decouple GHG emissions from economic growth
in recent years (1990–2017) and decrease the
emissions of 22% while increasing GDP by 58%
[18]. However, there is still much work to be done
to stabilize atmospheric CO 2 levels. There are
several natural mechanisms of CO 2 fixation,
such as ocean fertilization or geological injection
(creation of carbonates). Reforestation of land and
desert greening are the next natural processes for
CO 2 removal from the atmosphere. Further, photosynthesis can be used in photo-bioreactor systems in which cyanobacteria or micro-algae can
transform CO 2 into useful products such as carbohydrates and oxygen [108]. This section however will focus on industrial technologies for
atmospheric CO 2 removal.
The major cost in CCS technologies comes
from CO 2 capture. This can increase the cost of
electricity production by up to 50% depending on
techniques used in the process. Hence, there is a
strong drive to improve the methods of carbon
capture to make it more cost-effective. The current
methods used in CCS include absorption, adsorption, membranes, and biotechnology [108]. Amines
have been used as sorbents in the natural gas industry for 60 years. The method is well studied and has
an efficient recovery rate from the flue gas (up to
98%). Nonetheless the absorption process can be
further improved in the areas of energy efficiency
and stability of the sorbent. In short, the process is
based on the injection of an amine solution such as
monoethanolamine (MEA) into the flue gas. There,
CO 2 is absorbed by the solution and creates MEA
carbamate. Next, the CO 2 product of the absorption
reaction is reheated to release almost pure CO 2 ; the
MEA solution is recycled and reused later. The
main disadvantages of MEA absorption are inefficient solvent regeneration (70% of operating cost),
rapid equipment corrosion, amine degradation, and
high energy consumption [108, 109].
The use of membranes for CO 2 capture has
encountered several problems which must be
addressed before the technology can become the
method of choice. Polymeric membranes are not
resistant to heat or chemicals; therefore, the flue
gas must be cooled and the chemicals removed
prior membrane separation, which induces extra
costs [108, 109]. Furthermore, the choice between
the two critical attributes of membranes, selectivity and permeability, has to be made, and one of
the parameters will be sacrificed to the other
[108]. However, recent research provides proof
that advances in membrane materials can significantly improve separation performance and make
membrane technology competitive with other
CCS technologies [110]. Various types of adsorbents can also be used for CO 2 capture. This
mainly includes activated carbon and lithium
compounds. Their efficiency is based on CO 2
capture capacity and their stability [108].
Apart from CO 2 being stored, it is also valuable
as a commodity. Flue gas has traditionally been an
important source of CO 2 , especially in remote locations lacking CO 2 by-product sources. CO 2 is
widely used in industry, food and beverage production, firefighting, solvent extraction in chemical
labs, and supercritical fluid chromatography.
Another industrial application of CO 2 is in enhanced
oil recovery (EOR), where CO 2 is used to force oil
from beneath the Earth. EOR relies heavily on cheap
CO 2 sources. Therefore, the viability of CSS
depends on CO 2 market and oil prices [109, 111].
Bioscrubbers
Livestock is a growing contributor to ammonia,
VOC, and H 2 S emissions and can influence O 3
and SOA formation. Bioscrubbers are a novel and
innovative technology that could seem like a perfect solution for livestock emissions removal. The
technology is based on the separation of VOCs
into the aqueous phase and subsequent biological
treatment of the water in two-unit operations. The
waste is firstly cleaned in an absorber, and the
pollutant gases are transferred from gas to aqueous phase. The water containing the dissolved
pollutants continues to biological treatment in a
bioreactor [104, 112].
The bioreactor is a tank, aerated with air bubbles and containing suspended activated sludge.
Microbial biodegradation takes place in a nutrient
solution in the aqueous phase. Furthermore, pH is
controlled to optimize biological activity. In addition to VOC, aerosols are absorbed into the water
phase. pH control is important in order to trap
H 2 S, SO 2 , and other highly water-soluble
compounds [112].
