounds which finally leads to extract the oil. No-solvent cell lysis or single step
extraction protocol is always promising since the extracted oil can be released from
wet microalgae, directly entering the subsequent steps. More information on this
methodology can be found in the patents US20120040428A1, US20160265011,
and US20110107655A1.
Compared with conventional and mechanical means of oil extraction, in which
cells into should be transformed into dried granules and different solvents are used,
alternative methods have been developed with an aim to further save time and
financial resources (see the patents US2012065416 and US2011225878). For
example, FAs can be simultaneously extracted and saponified from dry biomass
using ethanol and hydroxide sodium in an argon atmosphere at 75–90 °C
(ES2289898A1). Even wet microalgae biomass can be extracted directly
(US2009227678A1 and US5928696A). A US patent publication 2014/0113363
entitled “process of producing oil from algae using biological rupturing” introduced
an oil extraction bioreactor operatively connected to algae growth reservoirs. In this
system, for biologically rupturing algal oil vesicles, a structured enzyme system
such as a cellulosome was claimed. Different patents, i.e., US8450111B2 and
US20110076748A1, claimed that utilizing a single hydrophilic ionic liquid was
effective for a one-step process for the lysis of microalgae cell walls and separation
of the lipids contained for use in biodiesel production.
Overall, diverse strategies have been put forth claiming success in oil extraction
from diverse set of dried and/or wet algal materials. To draw a distinction, patents
US20130210093 and WO2010039030A1 made a comparison among the methods
described in the other patents, from routine solvent extraction to supercritical fluid
extraction and a modified Bligh and Dyer method. The findings reported showed
that more long-chain omega-3 FAs could be obtained using a solvent miscible with
water in comparison with the supercritical fluids extraction and hexane extractions.
4 Conclusions
In this chapter, patents published since 70s on biofuels production from microalgae
were reviewed and discussed in order to shed light on the state of the art of algal
fuel production. Overall, a significant number of patents could be found on various
aspects of biofuels production from microalgae with a sensible increase in their
304
A. F. Talebi et al.