and HCO 3
− /CO 3
2−
, and this would prevent strong acidification of water.
Overdosing CO 2 is not so dangerous as overdosing H 2 SO 4 ; sparkling water is
not dangerous at the end! Such technology, known since more than 30 years, is
now growing in interest and application as people gain environmental
awareness and are more conscious of the danger of storing and handling
concentrated sulphuric acid. Other advantages toward the use of classical acids
are use of less toxic reagents, less need of devices for monitoring, less
downtime, increased human safety, longer equipment life, etc.
iii. The water-well rehabilitation technique consists in injecting gaseous carbon
dioxide at the desired depth to produce an abrasive acid solution that penetrates
far into the surrounding formation. Liquefied carbon dioxide is then injected
under controlled conditions at various temperatures and pressures. When it
comes in contact with the water, it expands rapidly, producing violent agitation
and the freezing of water within the formation around the well, resulting in
superior disinfection and dislodging of mineral encrustation.
After treatment the well is mechanically cured using surge/airlift methods that
remove the newly dislodged particulate matter from the well. The well pump is
then reinstalled and the well returned to service.
iv. The desalination of seawater to produce soft water even usable for drinking,
especially in Israel and the Middle East, is more and more using CO 2 as curing
agent for the reasons discussed above. Today more than 80% of the desalination plants are located in the Gulf States, and the technology is strongly
expanding in Saudi Arabia. The estimated CO 2 consumption for this application is at the level of 33–50 g CO2 m
−3 of desalinated water.
8.3.10 Greenhouses
The use of CO 2 in greenhouses for increasing the CO 2 level to 600 ppm instead of
ca. 410 ppm stimulates the growth of some plants often up to 20%. This is true not
only for vegetables such as tomato, cucumber, lettuce and other greens, strawberry
but also for potted plants and cut flowers. This is popular in the Netherlands since
long time, where LINDE’s OCAP [14] has built a 85 km transport pipeline
(300 km total distribution network) which distributes over 450 kt y
−1 of CO 2 to
over 550 greenhouses. Such CO 2 originates from a Shell refinery and the AlcoBioFuel bioethanol plant, both located in the Rotterdam area [15]. In the US, such
application has recently started to grow (>50% in the last 10 years), pushed in the
last years by the safe conditions required to grow legally cannabis.
Growing microalgae in photobioreactors (see Chap. 11) represents a way to a
fast conversion of CO 2 . Each kg of algae demands ca. 2 kg of CO 2 . The economics
of such practice is viable if products for food (omega 3, proteins, specific nutrients),
pharmaceuticals, colors, and other similar sectors are targeted; it is not viable when
fuels alone are targeted. Such application, which mimics greenhouses, is expanding
as alternative to use of plants that demand arable land that in some areas is scarce.
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− /CO 3
2−
, and this would prevent strong acidification of water.
Overdosing CO 2 is not so dangerous as overdosing H 2 SO 4 ; sparkling water is
not dangerous at the end! Such technology, known since more than 30 years, is
now growing in interest and application as people gain environmental
awareness and are more conscious of the danger of storing and handling
concentrated sulphuric acid. Other advantages toward the use of classical acids
are use of less toxic reagents, less need of devices for monitoring, less
downtime, increased human safety, longer equipment life, etc.
iii. The water-well rehabilitation technique consists in injecting gaseous carbon
dioxide at the desired depth to produce an abrasive acid solution that penetrates
far into the surrounding formation. Liquefied carbon dioxide is then injected
under controlled conditions at various temperatures and pressures. When it
comes in contact with the water, it expands rapidly, producing violent agitation
and the freezing of water within the formation around the well, resulting in
superior disinfection and dislodging of mineral encrustation.
After treatment the well is mechanically cured using surge/airlift methods that
remove the newly dislodged particulate matter from the well. The well pump is
then reinstalled and the well returned to service.
iv. The desalination of seawater to produce soft water even usable for drinking,
especially in Israel and the Middle East, is more and more using CO 2 as curing
agent for the reasons discussed above. Today more than 80% of the desalination plants are located in the Gulf States, and the technology is strongly
expanding in Saudi Arabia. The estimated CO 2 consumption for this application is at the level of 33–50 g CO2 m
−3 of desalinated water.
8.3.10 Greenhouses
The use of CO 2 in greenhouses for increasing the CO 2 level to 600 ppm instead of
ca. 410 ppm stimulates the growth of some plants often up to 20%. This is true not
only for vegetables such as tomato, cucumber, lettuce and other greens, strawberry
but also for potted plants and cut flowers. This is popular in the Netherlands since
long time, where LINDE’s OCAP [14] has built a 85 km transport pipeline
(300 km total distribution network) which distributes over 450 kt y
−1 of CO 2 to
over 550 greenhouses. Such CO 2 originates from a Shell refinery and the AlcoBioFuel bioethanol plant, both located in the Rotterdam area [15]. In the US, such
application has recently started to grow (>50% in the last 10 years), pushed in the
last years by the safe conditions required to grow legally cannabis.
Growing microalgae in photobioreactors (see Chap. 11) represents a way to a
fast conversion of CO 2 . Each kg of algae demands ca. 2 kg of CO 2 . The economics
of such practice is viable if products for food (omega 3, proteins, specific nutrients),
pharmaceuticals, colors, and other similar sectors are targeted; it is not viable when
fuels alone are targeted. Such application, which mimics greenhouses, is expanding
as alternative to use of plants that demand arable land that in some areas is scarce.
134
8 Use of CO 2 as Technical Fluid (Technological Uses of CO 2 )