Industrial Emissions Control Technologies: Introduction
501
in recent years (1990–2017) and decrease the
emissions of 22% while increasing GDP by 58%
[18]. However, there is still much work to be done
to stabilize atmospheric CO 2 levels. There are
several natural mechanisms of CO 2 fixation,
such as ocean fertilization or geological injection
(creation of carbonates). Reforestation of land and
desert greening are the next natural processes for
CO 2 removal from the atmosphere. Further, photosynthesis can be used in photo-bioreactor systems in which cyanobacteria or micro-algae can
transform CO 2 into useful products such as carbohydrates and oxygen [108]. This section however will focus on industrial technologies for
atmospheric CO 2 removal.
The major cost in CCS technologies comes
from CO 2 capture. This can increase the cost of
electricity production by up to 50% depending on
techniques used in the process. Hence, there is a
strong drive to improve the methods of carbon
capture to make it more cost-effective. The current
methods used in CCS include absorption, adsorption, membranes, and biotechnology [108]. Amines
have been used as sorbents in the natural gas industry for 60 years. The method is well studied and has
an efficient recovery rate from the flue gas (up to
98%). Nonetheless the absorption process can be
further improved in the areas of energy efficiency
and stability of the sorbent. In short, the process is
based on the injection of an amine solution such as
monoethanolamine (MEA) into the flue gas. There,
CO 2 is absorbed by the solution and creates MEA
carbamate. Next, the CO 2 product of the absorption
reaction is reheated to release almost pure CO 2 ; the
MEA solution is recycled and reused later. The
main disadvantages of MEA absorption are inefficient solvent regeneration (70% of operating cost),
rapid equipment corrosion, amine degradation, and
high energy consumption [108, 109].
The use of membranes for CO 2 capture has
encountered several problems which must be
addressed before the technology can become the
method of choice. Polymeric membranes are not
resistant to heat or chemicals; therefore, the flue
gas must be cooled and the chemicals removed
prior membrane separation, which induces extra
costs [108, 109]. Furthermore, the choice between
the two critical attributes of membranes, selectivity and permeability, has to be made, and one of
the parameters will be sacrificed to the other
[108]. However, recent research provides proof
that advances in membrane materials can significantly improve separation performance and make
membrane technology competitive with other
CCS technologies [110]. Various types of adsorbents can also be used for CO 2 capture. This
mainly includes activated carbon and lithium
compounds. Their efficiency is based on CO 2
capture capacity and their stability [108].
Apart from CO 2 being stored, it is also valuable
as a commodity. Flue gas has traditionally been an
important source of CO 2 , especially in remote locations lacking CO 2 by-product sources. CO 2 is
widely used in industry, food and beverage production, firefighting, solvent extraction in chemical
labs, and supercritical fluid chromatography.
Another industrial application of CO 2 is in enhanced
oil recovery (EOR), where CO 2 is used to force oil
from beneath the Earth. EOR relies heavily on cheap
CO 2 sources. Therefore, the viability of CSS
depends on CO 2 market and oil prices [109, 111].
Bioscrubbers
Livestock is a growing contributor to ammonia,
VOC, and H 2 S emissions and can influence O 3
and SOA formation. Bioscrubbers are a novel and
innovative technology that could seem like a perfect solution for livestock emissions removal. The
technology is based on the separation of VOCs
into the aqueous phase and subsequent biological
treatment of the water in two-unit operations. The
waste is firstly cleaned in an absorber, and the
pollutant gases are transferred from gas to aqueous phase. The water containing the dissolved
pollutants continues to biological treatment in a
bioreactor [104, 112].
The bioreactor is a tank, aerated with air bubbles and containing suspended activated sludge.
Microbial biodegradation takes place in a nutrient
solution in the aqueous phase. Furthermore, pH is
controlled to optimize biological activity. In addition to VOC, aerosols are absorbed into the water
phase. pH control is important in order to trap
H 2 S, SO 2 , and other highly water-soluble
compounds [112].
Industrial Emissions Control Technologies: Introduction
501